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Bioremediation of Petroleum Hydrocarbon-Contaminated Soil by Composting In Biopiles
Abstract
Composting of contaminated soil in biopiles is an ex situ technology, where organic matter such as bark chips are added to contaminated soil as a bulking agent. Composting of lubricating oil-contaminated soil was performed in field scale ( [Formula: see text] m(3)) using bark chips as the bulking agent, and two commercially available mixed microbial inocula as well as the effect of the level of added nutrients (N,P,K) were tested. Composting of diesel oil-contaminated soil was also performed at one level of nutrient addition and with no inoculum. The mineral oil degradation rate was most rapid during the first months, and it followed a typical first order degradation curve. During 5 months, composting of the mineral oil decreased in all piles with lubrication oil from approximately 2400 to 700 mg (kg dry w)(-1), which was about 70% of the mineral oil content. Correspondingly, the mineral oil content in the pile with diesel oil-contaminated soil decreased with 71% from 700 to 200 mg (kg dry w)(-1). In this type of treatment with addition of a large amount of organic matter, the general microbial activity as measured by soil respiration was enhanced and no particular effect of added inocula was observed.
... Biopiling Biopiling (biocells, bioheaps or biomounds) is a remediation technology in which contaminated soil is excavated; treated with bulking agents such as straw, saw dust, etc., nutrients and water; and piled in a heap for biodegradation. Mixing may be done though aeration pipe or special mixing devices (Jorgensen et al. 2000;Li et al. 2004). Biopiling of lubricating oil-contaminated soil with bark chips and nutrients degrades about 70% of the mineral oil within 5 months (Jorgensen et al. 2000). ...
... Mixing may be done though aeration pipe or special mixing devices (Jorgensen et al. 2000;Li et al. 2004). Biopiling of lubricating oil-contaminated soil with bark chips and nutrients degrades about 70% of the mineral oil within 5 months (Jorgensen et al. 2000). Biopiling of diesel-contaminated soils achieve 70% decontamination in 40 days and reached 85% in 76 days (Chemlal et al. 2012(Chemlal et al. , 2013. ...
... Biopiling method is also effective to remediate diesel oil contaminated soil in the sub-Antarctic region (Delille et al. 2008). Optimization of C/N/P ratio, pH, adequate moisture and optimum temperature in biopiling is necessary to improve efficiency of microbial hydrocarbon metabolism (Jorgensen et al. 2000;Siles and Margesin 2018;Zhang et al. 2021). ...
Soil pollution arising from either inorganic or organic sources causes undesirable change in the physical, chemical and biological characteristics of the soil and affects the environment as well as plant and human life through the food chain. Major inorganic contaminants include heavy metals, radionuclides, nanoparticles and asbestos, whereas organic contaminants are carbon-based molecules such as antibiotics, pesticides, radionuclides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), halogenated organics and volatile organic compounds, by-products from mining and petroleum industries, etc. Many of these foreign substances are highly persistent and accumulate in the soil, thereby posing severe threat to agricultural productivity and soil sustainability. As healthy and fertile soil are pertinent to healthy crop production in drylands, removal of these pollutants through various remediation measures that reduce their toxicity and restore soil to its original functional capacity is gaining considerable attention in recent years. This chapter elucidates the different forms of soil pollutants and their major sources, their adverse effect on crop morphology and physiological processes. It also discusses various in situ and ex situ remediation methods that have been developed over the past few decades. These remediation technologies employ physical, chemical, electrical, thermal and biological methods to clean up polluted sites. Strategies include containment, transformation and/or transport based. Choice of any remediation method depends on the nature, origin and magnitude of contamination; effectiveness, efficiency and cost of the technology; and topography, soil structure and physicochemical properties of the polluted site. A combination of two or more remediation approaches may also be employed to improve the efficiency of remediation. Even though many remediation technologies are available at present, owing to the cost and time involved, it is of paramount importance to prevent soil pollution.
... The vigorous microbial movement debases the oilbased constituents adsorbed to soil particles, subsequently lessening the groupings of these foreign substances. Soils laden with petroleum hydrocarbons, Polycyclic Aromatic Hydrocarbons (PAH), chlorophenols, and nitroaromatics have been remediated successfully utilizing procedures such as aeration, turning, amendment of inert material, and biostimulation [30]. ...
... Biopile combined with phytoremediation on industrial soil such as sandy loam contaminated by petroleum hydrocarbon was found to save cost but takes a longer time for remediation [34,35]. Various limitations in composting can be overcome by combining with biopile process on mineral oil and diesel oil-contaminated soil which produced some satisfactory results in the degradation process of contaminants [30,36]. Landfarming technique is a costly method for bioremediation but when combined with other bioremediation techniques causes a significant increase in removal efficiency and reduces the overall effective cost [37] This review paper summarizes the different treatment mechanisms prevailing in a soil-biopile system along with the various factors influencing the degradation process of different contaminants. ...
... Composting with biopiling of oil-contaminated soil with the addition of bulking agent (bark chips) along with nutrients (nitrogen, phosphorus, potassium) causes an increase in organic matter and enhancement of microbial activities. It has been found out that contaminated soil removal efficiency touched 70% in a period of five months [30]. ...
Biopile treatment is a controlled organic cycle where biodegradable foreign substances are changed over to their fundamental mineral constituents (water and carbon dioxide) under oxygen-consuming conditions. The contaminated soil is excavated and accumulated in the treatment region. This uncovered soil is then framed into a pile which is termed as biopile, and the air is circulated through to advance biodegradation which is usually accomplished by native microorganisms. The debasement efficiency is enhanced by controlling parameters such as dampness content, pH, air circulation, temperature, and carbon-to-nitrogen proportion. This method is most effective in hydrocarbon-rich contaminant soils. Furthermore, the vigorous microbial movement debases the oil-based constituents adsorbed to soil particles, thereby subsequently reducing the groupings of these foreign substances. Target toxins, like gas, stream fuel, diesel fuel, and other petrol-derived items are taken out from the dirt by biodegradation and volatilization in the biopile. In this review, a thorough discussion is made on the different types of soils subjected to biopile treatment and the influence of several factors such as oxygen content, moisture content, pH, temperature, and nutrients on the efficiency of the biopile remediation technique. A comprehensive comparison is also drawn between the several types of bioremediation techniques such as landfarming, bioventing, phytoremediation, and composting to name a few. The cost-effectiveness of biopile treatment over other existing bioremediation techniques is also addressed.
... Biochar type with a lower level of contamination ( Jørgensen et al., 2000;Sayara et al., 2010;Wu et al., 2013;Zappi et al., 1996). It happens so, as microbes prefer abundantly present degradable nutrients instead of PAHs present at low concentrations. ...
... A drawback of composting approach is the risk of significantly incomplete remediation of organic contaminants, thereby ending up with a larger contaminated pile of compost! Usually, around two-third of an organic 55 Complementing compost with biochar contaminant can be degraded rapidly (2 months) in a composting system; the residual (and aged) contaminants may degrade very slowly ( Jørgensen et al., 2000) due to being inherently recalcitrant or locked up in soil/organic particle pores (Huesemann, 1997). Therefore, as a strategy, contaminated soil must not be added to a composting pile in excess to avoid residual PAH at a toxic level. ...
We are racing to manage a phenomenally increasing volume of organic wastes from urban, industrial and agricultural entities. Composting is one of the preferred ways to convert biodegradable wastes into nutrient-rich soil conditioners. The
age-old technique of composting process is being improved with innovative scientific means. Biochar, a widely studied soil amendment, is a carbonaceous material that can hold nutrients from endogenic/exogenic sources. Biochar-compost, a biochar complemented compost, may provide a wide range of benefits expected from both materials. Compost and biochar can improve physicochemical and microbiological attributes of soils by supplying labile and stable carbons, and nutrients. Compost
may also supply beneficial microbes. This means biochar-compost is a synergic soil amendment that can improve soil quality, increase crop production, and remediate contaminated soils. Having stable carbon, large reactive surface with nutrient loads,
biochar can interact widely with organic biomass and modify physicochemical and-microbial states during a composting process while making biochar-compost. Production and application methods of biochar, compost and biochar-compost are covered for agricultural and contaminated soils. Metal and organic contaminations are also discussed. A case study on making and field-testing a mineral-enhanced biochar and a biochar-compost to improve rice yield, is presented at the end.
... Improvement of basic soil parameters including nutrients by spent mushroom substrate from hydrocarbon contaminated soils has been reported. Accordingly spent mushroom substrate; a composted organic material remaining, after a mushroom crop has been harvested improve the soil physico-chemical parameters [11] and reduce total petroleum hydrocarbon [12]. This substrate is highly rich in essential nutrients such as nitrogen, phosphorus and also contains micronutrients such as iron, manganese, copper and zinc in very low average between 0.01 and 0.2. ...
... These observed improvements agree with the report that spent mushroom substrate as organic waste causes rapid improvement of soil physic-chemical parameters [11]. ...
The remediation potentials of spent mushroom substrate (Pleurotus astreatus) (Oyster mushroom) was investigated on soils contaminated with spent automobile lubricant at University of Port Harcourt farm (Dec-Feb. 2015) to determine the available nutrients and concentration of total hydrocarbon content. Sixteen sub-plots were contaminated with 2-L and 4-L of spent automobile lubricant, and 4 sub-plots without any contamination (control). Eight of the contaminated plots; were treated (remediated) with 1.7kg of spent mushroom substrate, 14 days post-contamination. Soil samples were collected at 10cm depth from each habitat 14 days post-remediation and taken to the laboratory for analysis of organic nitrogen using calorimetric measurement by Brucine method, organic carbon by rapid titrimetric method. Total hydrocarbon content (THC) was measured by spectrophotometer and available phosphorus by the Bray's P method and potassium by Flame Atomic Absorption Spectrophotometer. Soil edaphic factors were also determined. Results obtained indicate that soil pH was 5.4 (2-L impacted), 6.11 (2-L remediated) habitat-types, and 6.06(control). Concentration of nitrogen was 0.089%, 0.16%, 0.15% in the impacted, remediated and control sites. Phosphorus and Potassium was 23.3mg/kg; 33.3mg/kg (impacted), 7.20mg/kg; 10.04mg/kg (remediated) and 46.2mg/kg; 12.0mg/kg (control) sites. Total hydrocarbon concentration (THC) was 3.9mg/kg (control), 12.1mg/kg (2-L impacted) and 4.8mg/kg (2-L amended) habitat-types. There was a significant difference in nutrient composition between the remediated and impacted habitat-types.
... The addition of organic waste is essential to promote the development of a diverse microbial community capable of breaking down complex contaminants (Aitken et al., 1992;Jorgensen et al., 2000;Ma et al., 2016). A case study on Mushroom compost-assisted remediation of soil contaminated with PAHs from a manufactured gas plant was conducted in a thermally insulated composting chamber. ...
... Most authors note the high efficiency of biopreparations for purification of oilcontaminated soils in different climatic conditions [10,11]. In addition, there are theoretical objections to bioaugmentation in the literature, associated with the risk of disturbing the ecological situation in the soil introducing an alien microbial biomass [12][13][14][15]. This is especially important for agricultural soils. ...
Remediation of agricultural soils subjected to accidental pollution by oil and oil products is an important economic and environmental problem. Bioaugmentation and biostimulation are the main strategies widely used in world practice for the purification of oil-contaminated soils. The effectiveness of bioremediation methods depends on their environmental safety. We studied the effectiveness of bioremediation of oil-contaminated agricultural soddy-podzolic soils in long-term field experiments. The initial content of oil products in soil was over 50.000 mg kg−1. Different methods of bioremediation were applied: introduction of mineral fertilizers, lime, sowing of grasses, various biopreparations. The effectiveness of the methods of remediation was evaluated using chemical, microbiological, biological and other indicators. Diagnostic parameters were the aboveground plant biomass, the biological activity of soils, determined by the production of CO2, and the rate of mineralization of oil products in the soil. These indicators made it possible to compare the effectiveness of remediation and to reveal the fundamentally different effects of used biopreparations. It is established that the joint use of agrochemical and biological methods is most effective if the biopreparation is selected correctly. The greater efficiency of a single application of biopreparations in comparison with self-purification processes can be noticeable for three years.KeywordsOil pollution of soilsBioremediationSelf-purificationSoil healthGrass aboveground biomassMineralization of oil productsSoil respiration
... In biopiles, several organic pollutants have been effectively Bioremediation. This method has been shown to work in field experimental or full-scale applications, particularly for petroleum hydrocarbons (Jørgensen et al. 2000). ...
Industrial waste is an umbrella term that encompasses all undesirable by-products arising from manufacturing processes or derived from industrial operations. It comprises an array of solid, liquid, or gaseous wastes produced due to industrial activities which can be hazardous or non-hazardous and are modulated by distinct bodies of law and regulation. Environmental Protection Agency (EPA) controls all forms of waste at the federal level, providing guidelines for abidance and enforcing a sturdy fine for violation of the same. In recent times, considering the stringency in regulations and environmental concerns, industrial waste disposal and remediation adopt sustainably efficient solutions to reduce the toxicological effects and volume of the waste generated. Consequently, the high workload on the industrial sector is the high production of industrial effluents. Unfortunately, the primary objective of traditional treatment methods was to minimize the volume of industrial waste at a cheaper rate without considering sustainable alternatives and detrimental impacts on the environment. Understanding and establishing an equilibrium between cost-effectiveness and efficiency is the key to undertaking an adequate treatment method for industrial by-products. Environmental responsibility and stewardship are crucial for the sustainable protection of the planet against global trash without slowing down business. This chapter will discuss the various conventional methodologies adapted to treat waste from industries and industrial sectors.KeywordsWasteWastewaterIndustrial wastewaterBioremediationWastewater treatment
... In biopiles, several organic pollutants have been effectively Bioremediation. This method has been shown to work in field experimental or full-scale applications, particularly for petroleum hydrocarbons (Jørgensen et al. 2000). ...
Anthropogenic activity and the gradual enhancement in environmental contamination have been notably and recently developed. Bioremediation is a revolutionary innovation that can be used with existing physical and chemical treatment methods to handle various environmental contaminants, including using organisms to remove or neutralize pollutants. It provides the benefit of cleaning contaminated places utilizing natural processes and is less expensive since it does not require as much equipment, workforce, or energy as other cleanup procedures. The current chapter discusses various bioremediation types, techniques, and microorganisms.KeywordsBioremediationMicroorganismsMethods
EnvironmentEco-friendly
... In biopiles, several organic pollutants have been effectively Bioremediation. This method has been shown to work in field experimental or full-scale applications, particularly for petroleum hydrocarbons (Jørgensen et al. 2000). ...
... The existence of kerosene in the soil reduces the number of available forms of phosphorus. (Okolo et al., 2005;Jørgensen et al., 2000;Devatha et al., 2019). According to the result of the granulomeres analysis of the soil in the root layer, they fluctuate within the medium loamy. ...
Studies of the influence of hydrocarbon rocket fuel kerosene T-1 on the physical and geochemical properties were carried out in laboratory circumstances on different types of soils: brown semi-desert soil designated as zone (U-25) located in Central Kazakhstan, mountainous brown desert soil zone (U-30) located in East Kazakhstan, and a model soil standard (control soil). The soil was treated with various concentrations (0.002–150.0 g/kg) of hydrocarbon rocket fuel kerosene T-1, while the contact time was 3, 10, and 30 days. Pollution with kerosene T-1 in concentrations 5.0–15.0 g/kg affects the hydraulic characteristics of soils from the U-25 zone, and the filtration rate decreases by 4–5 times. For the mountainous brown desert soil from the U-30 zone, the concentration of kerosene up to 15.0 g/kg does not affect the mechanical composition of the soil, as well as the availability of the main nutrients (potassium, phosphorus, nitrogen). According to the mechanical composition, both soils belong to medium loamy soils. It has been established that when soil is contaminated from the U-25 zone in concentrations 15.0–150.0 g/kg, the fraction from 1.0 to 0.05 mm increases by 4–5%, and the silty and clay fractions in the soil decrease.
... We observed a 40%-69% decrease in 60 days with an initial concentration of 22,897 mg kg −1 . A 58%-66% decrease in hydrocarbon content was observed by Jørgensen et al. (2000) within 35 days with an initial oil concentration of 2.4 g kg −1 . ...
A greenhouse experiment was conducted to assess the effect of phytoremediation and biochar application on hydrocarbon degradation in crude oil–contaminated soils. The experiment consisted of four levels of biochar application (0, 5, 10, and 15 t/ha) and the presence or absence of Vigna unguiculata (cowpea; +C, −C) replicated thrice and arranged in a 4 × 2 × 3 factorial completely randomized design. Samples were taken on days 0, 30, and 60 for total petroleum hydrocarbon (TPH) analysis. A significantly higher TPH degradation efficiency of 69.2% (7033 mg/kg) was observed in contaminated soils amended with 15 t/ha biochar only after 60 days of incubation. Highly significant interactions were observed between biochar × plant (p < 0.001) and biochar × days (p = 0.0073). Biochar also improved the growth of plants in contaminated soils, with the highest height of 23.50 cm and stem girth of 2.10 cm obtained when plants were amended with 15 t/ha biochar at 6 weeks after planting. The potential of biochar to increase the degradation efficiency of hydrocarbons should be explored in the long run for the cleanup of crude oil–contaminated soils.
... Sludges that have accumulated in oil storage tanks as a result of oil-water separators, drilling operations, or dissolved air floatation units are also treated using this method [119][120][121][122]. In the beginning of seventies, oil industries in the US started to use landfarming to treat oil waste by combining them with soil to stimulate mineral oil biodegradation [123][124][125]. In light of this experience, landfarming was created to take into consideration for various factors associated to the long-term remediation of polluted soils, including space requirements, cost, energy demand, time, public acceptance, and raw material use [123,126]. ...
... On the one hand, it may be because the n-alkanes and naphthenic hydrocarbons with less carbon were consumed in large quantities at the beginning of remediation, and then the microorganisms began to degrade the refractory aromatic hydrocarbons (Chaineau et al., 1995;Langbehn and Steinhart, 1995). On the other hand, it may be that the TPH intermediate metabolites accumulated in the degradation process, such as aldehydes, ketones, fatty acids (Jorgensen et al., 2000), and metabolites produced by microorganisms change the soil environment, and affect the microorganisms with TPH degradation ability, resulting in slow degradation rate. The overall concentration of group E and group F without microbial agents for natural degradation did not change significantly. ...
Introduction: Bioremediation has been shown to be an effective strategy for removing toxic pollutants from the environment, particularly organic chemicals such as petroleum hydrocarbons. This paper investigates the changes in toxicity of petroleum-contaminated soil as a result of microbial remediation processes.
Methods: Changes in the ecotoxicity of the contaminated soil were examined using a plant, earthworm, enzyme activity and luminescent bacteria toxicity tests.
Results: The results showed that bioremediation could effectively degrade petroleum hydrocarbon (C10–C40) pollutants. After 42 days of remediation, the petroleum hydrocarbon (C10–C40) content of Group A (bioaugmented polluted wetland soil) decreased from 1.66 g/kg to 1.00 g/kg, and the degradation rate was 40.6%. The petroleum hydrocarbon (C10–C40) content of Group B (bioaugmented polluted farmland soil decreased from 4.00 g/kg to 1.94 g/kg, and the degradation rate was 51.6%. During the microbial remediation progress, the ecological toxicity of petroleum-contaminated soil first increased and then decreased. The photosynthetic pigment content index in the higher plant toxicity test, the earthworm survival index and the soil catalase activity all showed good agreement with the relative luminescence index of extracted DCM/DMSO in the luminescent bacterial toxicity test. The soil toxicity decreased significantly after remediation. Specifically, the photosynthetic pigment content of wheat were inhibited in the soil during the whole process (remediation for 42 days), and decreased to the minimum on remediation day 21. The 7-day and 14-day survival rate of earthworms in Group A and Group B gradually decreased in the soil remediation process, and then gradually increased, survival rate at the end of remediation was higher than at the beginning. Soil catalase activity was significantly negatively correlated with petroleum hydrocarbon (C10–C40) content (−0.988, −0.989). The ecological toxicity of contaminated soil reached to the maximum on the 21st day of remediation, relative luminosity of luminescent bacteria in dichloromethane/dimethyl sulfoxide extracts from Group A and Group B were 26.3% and 16.3%, respectively.
Conclusion: Bioremediation could effectively degrade petroleum hydrocarbon (C10–C40) pollutants. Wheat photosynthetic pigment content, earthworm survival rate, soil catalase activity and relative luminescence of luminescent bacteria can better indicate the ecological toxicity of petroleum-contaminated soil in bioremediation process.
... However, chemical oxidation causes negative effects in the environment and in humans. In recent decades, an environmentally friendly and interesting strategy to solve this problem is the remediation of soils using microorganisms 4,5 that have the ability to use hydrocarbons as an energy source in contaminated environments 6 . Microbial degradation helps eliminate hydrocarbons that are spilled in the environment through various physical and chemical methods 7 . ...
Bioremediation, is currently one of the most studied techniques for the elimination of polycyclic aromatic hydrocarbons in soils. However, in order to have a more efficient degradation process, the use of autochthonous bacteria from the contaminated region is recommended because these bacteria are adapted to the climatic and environmental conditions of the site to be remedied. The aim of this work was to isolate and characterize bacteria strains from the city of Reynosa, Mexico, with the potential to degrade naphthalene. Strain isolation was carried out whit soil samples from the shore of“La Escondida” lagoon, a former landfill of pollutants of the petrochemical industry. The isolates were subjected to the emulsion index test as a selective factor to later evaluate their effect in the drop collapse, drop displacement and naphthalene tolerance tests. Finally, sixty-two strains were identified by amplification of the 16S rRNA gene. Ten strains showed the best values in the drop collapse, oil displacement and naphthalene tolerance tests. Four strains had the best naphthalene degradation potential; Pseudomonas aeruginosa (1P2 and 5P2), Bacillus cereus (5S1) and Bacillus subtillis (P52). A degradation of naphthalene was observed in the IR spectrum and UPLC chromatogram after 12 days by 1P2 strain.
... Biopile: contaminated soil is piled followed by the addition of nutrients and oxygen, which enhance degradation. A water system can be added or organic materials that acts as bulking agents [14,18,19]. ...
Crude oil is a viscous dark liquid resource composed by a mix of hydrocarbons which, after
refining, is used for the elaboration of distinct products. A major concern is that many petroleum
components are highly toxic due to their teratogenic, hemotoxic, and carcinogenic effects, becoming
an environmental concern on a global scale, which must be solved through innovative, efficient, and
sustainable techniques. One of the most widely used procedures to totally degrade contaminants are
biological methods such as bioremediation. Synthetic biology is a scientific field based on biology
and engineering principles, with the purpose of redesigning and restructuring microorganisms to
optimize or create new biological systems with enhanced features. The use of this discipline offers
improvement of bioremediation processes. This article will review some of the techniques that use
synthetic biology as a platform to be used in the area of hydrocarbon bioremediation.
... Sphingobacterium is among the PAH degrader that was isolated from soil and marine ecosystem polluted by petroleum-based chemical (Janbandhu and Fulekar, 2011). The genus is also ubiquitous in nature as it has been isolated in many environments such as different soil types, stagnant water, compost, wastewater sludge, plants, human blood and human clinical specimen (Hibi and Kumano, 2017;Lambiase et al., 2009;Tronel et al., 2003;Jørgensen et al., 2000). ...
Biodegradation is the economically viable solution to restore land contaminated by hazardous pollutants such as benzo(a)pyrene (BaP). The present study focuses on the biodegradation of benzo(a)pyrene by Sphingobacterium spiritovorum in contaminated soil. The biodegradation kinetics and bacterial growth were evaluated while the biokinetic model that described the benzo(a)pyrene biodegradation was established. The Monod, Haldane, Powell and Edward models were used to model the bacterial growth in benzo(a)pyrene contaminated soil. Excel template was developed with Fourth order Runga-Kutta numerical algorithm to find the biokinetic parameters of the complex non-linear regression model. An Excel Solver function was used to obtain reasonable best-fit values of kinetic parameters. The Haldane and Edward models are well fit to describe the growth trend and model the kinetics of benzo(a)pyrene biodegradation. Enzyme substrate inhibition is the critical factor that affects the benzo(a)pyrene degradation by S. spiritovorum, which the model defines physically. The results demonstrated that removing benzo(a)pyrene showed positive interaction between substrate inhibition, the concentration of benzo(a)pyrene and sorption of the contaminants on soil particles.
... They can be covered or enclosed within large sheds. They are static, the soil is not turned, but can have forced aeration systems if required (Jørgensen et al., 2000). Biopiles can take weeks to months for the remediation to be completed, due to their static nature a drawback can be dead zones where biodegradation is not successful. ...
The success of clean‐up efforts were fundamental in boosting interest in the potential applicability of bioremediation technologies. Land contamination is used to describe a broad range of soil and groundwater conditions where potentially toxic substances can cause harm to human health or the environment. In order to balance social, environmental, and economic approaches the concept of sustainable remediation has been developed to promote best practice when managing land and groundwater issues. The lines of evidence for verification should also be based around how the pollutant linkage is broken and should be monitored from the start of the remediation process. Bio‐electrochemical systems are engineered devices that transfer electrons from an anode to a cathode using microbial activity. The biogeophysics discipline offers a wide range of techniques that will be of use to biotechnologists who need to monitor the effectiveness of bio‐electrochemical systems beyond the lab and into the field.
... In order to provide the required conditions for composting contaminated materials, these can be mixed with residues such as sludge, which contribute nutrients and microorganisms, facilitating the bioremediation of waste contaminated by hydrocarbons [4]. Furthermore, this waste can be mixed with a bulking agent that is able to deliver sufficient porosity for the microorganisms present in the mixture to obtain the necessary amount of oxygen [5]. ...
Cleaning the oil industry's fuel storage and management facilities generates high levels of hazardous waste. This research aims to assess the use of biological bioremediation treatments, most commonly used for decontaminating soil, by applying them to hydrocarbon-contaminated waste. Turned pile composting using food-derived sludge as a co-substrate and the necessary proportion of bulking agent enabled the bioremediation of the initial mixture via the succession of microbial populations (PLFAs), with a 70% lower TPH concentration obtained 6 months after the start of the process. Subsequent bioassays using the composted material showed survival rates of over 80% with earthworms ( Eisenia andrei ) and a larger decrease in TPH in the joint treatment with earthworms and plants ( Pennisetum clandestinum ). The composting process reduces the concentration of hazardous organic compounds, allowing for the proper development of fauna and flora in the compost by improving the biodegradation rate.
Graphical Abstract
... The result also correlates the report of previous workers (Esumeh et al., 2009) who isolated more of Gram negative organisms suggesting that they are better degraders of crude oil when compared with their Gram positive counterparts. The higher ability of Gram-negative bacteria to utilize crude may not be unconnected with the possession of plasmid-borne or chromosomal genes involved in hydrocarbon degradation and porins in their cell wall which helps in the uptake of certain substances by the cell or extrusion of others which may be harmful (Vahaboglon at al., 1996;Jørgensen et al., 2000;Akpe et al., 2013). ...
An explosion in the world’s population has led to an increase in the demand for crude oil and its products resulting in an increased environmental pollution and thus leading to loss in biodiversity. Environmental reclamation by natural technique is believed to be eco-friendly and cost effective. This research investigated the biodegradation of crude oil supported on different soil particle sizes. Soil samples were randomly collected from different locations within Botanical garden of BUK and sieved into four (4) different particle sizes (0.6mm, 0.3mm, 0.15mm and 0.075mm) 200g of each of the sieved soil particle sizes were weighed and introduced into masonjar bottle. These were then uniformly contaminated with 60ml of crude oil. The set up were replicated in triplicate with each having two (2) controls. They were incubated aerobically at 37oC for 56 days. Enumeration of total aerobic heterotrophic bacteria (TAHB) was done on Nutrient agar (NA) and hydrocarbon utilizing bacteria (HUB) on Bushnell’Haas medium (BHM) supplemented with crude oil. The bacterial isolates were identified based on Grams reaction and biochemical tests. The degradation efficiency was confirmed by GC-MS analysis, which indicated that the microbial isolates utilized most of the crude oil components. The result shows that the mean microbial counts for both TAHB decrease from 5.93 ± 0.1 to 5.38 ± 0.08 x105cfu/g during 56 days period of the study. The result also shows an increase in the mean counts of HUB from 0.00 ± 0.0x103 to 3.74 ± 0.03x103 cfu/g. Particle size A has the highest increase. The HUB identified were Bacillus spp., Pseudomonas spp., Staphylococcus spp., Escherichia coli and Proteus spp. The results indicate that larger particle size favors faster hydrocarbon biodegradation. Keywords: Reclamation, Biodegradation, Hydrocarbon
... Normally, the secondary product of the bioremediation process is harmless, such as water, cell biomass, and CO 2 (Cai, 2007;Alves et al., 2019). In bioremediation, microorganisms usually produce enzymes that are required for the biodegradation reaction and then eliminate the pollutants; therefore, the microbes can be regarded as scavengers in bioremediation (Jørgensen et al., 2000). Many studies have found that the microorganisms within the indigenous community are dominant and capable of degrading petroleum hydrocarbons, whereas the microbial variety is reduced in the polluted soil due to the influences of the toxic petroleum hydrocarbons upon the organisms (Ortega, 2018;Jain, 2011). ...
Environmental pollution is regarded as a major problem, and traditional strategies such as chemical or physical remediation are not sufficient to overcome the problems of pollution. Petroleum-contaminated soil results in ecological problems, representing a danger to human health. Bioremediation has received remarkable attention, and it is a procedure that uses a biological agent to remove toxic waste from contaminated soil. This approach is easy to handle, inexpensive, and environmentally friendly; its results are highly satisfactory. Bioremediation is a biodegradation process in which the organic contaminants are completely mineralized to inorganic compounds, carbon dioxide, and water. This review discusses the bioremediation of petroleum-contaminated soil and the limiting factors that affect it. Furthermore, the advantages and disadvantages of the bioremediation process are reported.
... Biopile: contaminated soil is piled followed by the addition of nutrients and oxygen, which enhance degradation. A water system can be added or organic materials that acts as bulking agents [14,18,19]. ...
Crude oil is a viscous dark liquid resource composed by a mix of hydrocarbons which, after refining, is used for the elaboration of distinct products. A major concern is that many petroleum components are highly toxic due to their teratogenic, hemotoxic, and carcinogenic effects, becoming an environmental concern on a global scale, which must be solved through innovative, efficient, and sustainable techniques. One of the most widely used procedures to totally degrade contaminants are biological methods such as bioremediation. Synthetic biology is a scientific field based on biology and engineering principles, with the purpose of redesigning and restructuring microorganisms to optimize or create new biological systems with enhanced features. The use of this discipline offers improvement of bioremediation processes. This article will review some of the techniques that use synthetic biology as a platform to be used in the area of hydrocarbon bioremediation.
... Currently, bioremediation technologies are well established for the clean-up process in industrial sector and also being applied commercially in large scale [79]. There are three types of bioremediation which are natural attenuation, biostimulation, and bioaugmentation. ...
This mini review aims to provide an overview of petroleum hydrocarbons degradation by Bacillus species. The first half of the scientific assessment is focusing on the impact of usage of petroleum hydrocarbons such as diesel fuels towards organisms and the surrounding environments. The other section of the literature collection discusses on the microbial remediation of this recalcitrant compounds by microbial species with special highlight on the genus Bacillus. This short evaluation will improve our present comprehension of bacterial degradation of petroleum hydrocarbons and their respective derivatives while providing an insight on the role of Bacillus species in microbial remediation communities.
... Biopiles, and landfarming are the common strategies are used in ex-situ treatments for hydrocarbon polluted soils. Biopiles is the process of mixing polluted soil with organic materials this improves microbial activity by enhancing aeration, moisture, and soil texture (Jørgensen et al., 2000). Landfarming is the process in which contaminated soil is mixed with some fertilizers and rotated occasionally. ...
The pros and cons of using the bioremediation method for the removal of petroleum pollutants are discussed in this review article. Other methods along with bioremediation have been used to remediate petroleum hydrocarbon contaminants in the past. Bioremediation is cheap and efficient method than any other because major constituents of the crude oils are biodegradable. Despite the fact that, as compared to physicochemical strategies, longer periods are normally required, complete pollutant degradation can be achieved, and no further containment of the contaminated matrix is required. According to hydrocarbon present in the contaminants different strategies and organism are used for the bioremediation. Common strategies include controlling environmental factors such as oxygen availability, hydrocarbon solubility, nutrient balance and managing hydrocarbon degrading bacteria by eliminating the rate limiting factors that may slow down the bioremediation rate. Microorganism dynamics during bioremediation is most important for understanding how they respond, adapt and remediate pollution. However, bioremediation can be considered one of the best technologies to deal with petroleum product contaminants.
... Typically the degradation process happens at an elevated temperature (in a range of 55 o -65 o C) resulted from the heat produced by the microorganisms themselves (Das and Dash, 2014). Composting has been mostly used in bioremediation of petroleum hydrocarbon contaminated soils (Jørgensen et al., 2000;Namkoong et al., 2002;Van Gestel et al., 2003). However, it can also be helpful in remediation of pesticide contaminants as well (Mena et al., 2003). ...
... The industrial exploitation of bio-based technologies for the treatment of TPH contaminated soils is infrequent, since it is time consuming and there is uncertainty in successful results. On the other hand, these approaches are extensively described in the literature as successful in the laboratory and at the pilot scale [30][31][32][33][34]. These experiments are, most of the time, associated with high levels of control of the different experimental parameters, to optimise the metabolism of the microorganisms competent in depleting the contamination. ...
Innovative culturomic approaches were adopted to isolate hydrocarbonoclastic bacteria capable of degrading diesel oil, bitumen and a selection of polycyclic aromatic hydrocarbons (PAH), e.g., pyrene, anthracene, and dibenzothiophene, from a soil historically contaminated by total petroleum hydrocarbons (TPH) (10,347 ± 98 mg TPH/kg). The culturomic approach focussed on the isolation of saprophytic microorganisms and specialist bacteria utilising the contaminants as sole carbon sources. Bacterial isolates belonging to Pseudomonas, Arthrobacter, Achromobacter, Bacillus, Lysinibacillus, Microbacterium sps. were isolated for their capacity to utilise diesel oil, bitumen, pyrene, anthracene, dibenzothiphene, and their mixture as sole carbon sources. Pseudomonas, Arthrobacter, Achromobacter and Microbacterium sps. showed plant growth promoting activity, producing indole-3-acetic acid and expressing 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity. In parallel to the culturomic approach, in the microbial community of interest, bacterial community metabarcoding and predictive functional metagenomic analysis were adopted to confirm the potentiality of the isolates in terms of their functional representativeness. The combination of isolation and molecular approaches for the characterisation of a TPH contaminated soil microbial community is proposed as an instrument for the construction of an artificial hydrocarbonoclastic microbiota for environmental restoration.
... Typically the degradation process happens at an elevated temperature (in a range of 55 o -65 o C) resulted from the heat produced by the microorganisms themselves (Das and Dash, 2014). Composting has been mostly used in bioremediation of petroleum hydrocarbon contaminated soils (Jørgensen et al., 2000;Namkoong et al., 2002;Van Gestel et al., 2003). However, it can also be helpful in remediation of pesticide contaminants as well (Mena et al., 2003). ...
Purpose: Scientists have identified a plenty of bacterial strains having ability to degrade pesticide residues accumulated in the environment. Due to wide variation of chemical properties of pesticides, a single strain may not be versatile. Hence, identification of bioremediation ability of various bacteria is important. This review focused on understanding and explaining the role of soil bacteria having pesticide detoxification ability. Research Method: Previous research articles, book chapters and literature on bioremediation ability of different soil bacteria were reviewed and various strains of soil bacteria having bioremediation ability, mechanisms behind microbial bioremediation, factors affecting bioremediation and limitations and recent advancements of bioremediation were identified. Based on identified research gaps, further perspectives were introduced. Findings: The results revealed that plenty of soil bacteria having a bioremediation potential have been identified worldwide. As the major mechanism of bioremediation, the microorganisms consume pesticide-contaminated in the soil as their energy or nutrient sources. Various factors such as Bioavailability, Substrate and Environmental factors effect on bioremediation potential. Biostimulation, Bioaugmentation, Biopiling, Composting, Bioreactors and Land farming are identified as popular bioremediation methods suitable for the bioremediation of pesticide contaminants. However, this technique still remains partially developed due to the lack of versatile microorganisms for detoxifying variety of different pesticides. Originality/Value: As this is still a developing area, conducting further researches is timely important. Hence, reviewing literature and identifying already covered areas are important in mitigating the research gap. Therefore, focusing further research goals for the researchers is greatly helpful.
... Aliquots of SCO and Texas oil were collected and analyzed for TPH, PAH, and metals (see section 2.3). Contaminated soil was prepared by adding 20 g of oil (SCO and Texas, respectively) per kg of soil based on previous studies [25][26][27][28][29][30][31]. Six kilogram of sieved soil (2 mm mesh) was mixed with 120 g of oils in a large aluminum tray (40 cm × 60 cm × 5 cm) with a glass stick until the soil texture was visually homogenized. ...
The increasing exploitation of the unconventional bitumen-derived oils from Alberta (Canada) have raised new environmental concerns because they are inherently different than conventional oils. Previous studies mainly focused on diluted bitumen, but the Synthetic Crude Oil (SCO) which takes 35% of market share (of bitumen oils) has not been well studied. The main purpose of this study was to characterize PAHs in the SCO, since they are usually high-risk contaminants that often being prioritized in environmental monitoring practices. The obtained PAHs profile of SCO was also compared to that from a common benchmark oil, the Texas intermediate crude. PAH composition and eco-toxicity (based on Escherichia coli, Eisenia andrei and Lactuca sativa) were studied by spiking the oil in soil microcosms. Results showed a sharp difference in relative abundance of PAH between SCO spiked soil (SCO-soil) and Texas-soil. SCO-soil were characterized by a significantly higher fraction of heavy PAHs (with 3- to 6-rings), 85% versus 36% of relative abundance in Texas-soil. The two soils were also characterized by contrasted PAH-loss rates (82% for SCO-soil and 93% for Texas-soil) likely resulting from their contrasted composition. As for the eco-toxicity, SCO had generally lower toxicity of than Texas. This could attribute to the lower total PAHs concentration and the lower bioavailability of heavy PAHs more abundant in SCO than Texas. This study also suggests that evaluations of oil contamination in soil using selected regulated PAHs would be incomplete and biased for SCO that contains a large fraction of unregulated alkylated PAHs.
... The poor and improper disposal of this waste has resulted in serious degradation of environmental and aesthetic qualities of the mangroves ecosystems and soil especially in the Niger Delta region of Nigeria. Several authors have reported the efficiency and effectiveness of employing bioremediation technique in treating petroleum contaminated sites [3,4,5,6]. The efficiency of several bioremediation techniques such as bio-augmentation and composting [7], biostimulation [8] and landfilling [9,10] in treating oily sludge contaminated sites have also been well documented. ...
Toxicity of raw and bio-slurry treated oily sludge (OS) on Nitrobacter species was determined using standard analytical procedures. The total petroleum content of the OS was 116.44 ± 3.57 g/kg. The TPH was rich with Saturate (40.46 ± 0.73 %). This was followed by Aromatics (27.94 ± 0.50 %) and Asphaltenes (26.58 ± 0.90 %), while NSO fraction had the least proportion (5.75 ± 0.47 %). Contamination of coastal soil with the OS increased the residual TPH concentration in the soil from 5.0561 ppm to 24.2305 ppm. The OS-ladened soil were subjected to biodegradation using 1.5-litter borosilicate glass bioreactors bioaugmented with single population of known OS utilizer (Pseudomonas aeruginosa) and consortium of known OS utilizer and biosurfactant producing bacterial species (Bacillus subtilis). Findings revealed that he bioslurry augmented with the bacterial consortium reduced the concentration of the residual TPH in the soil to 6.313 ppm (73.95% reduction) while 11.5751 ppm (52.23%) was recorded for the single bacterial population. Findings also revealed that the consortium were able to remarkable reduce the toxicity of the raw OS (LC50 = 20.94 ppt) on Nitrobacter species. The LC50 for the consortium treated OS was 104.64 ppt while that of single bacterial population treatment was 36.25 ppt. The reduction in the toxicity of the OS treated with the bacterial consortium indicates the potentials of the synergistic action between the biosurfactant producer and OS utilizer to reduce OS toxicity. The findings of this study can be explored as a cost-effective method for oily sludge waste management in the Oil and Gas industry.
... The composting process can be employed in diesel oil degradation by adding sewage sludge and compost as a catalyst to enhance degradation (Namkoong, Hwang, Park, & Choi, 2002). As Jørgensen, Puustinen, and Suortti (2000) described how the composting of contaminated soils in biopiles be done rapidly by adding organic material. ...
Biofertilizers are the substances containing variety of microbes having the capacity to enhance plant nutrient uptake by colonizing the rhizosphere and make the nutrients easily accessible to plant root hairs. Biofertilizers are well known for their cost effectiveness, environment-friendly nature, and composition. These are effective alternatives to the hazardous synthetic fertilizers. This chapter covers various types of microbial biofertilizers pronouncing symbiotic and free-living nitrogen-fixers, phosphorus-solubilizer and mobilizers, their formulations, applications of few commercially available biofertilizers toward sustainable agriculture, and recent approaches to develop next-generation biofertilizers.
... In the biopiles, airing is done by tubes located in the bottom part of the biopile using compressor, whereas in the terrestrial methods, airing is done by a tractor that excavates the soil (Ronneau & Bitchaeva, 1997). Synonyms of biopiles include biomounds, compost cells, biocells, and bioheaps (Jorgensen et al., 2000). The treatment regions are basically surrounded by an impermeable liner to prevent the spread of contaminants or contaminated soil to the environment. ...
The fast pace of increasing human population has led to an enhanced crop production, due to which a significant increase in the application of pesticides has been recorded worldwide. Following the enhancement in the utilization of pesticides, the degree of environmental pollution, particularly soil pollution, has increased. To address this challenge, different methods of controlling and eliminating such contaminants have been proposed. Various methods have been reported to eradicate or reduce the degree of contamination of pesticides in the soil. Several factors are crucial for soil contamination, including pH, temperature, the number and type/nature of soil microorganisms. Among the accessible techniques, some of them respond better to contamination removal. One of these methods is bioremediation and it is one of the ideal solutions for pollution reduction. In this innovative technique, microorganisms are utilized to decompose environmental pollutants or to curb pollution. This paper gives detailed insight into various strategies used for the reduction and removal of soil pollution.
... The composting process can be employed in diesel oil degradation by adding sewage sludge and compost as a catalyst to enhance degradation (Namkoong, Hwang, Park, & Choi, 2002). As Jørgensen, Puustinen, and Suortti (2000) described how the composting of contaminated soils in biopiles be done rapidly by adding organic material. ...
Purple nonsulfur bacteria (PNSB), a diverse group of photosynthetic microorganisms, inhabit in a wide variety of aquatic habitats where sunlight penetrates. These microorganisms show pigmentation ranging from deep red to brown and propagate under anoxic conditions. Depending on the presence of nutrients, oxygen concentration, and light intensity, they can shift their modes of metabolism between photoautotrophy, photoheterotrophy, and chemoheterotrophy. Most promisingly, many of the PNSB are known to thrive in the presence of various toxicants such as heavy metals and thus play an important role in the remediation of contaminated sites. PNSB are one of the most potential candidates for the production of biohydrogen, taking us a step further towards the era of “green technology.” They also serve as a potential source of single-cell proteins, enzymes, biofertilizers, carotenoids, plant growth-producing hormones, and several precursor molecules. This chapter discusses the versatile and important role of PNSB in biotechnology.
Over the years, as a consequence of anthropogenic activities, the release of a wide range of organic and inorganic xenobiotic moieties and their accumulation have generated hazardous waste sites worldwide. These xenobiotic compounds persist in the environment due to their recalcitrant nature and are toxic, carcinogenic, and mutagenic posing severe risks to human health, animals, and the natural environment. Microbes, due to their metabolic versatility as well as their capability to adapt to changing environmental conditions, play a vital role in xenobiotic degradation and rejuvenation of the contaminated site naturally through the process of bioremediation. Moreover, in contrast to the physical and chemical remedial degradation of xenobiotics, bioremediation is a cost-effective, sustainable approach empowered by microbes and their enzymes. Depending upon the region and extent of contamination, treatment cost, and pollutant type, ex situ or in situ bioremediation approaches can be used. This chapter gives a comprehensive detail of xenobiotic remediation through different microbes, mechanisms involved in xenobiotic degradation, and recent advancements such as bioinformatics, nanotechnology, and genetic engineering approaches in bioremediation. Further, it also discusses the associated challenges, limitations, and future prospects in bioremediation.
The use of various agrochemicals or pesticides has undoubtedly increased agri- cultural crop productivity and protected crops from different types of pests and diseases. It also provides an economical advantage to farmers. At the same time, because of the overuse of pesticides to satisfy the demands of an ever-increasing population, environmental pollution is also increasing which poses a great threat to environmental and human health. To tackle this problem, there are several eco- friendly, competent, efficient, and inexpensive emerging technologies for pesticide degradation and detoxification, known as bioremediation (including phytoreme- diation). Bioremediation is a multidisciplinary approach which uses the catabolic potential of bacteria, fungi, algae, and other organisms for biodegradation and detoxification. This chapter will be focused on different aspects, limitations, and challenges associated with bioremediation techniques and, finally, to assess the possible uses of these remedial methods for pesticide elimination or reduction from the soil and water ecosystem.
Keywords: Bioremediation, phytoremediation, pesticides, biodegradation, pollutions, detoxification
There is increasing demand for low-carbon remediation strategies for reducing greenhouse gas emissions and promoting sustainable development in the management of environmental contamination. This trend is within the broader context of sustainable remediation strategies that balance environmental, economic, and social aspects. This article critically reviewed existing literature to evaluate and compare various low-carbon remediation methods, such as bioremediation, phytoremediation, in situ chemical oxidation, soil vapour extraction, and electrokinetic remediation, to identify suitable techniques for the remediation of oil-contaminated sites in the Niger Delta region of Nigeria. We analysed the UK sustainable remediation frameworks (SuRF-UK) to glean lessons for the Nigerian context. Our findings indicate that bioremediation and phytoremediation are particularly promising low-carbon remediation technologies for the Niger Delta region due to their cost-effectiveness and adaptability to local conditions. We proposed a framework that deeply considers opportunities for achieving multiple goals including effective remediation and limited greenhouse gas emissions while returning net social and economic benefit to local communities. The proposed framework will help decision makers to implement effective remediation technologies that meet sustainability indices, integrates emissions considerations return net environmental benefit to local communities. There is a need for policymakers to establish and enforce policies and regulations that support sustainable remediation practises, build the capacity of stakeholders, invest in research and development, and promote collaboration among stakeholders to create a regulatory environment that supports sustainable remediation practises and promotes environmental sustainability in the region. This study provides insights for achieving low-carbon remediation in regions addressing land contamination by different contaminants and facilitates the adoption of remediation technologies that consider contextual socio-economic and environmental indices for sustainable development.
In the course of the conducted studies, main groups of soil microorganisms in the southern chernozem were identified. The resistance of isolates to the action of oil in the concentration range of 15–25%, the possibility of using it as a carbon source, the ability of soil microbiota to biodegradate oil in contaminated soil and the resistance of bacteria to low temperatures, high NaCl concentrations, acid and alkali resistance were established. 15 genera (31 species) of heterotrophic bacteria were isolated from uncontaminated soil samples of the southern chernozem subtype. Our assessment of the abundance dynamics of microorganisms isolated from laboratory contaminated soils showed that as a result of oil exposure, there was a significant decrease in the numbers of microorganisms: by the 180th day of our experiment, 10 bacteria species belonging to 3 genera were isolated, namely: Bacillus, Micrococcus and Serratia. Among the isolated bacteria, resistance to the action of the pollutant at a concentration of 25% was established for B. coagulans, B. mojavensis, B. megaterium, M. luteus, as well as for the museum strain of B. pumilus CM. By cultivating the studied bacterial strains on a carbon-free medium M9 with 15 and 20% oil added, their ability to use petroleum hydrocarbons as the only carbon source was established; however, when the concentration increased to 25%, only M. luteus, B. mojavensis and B. pumilus KM retained this ability. The presence of hydrocarbon-oxidizing bacteria in soil samples contributed to the 42% decrease in the oil mass concentration in 180 days. The most significant decrease in the concentration of petroleum products occurred in the period from the 10th to the 30th day and amounted to 25%, which is probably due to the increase in the numbers of heterotrophic bacteria. The ability to grow at a temperature of +4°C was established for representatives of the genus Bacillus, including the museum strain of B. pumillus CM, 4 strains of bacilli remained viable in an acidic environment (pH 5), 7 strains of bacilli and M. luteus and S. plymuthica remained viable in an alkaline environment (pH 9). The studied bacterial strains were growing on a GRM-agar with a NaCl concentration of 7%, the ability to grow at a NaCl concentration of 15% was preserved only by the museum strain of B. pumillus KM. The obtained results open the prospects for the use of hydrocarbon-oxidizing bacteria with a high adaptive potential as potential oil destructors capable of biodegradation at low temperatures, in conditions of high salinity and in a wide range of pH of the medium.
Written for researchers and practitioners in environmental pollution, management and ecology, this interdisciplinary account explores the ecological issues associated with industrial pollution to provide a complete picture of this important environmental problem from cause to effect to solution. Bringing together diverse viewpoints from academia and environmental agencies and regulators, the contributors cover such topics as biological resources of mining areas, biomonitoring of freshwater and marine ecosystems and risk assessment of contaminated land in order to explore important questions such as: What are the effects of pollutants on functional ecology and ecosystems? Do current monitoring techniques accurately signal the extent of industrial pollution? Does existing policy provide a coherent and practicable approach? Case studies from throughout the world illustrate major themes and provide valuable insights into the positive and negative effects of industrial pollution, the provision of appropriate monitoring schemes and the design of remediation and restoration strategies.
Written for researchers and practitioners in environmental pollution, management and ecology, this interdisciplinary account explores the ecological issues associated with industrial pollution to provide a complete picture of this important environmental problem from cause to effect to solution. Bringing together diverse viewpoints from academia and environmental agencies and regulators, the contributors cover such topics as biological resources of mining areas, biomonitoring of freshwater and marine ecosystems and risk assessment of contaminated land in order to explore important questions such as: What are the effects of pollutants on functional ecology and ecosystems? Do current monitoring techniques accurately signal the extent of industrial pollution? Does existing policy provide a coherent and practicable approach? Case studies from throughout the world illustrate major themes and provide valuable insights into the positive and negative effects of industrial pollution, the provision of appropriate monitoring schemes and the design of remediation and restoration strategies.
Written for researchers and practitioners in environmental pollution, management and ecology, this interdisciplinary account explores the ecological issues associated with industrial pollution to provide a complete picture of this important environmental problem from cause to effect to solution. Bringing together diverse viewpoints from academia and environmental agencies and regulators, the contributors cover such topics as biological resources of mining areas, biomonitoring of freshwater and marine ecosystems and risk assessment of contaminated land in order to explore important questions such as: What are the effects of pollutants on functional ecology and ecosystems? Do current monitoring techniques accurately signal the extent of industrial pollution? Does existing policy provide a coherent and practicable approach? Case studies from throughout the world illustrate major themes and provide valuable insights into the positive and negative effects of industrial pollution, the provision of appropriate monitoring schemes and the design of remediation and restoration strategies.
Written for researchers and practitioners in environmental pollution, management and ecology, this interdisciplinary account explores the ecological issues associated with industrial pollution to provide a complete picture of this important environmental problem from cause to effect to solution. Bringing together diverse viewpoints from academia and environmental agencies and regulators, the contributors cover such topics as biological resources of mining areas, biomonitoring of freshwater and marine ecosystems and risk assessment of contaminated land in order to explore important questions such as: What are the effects of pollutants on functional ecology and ecosystems? Do current monitoring techniques accurately signal the extent of industrial pollution? Does existing policy provide a coherent and practicable approach? Case studies from throughout the world illustrate major themes and provide valuable insights into the positive and negative effects of industrial pollution, the provision of appropriate monitoring schemes and the design of remediation and restoration strategies.
Written for researchers and practitioners in environmental pollution, management and ecology, this interdisciplinary account explores the ecological issues associated with industrial pollution to provide a complete picture of this important environmental problem from cause to effect to solution. Bringing together diverse viewpoints from academia and environmental agencies and regulators, the contributors cover such topics as biological resources of mining areas, biomonitoring of freshwater and marine ecosystems and risk assessment of contaminated land in order to explore important questions such as: What are the effects of pollutants on functional ecology and ecosystems? Do current monitoring techniques accurately signal the extent of industrial pollution? Does existing policy provide a coherent and practicable approach? Case studies from throughout the world illustrate major themes and provide valuable insights into the positive and negative effects of industrial pollution, the provision of appropriate monitoring schemes and the design of remediation and restoration strategies.
Environmental pollution and its consequences on humans and other living organisms have received increased public attention in recent years. Consumer interest in taking practical corrective measures to preserve lubricants and use them properly has increased as a result of rising environmental consciousness and stricter legislative restrictions on the usage of petroleum products. The number of petroleum products contaminated with inorganic contaminants has increased significantly over time. Vehicle servicing centers dump untreated harmful effluents including heavy metals, oils/grease, and other toxic compounds into the soil and groundwater system on a daily basis, polluting the soil and groundwater system. This contaminates the groundwater and enters the food chain via soil and plants, providing a health risk to humans.
The current study focuses on the soil and water quality in and surrounding motor maintenance workshops present in the Dehradun valley during the pre-and post-monsoon seasons. To assess the environmental impact of effluents, samples were collected from the motor servicing centers and its surrounding. The wastewater created by auto repair workshops was collected and analyzed. Basic physicochemical properties of the water sample were determined, including temperature, turbidity, TDS, conductivity, pH, DO, bicarbonates, total hardness, calcium hardness, the concentration of calcium, magnesium, sodium, potassium, and oil and grease. Using a spectrophotometer, air samples were also analyzed for various parameters such as SPM, RSPM, SOx, and NOx. The concentration of oil and grease in the wastewater of motor servicing centers was found to be alarmingly high, exceeding WHO and BIS recommendations. The lubricants that come out of the vehicles or industries are disposed of either directly or indirectly into the ground without having proper disposal plans, and the latter contaminates not only the soil but also the groundwater system of the area.
In the previous decades, the pollutionPollution of the environmentEnvironment has increased due to rapid growth in human population, urbanization, and industrialization. The indiscriminate use of the resources by the ever-increasing human population has increased the pollutionPollution of environmental sites mainly by industrial effluents, sewage, surface runoff from agricultural fields, fertilizers, and pesticidesPesticides. The widespread degradationDegradation of natural ecosystems by pollutants cause serious threatsThreats as they get into various environmentsEnvironment (air, soil, and water) and accumulate in food chains. Conventional methods used in the remediation/treatment processes of contaminated environmentsEnvironment are expensive, inefficient, leave toxic residues in the environmentEnvironment, and are not reliable. Therefore, bioremediationBioremediation is viewed as an evolving and promising technique in the treatment of various types of contaminants. BioremediationBioremediation of polluted environmentsEnvironment has proven successful, efficient, and reliable because of its environmentEnvironment-friendly features. The basic principle of bioremediationBioremediation is natural attenuation also known as intrinsic bioremediationBioremediation, which involves the remediation of polluted sites naturally in the environmentsEnvironment without any anthropogenicAnthropogenic interference to reduce the toxicity, mass, and concentration of pollutants in those media. BioremediationBioremediation may involve the use of plants, fungi, bacteria, and other algae for remediation but the process mainly focuses on the use of microorganisms. This chapter, therefore, tries to provide a comprehensive knowledge of the potential role of bioremediationBioremediation technologies and processes for the potential remediation of contaminated sites.
Soil pollution is one of the main environmental issues worldwide. The intensive use of the soil for industrial and agricultural purposes increases the necessity of recovering brownfields and other polluted emplacements. There are many remediation technologies used until now for this aim, with nanoremediation and bioremediation being the most successful ones in terms of effectiveness and cost. On the one hand, zerovalent iron nanoparticles and their derivatives have been described as highly favorable remediation agents, being extensively used in soil and groundwater remediation. On the other hand, bioremediation, compared with nanoremediation that requires more time to reduce the same amount of pollutants, has many biological benefits, including making the soil ready for reuse. Considering the advantages and disadvantages of both technologies, a combined technology known as nanobioremediation has been developed, which acts as an extremely interesting alternative to merge the main advantages of nano- and bioremediation. In this chapter, the main aspects of nanoremediation and bioremediation are reviewed, and some examples of their use on full-scale applications are described. Finally, the application of a combined method, that is, nanobioremediation, is described.
The present work was carried out to find out a suitable eco-friendly sustainable technique for remediation of oily sludge generated from the petroleum industry. Hence, three experimental sets, one with simple land degradation serving as C- set (control), the second one with compost (C+ set), and the third one with silver (Ag) nanoparticles (N set) was used to study the remediation of oily sludge. The three experimental sets each with 500 g of sample were sampled initially at 0 days followed by 15, 30, 45, and 60 days for quantifying pH, conductivity, heavy metals (Pb, Ni, As, and Fe), and total petroleum hydrocarbon (TPH). Our study found that the C+ set (compost) has the highest removal efficiency for heavy metals namely Fe (91.77%), Pb (54.44%), Ni (76.11%) and As (33.48%) as well as TPH (65.52%). All the sets exhibited a positive correlation between pH and TPH as well as between As (Arsenic) and Fe (Iron) and a negative correlation between conductivity and TPH. The pollution index (PI) of As (Arsenic) was between 6.7 to 10.7 exhibiting a very strong level of pollution for all the sets under study. Potential ecological risk index depicted a low level of risk for Pb (0.5-0.30) and Ni (0.043-0.064) whereas moderate level of risk for As (67) in N set and higher level of risk for C- (88) and C+ (107) set. Based on the results of the present experiment, the application of compost for remediation of oily sludge is better than using nanoparticles and simple land degradation. However, the experiment needs to be carried on for a long period to conclude.
Retention of nanodiamonds (NDs) by soils = f ( ζ -potential, water-extractable Fe and Si).
The petroleum industry’s development has been supported by the demand for petroleum and its by-products. During extraction and transportation, however, oil will leak into the soil, destroying the structure and quality of the soil and even harming the health of plants and humans. Scientists are researching and developing remediation techniques to repair and re-control the afflicted environment due to the health risks and social implications of petroleum hydrocarbon contamination. Remediation of soil contamination produced by petroleum hydrocarbons, on the other hand, is a difficult and time-consuming job. Microbial remediation is a focus for soil remediation because of its convenience of use, lack of secondary contamination, and low cost. This review lists the types and capacities of microorganisms that have been investigated to degrade petroleum hydrocarbons. However, investigations have revealed that a single microbial remediation faces difficulties, such as inconsistent remediation effects and substantial environmental consequences. It is necessary to understand the composition and source of pollutants, the metabolic genes and pathways of microbial degradation of petroleum pollutants, and the internal and external aspects that influence remediation in order to select the optimal remediation treatment strategy. This review compares the degradation abilities of microbial–physical, chemical, and other combination remediation methods, and highlights the degradation capabilities and processes of the greatest microbe-biochar, microbe–nutrition, and microbe–plant technologies. This helps in evaluating and forecasting the chemical behavior of contaminants with both short- and long-term consequences. Although there are integrated remediation strategies for the removal of petroleum hydrocarbons, practical remediation remains difficult. The sources and quantities of petroleum pollutants, as well as their impacts on soil, plants, and humans, are discussed in this article. Following that, the focus shifted to the microbiological technique of degrading petroleum pollutants and the mechanism of the combined microbial method. Finally, the limitations of existing integrated microbiological techniques are highlighted.
Bioremediation has been used to treat soils contaminated with complex mixtures of organic compounds such as total petroleum hydrocarbons (TPH), oil and grease (O&G), or polycyclic aromatic hydrocarbons (PAHs). Despite the common use and cost-effectiveness of bioremediation for treating hydrocarbon-contaminated soils, it has been observed that a residual fraction remains undegraded in the soil even when optimal biodegradation conditions have been provided. This paper provides a brief review of the two major conceptual models that have been used to explain why a residual hydrocarbon fraction remains in the soil after bioremediation treatment. The contaminant sequestration model is based on the assumption that a certain fraction of hydrocarbons is “locked up” in small soil pores within soil particles or aggregates. These sorbed hydrocarbons are believed to be inaccessible to soil microorganisms. Consequently, limitations in bioavailability are thought to be the major reason for incomplete hydrocarbon biodegradation, particularly in aged or weathered soils. Alternatively, according to the inherent recalcitrance model, incomplete TPH biodegradation may be caused by the presence of certain hydrocarbons that are inherently recalcitrant to biodegradation or are only extremely slowly degradable even under optimal conditions. Each conceptual model provides different explanations regarding the potential risks of the residual hydrocarbon fraction. If the residual TPH is truly sequestered within the soil pore space, it is unlikely that these compounds will pose any significant risk to human or environmental receptors. By contrast, these risks may be considerably greater if the residual TPH fraction consists of inherently recalcitrant compounds that reside mostly on the surface of soil particles and therefore are much more available to potential receptors. Both conceptual models and their implications for the potential risk of the residual TPH fraction are discussed.
A bioremediation treatment that consisted of liming, fertilization, and tilling was evaluated on the laboratory scale for its effectiveness in cleaning up a sand, a loam, and a clay loam contaminated at 50 to 135 mg g of soil by gasoline, jet fuel, heating oil, diesel oil, or bunker C. Experimental variables included incubation temperatures of 17, 27, and 37 degrees C; no treatment; bioremediation treatment; and poisoned evaporation controls. Hydrocarbon residues were determined by quantitative gas chromatography or, in the case of bunker C, by residual weight determination. Four-point depletion curves were obtained for the described experimental variables. In all cases, the disappearance of hydrocarbons was maximal at 27 degrees C and in response to bioremediation treatment. Poisoned evaporation controls underestimated the true biodegradation contribution, but nevertheless, they showed that biodegradation makes only a modest contribution to gasoline disappearance from soil. Bunker C was found to be structurally recalcitrant, with close to 80% persisting after 1 year of incubation. The three medium distillates, jet fuel, heating oil, and diesel oil, increased in persistence in the listed order but responded well to bioremediation treatment under all test conditions. With bioremediation treatment, it should be possible to reduce hydrocarbons to insignificant levels in contaminated soils within one growing season.
We evaluated the use of straw compost and remediated soil as inocula for bioremediation of chlorophenol-contaminated soil. The in situ biotransformation of pentachlorophenol (PCP) and mineralization of radiolabeled [U-(sup14)C]PCP by straw compost and remediated soil were studied under field-simulating conditions before and after 3 months of adaptation with PCP in a percolator. After PCP adaptation, the straw compost mineralized up to 56% of the [(sup14)C]PCP. No partial dechlorination of PCP was found. The native straw compost did not mineralize PCP, but partial dechlorination of PCP occurred (i) at pH 8 under near-thermophilic conditions (45(deg)C) and (ii) at pH 7 under aerobic and mesophilic conditions. No biotransformation reactions occurred at room temperature (25(deg)C) at pH 8. Enrichment in the percolator enhanced the mineralization rate of remediated soil to 56% compared with that of the native remediated soil, which mineralized 24% of [(sup14)C]PCP added. Trace amounts of chloroanisoles as the only biotransformation products were detected in PCP-adapted remediated soil. Both inoculants studied here showed effective mineralization of PCP when they were adapted to PCP in the percolator. No harmful side reactions, such as extensive methylation, were observed.
Microbial transformations of cyclic hydrocarbons have received much attention during the past three decades. Interest in the degradation of environmental pollutants as well as in applications of microorganisms in the catalysis of chemical reactions has stimulated research in this area. The metabolic pathways of various aromatics, cycloalkanes, and terpenes in different microorganisms have been elucidated, and the genetics of several of these routes have been clarified. The toxicity of these compounds to microorganisms is very important in the microbial degradation of hydrocarbons, but not many researchers have studied the mechanism of this toxic action. In this review, we present general ideas derived from the various reports mentioning toxic effects. Most importantly, lipophilic hydrocarbons accumulate in the membrane lipid bilayer, affecting the structural and functional properties of these membranes. As a result of accumulated hydrocarbon molecules, the membrane loses its integrity, and an increase in permeability to protons and ions has been observed in several instances. Consequently, dissipation of the proton motive force and impairment of intracellular pH homeostasis occur. In addition to the effects of lipophilic compounds on the lipid part of the membrane, proteins embedded in the membrane are affected. The effects on the membrane-embedded proteins probably result to a large extent from changes in the lipid environment; however, direct effects of lipophilic compounds on membrane proteins have also been observed. Finally, the effectiveness of changes in membrane lipid composition, modification of outer membrane lipopolysaccharide, altered cell wall constituents, and active excretion systems in reducing the membrane concentrations of lipophilic compounds is discussed. Also, the adaptations (e.g., increase in lipid ordering, change in lipid/protein ratio) that compensate for the changes in membrane structure are treated.
Microbial transformations of cyclic hydrocarbons have received much attention during the past three decades. Interest in the degradation of environmental pollutants as well as in applications of microorganisms in the catalysis of chemical reactions has stimulated research in this area. The metabolic pathways of various aromatics, cycloalkanes, and terpenes in different microorganisms have been elucidated, and the genetics of several of these routes have been clarified. The toxicity of these compounds to microorganisms is very important in the microbial degradation of hydrocarbons, but not many researchers have studied the mechanism of this toxic action. In this review, we present general ideas derived from the various reports mentioning toxic effects. Most importantly, lipophilic hydrocarbons accumulate in the membrane lipid bilayer, affecting the structural and functional properties of these membranes. As a result of accumulated hydrocarbon molecules, the membrane loses its integrity, and an increase in permeability to protons and ions has been observed in several instances. Consequently, dissipation of the proton motive force and impairment of intracellular pH homeostasis occur. In addition to the effects of lipophilic compounds on the lipid part of the membrane, proteins embedded in the membrane are affected. The effects on the membrane-embedded proteins probably result to a large extent from changes in the lipid environment; however, direct effects of lipophilic compounds on membrane proteins have also been observed. Finally, the effectiveness of changes in membrane lipid composition, modification of outer membrane lipopolysaccharide, altered cell wall constituents, and active excretion systems in reducing the membrane concentrations of lipophilic compounds is discussed. Also, the adaptations (e.g., increase in lipid ordering, change in lipid/protein ratio) that compensate for the changes in membrane structure are treated.
In a former derelict coal plant, PAH content ranged between 30 and 47 g/kg DW. Lab-scale solid-phase bioremediation resulted in high yields of PAH removal (95%), provided supplementation is well-suited. Pilot-scale bioremediation of 2.5-ton beds in confined greenhouse confirmed the laboratory results after a 6-month treatment.
Biological treatment of contaminated soil has received much attention during the last decade. Microbes are known to be able to degrade many oil hydrocarbons and also several commercial microbial inoculants are now available for this purpose. However, research is needed to ensure that bioremediation technologies are implemented in a safe and reliable way also under cold (boreal) climatic conditions. The main points of interest are the rate of the degradation as well as the survival and efficiency of microbial inoculants possibly introduced.
Aboveground applications include land farming, solid phase bioremediation, soil slurry reactors, biologically enhanced soil washing, engineered soil piles, and composting. In situ bioremediation applications include bioventing of the vadose zone, vacuum extraction combined with subsurface sparking to remediate vadose and saturated zone soils, and remediation strategies for groundwater and saturated zone soils. -from Authors
Seven soil samples and seven groundwater samples from a site contaminated with fuel-oil were investigated using several chemical and microbiological techniques. In soil samples, 500 to 7,500 mg/kg of total hydrocarbons were found. These samples contained no n-alkanes but iso- and branched chain alkanes. No polychlorinated biphenyls could be detected. Microbiological investigations included estimations of total cell counts, viable cell counts on different media, and numbers of methylotrophic, denitrifying, sulphate reducing, anaerobic (with the exception of methanogenic organisms), and hydrocarbon degrading bacteria. Viable and hydrocarbon degrading bacteria were found in all samples. A total of 1,366 pure cultures was characterized morphologically and physiologically and identified by numerical identification using a data base of more than 4,000 reference strains. Groundwater samples were dominated by gram-negative bacteria of the generaPseudomonas, Comamonas, Alcaligenes, andAcinetobacter, which were also found in soil samples. In addition, more grampositive bacteria belonging to the generaArthrobacter, Nocardia, andBacillus could be isolated from soil samples.
The efficacy of ten commercial bioremediation products in enhancing the biodegradation of crude oil was investigated in the laboratory at 10 or 30a°C for 90 d with and without supplemental nitrogen and phosphorus. Oil was added to a 1-cm layer of water covering sediments from a salt marsh. The products did not increase the numbers of hydrocarbon-degrading microorganisms in water and sediments but did increase heterotrophic populations at 21 d. Some bioremediation products more than doubled the quantity of hydrocarbons degraded in 45 d at 10°C. At 30°C, no product increased degradation compared to the fertilized control in which 70% of the added hydrocarbons were degraded. Two products increased the percentage of hydrocarbons degraded from 42% to approximately 65% in 45 d at 30°C when supplemental fertilizer was not provided. The hydrocarbon concentration was not significantly reduced between 45 and 90 d for most product treatments at either temperature. At 10°C, products seemed to have the greatest potential for enhancing oil bioremediation compared to the control.
We studied the fate of chlorophenols during the composting of sawmill soil and impregnated wood to see whether chlorophenols, in addition to mineralization, would form any harmful metabolites. The toxicity assessed by luminescent bacteria tests decreased during the composting, and it followed the chlorophenol concentrations in the compost piles. The threshold value for chlorophenol toxicity ap peared to be 200 mg of total chlorophenols/kg dry weight. Polymerization of chlorophenols was studied by determining the molecular weight distribution of organic halogen compounds during the bioremediation. Organic chlorine compounds appeared in high molecular weight sizes, indicating that binding to soil organic matter had taken place during the long exposure time to the wood preservative Ky-5 in the contaminated soil. No major polymerization occurred during the composting, but the polymerized fraction was not either degraded or remobilized. Large amounts of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) originating from the wood preservative were found in the compost piles, but their concentrations did not significantly change during the bioremediation process. The congener composition of PCDD/Fs resembled the one in original wood preservative. Since PCDD/Fs were released from the wood chips of the former Ky-5 dipping basin and not degraded during the bioremediation, it is not recommended to treat PCDD/F-contaminated wood chips in biopiles.
A pilot-scale composting of chlorophenol-contaminated soil was performed to compare chlorophenol degradation by two different inoculants, straw compost and remediated soil, with that by indigenous soil microbes. Four compost piles with a size of 13 m3 each were constructed. Chlorophenol and chloroanisole concentrations as well as numerous physical and microbiological parameters were monitored during 6 months of composting. Over 90% of the chlorophenols were removed during the composting period. The biodegradation of chlorophenols was efficient and fast despite the inocula. Frequent mixing and control of the nutrient level enhanced the chlorophenol degradation activity of the indigenous microbes in the contaminated soil. In a parallel bench-scale experiment, an average of 60% mineralization of radiolabeled pentachlorophenol ([14C]PCP) was obtained in 4 weeks in 1-kg piles with or without inocula. This result showed that a major part of chlorophenols was completely mineralized.
Microbiological decontamination of technical chlorophenol-containing soil by composting was studied. In two 50 m3 windrows the concentration of chlorophenols went down from 212 mg kg-1 to 30 mg kg-1 in 4 summer months and after the second summer of composting it was only 15 mg kg-1. All chlorophenol congeners present in the technical chlorophenol were degraded, but the main dimeric impurities, polychlorinated phenoxyphenols were recalcitrant. The contaminated soil was found to contain chlorophenol-degrading microbes, 5x106 cfu g-1 of dry windrow soil. Laboratory experiments with samples from the windrow compost showed that chlorophenols were truly degraded and that chlorophenol loss by evaporation was less than 1.5% under the circumstances studied. Laboratory experiments also showed that degradation of chlorophenols (120 mg kg-1) was accelerated when sterilized contaminated soil was inoculated with Rhodococcus chlorophenolicus (mineralizer of several chlorophenols) or naturally occurring microbes of the field composts. Biomethylation of chlorophenols in the composts was insignificant compared to biodegradation.
This study examined the microbial degradation of fuel oil by nine highly adapted different commercially available mixed bacterial cultures (DBC-plus, Flow Laboratories, Meckenheim, F.R.G.) and a bacterial community from a domestic sewage sludge sample. All mixed cultures were cultivated under aerobic batch conditions shaking (110 rpm) at 20C in a mineral base medium containing 1 or 5% (v/v) fuel oil as the sole carbon source. Percent degradation of fuel oil and the n-alkane fraction was recorded for the nine DBC-plus cultures and the mixed population of the activated sludge sample. The increase in colony counts, protein, and optical density was studied during a 31-day incubation period for DBC-plus culture A, DBC-plus culture A2 and the activated sludge sample. The activated sludge mixed culture was most effective in degrading fuel oil, but various isolated bacterial strains from this bacterial community were not able to grow on fuel oil as the sole carbon source. In contrast, the n-alkane degradation rates of the DBC-cultures were lower, but single strains from the commercially available mixed cultures were able to mineralize fuel oil hydrocarbons. Strains ofPseudomonas aeruginosa were isolated most frequently and these organisms were able to grow very rapidly on fuel oil as a complex sole carbon source. The results indicate that fuel oil degradation in domestic sewage sludge is performed by mixed populations of naturally occurring bacteria and does not depend on the application of highly adapted commercially available cultures.
A method is described for the rapid and objective estimation of the amount of carbon in the living, non-resting microbial biomass of soils. The method, which is based on the initial respiratory response of microbial populations to amendment with an excess of a carbon and energy source, was quantified using an expanded version of Jenkinson's technique.The simultaneous application of the two methods to 50 soil samples showed a highly significant correlation (r = 0.96) between both. From this correlation it could be deduced that at 22°C, a substrate-induced maximal respiratory rate of 1 ml CO2· h−1 corresponds to c. 40 mg microbial biomass C. Evidence supporting these results was obtained from pure culture studies. The various soil types investigated were collected from agricultural as well as forest sites and they contained between 15 and 240 mg microbial C·100g dry soil−1. The respiratory method provides reproducible estimates of biomass size within 1–3 h after soil amendment. It can be combined without difficulty with a selective inhibition method for determination of bacterial and fungal contributions to soil metabolism.
Microbial status during a successful full-scale bioremediation by composting chlorophenol-contaminated soil was studied in three different ways: conventional enumeration of microbes on selective and general media, microbial activity assessed by soil respiration, and community structure studied by the utilization pattern of a large range of substrates using Biolog® microtitre plates. Utilization of ammonium, nitrate and soluble P was also followed. Chlorophenols were well removed in all compost piles which were mixtures of contaminated soil and bark chips or straw compost. The best indicator of the actual chlorophenol degradation efficiency was the number of microbes growing on plates with 2 mM pentachlorophenol (PCP) as the sole carbon source. Nutrient analyses showed that ammonium was rapidly used, and nitrification took place in some of the compost piles. The data from Biolog® microtitre plates was analyzed using the toolbox of Matlab® mathematical software. The areas under the substrate utilization curve were integrated for each substrate used, and they were used for principal component analysis. We were able to see pile-specific substrate usage for piles containing straw compost, but not for pile containing bark chips. All these characteristic substrates were either amino acids or amines. The results suggested that fast-growing microbes responsible for utilization of easily available substrates, measured by respiratory activity and substrate utilization patterns in Biolog, originated mainly from the added bulking agents, straw compost and bark chips. The chlorophenol-degraders originating from contaminated soil seemed not directly to contribute to the Biolog utilization pattern, but probably had benefited from the enhanced general microbial activity in the composts by cometabolism or synergism.
Several denitrifying Pseudomonas spp., isolated with various aromatic compounds, were tested for the ability to degrade toluene in the absence of molecular oxygen. Four out of seven strains were able to degrade toluene in the presence of N2O. More than 50% of the 14C from ring-labelled toluene was released as CO2, and up to 37% was assimilated into cell material. Furthermore it was demonstrated for two strains that they were able to grow on toluene as the sole carbon and energy source in the presence of N2O. Suspensions of cells pregrown on toluene degraded toluene, benzaldehyde or benzoate without a lag phase and without accumulation of intermediates. p-Cresol, p-hydroxybenzylalcohol, p-hydroxybenzaldehyde or p-hydroxybenzoate was degraded much slower or only after distinct lag times. In the presence of fluoroacetate [14C]toluene was transformed to [14C]benzoate, which suggests that anaerobic toluene degradation proceeds through oxidation of the methyl side chain to benzoate.
Microbial transformations of cyclic hydrocarbons have received much attention during the past three decades. Interest in the degradation of environmental pollutants as well as in applications of microorganisms in the catalysis of chemical reactions has stimulated research in this area. The metabolic pathways of various aromatics, cycloalkanes, and terpenes in different microorganisms have been elucidated, and the genetics of several of these routes have been clarified. The toxicity of these compounds to microorganisms is very important in the microbial degradation of hydrocarbons, but not many researchers have studied the mechanism of this toxic action. In this review, we present general ideas derived from the various reports mentioning toxic effects. Most importantly, lipophilic hydrocarbons accumulate in the membrane lipid bilayer, affecting the structural and functional properties of these membranes. As a result of accumulated hydrocarbon molecules, the membrane loses its integrity, and an increase in permeability to protons and ions has been observed in several instances. Consequently, dissipation of the proton motive force and impairment of intracellular pH homeostasis occur. In addition to the effects of lipophilic compounds on the lipid part of the membrane, proteins embedded in the membrane are affected. The effects on the membrane-embedded proteins probably result to a large extent from changes in the lipid environment; however, direct effects of lipophilic compounds on membrane proteins have also been observed. Finally, the effectiveness of changes in membrane lipid composition, modification of outer membrane lipopolysaccharide, altered cell wall constituents, and active excretion systems in reducing the membrane concentrations of lipophilic compounds is discussed. Also, the adaptations (e.g., increase in lipid ordering, change in lipid/protein ratio) that compensate for the changes in membrane structure are treated.
Biodegradation was considered to be a feasible approach to remediate petroleum hydrocarbon-contaminated soil from a site at the University of Idaho. Before a full-scale treatment process was designed, the biodegradative capacity of the soil's indigenous microorganisms was tested. Gas chromatography was used to measure gasoline vapor components in the headspace above the contaminated soils held in closed containers. In a study of biodegradation kinetics, gasoline degradation rates under various conditions (different soil cores, temperatures, oxygen concentrations, and nutrient concentrations) were tested. It was found that gasoline hydrocarbons could be biodegraded at relatively high rates after appropriate nutrient additions. An unexpected observation was that the optimal concentration of oxygen for the gasoline-degrading microorganisms in these soils was only 10%.
Blow out of Trecate 24 crude oil well: how bioremediation techniques are solving a major environmental emergency in a valuable agricultural area
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