A newly developed membrane performance enhancer (MPE) was used to prevent membrane fouling in a membrane bioreactor (MBR) process. It transpired that 1,000 mg/l of MPE reduced polysaccharide levels from 41 mg/I to 21 mg/I on average under the experimental condition. Repeated experiments also confirmed that 50-1,000 mg/l of MPE could reduce membrane fouling significantly and increase the intervals between membrane cleanings. Depending on MPE dosages and experimental conditions, trans-membrane pressure (TMP) increase was suppressed for 20-30 days, while baseline TMP surged within a few days. In addition, MPE allowed MBR operation even at 50,000 mg/l of total solid and reduced permeate COD. However, no evidence of toxicity for sludge was found from respiratory works.

Recently developed polymeric membrane performance enhancer product, MPE50, was tested in various pilot-and full-scale membrane bioreactors (MBRs). The Initial MPE50 dosage was determined by visual jar tests and by using various bench-top filtration tests. Different amounts of MPE50 were dosed, and the particle size and supernatant clarity of the mixed liquor were monitored visually. Bench-top filtration tests were also conducted. A 50% higher MPE50 dosage is recommended to be added to the pilot/full-scale bioreactors because, based on experience, some of the soluble microbial products in the mixed liquor do not completely react with polymer during the relatively short bench-test mixing time interval. With the addition of 400 mg/L MPE50 to a pilot MBR, the design flow was increased twofold without any significant transmembrane pressure (TMP) increase for 1 day. The control TMP surged within a few hours without MPE50. Long-term field trials in a full-scale plant also showed a substantial flux increase. In addition to flux enhancement, MPE50 helped to remove foam from the bioreactors and improved plant aesthetics, safety and general operating performance.

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