Effect of aeration on fresh and aged municipal solid waste

Under the anaerobic conditions of conventional sanitary landfill, entombed municipal solid waste (MSW) is slow to stabilize necessitating long-term monitoring and pollution control. Although anaerobic conditions can provide revenue through energy generation, aerobic stabilization may offer several advantages including reduced fugitive greenhouse gas emissions, accelerated landfill stabilization, and increased landfill airspace recovery. Air injection was applied to bench-scale bioreactor landfills in order to determine the potential for active aeration to accelerate municipal solid waste stabilization and settlement in both new and pre-existing landfills. Fresh and aged wastes were used to represent newly constructed and existing landfill matrices over 130 days. In the fresh MSW bioreactors, aeration reduced the time to stabilization of leachate pH by 44%, TSS by 25%, TDS by 54%, BOD5 by 38% and COD by 59%. Ammonia concentrations stabilized after 129 days of aeration, but remained problematic in the anaerobic bioreactors at the study conclusion. Final leachate concentrations were consistently lower in the aerobic bioreactors than in their anaerobic counterparts. Physical settlement also improved, resulting in a 21.5% recovery of landfill airspace in the aerobic fresh waste bioreactors. Aeration had a similar but reduced influence in the aged waste bioreactors since they were near stabilization at the study inception. The results of this study indicate that aeration significantly accelerates stabilization of MSW with greatest influence on fresh waste with a high biodegradable organic fraction.

Effect of aeration on fresh and aged municipal solid waste

Under the anaerobic conditions of conventional sanitary landfill, entombed municipal solid waste (MSW) is slow to stabilize necessitating long-term monitoring and pollution control. Although anaerobic conditions can provide revenue through energy generation, aerobic stabilization may offer several advantages including reduced fugitive greenhouse gas emissions, accelerated landfill stabilization, and increased landfill airspace recovery. Air injection was applied to bench-scale bioreactor landfills in order to determine the potential for active aeration to accelerate municipal solid waste stabilization and settlement in both new and pre-existing landfills. Fresh and aged wastes were used to represent newly constructed and existing landfill matrices over 130 days. In the fresh MSW bioreactors, aeration reduced the time to stabilization of leachate pH by 44%, TSS by 25%, TDS by 54%, BOD5 by 38% and COD by 59%. Ammonia concentrations stabilized after 129 days of aeration, but remained problematic in the anaerobic bioreactors at the study conclusion. Final leachate concentrations were consistently lower in the aerobic bioreactors than in their anaerobic counterparts. Physical settlement also improved, resulting in a 21.5% recovery of landfill airspace in the aerobic fresh waste bioreactors. Aeration had a similar but reduced influence in the aged waste bioreactors since they were near stabilization at the study inception. The results of this study indicate that aeration significantly accelerates stabilization of MSW with greatest influence on fresh waste with a high biodegradable organic fraction.

Insights from Mathematical Modelling into Energy Requirement and Process Design of Continuous and Batch Stirred Tank Aerobic Bioreactors

Bioreaction kinetics, oxygen transfer and energy modelling were applied to stirred tank aerobic bioreactors. This was done to investigate how key input design variables influence bioreactor size, feed and wasted substrate, and electrical energy requirements for aeration and cooling, and to compare batch and continuous modes of operation. Oxygen concentration in the liquid is a key input design variable, but its selection is challenging as it can result in design trade-offs. Reducing its value caused a decrease in electrical energy requirement, however this tended to increase the working volume of the bioreactor. The minimum or near-to-minimum total energy requirement for oxygen transfer occurred when operating at the onset of flooding throughout the bioreaction time. For typical KS values, continuous mode of operation required a much smaller bioreactor volume, due to higher operating cell concentration, and this is a major advantage of continuous over batch.

Municipal Solid Waste Management Using Bioreactor Landfill in the Treatment of Organic Waste from Jatibarang Landfill, Semarang-Indonesia

Landfilling is one of the easiest methods to be applied in the management of municipal solid waste (MSW). In its development, bioreactor landfill methods that have various advantages over conventional landfill emerge. This experiment aims to study the use of bioreactor landfills for the management of organic waste in Jatibarang Landfill, Semarang-Indonesia. There are 4 bioreactor landfills operated: 2 anaerobic bioreactors with leachate recirculation and addition of water, and 2 aerobic bioreactors. Different results are shown from these two types of bioreactor, where aerobic bioreactors reach peak temperatures (55oC each) faster even though anaerobic bioreactors reach higher temperatures (60oC and 61oC respectively). Anaerobic bioreactors reach a higher final pH value than aerobes while the accumulation of nitrogen content from an aerobic bioreactor is 2 times higher than anaerobes.

Define of internal recirculation coefficient for biological wastewater treatment in anoxic and aerobic bioreactors

The biological wastewater treatment technologies in anoxic and aerobic bioreactors with recycle of sludge mixture are used for the effective removal of organic compounds from wastewater. The change rate of sludge mixture recirculation between bioreactors leads to a change and redistribution of concentrations of organic compounds in sludge mixture in bioreactors and change hydrodynamic regimes in bioreactors. Determination of the coefficient of internal recirculation of sludge mixture between bioreactors is important for the choice of technological parameters of biological treatment (wastewater treatment duration in anoxic and aerobic bioreactors, flow capacity of recirculation pumps). Determination of the coefficient of internal recirculation of sludge mixture requires integrated consideration of hydrodynamic parameter (flow rate), kinetic parameter (rate of oxidation of organic compounds) and physical-chemical parameter of wastewater (concentration of organic compounds). The conducted numerical experiment from the proposed mathematical equations allowed to obtain analytical dependences of the coefficient of internal recirculation sludge mixture between bioreactors on the concentration of organic compounds in wastewater, the duration of wastewater treatment in bioreactors.