PILOT-SCALE INVESTIGATION OF MEMBRANE BIOREACTOR TREATMENT OF A HIGH SALT CONCENTRATION WASTEWATER FROM CARRAGEENAN PRODUCTION

A pilot-scale membrane bioreactor (MBR) system was operated at the FMC Marine Colloids Philippines, Inc. carrageenan production facility located in Cebu, Philippines from July to November 2006. Approximately 10,000 to 15,000 kg of salt per day is brought into the carrageenan manufacturing process predominantly from locally harvested seaweed which, when combined with a process flow of 300 to 450 m3/d, creates a unique and challenging wastewater. The MBR pilot treated real-time raw wastewater from the facility under different influent loading and TDS concentration conditions. The pilot MBR system employed Kubota submerged flat-plate membrane technology.The study objectives were to determine if the MBR could consistently meet the required effluent limits, investigate the relative impact of elevated BOD, TDS, salt, and chloride concentrations on process performance, and to evaluate membrane fouling and cleaning requirements for treating this wastewater. The MBR process was chosen for investigation since the high TDS concentrations (typically 30,000 to 45,000 mg/l) and high salt concentrations (8,000 to 11,000 mg/l chloride) were thought to be too problematic for effective treatment in a more conventional activated sludge system, due to very high inorganic TDS levels and their negative impact on sludge setting and effluent TSS concentrations. Limited plant space also made the MBR process attractive due to its relative compactness compared to alternative treatment technologies. The MBR pilot system was effective in treating the raw wastewater with high TDS concentrations and a full-scale MBR system was designed and built to treat the wastewater discharged from the facility.