Simulation and optimisation of full-scale palm oil mill effluent (POME) treatment plant with biogas production

Palm oil mill effluent (POME) is the primary source of water pollution in the oil palm industry. Most palm oil mills are employing a series of anaerobic and aerobic ponds for POME treatment, in order to comply with environmental regulation. In recent years, some mills are installed with biogas capture facilities in order to reduce the emission of greenhouse gas, as well as to raise some profits. In this work, a covered lagoon process for POME treatment, coupled with biogas production was modelled using commercial process simulation software SuperPro Designer v9.0. The simulation results revealed that 29 m(3) of biogas can be produced per tonne of treated POME, with a removal efficiency of 92 % for its chemical oxygen demand (COD). Cost analysis has proven that the process is economically viable, with a net present values of $ 2,830,000, IRR of 14.3 %, and payback time of 4.66 years. Process optimisation revealed that the optimal recycle ratio of sludge should be set to 30 %, where the minimum net expenditure ($11,812/y) is achieved, with final effluent COD content of 18 ppm. Note that this takes into consideration of the trade-off between capital and operating costs.