The effect of clay catalyst on the chemical composition of bio-oil obtained by co-pyrolysis of cellulose and polyethylene

Cellulose/polyethylene (CPE) mixture 3:1, w/w with and without three clay catalysts (K10 – montmorillonite K10, KSF – montmorillonite KSF, B – Bentonite) addition were subjected to pyrolysis at temperatures 400, 450 and 500 °C with heating rate of 100 °C/s to produce bio-oil with high yield. The pyrolytic oil yield was in the range of 41.3–79.5 wt% depending on the temperature, the type and the amount of catalyst. The non-catalytic fast pyrolysis at 500 °C gives the highest yield of bio-oil (79.5 wt%). The higher temperature of catalytic pyrolysis of cellulose/polyethylene mixture the higher yield of bio-oil is. Contrarily, increasing amount of montmorillonite results in significant, almost linear decrease in bio-oil yield followed by a significant increase of gas yield. The addition of clay catalysts to CPE mixture has a various influence on the distribution of bio-oil components. The addition of montmorillonite K10 to cellulose/polyethylene mixture promotes the deepest conversion of polyethylene and cellulose. Additionally, more saturated than unsaturated hydrocarbons are present in resultant bio-oils. The proportion of liquid hydrocarbons is the highest when a montmorillonite K10 is acting as a catalyst.     

Biodegradation of acrylic acid polymers and oligomers by mixed microbial communities in activated sludge

The biodegradability (mineralization to carbon dioxide) of acrylic acid oligomers and polymers was studied in activated sludge obtained from continuous-flow activated sludge (CAS) systems exposed to mixtures of low molecular weight (Mw < 8000) poly(acrylic acid)s and other watesoluble polymers [poly(ethylene glycol)s] in influent wastewater. Dilute preparations of activated sludge from the CAS units were tested for their ability to mineralize acrylic acid monomer and dimer, as well as a series of model acrylic acid oligomers and polymers (Mw 500, 700, 1000, 2000, and 4500), as sole carbon and energy sources. Complete mineralization of acrylic acid monomer and dimer was observed in low-biomass sludge preparations previously exposed to the polymer mixture, based on carbon dioxide production and residual dissolved organic carbon analyses. Extensive (though incomplete) degradation was also observed for the low molecular weight acrylic acid oligomers (Mw 500 and 700), but degradation dropped off sharply for the 1000, 2000, and 4500 Mw polymers. Radiochemical (¹⁴C) data also confirmed the low degradation potential of the 1000, 2000, and 4500 Mw materials. Degradation of two commercial poly(ethylene glycol)s at 1000 and 3400 Mw was complete and comparable to that of the acrylic acid monomer and dimer. Our results indicate that mixed populations of activated sludge microorganisms can extensively metabolize acrylic acid oligomers of seven units or less. Complete mineralization, however, could be confirmed only for the monomer and dimer material, and carbon mass balance data suggested that the true molecular weight cutoff for complete biodegradation was significantly less than the 500–700 Mw range tested.     

Effect of substrate feeding frequencies on the methane production and microbial communities of laboratory-scale anaerobic digestion reactors

Even though full-scale digesters have been designed based on laboratory-scale tests, the substrate feeding modes of laboratory-scale tests might be different from those of full-scale digesters. The effect of substrate feeding frequencies on the performance and microbial community of laboratory-scale anaerobic digestion reactors was investigated. Feeding frequencies of twice a day, once a day, and every two days were tested in three 2-L reactors with an organic loading rate of 0.5 g-glucose/L/day under mesophilic condition. According to the results of this study, all the reactors showed similar methane production rates and SCOD removal efficiencies after sufficient time of acclimation, but frequently feeding promoted more stable digestion. Although there was no significant difference in microbial diversities from pyrosequencing analyses, the changes of archaeal community composition were observed. The decrease in feeding frequency appeared to cause shifts from acetoclastic methanogens affiliated with Methanosaeta to H₂-utilizing methanogens. The increase of Methanosaeta at a frequently feeding might contribute to the stability of reactor operation. Since this study uses glucose as the substrate, there is still possibility of different results for more complex substrates, such as sludge, food waste, etc.     

Investigation into the effect of high concentrations of volatile fatty acids in anaerobic digestion on methanogenic communities

A study was conducted to determine whether differences in the levels of volatile fatty acids (VFAs) in anaerobic digester plants could result in variations in the indigenous methanogenic communities. Two digesters (one operated under mesophilic conditions, the other under thermophilic conditions) were monitored, and sampled at points where VFA levels were high, as well as when VFA levels were low. Physical and chemical parameters were measured, and the methanogenic diversity was screened using the phylogenetic microarray ANAEROCHIP. In addition, real-time PCR was used to quantify the presence of the different methanogenic genera in the sludge samples. Array results indicated that the archaeal communities in the different reactors were stable, and that changes in the VFA levels of the anaerobic digesters did not greatly alter the dominating methanogenic organisms. In contrast, the two digesters were found to harbour different dominating methanogenic communities, which appeared to remain stable over time. Real-time PCR results were inline with those of microarray analysis indicating only minimal changes in methanogen numbers during periods of high VFAs, however, revealed a greater diversity in methanogens than found with the array.     

Study of the effect of political measures on the citizen participation rate in recycling and on the environmental load reduction

Obtaining the cooperation of citizens to participate in separate waste collection is essential to create a recycling-oriented society. In this research, the degree of change in the citizen participation rate, which occurs when the contents of political measures such as the raising of awareness, provision of information, and the conditions of collection services were changed, was estimated together with the effect on the reduction in environmental load. A questionnaire survey was conducted, targeted at residents of Itabashi Ward, while logistic regression analyses were also conducted to create predictive models for recycling behavior, and sensitivity analyses of the models were carried out to estimate the increase in citizen participation rate achievable through the implementation of various political measures. It was found that the effect of "thorough perception of information" was the largest, followed by "minimization of evaluation of trouble" and "thorough perception of efficacy of measures." The effect of the improvement in the citizen participation rate on the reduction in environmental load was also evaluated quantitatively by life cycle inventory analyses. It was indicated that "maximization of perception of information" had the greatest effect. However, the reduction effect with "paper packs" and "PET bottles" was relatively small compared with that of "bottles/cans."     

The influence of degree of substitution on blend miscibility and biodegradation of cellulose acetate blends

In this account, we report our findings on blends of cellulose acetate having a degree of substitution (DS) of 2.49 (CA2.5) with a cellulose acetate having a DS of 2.06 (CA2.0). This blend system was examined over the composition range of 0–100% CA2.0 employing both solvent casting of films (no plasticizer) and thermal processing (melt-compressed films and injection molding) using poly(ethylene glycol) as a common plasticizer. All thermally processed blends were optically clear and showed no loss in optical quality after storage for several months. Thermal analysis and measurement of physical properties indicate that blends in the middle composition range are partially miscible, while those at the ends of the composition range are miscible. We suggest that the miscibility of these cellulose acetate blends is influenced primarily by the monomer composition of the copolymers. Bench-scale simulated municipal composting confirmed the biodestructability of these blends and indicated that incorporation of a plasticizer accelerated the composting rates of the blends.In vitro aerobic biodegradation testing involving radiochemical labeling conclusively demonstrated that both the lower DS CA2.0 and the plasticizer significantly enhanced the biodegradation of the more highly substituted CA2.5.While this work was in progress, Robert Gardner was struck with cancer and died on June 6, 1995. This paper is dedicated to his memory and to his contributions as a friend and colleague.     

Comparison of the food waste degradation rate and microbial community in the matrix between two biodegradation agents in a food waste disposer

To reduce the proportion of food waste in municipal solid waste, a food waste biodegradation experiment with two biodegradation agents was conducted for seven weeks with 500 g of food waste added every day into each disposer. The agent containing four biodegradation bacterial strains showed higher degradation rates and matrix temperatures than that containing two. Furthermore, significant differences in the microbiological community structures of the matrixes were found not only between the two biodegradation systems but also among different stages in the same degradation system based on DGGE profiles. The F2 strain exhibited the highest DGGE optical density (OD) value among biodegradation systems and at all experimental stages, suggesting it was a dominant strain during food waste degradation.     

Vermicomposting of source-separated human faeces by Eisenia fetida: effect of stocking density on feed consumption rate, growth characteristics and vermicompost production

The main objective of the present study was to determine the optimum stocking density for feed consumption rate, biomass growth and reproduction of earthworm Eisenia fetida as well as determining and characterising vermicompost quantity and product, respectively, during vermicomposting of source-separated human faeces. For this, a number of experiments spanning up to 3 months were conducted using soil and vermicompost as support materials. Stocking density in the range of 0.25-5.00 kg/m² was employed in different tests. The results showed that 0.40-0.45 kg-feed/kg-worm/day was the maximum feed consumption rate by E. fetida in human faeces. The optimum stocking densities were 3.00 kg/m² for bioconversion of human faeces to vermicompost, and 0.50 kg/m² for earthworm biomass growth and reproduction.     

The effect of chlorine position of chlorinated phenols on their dechlorination kinetics by Fenton's reagent

Chlorine position of chlorophenol isomers has a significant effect on the dechlorination kinetics of monochlorophenols, dichlorophenols, and trichlorophenols during Fenton oxidation. The effects have been evaluated by the rate constants of the dechlorination kinetic model developed in this study. It is found that the dechlorination rate of 3-CP is faster than that of 4-CP, which is faster than that of 2-CP. Since OH and Cl groups on the aromatic ring are ortho and para directors, the directory effect of OH and Cl groups enhances the dechlorination kinetics of 2-CP due to acceleration of the hydroxylation of 2-CP. Therefore, the dechlorination kinetics increases accordingly. For trichlorophenols (TCP), steric hindrance plays an important role during their dechlorination process. Specifically, the closer the chlorine atoms locate with each other on the aromatic ring, the more difficult the dechlorination processes will be. The dechlorination kinetics of dichlorophenols seems to be affected by both directory effect of OH and Cl groups and the effect of steric hindrance of chlorine atoms. The directory effect of OH and Cl groups on trichlorophenols decreases since the chlorine atom occupied the positions which are the most favorable for hydroxyl radical attack.     

Production and characterization of KOH-activated carbon derived from polychlorinated biphenyl residue generated by the sodium dispersion process

Polychlorinated biphenyl (PCB) residues from the sodium dispersion (SD) process were employed as the raw materials for the production of activated carbon using KOH activation. The pore properties, such as the specific surface area and pore size distribution, were characterized using the Barrett–Joyner–Halenda method and the Horvath–Kawazoe method based on the N₂ adsorption isotherm at 77 K. The activated carbon produced showed similar adsorption capacities and specific surface areas to the commercially available product. The effects of the activation conditions on the porosity of the activated carbon produced were studied. The most significant factor affecting the specific surface proved to be the activation temperature. The activated carbon produced from PCB residues from the high-temperature (423–443 K) SD process had a binary pore size distribution well developed in the 4 nm region and in the micropore region. The pore structure of the carbon produced from PCB residues from the low-temperature (333–393 K) SD process had a wide range of micropores and mesopores.     

粉煤灰对单体直接染料脱色效果的研究

就粉煤灰的投加量、染料的初始浓度、pH值及脱色时间等因素对单体直接染料脱色效果进行了研究,结果表明:在加灰量为0.006 g/ml、pH值为2～10、脱色时间为20～30 min时,粉煤灰对单体直接染料具有良好的脱色效果.     

The effect of accelerated carbonation on the properties of cement-solidified waste forms

Ordinary Portland cement blended with blast furnace slag and pulverised fuel ash was used to solidify two industrial wastes containing large amounts of metals. The solidified mixes were carbonated using an accelerated regime previously established and compared for strength development, leaching characteristics and phase development against their non-carbonated analogues. A significant difference in the immobilisation of metals such as Zn, Ni and As was recorded for samples in which carbonation was optimised. The work has shown that by controlling mix parameters it is possible to improve the immobilisation of specific metals. Electron microanalysis showed that this is partly due to the precipitation of calcite in the solidified waste pore structure. Carbonation was also found to accelerate C₃S hydration in all carbonated samples and to modify the morphology of residual cement grains through the formation of a calcite coating over de-calcified hydration rims. Some metals appear to be incorporated in both of these zones.     

The effect of storage and mechanical pretreatment on the biological stability of municipal solid wastes

Modern mechanical–biological waste treatment plants for the stabilization of both the source-separated organic fraction of municipal solid wastes (OFMSW) and the mixed stream of municipal solid wastes (MSW) include a mechanical pretreatment step to separate recyclable materials such as plastics, glass or metals, before biological treatment of the resulting organic material. In this work, the role of storage and mechanical pretreatment steps in the stabilization of organic matter has been studied by means of respiration techniques. Results have shown that a progressive stabilization of organic matter occurs during the pretreatment of the source-separated OFMSW, which is approximately 30% measured by the dynamic respiration index. In the case of mixed MSW, the stabilization occurring during the reception and storage of MSW is compensated by the effect of concentration of organic matter that the pretreatment step provokes on this material. Both results are crucial for the operation of the succeeding biological process. Finally, respiration indices have been shown to be suitable for the monitoring of the pretreatment steps in mechanical–biological waste treatment plants, with a strong positive correlation between the dynamic respiration index and the cumulative respiration index across all samples tested.     

Effect of some environmentally degradable materials on the pyrolysis of plastics II: influence of cellulose and lignin on the pyrolysis of complex mixtures

Pyrolysis of polymer mixtures with a composition similar to that of municipal plastic waste containing polyvinyl chloride (PVC) and of municipal plastic waste free of PVC was performed in the presence of components of biomass, namely lignin, cellulose, or both. The pyrolysis products were characterized by standard methods utilized in the petrochemical industry, i.e., paraffins-isoparaffinsolefins-naphthenes-aromatics analysis, proton nuclear magnetic resonance and infrared spectroscopy, and gas chromatography-mass spectrometry. Up to 3 wt% lignin, cellulose, or both in mixed polymers changed the material balance of pyrolysis by decreasing the amount of waxy products. The presence of both PVC and biomass components significantly changed the material balance by decreasing the waxy product yield and increasing the gas and coke yield. The composition of all pyrolysis products was also modified with the addition of PVC, components of biomass, or both.     

园区循环化改造的建设成效及实施过程探索

发展循环经济对缓解环境压力、促进产业结构调整、发展生态文明、践行五大发展理念具有重大的意义。园区是我国经济发展的重要支撑,也是我国发展循环经济的重点领域。介绍了园区循环化的改造方向、改造目标及园区循环化试点工作及实践成效,并总结概括了园区循环化改造的下一步重点工作,供后续工作参考。     

The effect of carbonate and biochar on carbon and nitrogen losses during composting

Journal of Material Cycles and Waste Management - Limited options and high prices have limited the application of additives in composting. The effect of applying carbonate (SRC) and biochar (BC) to...     

The effect of food waste disposers on municipal waste and wastewater management.

This paper examines the feasibility of introducing food waste disposers as a waste minimization option within urban waste management schemes, taking the Greater Beirut Area (GBA) as a case study. For this purpose, the operational and economic impacts of food disposers on the solid waste and wastewater streams are assessed. The integration of food waste disposers can reduce the total solid waste to be managed by 12 to 43% under market penetration ranging between 25 and 75%, respectively. While the increase in domestic water consumption (for food grinding) and corresponding increase in wastewater flow rates are relatively insignificant, wastewater loadings increased by 17 to 62% (BOD) and 1.9 to 7.1% (SS). The net economic benefit of introducing food disposers into the waste and wastewater management systems constitutes 7.2 to 44.0% of the existing solid waste management cost under the various scenarios examined. Concerns about increased sludge generation persist and its potential environmental and economic implications may differ with location and therefore area-specific characteristics must be taken into consideration when contemplating the adoption of a strategy to integrate food waste disposers in the waste-wastewater management system.     

Impact of food waste disposers on the generation rate and characteristics of municipal solid waste

Field surveys were carried out to ascertain the reduction in the generation rate of municipal solid waste as a result of the use of food waste disposers (FWDs). The generation rate and characteristics of garbage and of the food waste ground by FWDs in households were investigated, and the effect of FWDs was discussed. In a medium-sized village, the amount of garbage collected per collection decreased from 251.2 kg to 114.7 kg as a result of FWD use. The unit loading of ground food waste was estimated to be 111 g/cap·day. In a small village, the amount of garbage collected weekly decreased from 175 kg to 112 kg. The average unit loading of ground food waste was measured and found to be 126 g/cap·day. The reduction rate of garbage varied from 25% to 39% monthly and the average reduction rate was 31% throughout the surveying period. Dramatic variations in the characteristics of the collected garbage were recognized: the ratio of food waste on a dry basis declined by more than half, the moisture content decreased to half or less, the combustible matter content increased approximately 1.7 times or more, and the lower heating value increased approximately 2.0 times or more compared to the case without FWD use.     

冷冻胶粉粒度对橡胶胶料力学性能的影响

研究了冷冻胶粉粒度对橡胶胶料力学性能的影响,发现添加冷冻胶粉会使胶料的力学性能下降,胶粉粒度越大,胶料性能下降的程度越严重。同时还发现,薄通处理可以改善胶粉的表面活性,减轻胶粉粒度对胶料性能的影响,改善胶料的力学性能。     

The effect of lignin and sugars to the aerobic decomposition of solid wastes

A series of experimental runs were conducted from 1995 to 1999 in Madison (WI, USA) with the goal to investigate the biodegradation process of seven (7) solid waste components and mixtures of them under near optimal aerobic conditions. It was shown that substrates with high initial lignin contents or high initial HWSM contents were observed to have relatively low and high degradation extents, respectively. Two linear equations were derived that correlate degradation extent (as indicated by the volatile solids reduction) to initial lignin and initial HWSM contents separately. The lignin equation was compared to a similar equation previously developed for anaerobic environments by Chandler et al. (Predicting methane fermentation biodegradability. In: Biotechnology and Bioengineering Symposium No. 10 (1980) New York: John Wiley & Sons). With comparison to the Chandler formula, lignin was found to be less inhibitory to the overall substrate decomposition in aerobic environments compared to anaerobic ones. Cellulose loss contributed to a higher than 50% to the overall dry mass loss for all substrates studied. In addition, the cellulose to lignin (C/L) ratio appeared to be a relatively accurate compost maturity indicator, since it reduced to a value less than 0.5 for most substrates that had reached their degradation extent.