International Journal of Engineering Research and Reviews
ISSN 2348-697X (Online) Vol. 10, Issue 1, pp: (1-7), Month: January - March 2022, Available at: www.researchpublish.com
Effect of Exhaust Gas Stirring on CH4 Production in Batch Digester Mostafa Ashmawy1, Osaid Abu El-Yazeed2, Yousef Ahmed Atay2, Mina Danial1 1 2
Civil Engineering Department, Faculty of Engineering at El Mattria
Mechanical Engineering Department, Faculty of Engineering at El Mattria Helwan University, Cairo, Egypt
Abstract: Sewage sludge is an undesirable organic matter, which is most frequently generated from the treatment process in wastewater treatment plants and causes environmental pollution if not well treated or used for energy generation. Sludge mostly contains biodegradable materials, which can produce methane as a generated biogas. Therefore, biogas production from sludge is a promising method of wastes treatment because it provides a good energy recovery as well as resolves environmental problems. In this study, secondary sludge and thickened sludge of a traditional activated sludge wastewater treatment plant were provided to determine the total solids content. The sludge types were digested for 30 days where generator exhaust was used for stirring for 15 minutes daily. Three experimental trials were conducted with a steel fixed dome, square-shaped anaerobic digester. Produced biogas was analyzed for the quantitative determination of methane (CH 4) and carbon dioxide (CO2). The produced CH4 was recorded to be zero, 60.7 % and 41.8 % when using secondary sludge, thickened sludge, and thickened sludge without stirring, respectively. Cumulative CH4 production was studied for seven, 15 and 30 days. For thickened sludge, the results showed that approximately 80 % of produced CH4 was between 15 and 21 days. A comparison between stirred digested thickened sludge and the digested thickened sludge without stirring was conducted and showed a good effect of the exhaust gas stirring. Increasing rate due to exhaust gas stirring was calculated and it was 31.14 %, 29.82 % and 20.39 % for 30, 15, 7 days, respectively. Keywords: Anaerobic digestion, Batch digester, Methane production, Sludge, biomass, biogas.
I. INTRODUCTION Renewable and clean energy play an important role in the process of life and particular biomass could contribute in a significant way because it is a carbon nature fuel and could be considered a sustainable power source useful for environmental human use [1, 2]. It very well may be utilized for enthusiastic transformation through various processes, like biochemical or warm substance ones, contingent upon the biomass properties[2]. The anaerobic bacterial interactions have been generally utilized for sludge digestion absorption in wastewater treatment plants or for treating natural compost, accomplishing biogas to produce and deliver energy [3, 4]. A group of anaerobic microorganisms catalysis the process and transforms complicated macromolecules into low molecular weight chemicals, this process is called anaerobic digestion/decomposition [5, 6]. The anaerobic digestion process could be defined as a sequence of metabolic transformations induced by various bacterial consortia: Extracellular enzymes must first liquefy organic substrate materials such as cellulose, hemicellulose, and lignin [7, 8]. Then, organic materials are treated by acidogenic bacteria and soluble organic components including hydrolysis products are converted into organic acids, alcohols, hydrogen, and carbon dioxide by acidogenic [9]. The rate of hydrolysis depends on pH value, temperature, composition, and concentration of organic and intermediate compounds [10]. Acidogenesis products are transformed into acetic acid, hydrogen, and carbon dioxide [11]. Methane gas is created by methanogenic bacteria from acetic acid, hydrogen, and carbon dioxide, as well as additional substrates, the most important of which being formic acid and methanol [4, 8].
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