Increased concern is being paid to the health and environmental risk caused by traceudnatural and synthetic hormones discharged from sewage treatment plant (STPs). Thisudstudy, which is part of a larger project on investigation of hybrid membrane processes forudtrace hormones removal, focuses on binding of hormones to microfiltration hollow fibreudmembranes in filtration of solutions containing trace hormones. The adsorption capacity ofudthe membrane, kinetics of adsorption and desorption of to/from microfiltration hollow fibreudmembranes, and the factors affecting adsorption to the membranes have been studiedudusing estrone as model solute. The experiments showed that the adsorption of estrone toudthe microfiltration membranes could result in high retention of estrone molecules.udHowever, since the mechanism of retention is adsorption rather than sieving, the retentionuddecreases with increase in the amount of estrone accumulated on the membrane andudbreakthrough occurs when the accumulated estrone on the membrane reaches anudequilibrium concentration corresponding to the feed concentration. For long-termudoperation, although membranes could be saturated by hormone molecules the membraneudprocesses could still have a function of buffer for instantaneous high hormonesudconcentration because the saturation surface concentration increased with the increase inudthe feed concentration. In addition, the experiments also indicated that the adsorptionudcapacity of the membranes for hormones could be affected by membrane types, pH,udaffinity of hormones to water, as well as the presence of other organics. These results areudof relevance to the potential release of trace hormones from water treatment systemsudwhere microfiltration membranes are used as a process barrier.
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