The Investigation And Analysis Of Water Quality In Rural Area Under Conditions Of Long-distance Water Transportation And Integration Mode Of Urban-rural Water Supply

Integrated urban and rural water supply is an important measure to improve the living conditions of rural population in China.During the“Twelfth Five-Year Plan”period,China has implemented special projects including the integration and demonstration of urban and rural water supply technology in Jiangsu Province,focusing on the research work at the town level.The research on water quality safety of rural users at the end of the pipe network has not been carried out.The implementation of the integration of urban and rural water supply,while ensuring rural water use,is also facing new challenges due to the long-distance transportation of the pipe network leading to the safety of water quality in rural water ends.Rural water supply in northern Jiangsu is faced with problems such as excessive microbial standards,low water quality compliance rate,and lack of effective monitoring measures.Therefore,it is necessary to carry out a detailed survey on the water quality of rural water supply under the urban-rural integrated water supply model and the identification of water quality risk factors under long-distance water transport conditions,and initially propose corresponding control measures.This paper conducts water quality surveys in rural areas of Gaoyou City,Siyang County,Yixing City,Xuzhou City and Yangzhou City in the eastern river network area,focusing on indicators such as turbidity and heavy metal ion content,and analyzing long-distance water transportation under the urban-rural water supply integration mode.The key factors and risk factors affecting the water quality of rural water ends under the conditions.This topic collects rural water quality data in the eastern river network area through literature survey,farmer consultation,water department interview,water sample collection and laboratory water quality sample index analysis and analysis,and analyzes the risk factors of water quality indicators such as turbidity.The mechanism of action leads to the following conclusions:（1）The main problems of the water quality of the rural user terminal in the surveyed area are that the fluoride ion content in the pipe network of Siyang and the Xuzhou and Yangzhou areas exceeds the standard.The limit of fluoride ion concentration in China’s national drinking water sanitation standard is 1.0 mg/L,and the maximum concentration of fluoride ion in the seven pipe network water monitoring points along the Chengzi Lake water supply area in Siyang is about 1.03 mg/L.The minimum value is about 0.93 mg/L,and the fluoride ion concentration value of the three monitoring points exceeds 1.0 mg/L;the concentration of fluoride ion is the largest among the 16 end pipe network water samples collected in the rural water supply area of Yangzhou.The value is about 1.11 mg/L,the minimum value is about 0.96 mg/L,the average value of 1.01 mg/L;in the nine pipe network water samples collected in Xuzhou,the maximum fluoride ion concentration reached 1.74 mg/L,The mean is 0.93 mg/L.The amount of disinfectant in the rural water supply areas of Yixing and Xuzhou is insufficient.Both of these areas are disinfected by liquid chlorine.The national drinking water sanitation standard stipulates that the amount of free chlorine in the terminal water of the pipe network needs to be≥0.05 mg/L,while in the total of 29 end-pipe network water samples in Yixing,there are 6 The free chlorine concentration of the water sample was less than 0.05 mg/L;only one of the eight water samples collected along the water pipe section in the rural area of Xuzhou reached the national drinking water standard.The ammonia nitrogen content in Gaoyou and Yixing areas exceeded the standard.The Situ rural water supply area of Gaoyou collected 22 water samples for the first time.The ammonia nitrogen concentration in 19 water samples was higher than the national standard limit of 0.3 mg/L,and the maximum value reached 1.1 mg/L.In the second collection,13 Among the water samples,the ammonia nitrogen concentration values of 10 water samples exceeded the standard,and the maximum value reached about 1.4 mg/L.Among the 15 rural pipe network water samples collected by Yixing,4 ammonia nitrogen concentration values were not up to standard.The maximum value is about 0.6 mg/L.The concentration of COD in the faucet water in Gaoyou and Siyang areas is high.The Situ area of Gaoyou is particularly serious.In the total of 35 water samples collected from two water samples,the COD concentration exceeded the national drinking water hygiene standard of 3 mg/L,and the maximum reached 4.7 mg/L;the Chengzi Lake area in Siyang only a small amount of water exceeded the standard,but the average of COD concentration also reached 2.7 mg/L.The hardness of drinking water in Xuzhou rural areas is too high,and the hardness of the collected water samples is close to the national standard（calculated as Ca CO₃）450 mg/L.Among them,the problems of fluoride ion,ammonia nitrogen and COD exceeding the standard are mainly caused by raw water.It is recommended that the water plant take measures to carry out in-depth treatment of relevant indicators.The problem of the amount of disinfectant is recommended to require chlorine in the middle of long-distance water delivery and to replace chlorine disinfection with chlorine dioxide when conditions permit.The water quality hardness in Xuzhou area exceeded the standard because the rural water supply section of Xuzhou was rerouted to the original water pipeline.The pipeline was old and the diameter was large.Therefore,the water quality deteriorated rapidly.It is recommended to replace the pipeline.（2）The turbidity of drinking water will increase with the increase of the transport distance in the pipe network.The fluidity of the drinking water in the ring pipe network is strong,and the turbidity is lower than the turbidity of the drinking water in the branch pipe network.There is a significant correlation between the turbidity and the concentration of metal particles in the water supply network.The iron and aluminum in the source water mainly exist in the form of particles.The turbidity of the water in the pipe network is mainly caused by the particles containing manganese,aluminum and iron in the water.Aluminum is mainly contributed by the use of coagulants,which are mainly derived from the corrosion of iron pipes.The increased concentration of dissolved manganese is due to the lower concentration of chlorine dioxide disinfectant,lower water flow rate,microbial or chemical reduction of manganese accumulated on the tube wall,or the adsorption of ionic manganese is released.The reason.As the pipeline lengthens,the increase in particulate manganese concentration is caused by the release of particulate manganese accumulated on the pipe network after opening the faucet.（3）The correlation between particulate manganese and aluminum or iron reflects the interaction or coprecipitation of the three in the pipe network.There is a significant increase or decrease in the water-aluminum concentration of the faucet compared to the factory water-aluminum concentration.This may be because the water flow rate is faster in the area closer to the water plant,the deposition condition of the granular aluminum is not good,and the deposition and release of aluminum is not obvious.The concentration of total aluminum and granular aluminum is close to the level of factory water;in the latter pipeline,due to the decrease of flow rate,the hydraulic conditions are more suitable for the deposition of granular aluminum,and under the condition of sudden large amount of water release during the detection,the formation The hydraulic disturbance will cause the accumulated particulate aluminum to be re-released into the water,so the particle aluminum content at these points is higher than or even higher than that of the factory water.