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Title: A comparative study of leachate quality and biogas generation in simulated anaerobic and hybrid bioreactors

Abstract

Highlights: • Temporary aeration shortened the initial acid inhibition phase for methanogens. • COD decreased faster in the hybrid bioreactor than that in the anaerobic control. • Methane generations from hybrid bioreactors were 133.4 L/kg{sub vs} and 113.2 L/kg{sub vs}. • MSW settlement increased with increasing the frequency of intermittent aeration. - Abstract: Research has been conducted to compare leachate characterization and biogas generation in simulated anaerobic and hybrid bioreactor landfills with typical Chinese municipal solid waste (MSW). Three laboratory-scale reactors, an anaerobic (A1) and two hybrid bioreactors (C1 and C2), were constructed and operated for about 10 months. The hybrid bioreactors were operated in an aerobic–anaerobic mode with different aeration frequencies by providing air into the upper layer of waste. Results showed that the temporary aeration into the upper layer aided methane generation by shortening the initial acidogenic phase because of volatile fatty acids (VFAs) reduction and pH increase. Chemical oxygen demand (COD) decreased faster in the hybrid bioreactors, but the concentrations of ammonia–nitrogen in the hybrid bioreactors were greater than those in the anaerobic control. Methanogenic conditions were established within 75 d and 60 d in C1 and C2, respectively. However, high aeration frequency led to the consumptionmore » of organic matters by aerobic degradation and resulted in reducing accumulative methane volume. The temporary aeration enhanced waste settlement and the settlement increased with increasing the frequency of aeration. Methane production was inhibited in the anaerobic control; however, the total methane generations from hybrid bioreactors were 133.4 L/kg{sub vs} and 113.2 L/kg{sub vs}. As for MSW with high content of food waste, leachate recirculation right after aeration stopped was not recommended due to VFA inhibition for methanogens.« less

Authors:
; ; ;
Publication Date:
OSTI Identifier:
22472523
Resource Type:
Journal Article
Resource Relation:
Journal Name: Waste Management; Journal Volume: 41; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; AERATION; AMMONIA; ANAEROBIC DIGESTION; BIOREACTORS; CARBOXYLIC ACIDS; CHEMICAL OXYGEN DEMAND; CHINA; CONCENTRATION RATIO; METHANE; NITROGEN; ORGANIC MATTER; SANITARY LANDFILLS; SIMULATION; SOLID WASTES; VOLATILITY

Citation Formats

Xu, Qiyong, Tian, Ying, Wang, Shen, and Ko, Jae Hac, E-mail: jaehacko@pkusz.edu.cn. A comparative study of leachate quality and biogas generation in simulated anaerobic and hybrid bioreactors. United States: N. p., 2015. Web. doi:10.1016/J.WASMAN.2015.03.023.
Xu, Qiyong, Tian, Ying, Wang, Shen, & Ko, Jae Hac, E-mail: jaehacko@pkusz.edu.cn. A comparative study of leachate quality and biogas generation in simulated anaerobic and hybrid bioreactors. United States. doi:10.1016/J.WASMAN.2015.03.023.
Xu, Qiyong, Tian, Ying, Wang, Shen, and Ko, Jae Hac, E-mail: jaehacko@pkusz.edu.cn. Wed . "A comparative study of leachate quality and biogas generation in simulated anaerobic and hybrid bioreactors". United States. doi:10.1016/J.WASMAN.2015.03.023.
@article{osti_22472523,
title = {A comparative study of leachate quality and biogas generation in simulated anaerobic and hybrid bioreactors},
author = {Xu, Qiyong and Tian, Ying and Wang, Shen and Ko, Jae Hac, E-mail: jaehacko@pkusz.edu.cn},
abstractNote = {Highlights: • Temporary aeration shortened the initial acid inhibition phase for methanogens. • COD decreased faster in the hybrid bioreactor than that in the anaerobic control. • Methane generations from hybrid bioreactors were 133.4 L/kg{sub vs} and 113.2 L/kg{sub vs}. • MSW settlement increased with increasing the frequency of intermittent aeration. - Abstract: Research has been conducted to compare leachate characterization and biogas generation in simulated anaerobic and hybrid bioreactor landfills with typical Chinese municipal solid waste (MSW). Three laboratory-scale reactors, an anaerobic (A1) and two hybrid bioreactors (C1 and C2), were constructed and operated for about 10 months. The hybrid bioreactors were operated in an aerobic–anaerobic mode with different aeration frequencies by providing air into the upper layer of waste. Results showed that the temporary aeration into the upper layer aided methane generation by shortening the initial acidogenic phase because of volatile fatty acids (VFAs) reduction and pH increase. Chemical oxygen demand (COD) decreased faster in the hybrid bioreactors, but the concentrations of ammonia–nitrogen in the hybrid bioreactors were greater than those in the anaerobic control. Methanogenic conditions were established within 75 d and 60 d in C1 and C2, respectively. However, high aeration frequency led to the consumption of organic matters by aerobic degradation and resulted in reducing accumulative methane volume. The temporary aeration enhanced waste settlement and the settlement increased with increasing the frequency of aeration. Methane production was inhibited in the anaerobic control; however, the total methane generations from hybrid bioreactors were 133.4 L/kg{sub vs} and 113.2 L/kg{sub vs}. As for MSW with high content of food waste, leachate recirculation right after aeration stopped was not recommended due to VFA inhibition for methanogens.},
doi = {10.1016/J.WASMAN.2015.03.023},
journal = {Waste Management},
number = ,
volume = 41,
place = {United States},
year = {Wed Jul 15 00:00:00 EDT 2015},
month = {Wed Jul 15 00:00:00 EDT 2015}
}
  • This paper was conducted to evaluate the effect of milling and alkali lime cooking pretreatments on the rate and extent of methane generation from sugar Cane bagasse. The effect of pretreatment process variables (Particle size 8.0.003 mm, temperature between 100 and 250[degree]C and alkaline dosage between 0 and 8g CaO/kg VS) on the biogas generation from Sugar Cane bagasse has been investigated. Methane generation from the pretreated cane bagasse was studied using serum bottle technique and an upflow anaerobic filter bioreactor. The optimum condition involves alkali-cooking of cane bagasse (0.5 mm) with 4% CaO at 200[degree]C, dissolving most of themore » cellulose and converting it in a mixture of organic acids, including formic, acetic, lactic, and succinic acids. About 80% of the COD content of the cellulose was retained in the cooked liquor. A very rapid biogas were observed in the first three days of 70% methane content from the pretreated cane bagasse and the digestion was completed within 8 days. It has been concluded, that the lime-cooking of CB could produce methane as much as 70% of that from glucose. Inhibition did not seems to be serious problem in the biogas generation from the alkali-cooking cane bagasse. 29 refs., 3 figs., 5 tabs.« less
  • Major variables reported in this study were retorting temperature, retorting atmosphere (inert, air added, air and CO/sub 2/ added), and groundwater quality (source). All leaching tests were made at atmospheric pressure and most at room temperature. Leaching tests were made with groundwater to observe the ability of spent shale to remove materials from groundwater and the possible ability of those materials to plug the pore structure of the spent shale and to minimize further leaching. The factor having the greatest effect on leachate composition was retort temperature. The presence of CO/sub 2/ during hightemperature retorting suppressed the amounts of baseformingmore » materials generated. All leachates were affected significantly by the groundwater used for leaching. As expected, more material was leached from the retorted Utah shale when the higher-purity groundwater was used. The addition of 2% Wyoming bentonite for the purpose of pH modification to the groundwater used for leaching the retorted shale (780 and 1000/sup 0/C (1,436 and 1,832/sup 0/F) retort atmosphere of air with 15% CO/sub 2/ added) showed that the bentonite had only a small effect on the leaching of monovalent cations and essentially no effect on the movement of the heavy, hazardous cations. The effect of retorting temperature was mixed with the exception of chromium, which increased four- to fivefold in the leachate. The permeability of Utah shale was determined by retorting two cores from Rock 2 at 780/sup 0/C (1,436/sup 0/F) for 48 hours in the presence of air alone. The differences in the final permeability of these cores can be attributed to differences in groundwaters.« less
  • A mathematical model simulating the hydrological and biochemical processes occurring in landfilled waste is presented and demonstrated. The model combines biochemical and hydrological models into an integrated representation of the landfill environment. Waste decomposition is modelled using traditional biochemical waste decomposition pathways combined with a simplified methodology for representing the rate of decomposition. Water flow through the waste is represented using a statistical velocity model capable of representing the effects of waste heterogeneity on leachate flow through the waste. Given the limitations in data capture from landfill sites, significant emphasis is placed on improving parameter identification and reducing parameter requirements.more » A sensitivity analysis is performed, highlighting the model's response to changes in input variables. A model test run is also presented, demonstrating the model capabilities. A parameter perturbation model sensitivity analysis was also performed. This has been able to show that although the model is sensitive to certain key parameters, its overall intuitive response provides a good basis for making reasonable predictions of the future state of the landfill system. Finally, due to the high uncertainty associated with landfill data, a tool for handling input data uncertainty is incorporated in the model's structure. It is concluded that the model can be used as a reasonable tool for modelling landfill processes and that further work should be undertaken to assess the model's performance.« less
  • Highlights: • Effect of low frequency ultrasound pretreatment on leachate was investigated. • Three different ultrasound energy inputs (200, 400 and 600 W/l) was applied. • Low-frequency ultrasound treatment increased soluble COD in landfill leachate. • Application of ultrasound to leachate increased biogas production about 40%. • Application of ultrasound to leachate increased total methane production rate about 20%. - Abstract: The aim of this study is to increase biogas production and methane yield from landfill leachate in anaerobic batch reactors by using low frequency ultrasound as a pretreatment step. In the first part of the study, optimum conditions formore » solubilization of organic matter in leachate samples were investigated using various sonication durations at an ultrasound frequency of 20 kHz. The level of organic matter solubilization during ultrasonic pretreatment experiments was determined by calculating the ratio of soluble chemical oxygen demand (sCOD) to total chemical oxygen demand (tCOD). The sCOD/tCOD ratio was increased from 47% in raw leachate to 63% after 45 min sonication at 600 W/l. Non-parametric Friedman’s test indicated that ultrasonic pretreatment has a significant effect on sCOD parameter for leachate (p < 0.05). In the second part of the study, anaerobic batch reactors were operated for both ultrasonically pretreated and untreated landfill leachate samples in order to assess the effect of sonication on biogas and methane production rate. In anaerobic batch reactor feed with ultrasonically pretreated leachate, 40% more biogas was obtained compared to the control reactor. For statistical analysis, Mann–Whitney U test was performed to compare biogas and methane production rates for raw and pretreated leachate samples and it has been found that ultrasonic pretreatment significantly enhanced biogas and methane production rates from leachate (p < 0.05) in anaerobic batch reactors. The overall results showed that low frequency ultrasound pretreatment can be potentially used for wastewater management especially with integration of anaerobic processes.« less
  • Aerobic, anaerobic and anaerobic/aerobic biotreatment of an industrial hazardous waste landfill leachate was evaluated in bench scale biofilm reactor systems operated under steady-and non-steady-state conditions. The leachate contained volatile and semi-volatile organics that exceeded the best-demonstrated-available-technology (BDAT) standard established for multi-source leachate wastewater under the Resources Conservation and Recovery Act (RCRA). The influent leachate stream was continuously applied to three parallel systems: (1) an upflow anaerobic filter followed by a submerged aerobic filter, both plastic packing, (2) an anaerobic granular activated carbon column, and (3) an upflow, plastic packed aerobic filter. All systems achieved steady-state COD removals of 66-82 percent.more » The sequential anaerobic/aerobic filter system was most resistant to hydraulic and organic shock loading, whereas the aerobic filter performance deteriorated significantly. Though transformations of specific chemical compounds were achieved in both anaerobic and aerobic treatment, the sequential anaerobic/aerobic system was cost effective for meeting BDAT standards for hazardous organics. 25 refs., 6 figs., 15 tabs.« less