Study On Water Quality Characteristics And Treatment And Protection Measures Of Urban Rivers In Hezhang County

Hezhang County is the birthplace of Liuchong river,At present,Jiayan water control project in Guizhou Province is under construction in the middle section of Liuchong river（drinking water source）,the protection of the source water source is not only related to the water ecological environment of Hezhang County,but also closely related to the sustainable development of the downstream Jiayan reservoir project.Therefore,it is necessary to study the river water quality characteristics and treatment and protection measures of Hezhang County.This paper continuously monitors the water quality by setting three monitoring sections at the upstream,downstream and exit of the Gangcheng River in Hezhang County After 7 years of measurement,the river water environmental quality is comprehensively evaluated,combined with the investigation and analysis of drinking water sources and pollution sources,based on which the water environmental protection measures are put forward and the changes of water environmental quality are predicted.Research results:（1）The changes of various monitoring factors in the water body in the study area over time show an overall change law of getting better year by year.According to the monitoring and analysis over the past seven years,most of the monitoring factors have good water quality.However,firstly,the concentration of fecal coliform is high,which is inferior to class V water quality in most years.Secondly,the total nitrogen and total phosphorus have deteriorated year by year since 2019.It is necessary to strengthen the treatment of domestic sewage to prevent water pollution Body eutrophication.At the same time,although Zn and Pb can meet the class III standard of surface water quality,due to the deterioration trend of the two water quality indicators,prevention and treatment should be carried out in advance,especially to strengthen the treatment of the upstream lead-zinc industry.（2）The water quality in the study area shows the characteristics of high fecal coliform group and high nitrogen.The changes of fecal coliform group and nitrogen in time and space are similar,that is,masangping is higher than qixingguan,and qixingguan is higher than the estuary.In particular,the fecal coliform group in masangping section far exceeds the inferior class V water quality in most years,which is the key factor restricting the quality of water environment in the study area.（3）The reason why fecal coliform,total nitrogen and total phosphorus do not meet the standard is that the urban sewage pipe network is imperfect,there are domestic sewage directly discharged into the river,fertilization of surrounding farmland and other nitrogen sources washed into the river with rainwater,as well as the discharge of livestock farms and slaughtering wastewater around the front and back rivers.（4）Take measures to accelerate the construction of domestic sewage treatment facilities,vigorously promote the treatment of livestock and poultry breeding pollution,actively promote agricultural non-point source pollution prevention and control projects,adjust measures to local conditions,accelerate the adjustment of agricultural industrial structure,strengthen the prevention and control of industrial wastewater pollution,and strictly enforce environmental law enforcement and supervision to protect the water resources of Liuchong River Basin in Hezhang County.After the relevant protective measures are taken,it can reduce the COD emission by 2993 tons,the ammonia nitrogen emission by 107 tons,the total nitrogen emission by 68 tons,and the total phosphorus emission by 29 tons,and reduce the cross-section concentration at the exit of qixingguan to COD21.34 mg/L,NH₃-N 0.49 mg/L,TN 3.41 mg/L,and TP 0.21 mg/L.