Technologies of Removal of Organics in Reverse Osmosis Concentrates from Petroleum Refinery Wastewater

The reverse osmosis concentrates (ROCs) with high concentration of chemical oxygen demand and salts are produced by a double-membrane technology , which has been widely used to treat the wastewaters from petroleum refinery enterprises. The ROCs are prohibited from directly discharging from environmental point of view and must be treated to comply with the tighter discharge limits of wastewater and solid wastes per the upgrading national emission standard. Therefore , effective technologies for the removal of organic matter and recovery of salts from ROCs have been committed to be developed. In this review , the recent progress on the treatment technologies of ROCs from petroleum refinery waste waters are summarized and discussed. Firstly, the compositions of ROCs, the basis of developing the treatment process, from several petroleum refinery plants are collected and analyzed. Subsequently , the removal methods of organic contaminants, such as physicochemical method, advanced oxidation method, and biochemical method, are elaborated in detail. Especially for some innovative advanced oxidation processes, including O-3 oxidation, Fenton method, electrochemical oxidation, photocatalytic oxidation, and ozonation-based combination processes , and their mechanisms , advantages and disadvantages for the treatment of ROCs from industrial sources are emphasized comprehensively. Finally , the methods of salts' recovery from ROCs are also discussed briefly.