Abstract
This study highlights an innovative piece of hybrid technology, whereby the combination of anaerobic and aerobic processes into a single reactor, namely, the integrated anaerobic–aerobic bioreactor (IAAB) can surpass the limits of conventional methods treating palm oil mill effluent (POME). Optimisation of IAAB using SuperPro Designer V9 simulator for maximum biogas yield while addressing its economic and environmental trade-offs was conducted for the first time. Parameters such as hydraulic retention time (HRT) and organic loading rate (OLR) were optimised in the anaerobic compartment from 10 days and 6.2 g COD/L day to 9 days and 6.9 g COD/L day, respectively. Furthermore, sludge recycle ratio was optimised from 20% to 50% in the aerobic compartment. The optimisation was successful where the biogas yield increased from 0.24 to 0.29 L CH4/g CODremoved with excellent Chemical Oxygen Demand (COD), and Biological Oxygen Demand (BOD) removal efficiencies up to 99% with 5.8% lower net expenditure. This simulation results were comparable against the pre-commercialized IAAB with 11.4% increase in methane yield after optimisation. Economic analysis had proven the optimised process to be feasible, resulting in return on investment (ROI), payback time, and internal rate of return (IRR) of 24.5%, 4.1 years, and 17.9%, respectively.
Highlights
Based on the pre-commercialized integrated anaerobic–aerobic bioreactor (IAAB) settings, the current IAAB parameters such as HRT in the anaerobic compartment (HRTan) (HRT for anaerobic process) and HRT of aerobic compartment (HRTa) (HRT for aerobic process) are taken as 10 days and 4 days, respectively, which are adopted from Chan et al [18] while the activated sludge recycle ratio is set at 20%
The simulated base case results in methane composition of 64%, which proved that the kinetic models, stoichiometry, and coefficient applied are correct and considered as reasonable estimation to proceed for further process optimisation
The simulation for complete treatment of palm oil mill effluent (POME) using IAAB has been successfully conducted by SuperPro Designer V9
Summary
Oil palm is one of the commodities among the third world countries and it is dominated by Malaysia, contributing to 28% of world palm oil production and 33%. According to Chen et al [2], the global population will continue to rise to 9.5 billion by year 2050 according to the medium-growth projection scenario of the United Nations. The positive response to global population growth will most likely increase the worldwide demand for food, water, and drink. The global demand for fats and oils are estimated to rise up to 360 million tonnes by 2043 the amount of palm oil mill is predicted to increase along with the consumption of lipids for global needs [1]. A study by Zaied et al [4] stressed that untreated
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