Production of biogas as a waste management option for textile effluent sludge: a case study of the a to z textile mills ltd

Abstract

Textile effluent sludge management is becoming a major environmental management issue in many agro-processing industries throughout Africa. This is mostly due to the limited and ineffective means of management. This research explored the potential of producing biogas as a strategy for reducing the on-site accumulation of textile effluent sludge. The co-digesting of the textile effluent treatment plant (ETP) sludge with substrates such as sewage treatment Plant (STP) sludge, cow dung (CD), and sawdust, was investigated as the main approach for the anaerobic digestion (AD) process. ETP sludge and STP sludge were collected from A to Z Textile Mills Ltd factory and a complete characterization was made in triplicate for essential parameters, namely chemical ogygen demand (COD), biological oxygen demand (BOD), alkalinity, volatile fatty acids (VFAs), carbon to nitrogen ratio (C/N ratio) and heavy metals. Sludge mixtures were analyzed before and after digestion. Biogas production was tested for 30 days at different mixing ratios (4:0, 3:1, 1:1, 0:4). A laboratory-scale reactor was assembled for the experiments. High biogas yield was achieved from the co-digestion of ETP sludge and STP sludge at a mixing ratio of 3:1, 1:1, and 1:3, and methane content was, respectively, 87.9%, 68.9%, and 69.5% of the gas composition. Results from the current study provide relevant information to improve the production of biogas from ETP sludge through co-digestion and various pretreatment methods.