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Effect of co-disposal of wastes containing organic pollutants with municipal solid waste—A landfill simulation reactor study
Abstract
Different phases of the life cycle of a landfill receiving municipal solid waste (MSW) were monitored in landfill simulation reactors (LSRs) with the aim of investigating the effects of co-disposal of wastes containing organic pollutants (OPs) with MSW. Two LSRs out of four filled with well-characterised MSW received waste materials containing OPs. These included two types of plasticised PVC flooring materials, freon-blown insulation and phosphorus- and nitrogen-based flame-protected materials. Each of the two LSRs was operated under acid fermentative and neutral methanogenic conditions, respectively as were their corresponding controls, i.e. without extra OP. The methanogenic consortia degrading MSW were hampered by the addition of wastes containing OPs, probably due to the presence of Freon R11 and its degradation product, R21. The concentrations of R11 and R21 ranged between 0.1 and 1800 mg m−3 depending on the biogas production rate in the OP-amended LSRs. Losses of butylbenzyl- (26%) and bis(2-ethylhexyl)phthalate (15%) from one of two flooring materials was observed, whereas the other remained unaffected. Methanogenic conditions favoured the loss of plasticisers as compared to acidogenic conditions. Total phosphorus was significantly higher in the OP-spiked LSRs, which indicated a transformation of the non-halogenated flame-retardants.
... Efforts have been made by various investigators, e.g. Lagerkvist (1995), Ejlertsson et al. (1996Ejlertsson et al. ( , 2003 and Mersiowsky et al. (2001), to elucidate processes involved in the leaching and transformation of hazardous compounds in landfills by studying them in laboratory-scale landfill simulation reactors (LSRs). However, although they are obviously much smaller than landfills these LSRs are sufficiently large to require several years to proceed through the ageing phases that typically occur in landfills (see below). ...
... In PVC plastic the PAEs have relatively long sidechains and, thus, are hydrophobic. PAEs of lower hydrophobicity, i.e. with shorter sidechains, are used as solvents inter alia in glues and paints (Ejlertsson et al., 2003), cosmetics, paint adhesives, cardboard, lubricants, fragrances and polymers, e.g. cellulose, polyvinyl acetate and polyurethane (Graham, 1973). ...
... Since the model waste and the products were unused/fresh its contents of microorganisms were much lower than those of real household waste. Therefore, the METS were seeded with an inoculum formed from a combination of garden soil, waste from Filborna landfill site (Helsingborg, Sweden), waste from mature LSRs (described in Ejlertsson et al. 2003) and thermophilic household compost. The 1L glass bottles, used as methanogenic leachate reactors, were filled with the same inoculum and water, then in addition to serving as leachate reservoirs they provided a means to force the progression from acidogenic to methanogenic conditions in the 3L jar. ...
... The leachate contains dissolved or suspended components originated in the waste matrix. Uncontrolled leachate migration fluxes downwards, and in addition to unpredictable concentration levels is capable of producing permanent damage to the public health, water, soil, flora and fauna (Ejlertsson et al., 2003). ...
... It is of crucial importance to start running programmes to separate hazardous domestic waste from the MSW stream, as it is known that HHW might have a detrimental effect on the MSW degradation process (Ejlertsson et al., 2003). In México, a rapid evolution of open dumps to sanitary landfills is taking place (Robinson et al., 2003), and the production of greenhouse gases (CH 4 and CO 2 ) should be controlled. ...
... In addition, organic pollutants coming from paints, plastics, pesticides, solvents, and the like undergo a range of biotic and abiotic processes. These reactions produce organic and inorganic compounds in the liquid and gaseous phases of the anaerobic decomposition and affect not only MSW mineralization (Ejlertsson et al., 2003) but the atmosphere and public health (Ö man and Hynning, 1993). Domestic HW, represented by the mentioned containers, contributes to the environment with chemical substances, but specific formulations or quantities are unknown, and so it is the synergistic effect they produce when co-disposed. ...
Household hazardous waste (HHW) generation in two Mexican regions was examined, a northern region (bordering with the USA) and a central region. The aim of this work was to determine the dynamics of solid waste generation and to be able to compare the results of both regions, regarding consumption patterns and solid waste generation rates. In the northern region, household solid waste was analysed quantitatively. In order to perform this analysis, the population was categorized into three socioeconomic strata (lower, middle, upper). Waste characterization revealed the presence of products that give origin to household hazardous waste. In the northern region (Mexicali city), household hazardous waste comprised 3.7% of municipal solid waste, the largest categories in this fraction were home care products (29.2%), cleaning products (19.5%) and batteries and electronic equipment (15.7%). In the central region, HHW comprised 1.03% of municipal solid waste; the main categories in this fraction were represented by cleaning products (39%), self care products (27.3%), and insecticides (14.4%). In Mexicali, the socioeconomic study demonstrated that the production of HHW is independent of the income level. Furthermore, the composition of the solid waste stream in both regions suggested the influence of another set of variables such as local climate, migration patterns and marketing coverage. Further research is needed in order to establish the effect of low quantities of HHW upon the environment and public health.
... VFA. Volatile fatty acids (VFA) were analyzed by way of gas chromatography. The samples were prepared and analyzed according to Ejlertsson et al (2003). The chromatograms that resulted were altered in accordance with the internal standard and the VFA concentrations were obtained. ...
... Calculating the values for Cu, we see 1.0 g/ kg P, 1.1 g/ kg P and 1.1 g/ kg P for reactors TW, RW and SW. The Cu values for cattle and swine fertilizer were 3.9 and 7.6 g/ kg P respectively (Ejlertsson, 2003). These two calculations illustrate that the heavy metals content of the sludge from the experimental biogas reactors all contain lower concentrations of Cd and Cu than do traditional cattle and swine fertilizers. ...
... Digester failure may happen under a high organic loading rate. Ejlertsson et al. (2003) have shown that addition of methanogenic inoculum can remove a few years of delay in solids decomposition in a landfill-simulating reactor by decreasing volatile fatty acids (VFA) concentration. This is in accordance with the observations of Barlaz et al. (1989), who concluded that, initially, acetate utilization, but ultimately polymer hydrolysis, limits the rate of methane production during solids decomposition. ...
... Moisture content, particle size, waste density, leachate recirculation, and neutralization are other important parameters affecting the rate of waste degradation (Barlaz et al., 1990). From the results presented by Ejlertsson et al. (2003), one may conclude that intermittent initial aeration, which removes easily degradable waste and prevents inhibition by high VFA concentrations, is an efficient way to enhance the development of anaerobic decomposition of more recalcitrant waste in landfills. For that, part of the initial methanogenic centers should survive in spite of the toxic aerobic environment produced by intermittent aeration. ...
Batch anaerobic codigestion of municipal household solid waste (MHSW) and digested manure in mesophilic conditions was carried out. The different waste-to-biomass ratios and intensity of mixing were studied theoretically and experimentally. The experiments showed that when organic loading was high, intensive mixing resulted in acidification and failure of the process, while low mixing intensity was crucial for successful digestion. However, when loading was low, mixing intensity had no significant effect on the process. We hypothesized that mixing was preventing establishment of methanogenic zones in the reactor space. The methanogenic zones are important to withstand inhibition due to development of acids formed during acidogenesis. The 2D distributed models of symmetrical cylinder reactor are presented based on the hypothesis of the necessity of a minimum size of methanogenic zones that can propagate and establish a good methanogenic environment. The model showed that at high organic loading rate spatial separation of the initial methanogenic centers from active acidogenic areas is the key factor for efficient conversion of solids to methane. The initial level of methanogenic biomass in the initiation centers is a critical factor for the survival of these centers. At low mixing, most of the initiation methanogenic centers survive and expand over the reactor volume. However, at vigorous mixing the initial methanogenic centers are reduced in size, averaged over the reactor volume, and finally dissipate. Using fluorescence in situ hybridization, large irregular cocci of microorganisms were observed in the case with minimal mixing, while in the case with high stirring mainly dead cells were found.
... Recently, important features of waste management studies have been the study of the process, characteristics, and patterns of landfill pollution. Such types of studies have used landfill simulation reactors (LSRs) to get a more realistic picture of waste degradation and leaching (Ejlertsson et al., 2003;Ledakowicz and Kaczorek, 2004;Sponza and Ağdağ, 2004). During the simulating phases, organic matter of waste is broken down in to small and converted to the gaseous and liquid phase. ...
Water hyacinth (WH), Eichhornia crassipes, is considered a noxious weed in many parts of the world as it grows very fast and depletes nutrients and oxygen rapidly from water bodies, adversely affecting flora and fauna. This study investigates the effect of biogas production in an anaerobic floating drum biogas reactor by using the combination of cow dung and water hyacinth as feedstock. The study was divided into 2 phases. In phase-I, eleven batch reactors are established and feed with varying the combination of cow dung and water hyacinth from 0,10,20,30,40,50,60,70,80,90 and 100% on the dry weight of water hyacinth and cow dung. In phase-II two continuous reactors were established with the best combinations from the phase-I study, the production of biogas was studied by continuous feeding process until the daily production of biogas attains a constant value. The performance of the reactor was monitored by analyzing the daily variations in parameters like VFA (volatile fatty acids) pH, temperature, biogas produced and total solids et.al. The results show that biogas production was possible with water hyacinth and it was seen that the reactors with 90% water hyacinth and 100% water hyacinth gave good results in terms of biogas production. The biogas production rate varies from 20-25L/kg of dry solids of water hyacinth. The percentage of methane found in biogas was 40-45% by using gas chromatography.
... Recently, important features of waste management studies have been the study of the process, characteristics, and patterns of landfill pollution. Such types of studies have used landfill simulation reactors (LSRs) to get a more realistic picture of waste degradation and leaching (Ejlertsson et al., 2003;Ledakowicz and Kaczorek, 2004;Sponza and Ağdağ, 2004). During the simulating phases, organic matter of waste is broken down in to small and converted to the gaseous and liquid phase. ...
Among the listed aquatic weeds Water hyacinth (Eichhornia crassipes) is one of the weeds that can double its size in 6–28 days, by forming a mat like structure on the water obstructing the sunlight. This plant affects the aquatic ecosystem (Malik, 2007). Any fresh water body has a potential threat from these types of aquatic weeds. Several control measures are added to the scientific journals among them one of the methods is using these weeds as a feed stock for the anaerobic digestion to produce biogas. Water hyacinth is suitable for anaerobic digestion process due to its carbon nitrogen ratio. Using weeds as a feedstock and converting them to useful bio-fuel may reduce the load on the conventional power generation processes from air, water and solar energy sources (Rao et al., 2010). The biogas producing capacity of the biodegradable wastes like weeds and agricultural wastages is estimated to be 40,734 m³ year in India (Rao et al., 2010). By using the mixture of cattle dung and Water hyacinth will lead to better biogas production (Kumar, 2005). The present study summons the usage of Water hyacinth in anaerobic digestion process. For better yield of biogas, cow dung was used in combination with Water hyacinth.
... Recently, important features of waste management studies have been the study of the process, characteristics, and patterns of landfill pollution. Such types of studies have used landfill simulation reactors (LSRs) to get a more realistic picture of waste degradation and leaching (Ejlertsson et al., 2003;Ledakowicz and Kaczorek, 2004;Sponza and Ağdağ, 2004). During the simulating phases, organic matter of waste is broken down in to small and converted to the gaseous and liquid phase. ...
Plastic waste is one of the major environmental concerns. Eight million to 12.7 million tonnes are dumped into the sea (https://www.sas.org.uk/our-work/plastic-pollution/plastic-pollution-facts-figures/). If plastic wastes are thrown in the land, it makes the soil less fertile and it also pollutes water and harms sea life. Plain concrete has a limited ductility and resistance to cracking (https://theconstructor.org/concrete/). The addition of fibres can improve the properties of concrete. These fibres are uniformly dispersed into the concrete mix which increases its structural integrity. This type of concrete is known as fibre reinforced concrete. This can be natural, animal fibres or polymers. Incorporating plastic into concrete is one possible environmentally friendly approach for their safe disposal. Polyethylene terephthalate is one of the most important and extensively used plastics in the world. PET (polyethylene terephthalate) is a form of polyester that is extracted or moulded into plastic bottles and containers (https://www.worldbank.org/en/news/immersive-story/2018/09/20/what-a-waste-an-updated-look-into-the-future-of-solid-waste-management). PET as fibre reinforcement in structural concrete can provide crack control and ductility enhancement for concrete (Kim et al., 2010). In recent years, a lot of experimental studies were carried out on using waste plastic bottles. The use of PET bottle fibres has a positive effect on the properties of the concrete (Subramani and Fizoor Rahman, 2017). PET-fibres as the partial replacement of aggregate in the Portland cement aggregate concrete. It shows an increase in compression and tensile strength (Ramadevi and Manju, 2012). Akcaözoglu et al. (2010) shredded waste PET bottles granules and used it as a lightweight aggregate in mortar. It was concluded that the use of shredded waste PET granules as aggregate resulted in the production of structural lightweight concrete. The PET-fibres increase the durability of concrete and it can be used to improve the ductility of the concrete (Foti, 2011). Long term durability performance of recycled PET-fibre reinforced cement composite can be achieved (Won et al., 2010). In this study, the effect of different sizes of PET fibres on concrete was evaluated. These PET fibres are produced from PET bottles. Also, the study of strength and failure mode of PET-fibres reinforced concrete is performed.
... Mechanical recycling is a method of re-processing plastic wastes employing comparatively high energy along with additives producing recycled product (Ejlertsson et al., 2003;Klink & Ham, 1982;Scaffaro et al., 2019). This method comprises of collection, sorting out, and reprocessing of polymers into recycled products. ...
Inefficient solid waste management of plastics and polymeric materials is one of the global challenges leading to environmental deterioration. This challenge has brought alarming concern to minimize volume of such wastes released into the environment. The concern proposes a solution to the existing problems to some extent by reuse, recycling, and efficient conversion of waste materials into alternative application. Chemical and thermo-mechanical conversion of plastic wastes into energy and their biodegradation were taken into account. Consequently, some newly employed recycling and conversion techniques of plastic wastes, and possible future alternatives with recommendations are reviewed in this article
... The significant features of waste management studies have been the study of the process, characteristics, and patterns of landfill pollution. Such studies have used landfill simulation reactors (LSRs) and lysimeters to obtain a more realistic picture of waste degradation and leaching (Ejlertsson et al., 2003;Mahar et al., 2016;Rafizul and Alamgir, 2012;Sponza and Ağdağ, 2004;Wang et al., 2012b). Few studies have explored tropical seasonal variation on leachate variability and favourable methanogenic conditions (Rafizul and Alamgir, 2012;Wang et al., 2012a). ...
Quantification, measurement of quality, post-treatment, and leachate control has been a significant problem due to the dumping of waste in an unscientific manner across the globe, and especially in developing countries like India. In this context, the objective of this study was to investigate the degradation of fresh mixed municipal solid waste (MSW) in an anaerobic landfill reactor operated with rainfall addition in laboratory conditions. Experiments were carried out in a landfill reactor of 1 m length × 1 m width × 1.1 m height. The reactor was simulated with 50 years weighted average actual rainfall rate of India. It contained the waste composition of 73% wet waste (food and kitchen) and 27% dry waste (paper, plastic, wood, textiles, and others). The leachate parameters were continually monitored for 39 weeks. In the fresh MSW landfill reactor it was evident that concentrations of leachate parameters were high initially, and there was a significant decrease in BOD5 (7041-39310 mg L-1), COD (15692-71630 mg L-1) and TS (9077-33200 mg L-1) in leachate. Therefore, rainfall had a direct influence on leachate quality. The developed first-order decay models were used for BOD5, COD, and total solids with adjusted R2 of 0.83, 0.92, and 0.96, respectively. Therefore, this model can be applied for leachate strength estimation at any given time from the period of deposition of waste under similar rainfall and waste compositions, and is largely applicable in India and tropical areas. This study is expected to be a good simulation for cities with the waste composition of high wet waste (>70%) as the estimations of important design parameters such as BOD5, COD, VFA, and NH4+-N were studied in this research. As the importance of moisture (precipitation) has been established in this study, some moisture additions can be designed in areas with low rainfall, such as arid zones.
... AOX is a sum parameter used as a proxy for persistent organic pollutants in water. Possible sources of AOX include landfilling with high organic waste fraction [39], open dumping and burning practices [40], or other sources including sludge and sewage infiltration [41,42]. It is worth mentioning that the use of AOX as an indicator of pollution is disputed by a portion of the scientific community [43]. ...
Lebanon is affected by a protracted environmental and solid waste crisis that is threatening the water resources and the public health of its communities. This study is part of a public participatory research project that aims to evaluate the impacts of solid waste disposal practices on water, air, and health in six villages of Lebanon, stigmatized by the presence of a regional landfill. Community mapping enabled the selection and testing of seven springs and three wells in the upstream basin and 11 wells in the lower basin, covering a broad list of chemical, physical, and bacteriological parameters. Two water quality indices (WQ-1 and WQ-2) were used to assess water quality in the study area. The results for the upstream wells and springs showed a significant bacteriological contamination, while the results in the lower wells showed high levels of conductivity, chlorides, and zinc along with the occurrence of organic micropollutants in trace concentrations. The comparison between the experimental data, with the natural background value established in the same area, did not show major differences, except for zinc and bacteriological indicators. The bacteriological contamination is most likely related to sewage infiltration into groundwater at the time of the assessment. Zinc may result from landfill leachate infiltration but also well corrosion. Saltwater intrusion affecting the coastal basin is masking the results for conductivity, chlorides, and sulfates, whereas the presence of small traces of organic micropollutants in the coastal aquifer may be related to leachate infiltration. WQI-1 results, which included bacteriological indicators, showed highly degraded water quality in the C1-C3 inner basin. In contrast, WQI-2, which includes physio-chemical indicators only, showed good water quality, slightly deteriorating in the coastal area, downstream of the Naameh landfill.
... Recently, important features of waste management studies have been the study of the process, characteristics, and patterns of landfill pollution. Such types of studies have used landfill simulation reactors (LSRs) to get a more realistic picture of waste degradation and leaching (Ejlertsson et al., 2003;Ledakowicz and Kaczorek, 2004;Sponza and Ağdağ, 2004). During the simulating phases, organic matter of waste is broken down in to small and converted to the gaseous and liquid phase. ...
Plastic waste is one of the major environmental problems, as the amount of plastic waste increases in the environment with the increase in population. The plastic waste is not easily disposable as it lasts in the environment for more than 1000 years. The reuse of plastic waste is not only economical but also helps in reducing the disposal problem around the world. Several studies were performed to identify safe and environment-friendly methods for disposing of plastics. Reuse of waste plastic in the concrete is considered to be one of the best environmental methods for solving the disposal problem. It can also reduce the pollution level in the environment. Plastic waste can be used in concrete for the production of new materials like plastic reinforced concrete. The plastic fibers can be obtained in different ways like cutting bottles or shredding plastic bags. In this study different percentages of plastic fibers were added to the mixed concrete specimen with different percentages of water-cement ratio. Plastic fibers are added in random orientation into the concrete mixtures. Mechanical tests like compressive strength tests and splitting tensile strength tests were done on plastic reinforced concrete after 30 days of curing. The result was compared with the control concrete specimen. The experiment shows that the workability of concrete containing waste plastic begins to decrease as the amount of waste plastic increases. Recycled plastic fibers can be used to produce light-weight concrete with an increase in the volume of the fibers in the concrete and can also enhance the performance of concrete. It also helps in improving the toughness and minimizing plastic shrinkage cracking of concrete. Cracking due to shrinkage was delayed in the plastic reinforced concrete compared to the cracking in the specimen without reinforced fibers which results in the crack controlling of the concrete specimen.
... However, it is difficult to increase the recycling ratio of plastics bags used in express industry due to low recycle value, inconvenience of collection, and the poor waste management in China (Duan et al., 2019;Fan et al., 2017;Rajendran et al., 2012;Verghese et al., 2012). Unrecycled plastic wastes are usually landfilled, incinerated, or otherwise be released into the environment if mismanaged (Ejlertsson et al., 2003;Geyer et al., 2017). However, limited information is currently available to evaluate environmental problems brought by the express plastic wastes. ...
The rapid development of the express industry brings not only convenience but also environmental problems such as plastic wastes. In this study, we collected plastic express packaging bags from major express companies in China to investigate phthalates in them. Infrared spectra indicated that all these samples were made from polyethylene but with different carbonyl index (CI) values. Total phthalates (∑Phthalates) concentrations in these samples ranged from 11.16 to 309.70 μg g-1. Di(2-ethylhexyl) phthalate, di-n-butyl phthalate, and di-isobutyl phthalate were predominant phthalates. The leaching amounts of ∑Phthalates after 48 h ranged from 181.44 to 5320.64 ng g-1. The leaching amounts of ∑Phthalates significantly positively related to ∑Phthalates concentrations of samples, while the leaching ratios presented opposite trends. Concentrations and leaching amounts of ∑Phthalates and major phthalates were significantly higher in samples from high CI value company group than those from low CI value company group. The results of our study indicate that plastic express packaging bags could be a critical source of phthalates. The involving of recycled plastics during the manufacture of plastic express packaging bags may influence the content and composition of phthalates in them and also increase the releasing risk of phthalates.
... Diferentes actividades generan varios tipos de desechos, los cuales afectan de forma particular el medio ambiente al que son arrojados. De tal forma, una planta cosechadora de verduras generará desechos orgánicos, los cuales pueden ser utilizados en un círculo virtuoso de recursos renovables, mientras que otras instancias, como los hospitales, generan residuos que van desde basura convencional hasta materiales peligrosos y bioinfecciosos, cuyo tratamiento inadecuado puede poner en peligro la salud de los diferentes organismos que componen el medio ambiente en el cual son expuestos (Ejlertsson, Karlsson, Lagerkvist & Hjertberg, 2003). ...
El objetivo de esta investigación es determinar la responsabilidad legal que tienen los hospitales en el manejo de los residuos sólidos, peligrosos y bioinfecciosos. Estos desechos, provenientes del aparato nosocomial, a menudo no son tratados según las normas técnicas estipuladas para ello, por lo que no solo se convierten en amplios fómites transmisores de enfermedades, sino que han pasado a formar parte de las grandes acumulaciones de basura que día a día se observan en diferentes partes del país. A su vez, generan desbalances en el medio ambiente, considerando que se suman a la gran acumulación de residuos sólidos en el entorno, transformándose, desde sus vertederos, en generadores de gases de efecto invernadero, sumándose a los problemas ambientales existentes. A menudo esos desechos no son manipulados con el cuido y las recomendaciones estipuladas por el Ministerio de Salud y a la luz de las recomendaciones internacionales. Ha perseguido además establecer si los hospitales están cumpliendo con las medidas de seguridad recomendadas para el manejo de los desechos sólidos, a efecto de delimitar la frontera de su responsabilidad y el inicio de la responsabilidad del recolector.
... It has been reported that plasticisers with high solubility such as dimethyl phthalate (DMP) are released in landfills in greater amounts than hydrophobic plasticisers such as diethylhexyl phthalate (DEHP) (Teuten et al., 2009). Migration of plasticiser decreases when the polymer reaches its glass transition state (Ejlertsson et al. 2003). Alkylphenols are additives with plasticising and stabilising properties (Hahladakis et al. 2018;Teuten et al., 2009). ...
In Europe over 5.25 billion tonnes of waste has been landfilled between 1995 and 2015. Among this large amount of waste, plastic represents typically 5-25 wt% which is significant and has the potential to be recycled and reintroduced into the circular economy. To date there is still however little information available of the opportunities and challenges in recovering plastics from landfill sites. In this review, the impacts of landfill chemistry on the degradation and/or contamination of excavated plastic waste are analysed. The feasibility of using excavated plastic waste as feedstock for upcycling to valuable chemicals or liquid fuels through thermochemical conversion is also critically discussed. The limited degradation that is experienced by many plastics in landfills (>20 years) which guarantee that large amount is still available is largely due to thermooxidative degradation and the anaerobic conditions. However, excavated plastic waste cannot be conventionally recycled due to high level of ash, impurities and heavy metals. Recent studies demonstrated that pyrolysis offers a cost effective alternative option to conventional recycling. The produced pyrolysis oil is expected to have similar characteristics to petroleum diesel oil. The production of valuable product from excavated plastic waste will also increase the feasibility of enhanced landfill mining projects. However, further studies are needed to investigate the uncertainties about the contamination level and degradation of excavated plastic waste and address their viability for being processed through pyrolysis.
... III Fredriksson* A., Nestor G., Svensson B.H. (2003). Effects of an organotin PVC stabiliser on anoxic degradation of organic matter. ...
... The landfill temperature, moisture content/additive water amount, water characteristics (i.e., precipitation rainfall or other water entering landfills), available oxygen, and waste characteristics are among the many factors contributing to gas and leachate generation at landfill sites and subsequently determine the characteristics of LFG and landfill leachate [4,6]. Furthermore, the different forms of degradation are not definitive, since dynamic variations in the environmental conditions result in changes in their distribution and rates within the landfill [4,7,8]. ...
This study was conducted to investigate heat generation in a landfill on a field scale, including the variation of temperatures. Data were collected at Štěpanovice landfill in southwestern Czech Republic. Temperatures were determined over a monitoring period of 21 months. Mean annual value of the difference between outdoor temperature and temperature at a depth of 100 cm in the landfill body in 2012 amounted to 5.4°C, and for the reporting period of 2013 it equailed 5.2°C. No significant differences among measured temperatures were recorded at particular depths (50 cm, 75 cm, and 100 cm). Mean temperature at the surface of the landfill within the whole reporting period was 3.2°C higher than ambient temperature (in the reporting period). This is explained due to the decomposition activity within the landfill site leading to the emission of warm gases. The results provide new information for the estimation of the selection of plant species suitable for reclamation, which have higher chances to tolerate the unfavorable conditions they would be exposed to a technically reclaimed landfill body.
... The landfill temperature, moisture content/additive water amount, water characteristics (i.e., precipitation rainfall or other water entering landfills), available oxygen and waste characteristics are among the many factors contributing to gas and leachate generation at landfill sites and subsequently determine the characteristics of LFG and landfill leachate [4]. Furthermore, the different forms of degradation are not definitive, since dynamic variations in the environmental conditions result in changes in their distribution and rates within the landfill [5,6]. ...
A demonstration pilot with seven anaerobic landfill simulators (LSRs) was used to study the impact of temperature in the range of 20 - 46 °C on long-term landfill emissions, characteristics and tendencies, because of an evident lack of knowledge in this area. The pilot ran more than 1400 days. Higher temperatures accelerated the waste degradation and gas generation, but also resulted in higher leachate COD and NH4-N concentrations, which will prolong the aftercare period in order to meet the effluent discharge limits. Gas generation showed the highest temperature sensitivity, 1.6- 2.8 % o C -1 , whereas COD, NH4-N and chloride emissions were on 0.8 - 1.5 % o C -1 level. The temperature coefficient of gas generation differs considerably from the scarce values given in landfill simulation studies, but is in accordance with hydrolysis solubilisation related behaviour and gives thus more detailed information of landfill behaviour at different temperatures. The simulator results were applied in European conditions in a typical big landfill containing mainly organic matter, giving the length of aftercare over 200 years to achieve effluent discharge limits. Within the same aftercare period (around 200 years), mesophilic conditions compromised high gas production and near lowest leachate concentrations. The in situ landfill leachate pre-treatment process and a specific leachate management system are essential in order to achieve cost-effective and shorter landfill aftercare. The results give new information for evaluation and modelling of landfill control strategies in long-term in various environmental conditions.
... Digester failure happens under a high organic loading rate. Ejlertsson et al. (2003) have shown that the addition of methanogenic inoculum can remove a few years of delay in solids decomposition in a landfill-simulating reactor by decreasing volatile fatty acid (VFA) concentration. Both the methanogenesis and the polymer hydrolysis of municipal solid waste (MSW) were inhibited for a long time. ...
A new multidimensional (3 and 2D) anaerobic digestion model for cylindrical reactor with non-uniform influent concentration distributions was developed to study the way in which mixing intensity affects the efficiency of continuous-flow anaerobic digestion. Batch experiments reported and simulated earlier by Vavilin and Angelidaki (2005) were used to modernize a kinetic scheme and to obtain the corresponding kinetic coefficients. In the new models, hydrolytic microorganisms were included using Contois kinetics for the hydrolysis/acidogenesis degradation of municipal solid waste (MSW). Monod kinetics was applied for description of methanogenesis. Both hydrolytic and methanogenic microorganisms were assumed to be inhibited by high volatile fatty acids (VFA) concentration. According to the new distributed models, the mixing level reduction expressed by increasing dimensionless Peclet number may improve the continuous flow reactor performance at the relatively low influent methanogenic biomass concentration. In the continuously stirred tank reactor (CSTR) there are two steady states with and without methane production at slightly different values of initial methanogenic biomass concentration. In the system, the threshold methanogenic biomass concentration existed because of inhibition by high VFA concentration. High methanogenic biomass concentration is required for efficient anaerobic digestion of MSW in order to avoid possible inhibition due to high VFA build-up. Thus, CSTR configuration might have unstable dynamics at high organic loading as shown in earlier experiments carried out by Stroot et al. (2001). A gradual increase of organic loading during the start up of a completely mixed digester causing an accumulation of methanogenic biomass is a solution to prevent a probable digester failure. According to the distributed models a plug-flow reactor with non-uniform influent concentration distributions where methanogenic and hydrolytic microorganisms are separated has significant methane production and solids removal at the relatively low influent methanogenic biomass concentration. Biotechnol. Bioeng. 2007;97: 354–366. © 2006 Wiley Periodicals, Inc.
... The leachate diester concentrations observed in the current study do not reflect these ration as that observed by Jonsson et al. (2003a). The limited presence of the predominantly commercially-produced diester DEHP in the leachates had been explained by Ejlertsson et al. (1997Ejlertsson et al. ( , 2003. In the surface water of landfill area, P 16 PAEs were 0.63-5.10 ...
This study aims to investigate the impact of MSW landfill on the contamination of phthalate esters (PAEs) in nearby environment. Landfill leachate, surface water, groundwater and soil profile samples were collected from a MSW landfill area in Wuhan, China. Contents of 16 PAEs were detected for each sample using gas chromatography method. Results showed that landfill had an obvious effect on the contamination of PAEs in groundwater, whereas showed no tremendous effect on the PAEs contamination in surface water and topsoil. Seven possible transportation processes of PAEs in landfill area were put forward. However, the especially important processes are the invasion of PAEs into aquifer through weathered crevice, horizontal transportation in aquifer and upward infiltration with groundwater. It is suggested that the whole landfill area should be engineered with seepage-proof membrane and clay so as to prevent landfill leachate from flowing out of the filling area. On the other hand, no weathering crevice is permitted in the landfill area as it will affect groundwater seriously.
... There were differences, however, in terms of the day on which control reactor started biogas production. This is corroborated by previous research in which higher methanogenic populations in initial conditions reduced the delay in biogas production and solid decomposition [4, 47]. Other studies have also emphasized the selection of inocula as critical for anaerobic digestion start-ups. ...
The effects of granules-inocula on the start-up of anaerobic reactors treating dairy manure were studied in a batch-fed reactor. The effects of start-up period and ratio of granules to feed were analyzed. Results indicated that the effects of start-up period could be described by Langmuir model, while the Extended Freundlich model could be used to model the effects of ratio of granules to feed on cumulative biogas production. In addition, transmission electron microscopes (TEM) and scanning electron microscope analysis were conducted to elucidate the distribution of microbial population and micro-colonies in granules and manure. From the TEM micrographs analyses, the ratios the Syntrophobacter and methanogens in granule and manure were shown to be 1.57 +/- 0.42 and 0.22 +/- 0.20, respectively. These results demonstrated that granules-inocula could reduce the period required for onset of biogas by 25%.
... As a consequence of the depletion of plasticizer from the polymer surface, migration from the inner part of the polymer product is enhanced. However, migration from the inner part to the outer surface seems to slow down and even stop as the polymer reaches its glass transition state ( Ejlertsson et al. 2003). Then, new release of plasticizers only occurs if the brittle polymer structure fractures to expose new surfaces. ...
Plastics debris in the marine environment, including resin pellets, fragments and microscopic plastic fragments, contain organic contaminants, including polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons, petroleum hydrocarbons, organochlorine pesticides (2,2'-bis(p-chlorophenyl)-1,1,1-trichloroethane, hexachlorinated hexanes), polybrominated diphenylethers, alkylphenols and bisphenol A, at concentrations from sub ng g(-1) to microg g(-1). Some of these compounds are added during plastics manufacture, while others adsorb from the surrounding seawater. Concentrations of hydrophobic contaminants adsorbed on plastics showed distinct spatial variations reflecting global pollution patterns. Model calculations and experimental observations consistently show that polyethylene accumulates more organic contaminants than other plastics such as polypropylene and polyvinyl chloride. Both a mathematical model using equilibrium partitioning and experimental data have demonstrated the transfer of contaminants from plastic to organisms. A feeding experiment indicated that PCBs could transfer from contaminated plastics to streaked shearwater chicks. Plasticizers, other plastics additives and constitutional monomers also present potential threats in terrestrial environments because they can leach from waste disposal sites into groundwater and/or surface waters. Leaching and degradation of plasticizers and polymers are complex phenomena dependent on environmental conditions in the landfill and the chemical properties of each additive. Bisphenol A concentrations in leachates from municipal waste disposal sites in tropical Asia ranged from sub microg l(-1) to mg l(-1) and were correlated with the level of economic development.
... As 64% of MSW produced in OECD countries is sent to landfill, it is here that disposal risks will center (3). Analyses of emissions from landfills that accept only MSW have revealed the presence of compounds with hazardous properties (4)(5)(6)(7)(8). However, other disposal routes used by householders, especially disposal to sewer and uncontrolled waste dumping ("fly tipping"), offer potentially more significant opportunities for environmental contamination and impacts on health. ...
The disposal of household products containing hazardous substances (household hazardous wastes; HHW) is of concern due to possible health and environmental effects as a consequence of environmental pollution. The potential risks of disposal are proportional to the amounts of products used and waste generated, but much of the data relating to quantities are old, inconsistent, or nonexistent. Hence, full-scale risk assessment is not yet feasible. This pilot study was aimed at an initial assessment of the amounts of hazardous products used or stored within the household and potential disposal routes. Representatives of 400 households from southeast England were interviewed about socio-demographic factors, perception of the risks associated with the use and disposal of hazardous waste generated in households, quantities of particular products currently in use or stored within the household, and times and methods of disposal of such products. The estimates of quantities obtained were compared with sales figures and waste estimates to improve understanding of product flow through to the HHW stream. The disposal routes investigated demonstrated that most householders claim to use the entire product priorto disposal in the general refuse bin. The relationship with socio-demographic factors demonstrated a difference between neighborhood size and length of residence in a household with regard to product quantities possessed and the disposal habits adopted.
... The leachate inventory substances (Table 2) and their potential concentration range were derived from the literature (Robinson, 1995;Yasuhara et al., 1997;Jensen and Christensen, 1999;Paxeus, 2000;Behnisch et al., 2001;Christensen et al., 2001;Yamamoto et al., 2001;Kjeldsen et al., 2002;Schwarzbauer et al., 2002;Coors et al., 2003;Ejlertsson et al., 2003). Over 200 organic chemicals have been recorded in MSW leachate, a number of which can be assumed to derive from the codisposal of HHW with MSW (Slack et al., 2005). ...
Municipal solid waste (MSW) landfill leachate contains a number of aquatic pollutants. A specific MSW stream often referred to as household hazardous waste (HHW) can be considered to contribute a large proportion of these pollutants. This paper describes the use of the LandSim (Landfill Performance Simulation) modelling program to assess the environmental consequences of leachate release from a generic MSW landfill in receipt of co-disposed HHW. Heavy metals and organic pollutants were found to migrate into the zones beneath a model landfill site over a 20,000-year period. Arsenic and chromium were found to exceed European Union and US-EPA drinking water standards at the unsaturated zone/aquifer interface, with levels of mercury and cadmium exceeding minimum reporting values (MRVs). The findings demonstrate the pollution potential arising from HHW disposal with MSW.
Quantifying product impact is one way to make the environmental consequences of purchases clear to consumers and retailers. This paper provides a Life Cycle Assessment (LCA) of the environmental impacts of common children's toys. We compare 3 Lego™ sets, 1 Barbie™, 1 Jenga game, 1 plush dog, 1 plush dog with battery components, and 1 Marble Frenzy™ game, each representing a larger category of toy. After determining the materials in each toy, we built these toys in OpenLCA with existing materials data from LCA databases. Our results showed that a Lego Star Wars set had the highest eutrophication potential with the largest single contribution to impact from injection molding. This Lego set also had the highest GHG (Greenhouse Gas) emissions due to the use of acrylonitrile butadiene styrene (ABS) plastic. Jenga had the highest acidification impact but the lowest GWP of all the toys despite having the highest mass. Our results indicate low GHG emissions and eutrophication potential of wood as a toy material. Wood's acidification potential, however, was the highest of all studied toy materials since impacts included land management for forestry though final wood processing. While plastic had a higher impact per mass than wood, the type of plastic used was important in determining the GHG emissions: ABS and polyvinylchloride (PVC) composition was lower impact than nylon granulate, and other plastics. Since our functional units determined impact per twenty hours of use over 2 years, increased toy longevity was one option to reduce toy impact, though even increased toy longevity should be combined with design for sustainability coupled with transparent environmental labeling to communicate the environmental value of low impact toys to consumers.
The generation of MSW in urban areas has increased with rapid urbanization and population growth. Leachate, a liquid origin from MSW, has been seen as a significant waste product that affects environmental resources such as surface and groundwater, public health and hygiene. The liquid generated due to the biodegradation process and precipitation travels downwards under self-weight (Naveen et al., 2017a). The leachate composition depends upon the landfill age, buried solid waste material. Decomposition of waste material through the biochemical process and other parameters like time, temperature and moisture content (Fatta et al., 1999). Unscientific management of solid waste management in India has led to the generation of a high amount of leachate. The contamination levels were high in surface and groundwater due to surface runoff and percolation of rainwater where the landfills do not have proper lining system, collection system of leachate and treatment facilities. In developing countries like India, there are not many studies on characteristics of leachate to design leachate treatment facilities (Naveen et al., 2017a). The solid waste in the landfills is converted organic and inorganic compounds in liquid and gaseous states through the degradation process. The degradation process is mainly divided into five stages: (1) aerobic phase, (2) acidogenic phase, (3) acetogenic phase, (4) methanogenic phase and (5) maturation phase (Gujer and Zehnder, 1983). The pollution from landfills is associated with waste composition, while in India, organic waste (wet waste) has a greater share (>50%) of the total composition (Joshi and Ahmed, 2016). These problems constantly related with high loads of organic pollutants like BOD5, COD, solids, cations and anions like sulphate, chloride, iron, zinc and heavy metals including Fe, Cd, Cu and Hg (Christensen et al., 2001).
Introduction Thailand is facing a management crisis of both urban and rural household hazardous waste (HHW). The collection and disposal of these wastes threaten both the environment and human health.
Material and methods: The objective of the study was to investigate the characterization and quantification of household hazardous waste at source by all local administrations in Nakhon Nayok province, Thailand.
Results
The quantity of HHW in the household waste stream constitutes 2.53% of total household wastes (about 2.90 t/day). Most HHWs were generated in the local administration level (3.2%) followed by the subdistrict (2.9%) and municipality level (1.2%). The characterization of HHWs included paint products (20.1%), household batteries (17.4%), and unused medicines (14.1%). HHW characterization can be grouped as automobile products from municipalities (38.5%), paint and its containers from the subdistricts (43.08%), and pesticides from the more rural local administrations (24.73%).
Conclusion and discussion: Albeit the amount of HHW waste found in the household waste stream is relatively small compared to the overall waste stream, it can still cause significant damage to human health and environment. This is because the elements and compounds that comprise hazard wastes are toxic at very low levels. Programs are needed to increase appropriate management of HHW to mitigate human health and environmental contamination risks. Reducing and separating HHW at source can minimize these problems during both normal and pandemic situations.
Volatile fatty acids (VFAs) are formed in the process of biodegradation of organic matter and therefore they are commonly present in municipal solid waste landfills, where they play a crucial role in converting organic matter to methane. Optimization of this process needs the knowledge and control of VFA content. Since VFAs also have a negative effect on the environment quality their content should be measured also in raw and treated leachate surface and groundwater and air in the area of the landfill. The most appropriate technique to determine individual VFAs is gas chromatography. The samples must be properly prepared before they can be introduced into GC for analysis. The sample preparation is generally based on VFA isolation, often accompanied by enrichment; though aqueous samples, after suspended matter removal, can also be injected to some GC systems.
The solidification/stabilization of hexachlorobenzene polluted soils in Portland cement was analyzed using simulated specimens for three different disposal scenarios including deionized water, a sulfuric-nitric acid mixture (pH=3.20±0.05) and an acetic acid buffer solution (pH=4.93±0.05) using leaching tests, long-term leaching tests and microstructure analyses. The results show that different mass percentages of cement gave different solidifications fractions with a cement mass percent of 50% stabilizing more than 99% of the HCB. The 30~40% cement can stabilize more than 98% of the HCB. The cumulative leaching ratios for a 121 days cycle were less than 1%, except for the quartz sand specimen in the acetic acid buffer solution which was 1.09%, which further demonstrates the high solidification/stabilization efficiency of Portland cement for HCB. After the three stages of rapid solution, slow diffusion and relative stability in the long-term leaching tests, the cumulative leaching ratio became stable after 20 days due to the low solubility of the hexachlorobenzene.
The degradation and adsorption behavior of dibutyl phthalate (DBP) in methanogenic phase refuse was investigated through laboratory microcosm experiments. The results showed that the half-life of DBP in the sterilized refuse was 5.9 times higher than in unsterilized samples, but that it decreased by 35.8% when dominant bacterial strains were added. Different concentrations of DBP did not have obvious effects on its degradation. The half-lives of DBP were decreased by 53.0%, 37.2% and 20.8% when the refuse moisture increased from 20%, 40% and 60% to 80%, respectively. The pH of refuse was an important factor influencing DBP biodegradation, with the optimal pH being around 7.0. The optimal temperature for DBP degradation in refuse was around 30°C. In addition, the Freundlich model fits the adsorption and desorption isotherm of DBP for refuse with n values that suggest nonlinear adsorption characteristics. The free energy change ΔG value (−23.5 kJ mol−1) indicates that the adsorption of DBP on refuse was a physical reaction. Desorption hysteresis was observed in the DBP desorption experiments. Overall, the results indicate that DBP may accumulate in refuse, and that its transformation and bio-availability may be limited under landfill conditions. © 2015, Gh. Asachi Technical University of Iasi. All rights reserved.
Considering the refuse and leachate as one whole system, a conventional landfill (CL) was set as a control, transformation of dioctyl phthalate (DOP) in recirculated landfill (RL) and bioreactor landfill (BL) was studied. Results showed that DOP was detected in both leachate and refuse from CL, RL and BL. The initial DOP amount was 0.8 μg g-1 in the landfill refuse. At the day of 310, refuse sedimentation rates were 7.0%, 11.9% and 24.3% in CL, RL and BL, respectively. DOP removal rates were 17.4%, 30.8% and 31.7% in the refuse from CL, RL and BL, respectively. The residual amounts of DOP with significant differences well fitted exponential decay models in CL, RL and BL. DOP biodegradation was accelerated with the operation of leachate recirculation compared to the conventional operation, and it was further promoted with the introduction of methanogenic reactor.
Persistent organic compounds are present as pollutants in wastewaters from industrial plants, landfill leachates, hospital effluents, and many other sources. Thus some oxidation processes are now an essential step of purification of many industrial effluent treatment plants (H2O2/UV, O3/UV). Photocatalysis could be an alternative purification method for the cleaning up of some types of polluted waters because it is a process that can lead to total mineralization of almost every organic compound.
The efficiency of photocatalysis has been demonstrated in small laboratory photoreactors, but the next step and current challenge is to develop a pilot-scale reactor that could be taken as part of an industrial water treatment process.
Photocatalysis is an heterogeneous process that involves adsorption of pollutants on the catalyst surface. Adsorption of phenol (chosen as model pollutant) has thus been studied on powdered or supported TiO2 based catalysts. Then, kinetics and degradation mechanism have been established using a batch reactor and different kinds of photocatalysts. The activity of supported catalysts has been quantified with or without addition of a disrupting organic compound (humic acid). Eventually, the last part of this work is dedicated to the implementation of these supported photocatalysts in a new kind of pilot scale photoreactor witch has been characterised in terms of phenol degradation rate and energetic yield.
A facultative bacterial strain isolated from municipal solid waste (MSW) obtained from a simulated landfill bioreactor was found to have the ability to use dibutyl phthalate (DBP) as its sole source of carbon and energy. Based on its morphology, physiochemical characteristics, and 16S rDNA sequence, the strain was identified as Enterobacter sp. T1. Evaluation of the degradation of DBP in refuse collected during the initial, acidic, and methanogenic phases of landfill before and after inoculation with Enterobacter sp. T1 revealed that the degradation fits first-order kinetic models for refuse from all phases. The removal rate of DBP in the refuse of the methanogenic phase increased from 59.3% to 74.5% when Enterobacter T1 was added. The half-life of DBP in refuse from the methanogenic phase that was inoculated with Enterobacter T1 decreased by 36.7% relative to uninoculated samples, and the intermediate products monobutyl phthalate (MBP) and phthalic acid were detected in all samples. These results provide new evidence for the potential of applying Enterobacter sp. for phthalic acid ester-polluted area remediation.
This study investigated the effect of aeration rates on the hydrolysis process of Waste Activated Sludge (WAS) with thermophilic aerobic microbes and explained by the change of solubilization of lipids, carbohydrates and proteins in sludge under different aeration rates (0.03 vvm, 0.05 vvm, 0.07 vvm, 0.09 vvm, 0.11 vvm). The results revealed that with the increase of aeration rate, the accumulation of volatile fatty acids (VFAs) in the treated sludge was decreased. Only 2 142 mg COD/L was accumulated at the ventilation rate of 0.11 vvm, while the highest accumulation which was 4 088 mg/L at the ventilation rate of 0.05 vvm. Further investigation showed that under optimal aeration rate which was 0.05 vvm, theromophilic aerobic microbes facilitated the organism hydrolysis and increased the biodegradability of WAS significantly. The concentration of carbohydrates was improved remarkably from 70 mg COD/L to 560 mg COD/L compared with the control (the process without aeration) at 65°C. Meanwhile, the concentration of protein was increased stably due to the high activity of protease, and reached the peak of 1 320 mg COD/L after 72h, then decline at the later period. The maximal soluble chemical oxygen demand (SCOD) was 5 600 mg/L and VFAs was 4 088 mg COD/L, which would be beneficial to the followed digestion process. Therefore, appropriate aeration is efficient to improve the accumulation of soluble organic matters and VFAs in WAS.
Simulated municipal solid waste (MSW) based on the actual proportional characteristics of MSW was loaded into a simulated leachate recirculation bioreactor landfill and the abundance of common and tolerant microbes exposed to dibutyl phthalate (DBP) were investigated in the initial, acidic and methanogenic phases. The results showed that the abundance of bacteria was greatest, while that of actinomycetes was smallest. The growth of microorganisms was not significantly inhibited by DBP during the initial phase; however, the growth of actinomycetes and fungi was inhibited during both the acidic and methanogenic phases, and the inhibition of actinomycetes was greater than that of fungi. When the DBP concentration was 5.0 g l-1, the inhibition ratio against actinomycetes was 89.5% and 80.9% in the refuse from the acidic phase and methanogenic phase, respectively, while it was 86.2% and 51.0%, respectively, against fungi during the same period. The toxic effects of DBP on microorganisms in refuse occurred in the order of actinomycetes > fungi > bacteria. In addition, the populations of bacteria, fungi and actinomycetes were significantly and positively correlated with dehydrogenase activity, but negatively correlated with the VSS and BDM of refuse (P
Enugu Metropolis were classified into eight, they include paints, garden chemicals, batteries, motoring products, medicines,
home cleaning products, e-waste and household glasses. Ten layouts were randomly selected out of 41. A total number of 30
households per Layout were selected, totalling 300 respondents. A total of 24 checklists were used to evaluate the responses
of householders to determine their level of awareness of HHW. Analysis of the awareness data was based on the frequency
values obtained from our checklists. From our awareness analysis it was found that the level of householders’ awareness on
the dangers of HHW in the Enugu metropolis is low. This low awareness level on the dangers associated with HHW may
largely be attributed to be attitudinal as income level and/ or level of education played little role in the general awareness level.
From our PCA we identified four indices which include: general disposal problems, health related issues, environmental
problems, and poor handling of HHW, which reflects low awareness of HHW in the study area. There is also no general
consensus as to what constitute HHW in the study area as well as their potential health and environmental impacts. This was
seen from variations in responses of like-hood impacts of HHW. For example while some respondents agreed that paints may
constitute danger to the human health and environment if not properly disposed, other disagree. This development it is
anticipated may frustrate any effort at HHW management unless people are sensitized and enlightened.
The degradation of dibutyl phthalate (DBP) before and after inoculation with its dominant bacterial strains in refuse collected during the initial, acidic and methanogenic phases of landfill was evaluated. The results showed that the degradation of DBP fit first-order kinetic models for refuse in different phases with rate constants of 0.0140–0.0187 d−1 and degradation half-lives of 37.1–49.5 d. DBP was degraded fastest in methanogenic phase refuse and slowest in acidic phase refuse, and pH was found to be the key factor influencing DBP biodegradation. The effects of different concentrations of DBP on its degradation were not obvious. Compared with the CK, the removal of DBP from methanogenic phase refuse increased from 60.3% to 74.5%, 72.4% and 87.3% when Enterobacter T1, Enterobacter T5 and mixed bacteria inoculated. The intermediate products including monobutyl phthalate (MBP) and phthalic acid (PA) were detected in the refuse. The degradation phase of a landfill determines the mineralization extent of DBP, and the major removal of DBP occurred under methanogenic condition.
The aim of the study was to investigate whether organotin-stabilized poly(vinyl chloride) (PVC) products could contribute to the pool of organotins observed in landfill leachates, and if the possible release could be related to different temperatures and landfill degradation phases. Small-scale anaerobic reactors filled with generic household waste, a mixture of inocula, and different PVC plastics were used in the study and incubated at 20, 37, 55, and 70°C. The reactor units incubated at temperatures of 20–55°C underwent the anaerobic degradation phases that are characteristic for the aging of landfilled waste material. There were, however, differences in the duration of the phases as well as in the total biogas production among the units. Under methanogenic conditions greater losses of organotin compounds were observed as compared to acidogenic conditions. It was shown that the release of organotin stabilizers increases considerably at temperatures above the glass transition of the PVC products. A dealkylation from di- into monoalkyltin species was observed, as well as a possible methylation of inorganic tin. However, the main part of the organotins was adsorbed into the solid waste matrix. J. VINYL ADDIT. TECHNOL., 13:176–188, 2007. © 2007 Society of Plastics Engineers
Degradation mechanism of diethylhexylphthalate, a pollutant of water bodies, is analyzed. A modified first-order equation
with a correction for a nondegradable fraction is suggested. The succession of biochemical reactions in the process of anaerobic
degradation of monoethylhexylphthalate is considered, and two stages—ester hydrolysis and phthalic acid transformation into
methane and carbon dioxide—are identified as limiting the overall rate. A one-dimensional distributed model is used to describe
the degradation of three phthalates with different water solubility: diethylphthalate DEP, which has a relatively high solubility;
dibutyl phthalate DBP, poorly soluble; and diethylhexylphthalate DEHP, almost insoluble. The physicochemical processes of
sorption/desorption play an important role in the process of their degradation. The enzymatic splitting, carried out by microorganisms,
reduces the concentration of dissolved diethylhexylphthalate and can facilitate desorption processes.
Keywordsanaerobic degradation-phthalate esters-reaction mechanism-kinetic coefficients-mathematical model
Management of landfill emissions, i.e., landfill gas (LFG) and landfill leachate, is an important and resource-intensive task.
A long-term demonstration pilot, consisting of landfill simulation reactors (LSRs), was used to study the impact of temperature
and the applied liquid/solid ratio (L/S ratio) on landfill emissions, characteristics, and trends. This pilot has already
run for more than 1000 days since the end of 2004 and will continue to run for some time. The degradation of waste at different
temperatures has impacts on the overall degradation degree and on the length of post-closure care required. Higher temperatures
accelerated the degradation, but also resulted in higher leachate chemical oxygen demand (COD) and ammonia concentrations,
which prolong the aftercare period. Meanwhile, at a given stabilization degree [e.g., 70 l gas/kg waste (dry)], the total
leached nitrogen under psychrophilic conditions was 3.5 times that under mesophilic/thermophilic conditions, which resulted
in a higher required effort for leachate treatment. The impact of L/S ratio or simulated annual L/S rates was also evaluated.
The results show the significance of efficiently obtaining the targeted L/S ratio in order to achieve low landfill emission
potential.
Some key aspects of organic waste degradation were analyzed by means of mathematical models using data obtained in laboratory
reactors. It was shown that an essential condition of effective methane production is the balance between sequential and parallel
stages not resulting in accumulation of intermediate products that are potential inhibitors of the process. Decreased initial
concentration of organic matter (dilution) and the introduction of seed culture (a methanogenic microbial community) favor
the balancing of the process. Decomposition of easily degradable organic substances may lead to excessive accumulation of
volatile fatty acids and acidification of the medium, which, in turn, blocks the degradation of difficult-to-degrade compounds.
If the process is unbalanced, agitation eliminates the initiation centers for methanogenesis by averaging the reagent concentrations,
which results in complete cessation of methane production. Such centers may be multicellular aggregates of Methanosarcina sp.
Key wordsorganic matter-anaerobic microbial community-balance of hydrolysis and methanogenesis rates-initiation centers for methanogenesis
There is increasing concern regarding the fate of methyltins in the environment, particularly since large amounts of polyvinyl chloride (PVC) plastics are deposited in landfills. The potential transformation of methyltin chlorides and stannic chloride in landfills was investigated, by incubating the target substances at concentrations relevant to landfill conditions (100 and 500 µg Sn L(-1)). The amounts of methane formed in all treatment bottles, and controls, were measured to evaluate the general microbial activity of the inocula and possible effects of methyltins on the degradation of organic matter. The methyltins and stannic chloride were found to have no significant inhibitory effects on the activity of landfill micro-organisms, and the methanol used to disperse the tin compounds was completely degraded. In some experimental bottles, the methanol degradation gave rise to larger methane yields than expected, which was attributed to enhanced degradation of the waste material. Alkyltin analyses showed that monomethyltin trichloride at an initial concentration of 500 µg Sn L(-1) promoted methylation of inorganic tin present in the inoculum. No methylation activities were detected in the incubations with 100 µg Sn L(-1) methyltin chlorides (mono-, di- or tri-methyltin), but demethylation occurred instead. Levels of soluble inorganic tin increased during the incubation period, due partly to demethylation and partly to a release of tin from the waste inocula.
In this study, the behavior of dibutyl phthalate (DBP) from municipal solid waste (MSW) in the leachate and refuse of two simulated landfill bioreactors was compared. In one reactor, the leachate was circulated between a landfill and a methanogenic reactor, while the other reactor was operated using direct recirculation of the leachate. The results revealed that the original concentration of DBP in the refuse was approximately 18.5 microg/g, and that this concentration decreased greatly during decomposition of the waste for both reactors. Furthermore, the major loss of DBP from the landfill occurred in an active methanogenic environment in the later period, while the environment was acidic due to a high concentration of volatile fatty acids (VFA) and contained a large volume of biologically degradable material (BDM) during the early stage. Circulating the leachate between the landfill and a methanogenic reactor resulted in an increase in the biodegradability of MSW and a high degree of waste stabilization. Furthermore, DBP degraded more rapidly in the landfill that was operated in conjunction with the methanogenic reactor when compared to the landfill in which there was direct leachate recirculation.
In this study, the effects of micro-aeration and liquid recirculation on the hydrolysis of vegetable and flower wastes during two-phase solid-liquid anaerobic digestion were assessed. To accomplish this, we evaluated the hydrolysis of five batches of waste that were treated under the following conditions: anaerobic, insufficient micro-aeration (aeration for 5 min every 24 h), and sufficient micro-aeration (aeration for 5 min every 12, 4 and 1h). Hydrolysis was found to depend on the level of micro-aeration. Specifically, insufficient micro-aeration led to unstable and decreased performance. Conversely, sufficient micro-aeration promoted the hydrolysis of easily biodegradable carbohydrates and proteins, but the microbial activity was later impaired by liquid recirculation using methanogenic effluent. The hydrolysis efficiency under anaerobic conditions was comparable to the efficiency observed under sufficient micro-aeration, while the cumulative TOC of the anaerobic batch was 1.4-2.4 times higher than that of the micro-aerated batches. In addition, liquid recirculation did not have a negative effect on the development of microbial activity under anaerobic conditions, which resulted in the lignocelluloses having a higher hydrolysis efficiency.
Phthalic acid diesters are additives in a variety of materials that can end up in landfills. Leachates from a series of full-scale young landfill cells were analysed over time for dimethyl, diethyl, dibutyl, butylbenzyl, and di(2-ethylhexyl) phthalate (respectively designated DMP, DEP, DBP, BBP, and DEHP), and their corresponding monoesters monomethyl, monoethyl, monobutyl, monobenzyl, and mono(2-ethylhexyl) phthalate (MMP, MEP, MbutP, MbenzP, and MEHP, respectively), as well as o-phthalic acid (PA). One landfill cell was created in each of three consecutive years by deposition of the same type of waste in July and August. The pH, volatile fatty acids (VFAs), and total organic carbon (TOC) were measured to characterise development of the degradation phases in three landfill cells, which revealed early acidogenic to initial methanogenic stages. Analysis of the phthalate compounds showed that observed concentrations of the degradation products were below the detection limit in the acidogenic leachates but exceeded concentrations of their corresponding diesters in leachates from cells in the initial methanogenic phase. Maximum and average concentrations of phthalic acid were 50 and 23 mg/l, respectively, and the corresponding values for the other phthalates were 430 and 27 microg/l. The concentrations of all phthalates decreased during the establishment of stable methanogenic conditions.
A landfill typically progresses through a series of microbial degradation phases, in which hydrolysis, production and consumption of fermentation products, such as fatty acids, and methane formation play important roles. For ultimate degradation of the waste, stable methanogenic conditions have to be attained, and maintained for sufficient time. Using experimental data from 100-L landfill simulation reactors containing municipal solid waste from a residential area, a distributed model, which accounts for vertical water flow, was developed. As a first step, the waste was divided into two fractions: readily degradable and recalcitrant waste. Secondly, the general hydrolysis of the recalcitrant waste was accounted for by including a specific, well-defined chemical substance in the model that generally occurs in Municipal Solid Waste (MSW) and is hydrolysed before its further degradation to methane. For this purpose we chose diethyl phthalate and its hydrolysis product monoethyl phthalate, for which leachate data are available from the reactors. The model indicated that inhibition of the hydrolytic and methanogenic processes occurred during the acidogenic phase and that it could be overcome either by improving the chemical environment or by the complete oxidation of the inhibiting, i.e. the easily degraded, fraction of the waste. The generality of the model was confirmed by the patterns of the phthalate di- and monoester transformations obtained. The validity of the model was further confirmed using experimental data from parallel reactors, which were subjected to either leachate exchange with an already methanogenic reactor or to initial aeration to force the reactor into stable methanogenic conditions.
Experimental data from a study using a landfill simulation reactor were used to develop and calibrate a one-dimensional distributed model of co-digestion of municipal solid waste and three phthalic acid diesters with different water solubilities. The three diesters were diethyl phthalate, dibutyl phthalate, and di-2-ethylhexyl phthalate. Two types of municipal solid wastes were assumed, easily degradable and recalcitrant. The model considered inhibition of hydrolysis of the recalcitrant fraction and phthalic acid esters, and also methanogenesis at acidic pH. The results indicated that the prolonged steady-state concentrations of the diesters in the leachates could be explained by equilibrium between physicochemical desorption and sorption processes for the three diesters. When methanogenic conditions were induced in the acidogenic landfill simulation reactor, inhibition of both hydrolysis of recalcitrant MSW and of phthalic acid esters ceased.
High membrane permselectivity for a gas mixture is well-known to correlate with low permeability of the desired product through the membrane. Exceptions to this rule exist, however, and this suggests the possibility of improved membranes for a number of important applications. This paper suggests possible polymer structural changes which may allow control over the magnitudes of permeabilities and selectivities. These suggestions result from considering the permeability and selectivity in terms of their separate thermodynamic solubility and kinetic mobility contributions. The two contributions vary markedly with changes in the polymer structure and correlate with variations in penetrant and polymer physical properties. The feasibility of developing extremely selective high flux membrane materials is explored in terms of these correlations.
The addition of cellulolytic enzymes to MSW has been tried under methanogenic and acidogenic conditions in 0.1 m3 landfill models. An enhanced degradation seems to follow the enzyme addition in both cases. During acidogenic conditions the observed conversion of cellulose was 42 and 29% respectively, with and without enzyme addition. The enzyme addition did not result in a change from methanogenic to acidogenic conditions. A similar conversion of VS can be achieved during methanogenic and acidogenic conditions; at the completion of this experiment the conversion of VS was in excess of 50% in the methanogenic models and somewhat lower than 40% in the acidogenic models (the latter still yielding strong leachates). The results of some standard waste-water analyses were compared and it is concluded that especially acid leachates may cause analytical problems.
Describes the basic biochemical processes taking place in a landfill in terms of the active microbial consortium undertaking the degradation and of the abiotic factors. -from Authors
The anaerobic bioconversion of selected phthalic acid esters (PAEs) was investigated using inocula from diverse natural habitats. Results of bioconversion studies indicated that di‐n‐butyl phthalate (DBP) and butyl benzyl phthalate (BBP) levels were reduced by 80% and 50%, respectively, after 4 weeks incubation in samples inoculated with diluted anaerobic digester sludge; greater than 90% bioconversion of DBP and BBP was observed in samples inoculated with either anaerobic freshwater or salt marsh sediment. Bis(2‐ethylhexyl) phthalate (DEHP) was not degraded by any inocula tested. The persistence of DEHP was apparently not associated with DEHP toxicity to indigenous microflora.
The content of readily volatile halogenated hydrocarbons (chlorinated and chlorinated, fluorinated hydrocarbons (VCCs/CFCs)) and the BTEX aromatic substances (benzene, toluene, ethylbenzene and xylene) in municipal solid waste (MSW) was determined by two different methods. Moreover, the emission potential of these substances via the gas and leachate phase was investigated during the different biological degradation phases in the landfill. Trichlorofluoromethane (R11), dichlorodifluoromethane (R12) and dichloromethane (R30) were the dominating halogenated trace substances detected in the MSW. In the acid phase, with some VCCs/CFCs the emittance may take place up to 30% via the water phase. Hexane, benzene, and toluene could be detected in all tests. Toluene often occurred in relatively high concentrations in MSW. It could be shown that R11 degraded into dichlorofluoromethane (R21).
The degradability of chlorinated aliphatic compounds (tetra chloromethane (TeCM); 1,1,1-trichloroethane (1,1,1-TCA); 1,1,2-trichloroethane (1,1,2-TCA); tetrachloroethene/per chloroethylene (PCE); and trichloroethene/trichloroethylene (TCE)) was studied under methanogenic conditions in batch reactors with leachate from eight landfills in Denmark. All landfill leachates showed fast abiotic degradation of TeCM and 1,1,1-TCA, while 1,1,2-TCA seemed unaffected during the methanogenic incubation. PCE and TCE were degraded biologically by reductive dehalogenation, but only in three of the eight leachates. The conversion rates of the chlorinated ethenes (PCE, TCE, dichloroethene (DCE)) and monochlo roethene/vinyl chloride (VC) varied significantly between the three landfill leachates transforming chlorinated ethenes. In one leachate, complete conversion of all ethenes, including conversion of VC, was observed within 40 days, while another leachate during the same period showed only about 50% con version of PCE. This indicates that transformation of these common solvents in the landfill environment may vary sub stantially between landfills.
A brief summary of secondary processes in PVC thermal degradation is given. This includes some details of crosslinking and gel formation, cyclization, chain scission and benzene formation, Diels-Alder reaction with additives, as well as oxidation of polyenes.
The structural changes in poly(vinyl chloride) during thermal degradation in nitrogen at 190°C have been investigated. From gel permeation chromatography analyses no chain scission, but only crosslinking reactions were observed. An increase in the molecular weight was measured even at 0.3% conversion. For longer polyene sequences and at higher conversions, a crosslinking reaction competed with the “zipper” propagation. The secondary reactions, were more extensive at longer polyene sequence lengths. The growing polyene sequences can be terminated not only by branching reactions but also at existing pendent chloromethylene groups. A decrease in the amount of short chain branching with conversion also indicated other types of secondary reactions. Such a decrease was also observed during thermomechanical degradation in a Brabender Plastograph. The average polyene sequence length was calculated to be around 10, depending somewhat on the type of analysis used. Although allylic chlorine atoms seem to be the main points of initiation, other sites cannot be excluded as the number of initiation points increases appreciably during the early stages of the degradation. Such an increase is, of course, also consistent with a radical mechanism.
Co-disposal of 12 compounds representing major organic classes (aromatic hydrocarbons, halogenated hydrocarbons, pesticides, phenols, and phthalate esters) with shredded municipal solid waste was tested using a laboratory-scale column and pilot-scale lysimeter to characterize transport and transformation phenomena including sorption, volatilization and bioassimilation. Leachate and gases emitted from the lysimeters were examined for identifiable products of biotransformation. The results of this investigation provided a mechanistic evaluation of the attenuating and assimilative capacity of municipal solid waste landfills for specific organic compounds. Physical/chemical organic compound characteristics were related to refuse characteristics and composition to predict compound fate. Such knowledge is useful in developng landfill management and operational strategies consistent with the need for control of pollutant releases.
Various aspects of the thermal decomposition, flammability and smoke evolution from PVC have been investigated in an attempt to account for the mechanism of evolution of aromatics from this polymer. The most relevant experimental observations for the understanding of the mechanism of thermal decomposition of PVC were obtained by the method of direct pyrolysis in the mass spectrometer. A number of facts that had partly escaped previous workers was revealed: that in each of the two degradation steps of PVC a family of aromatic hydrocarbons was formed with different structures; that the two families of aromatics are suppressed at considerably different rates by the addition of metal oxides. The selective suppression of aromatics is related to the fact that the two families of aromatics are evolved from linear and from crosslinked polyene chains, respectively. Another conclusion is that the intramolecular cyclization processes in linear and crosslinked polyenes are satisfactorily explained by the cyclization of polyene radicals, whereas mechanisms based solely on Diels-Alder processes meet with several difficulties. The close analogy found with the thermal degradation of polyacetylene supports these conclusions. Another model system is provided by PVC2 and PVF2. These vinylidene polymers do not form alkyl-aromatics, only unsubstituted aromatics are evolved and the thermal degradation occurs in a single stage.
Report is given on the combustion and pyrolysis conditions. The analytical procedure is described. During combustion and pyrolysis of pure polyvinylchloride (PVC) and PVC-cable sheathings in an air atmosphere, PCDD/PCDF are formed in significant amounts up to the ppm range. In general furans were formed predominantly. Especially higher levels of octa- and heptachlorinated furans were generated in the pyrolysis experiments, whereas lower chlorinated furans were produced predominantly by combustion.
The potential for biological transformation of 23 xenobiotic compounds by microorganisms in municipal solid waste (MSW) samples from a laboratory scale landfill reactor was studied. In addition the influence of these xenobiotic compounds on methanogenesis was investigated. All R11, 1,1 dichloroethylene, 2,4,6 trichlorophenol, dimethyl phthalate, phenol, benzoate and phthalic acid added were completely transformed during the period of incubation ( > 100 days). Parts of the initially added perchloroethylene, trichloroethylene, R12, R114, diethyl phthalate, dibutyl phthalate and benzylbutyl phthalate were transformed. Methanogenesis from acetate was completely inhibited in the presence of 2,5 dichlorophenol, whereas 2,4,6 trichlorophenol and R11 showed an initial inhibition, whenafter methane formation recovered. No transformation or effect on the anaerobic microflora occurred for R13, R22, R114, 3 chlorobenzoate, 2,4,6 trichlorobenzoate, bis(2 ethyl)hexyl phthalate, diisodecyl phthalate and dinonyl phthalate. The results indicate a limited potential for degradation, of the compounds tested, by microorganisms developing in a methanogenic landfill environment as compared with other anaerobic habitats such as sewage digestor sludge and sediments.
Anaerobic microorganisms in municipal solid waste samples from laboratory-scale landfill reactors and a pilot-plant biogas digestor were investigated with the aim of assessing their ability to transform four commercially used phthalic acid esters (PAEs) and phthalic acid (PA). The PAEs studied were diethyl phthalate (DEP), butylbenzyl phthalate (BBP), dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP). No biological transformation of DEHP could be detected in any of the experiments. Together with waste samples from the simulated landfilling conditions, the PAEs (except DEHP) were hydrolytically transformed to their corresponding monoesters. These accumulated as end products, and in most cases they were not further degraded. During incubation with waste from the biogas digestor, the PAEs (except DEHP) were completely degraded to methane and carbon dioxide. The influence of the landfill development phase on the transformations was investigated utilizing PA and DEP as model substances. We found that during both the intense and stable methanogenic (but not the acidogenic) phases, the microorganisms in the samples had the potential to transform PA. A shorter lag phase was observed for the PA transformation in the samples from the stable methanogenic phase as compared with earlier phases. This indicates an increased capacity to degrade PA during the aging phases of the municipal solid waste in landfills. No enhancement of the DEP transformation could be observed as conditions in the methanogenic landfill model changed over a year's time. The results indicate that microorganisms developing in a methanogenic landfill environment have a substantially lower potential to degrade compared with those developing in a biogas reactor.
Forty-five organic compounds have been identified in leachates from a Swedish municipal landfill. The samples were taken from the interior of the landfill to minimize alterations caused by contact with the surroundings and were identified and quantified by gas chromatography combined with mass spectrometry. Two analytical procedures were used, one for priority pollutants, the other for a wider range of phenolic and neutral compounds and acids. Analyses of the leachates for water quality parameters indicated that the part of the landfill which was sampled had reached an anaerobic stage in which methane was being produced. Possible origins for most of the compounds identified have been suggested.
Development of a polyol system with improved demould characteristics for appliance insulation
- Schindler Kuhn
- E Kuhn
- P Schindler
- Schindler Kuhn
- E Kuhn
- P Schindler
Toxic components in biogas extracted from landfills
- H.C. Willumsen
- P. Burian-Hanssen
- P.E. Jensen
- H.C. Willumsen
- P. Burian-Hanssen
- P.E. Jensen
Beschreibung eines Verfahrens zur Untersuchung anaerober Umsetzungsprozesse von Festen Abfallstoffen im Deponiekörper
- Stegmann Stegmann
- Stegmann Stegmann
Deponiegase als Quelle halogenierter Kohlenwasserstoffe
- Laugwitz
Toxic components in biogas extracted from landfills Anaerobic Digestion
- H C Willumsen
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- P E Jensen
Willumsen, H.C., Burian-Hanssen, P., Jensen, P.E., 1988. Toxic components in biogas extracted from landfills. In: Hall, E.R., Hobson, P.N. (Eds.), Anaerobic Digestion 1988, Fifth International Symposium on Anaerobic Digestion. Pergamon Press, Bologna, pp. 507–512.
Distri-bution of CFC-11 in aged urethane and isocyanurate CLBS foam. 32nd Annual Polyurethane TechnicalyMarketing Con-ference
- P D Gaarenstroom
- J B Letts
- A M Harrison
Gaarenstroom, P.D., Letts, J.B., Harrison, A.M., 1989. Distri-bution of CFC-11 in aged urethane and isocyanurate CLBS foam. 32nd Annual Polyurethane TechnicalyMarketing Con-ference Oct. 1–4 1989, Technomic Publishing Co. Inc., 163–168
Fundamental principles and management strategies for landfill codisposal practices
- F R Pohland
Pohland, F.R., 1991. Fundamental principles and management strategies for landfill codisposal practices. Sardinia 91. Proceedings from the third International Landfill Symposi-um, 14–18 October, Sardinia, Italy, Imola: Grafiche Galeati, 1445–1460.
Beschreibung eines Verfahrens zur Unter-suchung anaerober Umsetzungsprozesse von Festen Abfalls-toffen im Deponiekorper. Mull Abfall 2 Anaerobic Transformation of Halogenated Aliphatics in Landfilled MSW
- R ¨ Stegmann
- B H Svensson
- E Johansson
- M Oquist
- J Ejlertsson
Stegmann, R., 1981. Beschreibung eines Verfahrens zur Unter-suchung anaerober Umsetzungsprozesse von Festen Abfalls-toffen im Deponiekorper. Mull Abfall 2. ¨ ¨ Svensson, B.H., Johansson, E., Oquist, M., Ejlertsson, J. ¨ Anaerobic Transformation of Halogenated Aliphatics in Landfilled MSW. Biodegradation, in preparation.
One-and two-phase anaerobic digestion of ley crop silage with and without liquid recirculation. Doctoral thesis no. 64. Department of Microbiology. Swed-ish University of Agricultural Sciences Anaerobic bioconversion of phthalic acid esters by natural inocula
- A E Nordberg
- W J Jones
Nordberg, A., 1996. One-and two-phase anaerobic digestion of ley crop silage with and without liquid recirculation. Doctoral thesis no. 64. Department of Microbiology. Swed-ish University of Agricultural Sciences, Uppsala. Painter, S.E., Jones, W.J., 1990. Anaerobic bioconversion of phthalic acid esters by natural inocula. Environ. Technol. 11, 1015–1026.
Materials selection for gas separation membranes
- R T Chern
- H B Koros
- H B Hopfenberg
- V T Stannet
Chern, R.T., Koros, H.B., Hopfenberg, H.B., Stannet, V.T., 1989. Materials selection for gas separation membranes. ACS Symp. Ser. 269, 25–46.
Encyclopaedia of Polymer Science and Technology
- J K Sears
- N W Touchette
Sears, J.K., Touchette, N.W., 1989. Encyclopaedia of Polymer Science and Technology. John Wiley and sons, New York.
Development of a polyol system with improved demould characteristics for appliance insu-lation. Polyurethanes World Congress
- E Kuhn
- P Schindler
Kuhn, E., Schindler, P., 1987. Development of a polyol system with improved demould characteristics for appliance insu-lation. Polyurethanes World Congress 1987 September 29– October 2, Aachen, Technomic Publishing Co. Inc., 756– 760.
New technology for flame-retardant of finishing cotton
- Sakai
Sakai, 1987. New technology for flame-retardant of finishing cotton. Japanese Textile News 9, 51–55.
Fate of phthalic acid esters during diges-tion of municipal solid waste under landfill conditions Doctoral thesis no. 158. Department of Water and Environ-mental Studies Anaerobic degradation of xenobiot-ics by organisms from municipal solid waste under landfill-ing conditions
- J Ejlertsson
Ejlertsson, J., 1997. Fate of phthalic acid esters during diges-tion of municipal solid waste under landfill conditions. Doctoral thesis no. 158. Department of Water and Environ-mental Studies. Linkoping University, Linkoping. ¨ ¨ Ejlertsson, J., Johansson, E., Karlsson, A., Meyerson, U., Svensson, B.H., 1996a. Anaerobic degradation of xenobiot-ics by organisms from municipal solid waste under landfill-ing conditions. Antonie van Leeuwenhoek 69, 67–74.
Distribution of CFC-11 in aged urethane and isocyanurate CLBS foam. 32nd Annual Polyurethane Technical/Marketing
- P D Gaarenstroom
- J B Letts
- A M Harrison
Anaerobic Transformation of Halogenated Aliphatics in Landfilled MSW
- B H Svensson
- E Johansson
- M Öquist
- J Ejlertsson
Degradation of phthalic acid esters in municipal solid waste under methanogenic conditions
- Ejlertsson
Development of a polyol system with improved demould characteristics for appliance insulation
- E Kuhn
- P Schindler
Beschreibung eines Verfahrens zur Untersuchung anaerober Umsetzungsprozesse von Festen Abfallstoffen im Deponiekörper
- R Stegmann
One- and two-phase anaerobic digestion of ley crop silage with and without liquid recirculation. Doctoral thesis no. 64
- Å Nordberg
Toxic components in biogas extracted from landfills
- Willumsen