The Combination of Air Flotation and a Membrane Bioreactor for the Treatment of Palm Oil Mill Effluent

Abstract

The combination of baffled air flotation and a membrane system for the treatment of palm oil mill effluent (POME) was studied. The POME was obtained from a palm oil factory in PTPN I Tanjong Seumantoh, Aceh, Indonesia. Operation variables and conditions, such as the hydraulic retention time and air flow rates, were varied to find the optimum process. The air flotation process is able to reduce the concentration of suspended solids and fats/ oils contained in the wastewater, which increases the performance of the membrane by reducing clogging. The results showed that this method was promising for POME treatment. The optimum organic removal efficiency of the air flotation pretreatment was obtained at HRT = 5 days and at an air flow rate of 11 L/min. The effluent was subsequently passed through an anaerobic membrane system to achieve the highest removal efficiency treatment. The removal efficiency of chemical oxygen demand (COD), total suspended solids (TSS), turbidity, mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids (MLVSS), and fats/oils after passing through the membrane system were 97%, 93.9%, 99.8%, 94.5%, 96.2%, and 99.9%, respectively. The results also showed that the pH could be neutralized to 6.18, while a dissolved oxygen (DO) level of 1.60 mg/L could be achieved. A high quality of effluent was obtained, which met the standards for POME effluent.

Treatment of Palm Oil Mill Effluent Using Membrane Bioreactor: Novel Processes and Their Major Drawbacks

“…In the last few years, intensive studies have been reported on the use of MBR for POME treatments [12,40,[56][57][58][59][60]. Principally, the MBR treatment processes constitute membrane-filtration and bio-decomposition of organic substance present in the mixed liquor to form a more innocuous product, such as carbon dioxide (CO 2 ) and water [61]. During the filtration process, the membrane retains the microbial flocs and any particles whose size is greater than the pores diameters within the concentrate and produce filtrate with more inoffensive substances [62].…”

“…The applications of the membrane for filtration process in MBR entail the physical estrangement of the suspensions into concentrates and permeate at a certain range of pressure [61,70]. This implies that a membrane acts as a discerning barrier based on the molecular weight of the constituted substances.…”

“…In view of this note, it can be deduced that pores sizes play a major role in terms of applications, the kinetic ability of mass transportation through the membrane, and the trans-membrane pressure (TMP) requirement [73][74][75][76][77]. The TMP provides the required force to conduct the substances of smaller sizes through the membrane pores [61,70]. During filtration, the TMP together with the pore sizes and membrane construction materials directly influence the overall selectivity and productivity performance of the membrane during treatment [71].…”

“…This defect in dead-end filtration justifies the usual batch process recommended, which ultimately obviates frequent fouling, diminishing critical flux and declination in selectivity [97]. This implies that, in a practical MBR application, the important membrane performance and functionality indices under variable processing conditions include the critical flux, TMP, and selectivity factors [40,61].…”

“…Faisal et al [61] attempted reducing the rate of bio-fouling by incorporating a dissolved air flotation (DAF) system with AnMBR. They observed a reduction in the membrane fouling rate and the overall organic pollutants removal efficiency improves significantly in the range between 94-99.9%.…”