Membrane Fouling Control by Ultrasonic Membrane Anaerobic System (UMAS) to Produce Methane Gas

In Malaysia, more than 30 tonnes of waste sugarcane was burned and damped to an open field. The direct discharge of sugarcane wastewater causes serious environmental pollution due to its high chemical oxygen demand (COD) and biochemical oxygen demand (BOD). Traditional methods for sugarcane treatment have both economic and environmental disadvantages. In this study, Ultrasonic membrane anaerobic system (UMAS) was used as an alternative, cost-effective method for treating raw sugarcane wastewater. Raw sugarcane wastewater treated by UMAS in a laboratory digester with an effective 200-litre volume. The ultrasonic frequency is 25 KHz, with 6 units of permanent transducers and bonded to the two (2) sided of the tank chamber and connected to one (1) unit of 250 Watts 25 KHz Crest’s Genesis Generator. The sugarcane wastewater had been added inside the reactor, and it acclimatized for 5 days before running the reactor. The initial value of COD recorded was 1984 mg/L; BOD was 556.8 mg/L, TSS, 0.586 mg/L, and VSS, 0.593 mg/L. The pH, pressure, and temperature were kept constant during this experiment with the value of 7.0-7.6, 1.5 bars, and 32OC respectively. The hydraulic retention time was reduced from 5 to 2 days, and then increased to 4 days to determine the organic loading rate. After 28 days of experiment, the COD removal efficiency obtained was 97%, and the methane gas composition nearly reached 79%. The TSS and VSS removal efficiency also reached 99% of removal. This shows that UMAS not only can treat high strength wastewater, but also can treat low strength wastewater in a short HRT and without membrane fouling. The results obtained in this study have exposed the capability of UMAS techniques as another promising method for treating wastewater. Further works are nevertheless required to provide deeper understanding of the mechanisms involved to facilitate the development of an optimum system applicable to the industry.