Anaerobic digestion of water hyacinth juice in upflow bubble column bioreactor for production of biogas and nutrient recovery

Author(s): Hailemariam Zewudu Achenef
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Institution or organization of origin: Bahir Dar University
Country: Ethiopia


This research aimed to study the anaerobic digestion of water hyacinth juice in an up-flow bubble column bioreactor for the production of biogas and nutrient recovery from digestate. The experiments were performed at a pH range of 6.5-7.5, temperature of 37ºC (mesophilic conditions), and at hydraulic retention time (HRT) of 3 and 6 days. 1mL/L of trace element was added. The proximate analysis of feedstock, the composition of effluent, and sludge were characterized for its pH, nutrients content, solid compositions, chemical oxygen demand (COD), and sludge volume index (SVI). The biogas was measured by a wet-type gas meter. The preliminary result showed that the total production of biogas was 38.42 L for a period of 90 days. The maximum biogas production rate was 2.35 L/day at HRT of 3 days. The composition of biogas, CH4, and CO2 were found to be 50-75% and 5-45% respectively. While other gases were estimated as low as 5%. Organic loading rate and hydraulic retention time have a significant (p< 0.005) effect on the yield of biogas. The concentration of nitrate nutrient increased to 69 ±9.36% effluent from the initial influent concentration of 54 ±11.32% and for phosphate it increases 7.47± 4.13% from the influent concentration of 3.97±1.92%. This study demonstrated that anaerobic digestion of water hyacinth biomass can be a potential candidate for the production of biogas energy and recovery of organic nutrients. Nevertheless, further research is needed to understand the complex interplay of the biochemical action with different biomass pretreatments and inoculum types.

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