The Removal Of Assimilable Organic Carbon By Nanofiltration Membranes And Reverse Osmosis

Assimilable organic carbon (AOC) refers to a fraction of the total organic carbon, which can be utilized by bacteria directly. Nowadays, AOC has been widely used in checking the biological stability of drinking water in order to make sure whether bacterial proliferation will occur in a drinking water distribution system. Many researches showed that the remove effect on AOC by conventional drinking water treatment process was limited. It is difficult for the water treated by conventional treatment process to reach the biological stability standard of drinking water. As a new-style advanced treatment technology, NF and RO processes have gained significant effect on making high quality drinking water.This dissertation used drinking water as research object. The effect of NF/RO on removal of AOC was investigated. The distribution molecular weight (MW) of AOC for feed and permeate was measured to evaluate the relationship of MW distribution between AOC and organic matters. It also took a systemic study on the single effect factors on the removal of AOC by NF/RO. The dissertation verified that the AOC removal by NF/RO was determined by the combined effect of both size exclusion and charge repulsion.Through a long-term experiment, it showed that the AOC average concentrations in raw water was 90μg/L. However, AOC concentrations of the raw water varied with seasons. The highest AOC concentrations could be 129.84μg/L, while the lowest AOC concentrations could be 54.85μg/L. Besides these, there were about 58% of the samples couldn't reach the drinking water biological stability requirement. After treated by NF/RO processes, the biological stability of the samples had been increased evidently. The AOC average concentrations of the two membrane permeate water were 33.18μgfL and 24.17μg/L respectively. The results showed that NF/RO could remove AOC effectively, with removal efficiency of 60% and 75% respectively. The study provided some important reference to develop the advanced treatment process for producing biological stability drinking water.It worked out the AOC-P17 concentrations took a great part in the AOC concentrations. The proportion was about 60% of the AOC concentrations. The most part of nutriment which utilized by strain P17 were organic matters with big molecular weight, such as amino acids, fatty-aromatic acids and so on. The proportion...