印染废水反渗透脱盐系统运行性能及膜污堵特性

反渗透(RO)脱盐工艺对实现印染废水再生利用具有重要的意义.膜污堵却制约了RO工艺应用.对广东省某工业园区印染废水RO脱盐系统运行性能及膜污堵特性进行了研究.结果表明,印染废水生化处理出水经臭氧氧化-砂滤-超滤(UF)预处理后,RO进水COD平均浓度为12.4 mg·L~(-1),浊度1 NTU.RO系统脱盐率稳定在98%,RO产水高锰酸盐指数约为0.7 mg·L~(-1),浊度约为0.12 NTU.但RO系统运行3 a后,跨膜压差高达0.6 MPa,产水量下降至120 m~3·h~(-1),且不能通过化学清洗恢复,在RO膜面沉积了不可逆的污堵物.RO膜面的有机物占总污堵物干重的(53.5±0.2)%,无机物占(46.5±0.2)%,RO膜面有机污堵与无机污堵贡献相近.Si、Al与Ca是RO膜面主要的无机元素.碱液(Na OH溶液)对沉积在RO膜面的Si与Al及有机物提取效果较好.

Operating Characteristics and Fouling Characteristics of a RO Membrane System for Desalination of Dyeing Wastewater

The reverse osmosis (RO) process is of great significance for the desalination and reclamation of dyeing wastewater. However, fouling of RO membranes has been a severe problem and key limiting factor in the widespread application of the RO process. The operating characteristics and fouling characteristics of a RO membrane system for desalination of dyeing wastewater were investigated in an industrial park in Guangdong Province. The results showed that the COD and turbidity of RO influent after ozone oxidation-sand filtration-ultrafiltration (UF) processes were 12.4 mg ·L^-1 and<1 NTU, respectively, with a stable desalination rate of the RO system of around 98%. The COD and turbidity of the RO effluent were 0.7 mg ·L^-1 and 0.12 NTU, respectively. However, after 3 years of operation, the pressure drop across the membrane reached 0.6 MPa, and the permeate flux decreased to 120 m³ ·h^-1, which could not be restored to its original flux by chemical cleaning. The organic and inorganic matter occupied (53.5±0.2)% and (46.5±0.2)% of the deposits on the RO membrane, respectively, suggesting both organic and inorganic fouling were the main problems for the RO membrane. Si, Al, and Ca were major inorganic elements on the RO membrane. Large amounts of Si, Al, and organic matter deposited on the RO membrane were dissolved easily by alkaline (NaOH) solution than acid (HCl) solution.