Topic
Biogas
About: Biogas is a research topic. Over the lifetime, 28571 publications have been published within this topic receiving 498545 citations.
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TL;DR: A number of techniques have been developed to remove H 2 S from biogas, such as pressure swing adsorption, membrane separation, physical or chemical CO 2 -absorption as discussed by the authors.
Abstract: Biogas from anaerobic digestion and landfills consists primarily of CH 4 and CO 2 . Trace components that are often present in biogas are water vapor, hydrogen sulfide, siloxanes, hydrocarbons, ammonia, oxygen, carbon monoxide and nitrogen. In order to transfer biogas into biomethane, two major steps are performed: (1) a cleaning process to remove the trace components and (2) an upgrading process to adjust the calorific value. Upgrading is generally performed in order to meet the standards for use as vehicle fuel or for injection in the natural gas grid. Different methods for biogas cleaning and upgrading are used. They differ in functioning, the necessary quality conditions of the incoming gas, the efficiency and their operational bottlenecks. Condensation methods (demisters, cyclone separators or moisture traps) and drying methods (adsorption or absorption) are used to remove water in combination with foam and dust. A number of techniques have been developed to remove H 2 S from biogas. Air dosing to the biogas and addition of iron chloride into the digester tank are two procedures that remove H 2 S during digestion. Techniques such as adsorption on iron oxide pellets and absorption in liquids remove H 2 S after digestion. Subsequently, trace components like siloxanes, hydrocarbons, ammonia, oxygen, carbon monoxide and nitrogen can require extra removal steps, if not sufficiently removed by other treatment steps. Finally, CH 4 must be separated from CO 2 using pressure swing adsorption, membrane separation, physical or chemical CO 2 -absorption.
1,117 citations
TL;DR: In this paper, a review of the methods that have been studied for pretreatment of lignocellulosic biomass for conversion to biogas is presented, including physical, chemical, and biological approaches.
1,062 citations
TL;DR: This paper presents a review of the main sludge treatment techniques used as a pretreatment to anaerobic digestion, and it is likely that low impact pretreatment methods such as mechanical and thermal phased improve speed of degradation, while high impact methods improve both speed and extent of degradation.
1,058 citations
TL;DR: The aim of this paper is primarily to review the recent literature about the occurrence of both acetotrophic and hydrogenotrophic methanogens during anaerobic conversion of particulate biomass to methane (not wastewater treatment), while this review does not cover the activity of the acetate oxidizing bacteria.
Abstract: Among different conversion processes for biomass, biological anaerobic digestion is one of the most economic ways to produce biogas from various biomass substrates In addition to hydrolysis of polymeric substances, the activity and performance of the methanogenic bacteria is of paramount importance during methanogenesis The aim of this paper is primarily to review the recent literature about the occurrence of both acetotrophic and hydrogenotrophic methanogens during anaerobic conversion of particulate biomass to methane (not wastewater treatment), while this review does not cover the activity of the acetate oxidizing bacteria Both acetotrophic and hydrogenotrophic methanogens are essential for the last step of methanogenesis, but the reports about their roles during this phase of the process are very limited Despite, some conclusions can still be drawn At low concentrations of acetate, normally filamentous Methanosaeta species dominate, eg, often observed in sewage sludge Apparently, high concentrations of toxic ionic agents, like ammonia, hydrogen sulfide (H2S) and volatile fatty acids (VFA), inhibit preferably Methanosaetaceae and especially allow the growth of Methanosarcina species consisting of irregular cell clumps, eg, in cattle manure Thermophilic conditions can favour rod like or coccoid hydrogenotrophic methanogens Thermophilic Methanosarcina species were also observed, but not thermophilic Methanosaetae Other environmental factors could favour hydrogentrophic bacteria, eg, short or low retention times in a biomass reactor However, no general rules regarding process parameters could be derivated at the moment, which favours hydrogenotrophic methanogens Presumably, it depends only on the hydrogen concentration, which is generally not mentioned in the literature
1,018 citations
TL;DR: The various techniques, which could be used to enhance the gas production rate from solid substrates are reviewed.
978 citations