超滤处理洗涤污水循环利用的中试研究

Pilot Study on the Treatment of Ultrafiltration for Laundry Wastewater Recycling and Reuse

采用不同材质国产超滤膜聚丙烯(PP)、聚丙烯腈(PAN)和聚砜(PS),进行了洗涤污水处理循环利用的现场中试研究.结合超滤工艺出水水质和膜污染分析,3种膜材质中PAN膜较优,有效去除了水中浊度、悬浮物、油脂等污染物,一定程度保留了游离阴离子表面活性剂(LAS),长期循环洗涤对衣物的白度无不良影响.根据相关性分析,超滤出水较高COD值很大程度上是由水中LAS引起的.超滤膜对细菌、大肠菌群的去除率较低,出水通过紫外消毒,当紫外线密度≥3 750 J/m2时,微生物水平能够达到国家饮用水水质标准.根据不同水力反冲洗条件下膜渗透通量和净产水量比较,PAN膜最佳水力反冲洗条件为0.5 h反冲洗2 min.长期运行时超滤膜化学清洗方法采用碱洗法方便有效.

A pilot study of the treatment for laundry wastewater recycling and reuse on the spot was carried out by ultrafiltration（UF） with different membrane material of PAN , PS and PP. According to the analysis of membrane fouling combined with UF effluent quality, PAN membrane was superior to the others. It removed the turbidity, suspended solid, fat oil and grease effectively, but kept anionic surfactant （LAS） to a certain degree in the UF effluent which is heneficial to recycling and reuse. By correlation analysis, it was found the high COD concentration of effluent was caused by LAS remained. The whiteness and softness of cotton cloth washed by UF effluent for a long term was not different with that washed by tap water. The removal of bacteria and E. coli by UF membrane was not very high, and so UF effluent was disinfected by ultraviolet（UV） further. As the dosage of UV was not less than 3 750 J/m^2 , the microbial level reached the China national standard of drinking water. The optimal UF operation condition is to backwash two minutes every thirty minutes＇ filtration. Adopted alkali liquor of pH 11 to 13 to carry out chemical cleaning, the membrane flux was recovered completely.