Techno-Economic Assessment of a 70 m3 Concrete Biodigester for Co-Digesting Pig Manure and Organic Waste

Abstract

Pig farming in the Ventanilla pig park (Callao, Peru) generates large volumes of manure that are currently managed in a precarious manner, with diffuse emissions of methane, leachates, and socio-environmental conflicts in a densely populated peri-urban area. Although biogas utilization offers a sustainable alternative, most of the solutions available to small and medium-sized producers are based on empirical designs, without clear criteria for organic load, hydraulics, or structural safety. The process sizing is based on a volumetric organic load of 2.5 kgSV/m3·day and a hydraulic retention time of approximately 23 days, considering 65 kg pigs with manure production of $8\%$ of live weight, 6% dry matter, and $95\%$ volatile solids. Under these assumptions, the system is designed to treat the manure of around 420 pigs, with a theoretical production of 43–44 m3/day of biogas (0.35 m3/kgSV), equivalent to about 96 kWh/day of electricity, sufficient to operate the 10 kWe generator for 9–10 hours per day. The civil plant already built and the planned integration of agitation equipment, gas hood, biogas lines, and generator set make this module a replicable demonstration platform for reducing environmental impacts and improving energy security in peri-urban pig farms