Full-Scale MBR Operating Experience for the Treatment of high Salt Concentration Wastewater from Carrageenan Production

A full-scale ADI-membrane bioreactor (MBR) system has been in operation at the FMC Marine Colloids Philippines, Inc.’s carrageenan production facility in Cebu, Philippines since 2007. 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 full-scale MBR system consists of two membrane tanks operating in parallel. Each membrane tank contains an aeration zone and a membrane filtration zone. Kubota ES200 submerged membrane units (SMUs) with flat-sheet membranes were utilized for solid and liquid separation in the membrane filtration zone. This paper provides a summary of observations, discussions and recommendations based on seven years of operating data (data from 2012 to 2014 is presented). The results have shown that the MBR system is achieving approximately 99 percent B OD removal with an average effluent TSS concentration of 4 mg/l. The MBR mixed liquor concentration varies between 30,000 mg/l and 7 0,000 mg/l, which is 2-4 times more than a typical MBR mixed liquor concentration (8,000 mg/l to 15,000 mg/l). However, membrane fouling rate is not significantly higher than what one would normally observe in a typical MBR system. The MBR has consistently met all the effluent discharge permit limits since the system was started up in 2007. The results confirm that the MBR system is very effective in treating carrageenan process wastewater. FMC Philippines has earned an award from the Philippine’s Department of Environment and Natural Resources for implementing clean technology, energy efficiency measures and water conservation programs in 2011 and 2012, partially based on the superior effluent quality from the ADI-MBR system. The membranes have had a very low percentage of failure/replacement after 7 years of operation (1.25 percent).