Effect of organic loading rate (OLR) on modified anaerobic baffled reactor (MABR) performance M. A. M. Aris*, S. Chelliapan**, M. F. M. Din*, A. N. Anwar*, R. Shahperi*, S. B. Selvam** * Department of Environmental Engineering, Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310, Skudai, Johor Bahru, Malaysia. (E-mail: mai.asnie@gmail.com) ** UTM Razak School of Engineering and Advanced Technology, Universiti Teknologi Malaysia, Jalan Semarak, 54100, Kuala Lumpur, Malaysia. Abstract The performance of a Modified Anaerobic Baffled Reactor (MABR) treating synthetic wastewater at different Organic Loading Rate (OLR) was investigated. The MABR was seeded with anaerobic sludge taken from a local municipal wastewater treatment plant and fed continuously with glucose at an OLR of 0.258, 0.787 and 2.471 kg COD m -3 d -1 at a Hydraulic Retention Time (HRT) of 4 days. Results showed that 99.7% Chemical Oxygen Demand (COD) removal was achieved during the OLR of 0.258 kg COD m -3 d -1 . However, when the OLR was increased to 0.787 kg COD m -3 d - 1 , a minor decrease in the COD removal efficiency (95%) was noted. Further increase of the OLR to 2.471 kg COD m -3 d -1 caused the reactor performance to deteriorate dramatically in a COD removal efficiency of 39.5%. Biogas yield was evaluated for the reactor system and followed similar decreasing trend (0.542, 0.524 and 0.214 l g -1 COD destroyed for the different OLRs respectively). There were no significant different in the pH profiles (6.71 – 7.01) during the first two OLRs (0.258 and 0.787 kg COD m -3 d -1 ). However, during the final OLR (2.471 kg COD m -3 d -1 ) the pH profile in MABR dropped to significantly as low as 4.01. Similar trend was also observed in the volatile acids (VA) profile where higher values (2880 mg/L) were found at highest OLR. The poor performance of the MABR at high OLR signifies that the microorganisms could not metabolise the organic substance and probably need more time for digestion. Keywords Modified anaerobic baffled reactor (MABR); effluent circulation, organic loading rate; synthetic wastewater INTRODUCTION Wastewater treatment engineering nowadays focuses on fulfilling these requirements; a) uncomplicated design, b) minimal construction and maintenance cost, and c) superior treatment success (Feng et al., 2008). Successful application of anaerobic technology for the treatment of industrial wastewaters is critically dependent on the development and the use of high rate anaerobic bioreactors. Among the high-rate anaerobic reactors, anaerobic baffled reactor (ABR) can be considered as one of the most convenient anaerobic treatment system. Apart of treating domestic wastewater, ABRs were extensively used in the treatment of recalcitrant wastewater such as palm oil mill effluent wastewater, swine wastes, pulp and paper mill black liquors, azo dyes containing wastewater, landfill leachate, synthetic tannery wastewater containing sulfate and chromium (III), treating whisky distillery wastewater, nitrogen containing wastewaters, sulfate containing wastewaters, textile dye wastewater, p-nitrophenol containing wastewaters, and brewery wastewater (Cui et al., 2014). ABR can be described as a series of up-flow anaerobic sludge blanket (UASB) but requires no special granule formation for its operation. This is done by the narrow down-flow and the wide up- flow inside each compartment of the ABR (Grover et al., 1999). Series of vertical baffles forces the wastewater to flow under and over them as it passes from an inlet to outlet. Bacteria within the reactor gently rise and settle due to flow characteristics and gas production in each of its compartment. Some bacteria move horizontally down the reactor at relatively slow rate. Its design ensures contact of biomass with substrates without the need to use any mechanical mixing. brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by Universiti Teknologi Malaysia Institutional Repository