Factors Influencing Organic Migration From HDPE Pipes Into Irrigation Water

Water quality is in contact with water pipes in a long distance、long time and a large area. Organics migrating from pipes directly affect safety of water quality. In recent years, the influence of plastic pipes material in drinking water quality safety was paid more attention. Along with application of drip irrigation technology widely use in agriculture facilities, the irrigation pipe making a difference to irrigation water quality can not be ignored. Chemical components of irrigation water quality changing can effect the plant growth and development, and pose a threat to human health. There is certain application prospect and practical significance to carry out the research of drip irrigation pipes influence on irrigation water quality and nutrient properties, according to different environment factors, water quality of different types and water pipes of different brands in this paper.In this research, regarding the high-density polyethylene pipe as a research object, specific conclusions are as follows:1、Different water organic and naturient solution characteristics changing, under the action of the high-density polyethylene pipe:(1) After the test, TOC and COD of water quality in contact with the HDPE pipe higher than glass controls, the organic components do exist migration from the irrigation pipe;(2) Regarding naturient solution as experimental water, after the test, TOC and COD of naturient solution are all higher than distilled water. It may be related to more ions in naturient solution. Regarding dispensed water as experimental water, after the test, TOC and COD of dispensed water are all higher than naturient solution. It could be due to free chlorine having a greater influence on organic components migrating from the HDPE pipe. The correlation analysis of TOC and COD values for each water quality, both significant linear relationship (R2>0.998);(3) pH of naturient solution also effect organic components migrating from the irrigation pipe. The strong acid environment, the more organic components migrate from the HDPE pipe. Organic components also effect on characteristics of the nutrient solution, EC values of cucumber nutrient solution changed significantly than tomato nutrient solution and chrysanthemum nutrient solution.2、Natural weathering effects on organic components migrating from the irrigation pipe(HDPE):(1) Based on temperature factor having effect on organic components migrating from the plastic irrigation pipe, we always choose temperature changed method in greenhouse. The varying environmental temperature can not only provide the required for plant growth, but also reduce the TOC and COD migration, to further ensure the safety of irrigation water quality.(2) Organic components migrating from the pipe increase with temperature. However, under the influence of the light, the total organic components migrating increase as the light increases.3、An integrated analysis of impact factors in organic components migrating from the irrigation pipe (HDPE).(1) Environmental factors having more significant effect for organic migration than water quality and the pipe, temperature PTOC is0.0001and the minimum PTOC of other factors is0.018; the light PTOC is0.0003and the minimum PTOC of other factors is0.0008;(2) The factors (temperature, water quality, the pipe) have very significant interactive effect (PTOC<0.0205). The factors (light, water quality, the pipe) have a significant interactive effect (PTOC<0.0167);(3) The correlation analysis of TOC and COD values is related to water quality.