NUMERICAL INVESTIGATION OF FEED CONFIGURATION AND REACTOR DESIGN TO IMPROVE BIOGAS DIGESTER EFFICIENCY USING CFD

Abstract

Biogas technology offers a sustainable and decentralized solution for organic waste management, energy generation, and nutrient recycling—especially in rural and semi-urban areas. However, many biogas plants in developing regions operate below capacity or are non-functional due to poor feedstock adaptability, inconsistent operational practices, and inadequate post-processing infrastructure. A comprehensive, multi-stage strategy was implemented to boost biogas plant performance across all process phases. An on-site field survey of 30 rural digesters identified common operational bottle necks, and a dedicated twoyear study of a 1-tonne anaerobic digester was conducted under real conditions. A key innovation was a novel pre-digester unit that cotreats diverse local wastes (e.g. temple flower waste, agricultural residues, cow dung), greatly increasing feed stock flexibility and yielding more gas (by improved hydrolysis) while also diverting solid waste to energy. In the main digester, standard best practices (feeding schedules, mixing, maintenance) were tightened to raise gas output and reliability. In post-processing, a simple water-based gas scrubber (a low-cost vertical scrubber column) was installed to remove roughly 30–40% of the CO₂ from raw biogas, thereby raising its methane content and calorific value these integrated changes, overall methane yield and plant resilience increased significantly. For example, adding heterogeneous solid waste in the pre-digester (as enabled by the new feed system) boosted gas production without upsetting the process. Similarly, the inexpensive water-scrubbing step enriched fuel quality (producing a carbonated byproduct usable as organic amendment with minimal complexity. This case study demonstrates that simultaneous optimization of preprocessing, digestion, and postdigestion subsystems can sustainably