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![Schematic showing different components and zones of a UASBR system. (Figure reproduced following van Haandel and Lettinga 1994, [63]).](profile/Mahbuboor-Choudhury/publication/331258675/figure/fig2/AS:728782541434894@1550766706671/Schematic-showing-different-components-and-zones-of-a-UASBR-system-Figure-reproduced.png)
Schematic showing different components and zones of a UASBR system. (Figure reproduced following van Haandel and Lettinga 1994, [63]).
Source publication
The up-flow anaerobic sludge blanket (UASB) process has emerged as a promising high-rate anaerobic digestion technology for the treatment of low-to high-strength soluble and complex wastewaters. Sewage, a complex wastewater, contains 30-70% particulate chemical oxygen demand (COD P). These particulate organics degrade at a slower rate than the solu...
Context in source publication
Context 1
... UASB process has been successfully implemented as a high-rate anaerobic technology for the treatment of low to high strength soluble wastewaters as well as complex wastewaters [56,57]. The up-flow anaerobic sludge blanket reactor (UASBR) schematic diagram, shown in Figure 2, indicates two parts in the reactor: (a) a vertical column, and (b) a gas-liquid-solid phase separator, which is placed in the upper section and divides the reactor into a lower (digestion zone) and an upper section (the settling zone) [58,59]. The sewage, introduced uniformly from the bottom of the reactor, passes through the sludge bed and enters into the settling zone via openings between the phase separator elements. ...
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Background
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Citations
... Although the highest SMY was observed when food waste was mixed in a major proportion, fruit and vegetable waste was also found to contain the highest amounts of lignin and hemicelluloses. The degradation rates of these organic materials are known to be slow, and considered to be the rate-limiting step during AD of materials with high lignocellulosic contents [44]. Additional pre-treatment such are thermal hydrolysis, chemical, or ultrasonic methods may be required to improve the PVSR during the AcoD of fish sludge mixed with high proportions of lignocellulose-rich food waste, as it improves the surface area of soluble organic matter through reduced particle size, leading to an increase in the methane yield and removal of organic content of the substrate [45]. ...
Anaerobic co-digestion (AcoD) of fish sludge (FS) with food waste (FW), and fruit and vegetable waste (FVW) for biogas and methane production was optimised in small-scale bioreactors, and batch and semi-continuous pilot-scale digesters, under mesophilic (37 ℃) conditions. An experimental mixture design was first applied to small-scale biomethane potential (BMP) tests, to determine the optimal mixture proportions of the AcoD of FS, FW, and FVW that maximise the specific methane yield (SMY in NmLCH4 gVS⁻¹). The optimal mixture proportion was 67%FS:18%FW:19%FVW (w/w), producing 401 mLCH4 gVS⁻¹, which was 8 times higher than the SMY when FS was mono-digested (48 mLCH4 gVS⁻¹). The SMY achieved in batch pilot-scale digesters were 70–82% of methane yields obtained in BMP tests under the same operating conditions, with stable biogas production and no apparent inhibition during the batch run. Semi-continuous operation of the pilot-scale digester was undertaken with organic loading rates (OLRs) of 1, 2, and 3 gVSL-1d-1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$gVS{L}^{-1}{d}^{-1}$$\end{document}, provided intermittently. However, the digester did not achieve stable biogas production at all of the evaluated OLRs, due to the intermittent feeding and accumulation of volatile fatty acids (VFAs): Improved process stability was achieved at an OLR of 2 gVSL-1d-1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$gVS{L}^{-1}{d}^{-1}$$\end{document}, compared to OLRs of 1 and 3 gVSL-1d-1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$gVS{L}^{-1}{d}^{-1}$$\end{document}. Optimisation of the AcoD process resulted in attractive biomethane yields from FS with FW and FVW co-feeds, indicating that producing biogas from co-digestion of FS with relevant substrates is a valuable managing tool for FS, while simultaneously providing renewable energy. The work provides novel data that elucidated optimal proportions in which to combine FS, FW and FVW to obtain optimal biogas production, and provided important new information relevant for the scale up and continuous operation of an AD process for treating FS.
Graphical Abstract
... Increasing temperature can influence biological process and chemical reactions, which can improve degradation rates, and finally, increasing temperature can improve particle settling properties by influencing flocculation and sedimentation (Wang et al., 2020a(Wang et al., , 2020b. As microbial activity increases, the capacity of a reactor to handle organics decreases and requires a smaller digester (Rajagopal et al., 2019). ...
... scale anaerobic digester Development and use of low-cost AD methods for the treatment of organic municipal solid waste (OMSW) Martí-Herrero et al. (2019)Sequencing batch reactor Optimal operating conditions (e.g., OLR, HRT, cycle length)Rajagopal et al. (2019) ...
Anaerobic digestion has emerged as a promising technology for the treatment of food waste as a result of its ability to produce renewable energy and mitigate environmental concerns. This article explores the challenges associated with waste food and proposes feasible solutions with future directions to improve its efficiency and sustainability. The main challenge in the AD process is the variable composition of waste food, including moisture content, nutritional content, and the presence of inhibitory substances (lipids and high ammonia) that lead to process instability. Fast-less feasible solutions include pretreatment techniques to improve substrate degradability, co-digestion with complementary substrates, and optimization of process parameters. Future directions for the anaerobic digestion of waste food involve the integration of emerging technologies, i.e. in situ product recovery, bioelectronic systems, and hybrid systems to maximize resource recovery and energy generation. In addition, efficient monitoring development, control systems, modeling tools, and comprehensive technoeconomic assessments will aid in the optimization and scale-up of anaerobic digestion facilities. Furthermore, optimizing process parameters, such as temperature, pH, and hydraulic retention time, has proven effective in enhancing AD performance. Overall, this review article provides information on challenges faced by waste food anaerobic digestion presents feasible solutions, and highlights future directions to explore process parameters, pretreatment methods, innovative monitoring and control solutions, process modeling tools, and techno-economic assessments that will facilitate the efficient operation and scalability of waste food anaerobic digestion systems.
... UASB reactors generate methane, which provides energy recovery along with the treatment of wastewater [82]. Moreover, UASB reactors have low sludge production, minimizing the costs involved in its treatment and the inconveniences related to their handling and disposal [83]. On the other hand, the UASB technology has some disadvantages that need to be addressed, such as slow startups (mitigated by inoculation with granular biomass) and the required treatment of effluent for the removal of nutrients and pathogens [83]. ...
... Moreover, UASB reactors have low sludge production, minimizing the costs involved in its treatment and the inconveniences related to their handling and disposal [83]. On the other hand, the UASB technology has some disadvantages that need to be addressed, such as slow startups (mitigated by inoculation with granular biomass) and the required treatment of effluent for the removal of nutrients and pathogens [83]. Indeed, substantial quantities of pathogenic organisms such as Cryptosporidium and Giardia have been identified in UASB effluents [84], which could lead to human and environmental health concerns. ...
... UASB reactors generate methane, which provides energy recovery along with the treatment of wastewater [82]. Moreover, UASB reactors have low sludge production, minimizing the costs involved in its treatment and the inconveniences related to their handling and disposal [83]. On the other hand, the UASB technology has some disadvantages that need to be addressed, such as slow start-ups (mitigated by inoculation with granular biomass) and the required treatment of effluent for the removal of nutrients and pathogens [83]. ...
Nowadays, the discharge of wastewater is a global concern due to the damage caused to human and environmental health. Wastewater treatment has progressed to provide environmentally and economically sustainable technologies. The biological treatment of wastewater is one of the fundamental bases of this field, and the employment of new technologies based on granular biofilm systems is demonstrating success in tackling the environmental issues derived from the discharge of wastewater. The granular-conforming microorganisms must be evaluated as functional entities because their activities and functions for removing pollutants are interconnected with the surrounding microbiota. The deep knowledge of microbial communities allows for the improvement in system operation, as the proliferation of microorganisms in charge of metabolic roles could be modified by adjustments to operational conditions. This is why engineering must consider the intrinsic microbiological aspects of biological wastewater treatment systems to obtain the most effective performance. This review provides an extensive view of the microbial ecology of biological wastewater treatment technologies based on granular biofilms for mitigating water pollution.
... An upflow anaerobic sludge blanket (UASB) reactor is a popular technology; however, it cannot remove harmful organic compounds and nitrogen from natural rubber production wastewater [10,11]. This has led to the application of conventional activated sludge as a posttreatment option for anaerobic treatment systems to improve the effluent quality [12][13][14]. The aerated tank has superior organic and nitrogen removal efficiency; however, the process requires high electricity input for oxygen supplementation and produces large amounts of excess sludge [15]. ...
Effluent from the rubber industry contains 2-mercaptobenzothiazole (2-MBT) as the major persistent pollutant. To remove 2-MBT, this study investigated the bioaugmentation of activated sludge with a 2-MBT-degrading bacterial consortium, which was previously enriched from rubber wastewater sludge. The consortium was immobilized in a commercial porous carrier to increase its efficiency and stability. The 16S rRNA gene analysis showed that the dominant Pseudomonas spp. and Stenotrophomonas spp. were maintained when it was repeatedly used for 4 cycles in a minimal medium containing 300 mg L−1 2-MBT. For bioaugmentation, a stirred tank reactor containing the immobilized consortium and activated sludge at a 1:2 mass ratio was constructed and found to remove 88.2 % of 100 mg L−1 2-MBT from synthetic wastewater. When the rubber industrial wastewater was applied at an organic loading rate (OLR) range of 1.0–3.0 kg COD m−3 d−1, the bioaugmentation reactor had 2-MBT and COD removal efficiencies of 70–79 % and 83–96 %, respectively. The reactors with either immobilized consortium or activated sludge alone had lower treatment efficiency. The bacterial community and its predicted functions corresponded to the activity of the added consortium and the operation of the reactor. Consequently, bioaugmentation should be applied to activated sludge for the treatment of rubber wastewater.
... Considering the complexity of MW and that consequently hydrolysis is the limiting step in its anaerobic digestion, the present HD was designed to operate under up flow and hydrolyticacidogenic conditions. This implied a low hydraulic retention time and sufficient solid retention time for the development of hydrolytic and acidogenic bacteria while the methanogenic phase is reduced or suppressed [30,31]. ...
... The characteristics (physical, chemical, biological, and operational features) of influent wastewater greatly influence the performance of the activated sludge process (ASP). The operational features include volatile suspended solid (VSS), organic load, dissolved oxygen, microorganism food ratio (F/M), mixed liquor volatile suspended solid (MLVSS), sludge retention time (SRT), hydraulic retention time (HRT), sludge return ratio, and surface hydraulic load (Latif et al. 2011;Rajagopal et al. 2019). The ASP of aeration tank is the main source of carbon dioxide (CO 2 ) and CH 4 which is estimated to be around (20.5 kg CO 2 -eq-d − ) is the main greenhouse gas largely contributing to global warming (Ahmad and Ghufran 2019;Islam et al. 2023). ...
This review covers the technological measures of a self-sustainable anaerobic up-flow sludge blanket (UASB) system compared with an aerobic activated sludge process (ASP) for wastewater treatment plants (WWTPs). The ASP requires a huge amount of electricity and chemicals and also results in the emission of carbon. The UASB system, instead, is based on greenhouse gas (GHG) emission reduction and is associated with biogas production for cleaner electricity. WWTPs including the ASP system are not sustainable due to the massive financial power required for clean wastewater. When the ASP system was used, the amount of production was estimated to be 10658.98 tonnes CO2eq-d- of carbon dioxide. Whereas it was 239.19 tonnes CO2eq-d-1 with the UASB. The UASB system is advantageous over the ASP system as it has a high production of biogas, needs low maintenance, yields a low amount of sludge, and is also a source of electricity that can be used as a power source for the WWTPs. Also, the UASB system produces less biomass, and this helps in reducing costs and maintaining work. Moreover, the aeration tank of the ASP needs 60% of energy distribution; on the other hand, the UASB consumes less energy, approximately 3-11%.
... Because there is no turbulence in the settler compartment, settlement takes place there. When solids reach the settler, they stay there for a while before slipping back into the sludge bed [90,91]. The key benefits of this reactor are its low sludge formation rate, simple design, high organic load handling capacity, and cheap operating and maintenance costs [92]. ...
... Schematic diagram of different components and zones of a UASB reactor[90]. ...
Clothing, one of the basic needs, demands the growth of textile industries worldwide, resulting in higher consumption and pollution of water. Consequently, it requires extensive treatment of textile effluent for environmental protection as well as reuse purposes. Primary treatment, secondary treatment, and tertiary treatment are the three major phases of textile wastewater treatment. Secondary treatment under aerobic and anaerobic circumstances is carried out to decrease BOD, COD, phenol, residual oil, and color, whereas primary treatment is utilized to remove suspended particles, oil, grease, and gritty materials. However, biological treatment is not fully capable of treating water according to discharge/reuse standards. Hence, tertiary treatment is used to remove final contaminants from the wastewater. Adsorption is regarded as one of the most feasible processes for dye and metal removal in consideration of cost and variation in the adsorbent. Though membrane filtration is an efficient process, the cost of operation limits its application. It’s unfortunate that there isn’t a universally applicable treatment solution for textile effluents. Therefore, the only flexible strategy is to combine several therapy modalities. Treatment of complicated, high-strength textile wastewater depending on pollutant load will be more successful if physical, chemical, and biological approaches are used in tandem. Enforcement of stringent environmental regulation policies, increasing costs and demand for freshwater, and the rising costs and difficulties associated with wastewater disposal are accelerating efforts toward achieving ZLD. Additionally, research into methods for extracting useful materials from wastewater has blossomed in recent years. As such, the purpose of this analysis is to give a holistic overview of textile wastewater treatment systems, with a focus on zero liquid discharge (ZLD) and efficient resource recovery, both of which may hasten the transition to more sustainable water management.
... Granular biomass's slow rate of production and growth, which necessitates prolonged start-up times, is one of the most severe drawbacks. The start-up phase could be shortened by inoculating already-granulated biomass (Rajagopal et al. 2019). This method also has difficulties operating the three-phase separation and the potential for foam and sludge washout. ...
Rapid developments are habitually connected with substantial wastewater production (sources- municipal, textile, landfill, digester reject, saline industry, tannery, greywater, petroleum, pharmaceuticals, coal gasification, etc.), which contains different pollutants like nitrogen, phosphorous, carbon, heavy metals, emerging pollutants (pharmaceuticals, personal care products, endocrine disruptive compounds) and others. In this critical situation and rising water demand, biological techniques are the need of the hour for wastewater treatment and reuse, thereby protecting the environment. This paper highlights the most used bioreactors like Biofilter, Vermifiltration, MFC, MBBR, UASB, and MBR and their unique features. Additionally, details like intermediates, microbiology, operational conditions, mechanisms, implications, advantages, recent advancements, shortcomings, and removal efficiency of target pollutants (carbon, nitrogen, phosphorous- CNP; emerging contaminants- pharmaceuticals, personal care products, endocrine disruptive compounds) were discussed. The traditional and advanced versions of those bioreactors were also emphasized. Moreover, the review highlights different case studies related to the reuse scope of treated water that must be addressed for upcoming expansions and large-scale application of biological techniques in water reuse and the further development of hybrid systems. MFC is a well-known treatment technology for removing pollutants from wastewater when undertaken on a small scale; however, attempts should be made to make it successful on a larger scale. In Vermifiltration, further attempts must to be conducted to develop and design of robust systems as earthworms are sensitive to temperature and moisture.
... Municipal wastewater treatment is the process of removing different contaminants from municipal wastewater in order to reuse or for release into the environment without any causative agents like bacteria, viruses, and parasites (including worms and protozoans) which are considered as hazardous pathogens to humans. For the treatment of municipal wastewater, many treatment methods such as trickling filters, activated sludge process, oxidation ponds, and up flow sludge blanket are used (Dhokpande et al. 2014;Hamaidi-Chergui et al. 2014;Butler et al. 2017;Rajagopal et al. 2019;Yang et al. 2019). These technologies are very expensive due to the expenses of building, maintenance and repair, as well as the costs of hiring experienced personnel for attentive operation (Bhamidimarri et al. 1991;Mburu et al. 2013). ...
The objective of this study was to investigate the potential for pollutant removal in a pilot-scale horizontal flow polyculture constructed wetland functioning in an arid region during different seasons. The analyzed system is located in the southeast of Algeria, where the climate is arid. During the research, 32 samples of sewage were collected from both the inflow and the outflow of the constructed wetland (CW). The effluent Biological Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Total Suspended Solid (TSS), Ammonia-Nitrogen (NH4-N) and Ortho-Phosphate-Phosphorus (PO4-P) from all of the treatments were significantly lower than the influent and had a removal efficiency of 71.83, 73.75, 82.77, 80.29 and 59.49% respectively. The results showed that pollution removal efficiency in the tested CW system was affected by the season (air temperature and sunlight hours). It was observed that the removal rate of pollutant indicators was higher in summer and autumn compared to winter and spring. Finally, these findings confirmed that CW with polyculture would be an excellent candidate for treating domestic wastewater in rural settlements under arid environments.
HIGHLIGHTS
The CWs with polyculture would be an excellent candidate species for treating domestic wastewater.;
The CWs have aesthetic, ecological, and cultural benefits in addition to being very efficient and robust.;
The performance of constructed wetland is heavily influenced by weather conditions.;
According to Algerian and international norms, the effluent characteristics of constructed weatland were adequate for irrigation.;
... According to a review report, domestic sewage contains both particulate and dissolved organics. These particulate organics are mostly found in the form of organic polymers, which degrade at a slower rate (Rajagopal et al., 2019). Domestic sludge's gas generating potential is so reduced. ...
... This has also been demonstrated in studies on the effects of pre-hydrolysis presence and absence on sewage treatment using an AD system. According to the study (Rajagopal et al., 2019), this pre-treatment improves bio-methane potential, solid reduction, and digestate disposal. ...
Technologies with resource recovery alternatives are suggested in metropolitan settings. Anaerobic digesters (AD) are the most common. The use of microcrystalline cellulose and a variety of grocery products as control feed increases the cost of bio methane potential analysis (BMP). This limits its replication, especially in developing countries. As a result, this study looks into the use of milled paper as a control feed during BMP analysis of sludge from sewer and exchange stations.
A batch experimental study at 37 °C with hydraulic retention times of 23 and 24 days for exchange station and sewage sludge, respectively, was established for the assessment. The pH of the sewage sludge was acidic during the analysis. To avoid underestimating the total (TS) and volatile solid (VS) ratios, the VS should indeed be determined through temperature or pH adjustment. As a result, the preceding alternative was implemented in this work.
According to the findings of the online biogas application, the blank (milled paper) accurately keeps the required validation standards. Furthermore, the gas production potential of sludge from the exchange station (ES) and the sewage line (SS) is 2.4 and 1.6 NL/gVs, respectively. The generated gas has an electric potential of 8.81 and 3.35 KWH for ESS and SS, respectively. Interestingly, the calorific values of the investigated substrates were also nearly equivalent.
In brief, using milled paper as a control feed in BMP analysis reduces laboratory costs and encourages BMP test repetition, which is especially important in developing countries. This advances research on the use of AD in the search for alternative energy sources.
