Pollution Analysis And Water Quality Control For Landscape Water

This study,which supported by the sub-project of national water projects that "The effects of nitrogen,phosphorus and trace elements on water quality in landscape water", choose Cui Hu lake, a typical landscape water of Kunming and which replenished by WWTP water, as our study object, and carry out a study on urban landscape water body pollution analysis and quality control. Under the investigation of water system change and pollution source, this paper carried out the source analysis and pollution assessment; This study carried out the seasonal variations in water quality, and examined the impacts of human activities on water quality; Besides, the introduction of Net Pollutants Accumulation(NPA) model make us carry out the in-out put and the accumulation of pollutants in Cui Hu lake,. and base on this, On this basis, the study identifies the main pollution indicators and control factors for water quality control in Cui Hu lake,and proposes a basic strategy of water pollution control and water quality improvement. The main conclusions are as follows:1. According to the collection of the historical change and hydrologic data in Cui Hu lake,and the investigation of the pollution sources distribution. This paper identified that the reclaimed water is the main point source pollution in Cui Hu lake, and the surface runoff, deposition and Black-headed Gull droppings are the three main non-point source pollution. Besides, this paper always investigate the water organoleptic indicators, nutrients nitrogen and phosphorus indicators and eutrophication. Finally, this study confirmed that the Cui Hu lake is Severe eutrophication.2.This paper investigate the seasonal variation and spatial distribution of water organoleptic indicators, organic matter,nitrogen, phosphorus nutrients and chlorophyll a by the continuous water quality monitoring in different points. Focusing on nutrients in the water, this study explored the form distribution and temporal variation of nitrogen and phosphorus in water and sediment. According to those results, a“water quality characteristic period” method, which based on nitrogen and phosphorus indicators,is proposed. The reclaimed water plays great important role in the deposition of phosphorus in Cui Hu Lake. It always shows that a migration phenomenon of biological available phosphorus exists in lake, interstitial water, and sediment;The result of correlation analysis among different forms of phosphorus shows that a reciprocal transformation trend could happen in different forms of phosphorus.3.This paper introduces a net pollutants accumulation(NPA) model,which combined with water balance research, to make a listing analysis about in-output of pollutants in Cui Hu lake. The result showed that the reclaimed water, deposition, surface runoff and Black-headed Gull droppings are the five main input way of pollutants; On the other hand, pollutants of output main include four ways: outflow water, water evaporation, Lake late leakage and Park watering. Secondly, this study select COD, TN and TP for model calculation, the model calculation result showed that reclaimed water is the main input way of COD, TN and TP, respectively accounted for total of 96.1%, and 94.3% and 39.7%; Seagull droppings is another important input way of TP, accounted for total of 38.4%; Outflow water and leakage water are two main output ways of COD, TN and TP, respectively accounted for total of 97.4%, and 97.1% and 97.1%; The NPA of COD is low(4.8% of the total input);however,the NPA of TN and TP is very high(44.9% and 40.2% of the total input).4.Basing on above findings, this study identified the main pollutants caused the deterioration of water and eutrophication of Cui Hu lake are TN and TP, found that the main input way are reclaimed water and seagull droppings. According to the result of NPA calaulation which based on water balance, this paper determined the water quality target, and proposed two measures that the upgrading of the municipal wastewater treatment process and water self-purification capacity strengthening,to control and improve the water quality of Cui Hu lake. By upgrading the A2/O treatment process into BCFS and increasing the Lotus cultivation to improve the self-purification capacity the NPA should be decreased. The calculation result shows that the NPA would tend to zero if the COD 、 TN and TP in reclaimed water are controlled in the range of 47.5~48.8mg/L, 5.99~6.49mg/L and 0.02~0.09mg/L. Secondly, under the current condition that the lotus planted area is about 30000 m2, the TN and TP in reclaimed water should be reduced to 1.4mg/L and 0.002mg/L respectively if we want the lake water quality meet the class V of the water quality standards for surface water.