The Effect of Monochloramine on Membrane Degradation

摘要

Correlation between monochloramines (NH_2Cl) and membrane solute rejection and productivity based on data from an extensive pilot study are summarized in this paper. Decreasing salt rejection was observed during selection of CSF pretreatment, which included Actiflo-Rapid Sand Filtration (RSF), Super Pulsator (SP)-RSF and Zenon submersed micro-filter. Decreasing productivity was observed in the long term phase of the project. Varying salt rejection and productivity indicated loss of membrane integrity and was correlated to NH_2Cl mass loading.rnDuring phase II, 4 LPRO membranes were tested using Actiflo-RSF and Zenon micro-filtration and chloramination. The performance of eight membranes performance was monitored continuously over 6 months. Membrane productivity and solute mass transfer mass loading models were developed from this data set and incorporated NH_2Cl mass loading in an overall mass transfer coefficient that incorporates time of operation and chloramine dose. Productivity and solute mass transfer coefficient changed with time due to natural film degradation, oxidation (NH_2Cl), fouling (NPDOC or UV-254) turbidity). NH_2Cl were found statistically significant correlation to membrane slow degradation.