ANAEROBIC EXPERIMENTATION TO DETERMINE KEY PARAMETERS FOR OPTIMAL PERFORMANCE OF A PILOT SCALE BIO-DIGESTER FOR EMULATING LANDFILL CONDITIONS AND GAS RECOVERY

ABSTRACT The increasing population and economic activities in Nigeria have encouraged high generation of wastes as well as high energy crisis, resulting in the continued use of fossil fuels and increment in greenhouse gases. Therefore, the necessity to tackle these setbacks via biomass landfill biogas production, a renewable energy system from wastes cannot be overemphasized. This study examined the optimal anaerobic digestion processes of a pilot-scale bio-digesters for emulating landfill conditions. Organic feedstock from variety of food waste, cow dung and distilled water were collected from cafeterias, restaurants, hotels, and households in Ikot Abasi metropolis and cattle range in Uyo, South South Nigeria. Segregation, characterization, homogenization, parametric tests, monitoring and extraction were carried out. These samples were digested using a bio-digester with parametric testing equipment. Different masses of feedstock ranging from 10 – 25 kg with two mix ratios of 1:1 and 2:1 each were employed. From the results, the hydraulic retention time (HRT) showed linearity with approximately 0.73 days per kg, a pH of 6.9 – 7.1 (pre-digestion), 6.7 – 6.8 (post-digestion) and mesophilic temperature of 22–33°C. Feedstock of 1:1 ratio had gas yield of 12 ml per kg whereas 1:2 ratio had 11.4 ml per kg. System pressure was respectively 0.16 Pa per day, 0.053 Pa per kg feedstock and 0.174 Pa per day, roughly 0.058 Pa per kg feedstock. It can be concluded that a positive correlation exists between feedstock mass and biogas yield with 1:1 ratio having a consistent advantage of 21-27% gas yield over the 2:1 ratio. The pilot-scale experiments also bridged the gap between laboratory-scale research and full-scale landfill applications, reducing greenhouse gas emissions and harnessing renewable energy. Keywords: Wastes, Energy crises, Biomass, Landfill, Feedstock, Pilot-scale