Pollutants removal characteristics of urban sewage treatment plants in Hainan Province

Based on the field investigation and data analysis of 21typical urban sewage treatment plants in Hainan Province,the techniques used in the plants and the quality of the raw wastewater and treated water were analyzed comprehensively.Results showed that most urban sewage treatment plants in Hainan were small or medium-sized,and the main treatment techniques were A/A/O and oxidation ditch.The raw wastewater was mainly from domestic sewage.The diversion of rain and sewage in Hainan still unfulfilled.The feed water qualities of sewage treatment plants was good,the pollutants concentration were relative low.The effluent of sewage treatment plant could satisfy the one class B of cities sewage treatment plant pollutant discharged standard(GB 18918-2002),some indexes could even conform to one-class A permitted criteria.The remove ratios of COD,BOD5,SS,TN,and ammonia nitrogen were generally high,but they were seriously affected by the quality of the raw wastewater and the type of the treatment techniques.