A Study On Analysis And Evaluation On Reclaimed Water Of Shenzhen

With the rapid development of Shenzhen, water shortage of Shenzhen becomesincreasingly severequs. As the second water source of a city, reclaimed water can helpto ease the shortage of water. Currently, reclaimed water is not widely used in china, andthe risk of reclaimed water is also not very clear.Most of reclaimed water standards islearn from foreign standards, and its applicability need to be verified. Therefore, it isnecessary to investigate the risks assessment for reclaimed water of shenzhen andanalyze the suitable concentration of main risk factor (ammonia).The influence of reclaimed water to river, the health risks assessment for reclaimedwater and the suitable ammonia concentration values were researched in this paper bythe following four-part experiment: the research and evaluation of water quality ofrivers use reclaimed water in shenzhen, assessment of Recycled water’s health risk inshenzhen, Research of river species and ecological evaluation in Shenzhen, and thestudy of common superscalar factor’influence, include ammonia’s influence on flushingwater, the influence of ammonia to eutrophication, research on the criteria forammonia-freshwater of Shenzhen.As the landscape river water, reclaimed water has little effect on the river. Thereclaimed water is basically stable in the pipline, except DO decreased slightly. Thequality of relclaimed fluctuates in a narrow range, DO,suspended solids, and colorationis doubled. Use Water quality specifications for reclaimed water and rain of Shenzhen(SZJG32-2010) and Environmental quality standards for surface water (GB3838-2002)as a reference point for water quality evaluation, the main risk factors are ammonia andtotal nitrogen, and the risk of ammonia is higher. It is too rigorous that The limit valueof ammonia in Water quality specifications for reclaimed water and rain of Shenzhen.Use reclaimed water as urban miscellaneous water, scenery and recreation water,and areacondenser water, the riskiest exposure is the road cleaner who work in the roaddust, then is the fishers and tourists in the sight riverway. The main factor of lifetimehealth risk is aluminum, fluoride and ammonia. In the process of use reclaimed water,we can increase publicity of security information, strengthen management andsupervision, take reasonable protection to reduce health risk, finally to ensure safety.The number of phytoplankton and fish species is very small in sight river ofShenzhen. Respectively among all the kinds of phytoplankton, chlorophyta andcyanophyta have the greatest proportion, this shows the characteristics of watereutrophication.According to fish species, bottom-living fish and small fish accounts for a largepart. The fish resource is very poor and in a single structure and the dominant speciesare invasive alien species like T. nilotica and G. affinis. The Futian river has the highest number of phytoplankton and fish species, then isthe Xinzhou river, the last one is the Shawan river. Phytoplankton density is closelyrelated to the nutritional status of the water. The Futian river and the Xinzhou river bothuse reclaimed water to add sources river, so they have rich ammonia and other nutrient.But the water for the Shawan river is mainly from the reservoir, without reclaimed waterto add. This is the main reason why the Futian river and the Xinzhou river have higherphytoplankton density.Research on criteria for ammonia-freshwater. When PH=7.7、30.3℃，the CMC andCCC of Shenzhen is respectively14.19、1.69mg/L. Use recycled water as flushingwater, due to the nitrification, the ammonia will change into nitrite and nitrate nitrogen.The water turbidity and chromaticity will rise over time, but rise marginally. To the endof the experiment (33days), the highest turbidity and color were1.08,13.6, within anacceptable range. Different concentrations of ammonia in reclaimed water (0.5、1、2、4、5mg/L) had no large differences in color, turbidity, smelly threshold value. Theresearch of ammonia’s influence on eutrophication shows ammonia in reclaimed waterhave no significant influence for reclaimed water eutrophication. Consider of the criteriafor ammonia-freshwater of Shenzhen, the influence of ammonia’s influence oneutrophication and flushing water, we suggest the suitable ammonia concentration ofreclaimed water in Shenzhen is between1.69~5mg/L.This paper analyzed the risk in the usage process of Shenzhen reclaimed waterfrom water quality, human health and ecological risk, provides a strong basis for riskcontrol for urban reclaimed water usage and the regeneration and sustainability ofreclaimed water. Meanwhile, this paper also learn from the EPA ammonia baselinemethodology, with study the influence of ammonia in reclaimed water to flushing waterquality and landscape eutrophication, discussed the major risk factor, ammonia’sappropriate concentration, provided a data and theoretical support for Shenzhenreclaimed water ammonia standard amendments.