Production of Methane and Hydrogen from Mild-Strength Industrial Wastewater

Abstract

Over the past two decades, fossil fuel reserves have sharply shrunk, which has resulted in a global fall in energy sources. Alternative carbon-neutral renewable energy sources have caught the interest of experts due to the erratic nature of energy prices and their severe ecological effects. The treatment plant’s mild-strength effluent from an equalization tank at an industrial factory was used in this study to generate hydrogen and methane. This mild-strength effluent had a chemical oxygen demand (COD) content of 2.8 ± 1.0 g COD/L. A double stage anaerobic digestion system’s hydrogen-generating digester was run at a hydraulic retention time of 8 h while the methane-generating digester was run at a hydraulic retention time of 24 h. The highest methane production rate (MPR), methane yield (MY), methane content and COD elimination were, in order, 71 ± 30 mL/L-d, 57 ± 10 mL/g COD, 90 ± 1% and 77%, respectively. In this experiment, energy efficiency was assessed using the following criteria: Maximum heating was at a value of 2.1 × 108 kcal/y. Utilizing energy-equivalent coal, natural gas, or fuel reduced annual carbon emissions by 8.7 × 104 kg CO2/y, 5.1 × 104 kg CO2/y and 7.1 × 104 kg CO2/y, respectively.