Experimental Study and Analysis of the Effect of Detergent on the Production of Biogas from Toilet Drainage System Linked to Biogas Digester in Ethiopia (Case study: Gamo, Wolayita, and Hadiya zone)

Abstract

The toilet-connected reactor collects, stores, and treats excreta through the use of a biogas reactor that is coupled to the toilet drainage system. The majority of biogas reactors built in Ethiopia are intended to accept human waste as input. Detergents released into the toilet drainage system feed into a biogas reactor in the absence of a waste treatment system and reach anaerobic digester, resulting in a negative effect on the generation of gases. In this study, the effect of detergent on the production of biogas from toilet-connected reactor has been investigated and analyzed. The chemical compositions of biogas produced at various detergent concentrations have been investigated to analyze the impact of detergent concentration on the production of biogas. For this study, three predominantly used detergents were selected based on collected data from different households. SPSS software was used to evaluate the collected data for sample detergent preparations. The experiment involved the use of a 5-litre plastic bottle as a biogas reactor and human waste as the substrate. Seven samples with various concentrations of detergent (COD) have been examined and result fed into the gas chromatography mass spectrometry (GCMS) system for the study. Additionally, the risk of hydrogen sulfide produced in the biogas reactor at various detergent concentrations on environmental and human health has been evaluated. The results demonstrate that during the early phases (blank test to 80 ppm) of COD addition, methane production increases from 62.5% to 63.8%. Methane production decreases by 6% when the detergent concentration increases from 160 ppm to 320 ppm. Methane production significantly decreases by 23% between 320 ppm to1200 ppm detergent concentrations. The decline in methane production results in an increase in gases like N2, HCl, NaC12H25SO4, C20H37NaO7S and others. The outcome of this process poses a threat to both the environment and human health, and it also leads to the production of substandard biogas. Additionally, the introduction of detergent has a significant impact on the generation of biogas and its quality, which depends on the concentration of detergent used.