热电厂双膜法中水深度处理系统运行效果与问题分析

中水已成为热电厂的重要水源，其深度处理是影响电厂水处理系统的关键。为评估双膜法在电厂深度处理中的潜力与稳定性，考察了山东某热电厂石灰混凝-超滤(UF)-反渗透(RO)系统不同季节的处理效果及污染物去除特征与各工段贡献率。研究表明：双膜法对浊度、色度、电导、碱度、COD和TOC的去除率分别达95.82%、96.62%、96.73%、98.22%、96.42%和89.13%，在夏季严重膜污堵的条件下，也可保障产水达标，是一种有效的中水深度处理技术。预处理仅去除某些大分子腐殖酸类有机物、硬度类物质、悬浮物，富里酸类有机物、氮等其他溶解性物质主要由RO去除(去除率均60%)，因此，存在膜结垢和污堵的风险。不同季节污染物浓度变化不显著，但夏季高温条件下微生物代谢和繁殖速率较高，荧光指数(fluorescence index, FI)大于2，生物指数(biological index, BIX)为1.2左右，这是夏季膜污堵爆发的关键原因。

Performance and limitations of a full-scale dual membrane process for advanced treatment and reuse of reclaimed water in a thermal power plant

Reclaimed water has been an important water source in thermal power plant (TPP) and the advanced treatment was the key process for its TPP application. In order to evaluate the potential and stability of a dual membrane process for advanced treatment of reclaimed water in a thermal power plant, the treatment performance in different seasons, pollutant removal characteristic and contribution rate of each treatment unit were investigated for a full-scale lime coagulation- UF- RO process in a TPP in Shandong province. The results showed that the remove efficiencies of the dual-membrane system for turbidity, color, conductivity, alkalinity, COD and TOC were 95.82%, 96.62%, 96.73%, 98.22%, 96.42% and 89.13%, respectively. Even under the condition of severe membrane fouling during summer, its effluent still met the related standards, which indicated its effectivity on the advanced treatment of reclaimed water. The pretreatment units only removed some high molecular weight humic acids, hardness and suspending matters, while RO mainly removed fulvic acids, nitrogen and other dissolved matters with 60% removal efficiencies. Thus, this phenomenon would cause the risk for membrane scaling and fouling. The variations of pollutants concentration were not significant, but the high rates of microbe metabolism and propagation occurred in summer, which led to high microbe activity (FI>2, BIX≈1.2) in water. The corresponding biofouling is the key reason for the outbreak of membrane fouling.