污水再生处理反渗透系统进水膜污堵潜势评价方法及指标体系

THE EVALUATION METHODS AND INDEX SYSTEM OF REVERSE OSMOSIS MEMBRANE FOULING POTENTIAL OF THE INFLUENT IN WASTEWATER RECLAMATION PROCESS:A REVIEW

由于污水中的有机物含量显著高于海水,因此污水再生处理反渗透(RO)系统面临比海水淡化RO系统更加严重的污堵问题。为了有效预测和控制RO膜的污堵,需要对RO系统进水污堵潜势进行全面评价。从颗粒物/胶体污堵、无机结垢、有机污堵和生物污堵4个方面,分析了目前RO系统理论研究和工程实践中常用的进水污堵潜势评价方法和指标体系的特点。针对颗粒物/胶体污堵和无机结垢,实际工程中的潜势评价与控制方法已经相对成熟。然而,目前污水再生处理RO系统的工程设计中尚无针对有机污堵和生物污堵的指标。现有研究表明,在污水再生处理RO系统中,当进水ρ(DOC)<4 mg/L时,RO膜的污堵速率显著降低,可将该数值作为RO系统进水水质设计的参考。除有机物总量外,还应综合考虑有机物分子量和亲疏水性-酸碱性等组分特性,大分子、疏水中性和酸性物质更容易沉积于RO膜面导致污堵。在生物污堵方面,现有的针对进水生物量和生物膜生长速率(BFR)的指标均不能有效反映进水的生物污堵潜势,因此,生物污堵的预防和控制,仍是未来RO系统污堵防控领域的研究重点。

Membrane fouling in the reverse osmosis(RO)system for wastewater reclamation is much more severe than that of seawater desalination,mainly due to much higher concentration of organic matters in wastewater.In order to predict and control the fouling problem of RO systems effectively,it is essential to systematically evaluate the RO membrane fouling potential of the feed water.Here,we assessed the most commonly-used indexes and methods for the evaluation of fouling potential in the theoretical research and engineering practice of the RO system,including colloid/particle fouling,inorganic scaling,organic fouling and biofouling.The evaluation and control strategies against colloid/particle fouling and inorganic scaling had been well developed in engineering practice.However,the valid indexes against organic and biological fouling are still deficient in the engineering design of the RO system for wastewater reclamation.As revealed by the recent research,the fouling rate of RO membranes for wastewater reclamation could be retarded effectively when DOC in feed water was below 4 mg/L,which could be used as an indicator of feed water in the engineering design of RO system.Besides,the total amount of organic matter,the organic fouling potential should also be evaluated based on the composition features of organic matter,including molecular weight distribution,hydrophilicity/hydrophobicity and acidity/basicity.Generally,the organic matters with higher molecular weight and hydrophobic-neutral/acidic features showed higher RO membrane fouling potential.As for biofouling,the current indexes could evaluate the total amount of microorganism in the feed water or the biofilm forming rate(BFR)of the feed water,but these indexes were usually ineffective in predicting the biofouling in engineering practice.Thus,the accurate prediction and effective control of biofouling is still the key point in the research field of fouling control for RO system.