科研之友
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摘要
Laundering industry consumes and discharges large amounts of water and surfactants, and the demand of surface active agents used for washing is increasing worldwide. Some of these substances are considered contaminants of emerging concern, as they persist in the environment. This work aimed at evaluating the feasibility of ultrafiltration as a method to treat the wash wastewater and possibly reuse the surfactant-rich permeate stream in laundry facilities. In particular, evaluation of surfactant recovery was performed through analysis of the permeate flux and properties obtained through polymeric and ceramic membranes. Wash water samples were collected at an industrial laundering facility for hospital linen and filtered through different ultrafiltration membranes with varying molecular weight cut-off. The critical micelle concentration of the detergent was quantified, and capillarity measurements were used to determine the concentration of free surfactants in water. The system was designed to comprise two filtration steps in series: a pre-filtration step did not allow recovery of surfactant or the production of a high quality permeate, but it was necessary to remove large contaminants and to minimize the amount of foulants in the feed water of the second filtration, from which reusable permeates were finally produced. Recovery of 43% and 39% of reusable surfactants were achieved using polymeric and ceramic membranes, respectively. Results suggest the existence of an optimal molecular weight cut-off, which for this work was equal to approximately 6 kDa. Since the operation temperature may have significant impact on the energy requirements of the washing process, the influence of feed water temperature on surfactant recovery was also preliminary investigated. Results suggested the possibility to recover water and surfactants by directly treating wastewater streams of high temperature and the potential of integrating an ultrafiltration system in large laundering facilities.
- 出版日期2017-1
