Kinetics and performance study of ultrasonic-assisted membrane anaerobic system using Monod Model for Palm Oil Mill Effluent (POME) treatment

The discharge of Palm Oil Mill Effluent (POME) to river or sewage has caused serious environmental problems for the past several decades. This has prompted many researchers to find alternative technologies such as the use of an ultrasonic-assisted membrane anaerobic system, also known as UMAS. However, further use of UMAS in treating POME tends to create blockage on the membrane surface, which is commonly known as membrane fouling. In this study, kinetic parameters of POME samples which contributed to the fouling were investigated, namely; the biomass growth rate, μmax and substrate utilization rate, Ks. Two different sources of POME samples were taken from namely; a final discharge pond at Felda Sungai Tengi, Selangor and decanter processing units at Felda Jengka, Pahang. The POME samples were treated by UMAS in a 26-Litre laboratory reactor which operated 5 ​h per day for a HRT of 7 days so as to observe their performance in terms of percentage COD removal and CH4 production. Performance results revealed that maximum COD removal efficiencies were 82.75% and 94.43% for the final discharge pond and decanter processing unit samples respectively. All these data were collected and curve fitting methods were then used to construct appropriate profiles for μmax and Ks following a Monod model. It was found that the high OLR sample (decanter) apparently yielded better efficiency of POME treatment (i.e. calculated μmax of 0.327 day−1, Ks of 0.361 ​g COD/g VSS. d, and volume of CH4 gas produced at 25 ​m3) compared to that of low OLR sample from ponds (i.e. calculated μmax of 0.237 day−1, Ks of 0.1674 ​g COD/VSS. d, and volume of CH4 gas produced at 9 ​m3). In conclusion, it shows that UMAS is a promising treatment to treat POME in which its calculated kinetic coefficients of μmax and Ks are similar to the theoretical values when Monod Model is employed in this study. •COD removal efficiencies were achieved at 82.75% and 94.43% for the pond and decanter samples, respectively.•Calculated values for µmax were 0.237 day-1 and 0.327 day-1 for the pond and decanter samples, respectively.•Calculated Ks value for the decanter sample was at 0.361 g COD/g VSS. d.•Calculated Ks value for the pond sample was at 0.167 g COD/ g VSS. d.•At 7 days HRT, CH4 gas produced was higher (25 m3) from the decanter samplecompared to 9 m3 only from the pond sample.