The Situation Of Manganese Contamination And The Analysis Of Affected Factors In Drinking Water Of Songjiang District

Manganese is an essential trace element for human growth and development and plays an important role in maintaining normal physiological function, but excessive exposure to manganese can cause nervous system dysfunction and endocrine disorders.The human can expose manganese through the air, drinking water and food, manganese is primarily absorbed in the intestine. Manganese in drinking water exists in the form of Mn2+. Excessive exposure to manganese by drinking water causes nervous system damage. Therefore, the study of manganese concentration in drinking water and exposure levels is an important basis for health effects research.The concentration of manganese,a key index in drinking water, often exceed the standards for drinking water quality. Previous studies have shown that the exceeded rate of manganese in finish water with the Huangpu River and its inner river water as raw water were 13.33%,17.82%,respecitively. Songjiang District is located in suburban of Shanghai, its water net belongs to the middle and upper stream of Huangpu River. With the development of industrial and agricultural in recent years, water pollution in Songjiang district is getting more and more serious and also affected the quality of drinking water. In 2006, the manganese exceeded standards of the rate in finish water was 20% in Songjiang District, the highest concentration was 0.230mg/L and exceed to 2.3 times of the national standards for drinking water quality (GB5749-2006). The production of drinking water in Songjiang District was carry out with mainly in the upper reaches of Huangpu River and inner river water near the water plant and as raw water.The purpose of this study is to investigate the situation of manganese contamination and trends in drinking water of Songjiang District over the years.20 centralized water supply water (2 District water plant and 18 Township water plant) were selected as objectives, the concentration of manganese in raw water, finish water and, pipe network water was detected from 2007 to 2009, and the changing trend was also analyzed. At the same time, the effects of the quality of raw water, treatment technology, pipe quality and rainfall on the manganese concentration in drinking water were investigated. The reason for manganese contamination excessive standards was explored by systematic analysis. The results is helpful to aim at the status of manganese contamination in drinking water and take effective measures control manganese contamination to ensure drinking water safetyPart I:The research on the status and trends of manganese contamination in drinking water of Songjiang DistrictTo investigate the status and changing trends of manganese contamination in different water body and drinking water of Songjiang District, the concentration of manganese in different raw water and corresponding finish water and pipe water was detected in each quarter from 2007 to 2009. The result show:1. The concentration of manganese is related to the type watercourse and its location, the exceeding rate of manganese in raw water of Huangpu river watercourse is 40.48% less than the raw water from Xiang Tang Jiang watercourse (86.96%). Xie Tang Jiang, the upstream of Huangpu River, the concentration of manganese was lowest among all raw water.2. The concentration of manganese in raw water is seasonal variation, lower in the spring and higher in the autumn. The concentration of manganese in finish water has a positive relationship with in raw water (r=0.318, P=0.001).3. The concentration of Manganese in finish water has a significant positive relationship with in pipe water (r=0.973,P=0.001). The manganese concentration of Manganese in piper water depends on its concentration in raw water and the quality of water. The manganese released from materials of pipe is limited to the concentration of Manganese.Part II:The analysis of the effect factors on the manganese exceeding standardsBased on previous study about manganese concentration in drinking water, this investigation explore multiple factors involved the raw water, process water system, pipe material, rainfall on the impact of manganese contamination of drinking water. The results show:1. The concentration of manganese is related to the polluted status of raw water. There is a significant positive relationship between the concentration of manganese and permanganate index and total phosphorus, a significant negative with dissolved oxygen.2. Conventional water treatment processes is limited to remove manganese in raw water. Potassium permanganate can effectively reduce and remove the manganese in raw water. Of manganese concentration in drinking water, chlorine dioxide disinfection of water below the chlorine as disinfector. Conventional chlorine disinfection process can only remove part of manganese in raw water. When the concentration of manganese in raw water is more than 0.153mg/L, manganese concentration in finish water will not meet the national standard 0.1 mg/L of requirement.3. Pipe of material is one of the affected factors to manganese concentration in water, the new polyethylene pipe laying has the lowest manganese concentration. Pipe with iron materials, the concentration of manganese will be slightly increased with the extension of water transported distance.4. Rainfall can cause increased manganese concentration in raw water. The pH change in raw water is not main factors for elevated manganese concentration in drinking water, the main factor.The study found that manganese excessive standards in drinking water was mainly seen in the areas where manganese concentration in raw water has far exceeded the standards. The manganese in drinking water was mainly from the raw water. Based on the results, we suggest that take measure to protect water sources, optimize the layout of water distribution, improve water technology, and strengthen water supply management to control of manganese contamination in drinking water.