PERFORMANCE EVALUATION OF AN ANAEROBIC REACTOR FOR THE PALM OIL MILL EFFLUENT TREATMENT

• Main Author: Sri Rahayu, Ade
• Format: Theses
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/47695
• Institution: Institut Teknologi Bandung

Anaerobic treatment is commonly practiced in the palm oil mill effluent treatment that contains high levels of COD. Product of anaerobic treatment in the form of biogas can be used as a renewable energy source. PT XYZ applies anaerobic technology using an in-ground bioreactor to its palm oil mill effluent treatment. The biogas produced is fed to the biogas engines to generate electricity. The reactor was designed to treat 409 m3/day POME flow, containing COD of 62,000 ppm, that resulting biogas production rate of 13,187 Nm3/day with methane concentration >50%. The anaerobic reactor operational data shows that the biogas production has instability of methane concentration and has decreased to <50%. The low methane content causes biogas engines consume more biogas. This research is conducted to evaluate the performance of the anaerobic reactor. Bioreactor operational data of PT XYZ in December 2017–November 2018 is used as a basis data of evaluation. In the calculations, the operational data is grouped into three data periods. The kinetic model that used is including substrate utilization and methane formation refer to Barthakur et.al, 1991. The reactor performance evaluation is done by comparing operational data to reactor design criteria, calculating the COD balance, and determining the bio-kinetic parameter value. Operational data evaluation shows that reactor performance decreased as indicated by the average reduction in reactor efficiency in each data group to 84%, 83%, 82% and a decrease in average methane concentration by 47%, 45.7%, 43.1%. Calculation result of the COD balance shows a decrease in COD degradation with an increase in COD effluent by 16%, 17%, 18% and a decrease in COD gas conversion in reactor by 66%, 55%, 53%. Calculation result of bio-kinetic parameter values also indicate an inhibition in the system that related to a decrease in reactor efficiency and methane concentration. The decreasing efficiency of the reactor is shown by increasing the R value by 0.140, 0.165, 0.177 and decreasing the methane concentration shown by decreasing the B0 value by 0.284 l/g, 0.233 l/g, 0.244 l/g. The reaction kinetic model used can predict the specific methane production value in the anaerobic system of PT XYZ with a relative error value <7%, but cannot accurately predict the COD effluent with a relative error value >76%. Further studies are needed to build a kinetic model that takes into account the hydrodynamic aspect so that the model used can be more representative.