Various Sludge Pretreatments: Their Impact on Biogas Generation

Abstract

Biogas produced through anaerobic degradation of waste activated sludge (WAS) in wastewater treatment plants has gained much more attention as it is a renewable energy resource. An apparent advantage of anaerobic digestion is the generation of biogas that presents a renewable substitute for utilization of fossil fuels. It was observed that pretreatment has to be done prior to anaerobic degradation (AD) to enhance the biogas generation. This review deals with various pretreatments-chemical, physical, mechanical, combinative, phase-separated pretreatment, their mode of action, advantages and their impact on biogas generation. An extensive review of these pretreatment techniques could plausibly aid in increasing the biogas production and thus rises the sustainable energy generation.

Microbial Responses to Different Operating Practices for Biogas Production Systems

“…Pretreatment is a well-proven approach to improve degradation of such waste. Common pretreatment strategies comprise physical (e.g., heat/pressure, irradiation, ultrasonic), chemical (e.g., acids/bases, ozonation, oxidation), and biological (addition of fungi/bacteria/enzymes under aerobic or anaerobic conditions) methods [16,157]. The general concept of pretreatment is that it should improve the accessibility of the material to microbial degradation by disrupting the structure, changing the biomass porosity, and reducing the particle size to enhance the surface area that can be attacked.…”

Disintegration of Wastewater Activated Sludge (WAS) for Improved Biogas Production

“…For example, in 2009 there were 6227 of these plants in Europe, by 2015 there were 17,376, an almost three -fold increase in only six years [8]. In China alone there are currently more than one million of these plants [9].…”

“…For example, in 2009 there were 6227 of these plants in Europe, by 2015 there were 17,376, an almost three -fold increase in only six years [8]. In China alone there are currently more than one million of these plants [9]. Anaerobic digestion process entails four steps, i.e., hydrolysis, acidogenesis, acetogenesis and methanogenesis [13]; the complex process is attainable only under strict anaerobic conditions, with hydrolysis being a rate limiting step [14].…”

Introductory Chapter: An Overview of Biogas

“…In order to increase the rate of hydrolysis, many researchers have adopted various pretreatment methods. Banu and Kavitha [1] have reviewed in detail regarding various pretreatment methods and their effects on anaerobic digestion.…”