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Greenhouse Gas Emissions through Biological Processing of Solid Waste and Their Global Warming Potential
Published in Sunil Kumar, Zengqiang Zhang, Mukesh Kumar Awasthi, Ronghua Li, Biological Processing of Solid Waste, 2019
Mukesh Kumar Awasthi, Hongyu Chen, Sanjeev Kumar Awasthi, Tao Liu, Meijing Wang, Yumin Duan, Jiao Li
By utilizing the metabolism of aerobic microorganisms under aerobic conditions, aerobic fermentation changes the complex organic matter of solid waste into carbon dioxide and water. The important point is to ensure adequate oxygen supply, stable temperature, and enough water. The actual project is to inject air or oxygen into the landfill so that microorganisms in the state of aerobic metabolism. Aerobic digestion significantly increases the rate of waste degradation and stability, greatly reducing the production of methane, the amount of toxic organic matter in the leachate, and the quantity of leachate (Rao et al. 2000; Zhou et al. 2004). Anaerobic fermentation is thought process, where use the anaerobic or facultative microbial metabolism under anaerobic conditions to dispose the organic waste. The main degradation products are methane and carbon dioxide, etc., but generally need to ensure that the temperature, anaerobic or low dissolved oxygen concentration maintained through the process.
Aerobic Digestion
Published in Glenn M. Tillman, Wastewater Treatment, 2017
Aerobic digestion is the separate aeration of primary sludge, waste biological sludge, or a blend of these two in an open or closed tank.A separate sedimentation tank may be used following aerobic digestion, or a one tank, batch type system where the sludge is aerated, mixed, settled, and decanted in the same tank may be used.The aerobic digestion process is an extension of the extended aeration process. The volatile material in the wastes is digested to a reasonable maximum with up to a 45 percent destruction of volatile solids.The decomposition of solids and regrowth of organisms is maintained until the available energy in active cells and the storage of waste materials are sufficiently low and stable enough for disposal.Aerobic digestion reduces the volume of sludge solids and reduces odors or other nuisances that may be a hindrance to final disposal.
Sludge Stabilization
Published in Syed R. Qasim, Wastewater Treatment Plants, 2017
Aerobic sludge digestion is commonly used at small plants to stabilize the organic matter in the sludge. The process involves aeration of sludge for an extended period in open tanks. The process is similar to an activated sludge and involves the direct oxidation of biodegradable matter and oxidation of microbial cellular material (endogenous respiration). Stabilization is not complete until there has been an extended period of primarily endogenous respiration (10–20 days). The process has the following advantages: (1) it is simple to operate, (2) it involves low capital cost; (3) the digested sludge is odorless, biologically stable, and has excellent dewatering properties; and (4) the supernatant is low in BOD5. The digested sludge is normally dewatered on sand drying beds. The disadvantage of aerobic digestion is a high operating cost.
Hydrothermal liquefaction of municipal wastewater sludge and nutrient recovery from the aqueous phase
Published in Biofuels, 2022
Vinod Kumar, Krishna Kumar Jaiswal, Mikhail S. Vlaskin, Manisha Nanda, M. K. Tripathi, Prateek Gururani, Sanjay Kumar, Harish Chandra Joshi
Common municipal sludge disposal methods include landfilling, agricultural use and incineration [6]. In waste treatment plants, an activated sludge process is used in which microorganisms remove micro-pollutants [10]. The activated sludge process is expensive and time consuming; e.g. aerobic digestion takes 20 or more days, and anaerobic digestion takes 20–30 days. The conversion of municipal sludge by hydrothermal liquefaction (HTL) into bio-crude oil can replace non-renewable energy and reduce the volume of waste as well as eliminating pathogens and harmful constituents [11]. Therefore, alternative solutions for municipal sludge disposal become more important. The selection of a municipal sludge management strategy is based on energy requirements which depend mainly on nitrogen, phosphorus and the use of carbon as an energy source [12]. In this study, we have met these two parameters by producing hydrocarbon-rich crude oil and recycling the nutrient-rich aqueous phase through microalgae cultivation.
Review of the effects of wastewater biosolids stabilization processes on odor emissions
Published in Critical Reviews in Environmental Science and Technology, 2019
Ruth M. Fisher, Juan Pablo Alvarez-Gaitan, Richard M. Stuetz
Aerobic digestion of the biosolids is used to reduce organic content. Few studies which reported odor emissions from sites using aerobic stabilization are available (Table S3). Research literature were mostly presented in conferences comparing emissions from full scale sites or the detailing the use of auto-thermal thermophilic aerobic digestion (ATAD). Many studies used headspace sampling with TVOSC monitoring (Table S3), however only the compositions of process emissions from the digesters at sites using ATAD were monitored in detail (Table 8). Flux hood sampling was used to identify odorants and odors from dewatered biosolids and compared to sites using anaerobic digestion (Fisher, Barczak, & Stuetz, 2018; Fisher, Barczak, et al., 2018) . Studies reporting emissions from dewatered activated sludge weren’t included, as they weren’t stabilized by additional aerobic digestion in a digester. While extended aeration is an accepted stabilization method, only one relevant study was found (Rutledge, 2014).
Effect of hydrodynamic cavitation on flocs structure in sewage sludge to increase stabilization for efficient and safe reuse in agriculture
Published in Bioremediation Journal, 2022
Giuseppe Mancuso, Michela Langone, Rosa Di Maggio, Attilio Toscano, Gianni Andreottola
Hence, the need to remove these contaminants from sewage sludge through stabilization processes in WWTPs, before it can be reused again in agriculture. The most widely employed biological wastewater treatment processes to stabilize sewage sludge in WWTPs are aerobic and anaerobic digestion. Aerobic digestion is characterized by higher operating costs due to the administration of air to the system; in contrast, anaerobic digestion shows as main advantages the recovery of energy in the form of biogas, the mass reduction of sewage sludge, and the improved dewatering properties of digested sludge (Cao and Pawłowski 2012).