Effective Optimization of Bacterial and Alkaline Augmented Plants Substrate on Biogas Yield Using Operational Conditions

Abstract

Biogas technology as an alternative energy source illuminates the need for less dependence on fossil fuel. This study highlights the importance of bacteria and alkaline augmentation on lignocellulose-rich biomass for enhanced biogas production. Three different plant substrates namely: maize cob (MC), rice straw (RS), water hyacinth (WH), were augmented with 10% alkaline (NaOH) and 1000 ml broth culture of isolated bacteria (Bacillus sp), while cow rumen (CR) waste served as inoculum. They were formed into three batches as Batch A (maize cob), Batch B (rice straw) and Batch C (water hyacinth). Hydraulic retention time, temperature and pH were monitored during the experiment while biogas production was obtained daily. The results showed that the highest biogas yield was obtained in bacteria augmented MC (626.265 ml/kg TS) at 28 °C and alkaline augmented WH (498.265 ml/kg) at 25 °C. The least biogas production yield was observed in bacteria augmented WH (290.398 ml/kg TS) and untreated MC (311.939 ml/kg TS) at 35 °C and 38 °C respectively. The methane concentrations of the biogas produced were highest in untreated WH and bacteria augmented RS at 3849 ppm and 8558 ppm, the least was observed in bacteria augmented WH at 1130 ppm. The pH of the slurry were within range as the least was 5.4 and the highest recorded was 7.4. The performance of the substrates indicates that plant substrates are impacted by augmentation. However, characteristics and operational conditions are vital irrespective of the required augmentation utilized to enhance production efficiency.