Research On The Characteristic Of Turbidity And Application Of Risk Assessment In Water Distribution Systems Of T City

Water Distribution Systems function to supply treated water safe for human con-sumption and complying with increasingly stringent quality regulations. As one of themost general indicator of water quality, the turbidity reflects the comprehensive statusof drinking water in water distribution systems. And considered primarily an aestheticissue, turbid water or discolouration is the largest cause of customer complaints associ-ated with water quality, which reduces customer trust on water supply industries.Therefore, reducing the limit-exceeding problems of turbidity in WDS is always one ofthe hot issues and major challenges for water suppliers worldwide.On the basis of summarizing the predecessors’ research results, with the WDS ofCity T in north China area as research object, this paper studies the characteristics ofwater turbidity index and presents the general regularity and main influence factors ofwater tuibidity in WDS. And then fuzzy comprehensive assessment based on analytichierarchy process (AHP) method is applied to assess the risk of water turbidity changingcaused by the pipeline so as to provide decision support for water supply enterprises toformulate corresponding management strategies on water turbidity.This paper studies the characteristic of water turbidity index in WDS. First,through the statistical analysis of real-time turbidity data from the monitoring sites andthe comparative analysis of the differences in water supply routes for each monitoringsite, the general regularity of turbidity index in WDS is summarized, and then the rulethat the differences of pipe properties and hydraulic conditions are the main influencefactors of water turbidity is confirmed. Then, through the static and dynamic experi-ments that simulate the state of water in WDS, the influence factors and basic mecha-nism on the changes of water tuibidity are studied. Results show that the main processescause the increasing of water tuibidity are pipeline corrosion, iron release and hyduaulicflushing against the pipe wall. Due to pipeline corrosion and iron release, the metalpipes have great effect on the increasing of water turbidity, and the rate of increase inturbidity decreases as the stability of pipe scale layer increases. The velocity also has agreat effect on the increasing of water turbidity, displays in two aspects: the veloctiy af-fects the processes such as diffusion, transfer of related factors in water, then indirectlyaffect the process of pipeline corrosion; the hyduaulic flushing against the pipe wallmakes water flow carry loose particles on the surface of pipe scale layer into the bulkflow and destroy the stability of pipe scale layer at the same time which may cause therapid increase of water turbidity.After then, from the view that the risk of water turbidity changing caused by indi-vidual pipeline, this paper puts forward the concept of turbidity risk via pipeline. Usingthe fuzzy comprehensive assessment method based on AHP, the turbidity risk assess- ment via pipeline system is established and applied to a case of network. And then thequantitative assessment of turbidity risk via pipeline is achieved and the turbidity risklevel of pipeline is determined. The assessment result accords with the actual situationof network and accurately and objectively expresses the changes of water turbidity inthe case. As a decision support tool for water supply enterprises to formulate manage-ment strategies on water turbidity, the turbidity risk assessment via pipeline system canbe used in at least three aspects: the quantitative assessment of turbidity safety in WDS;the optimal allocation of online monitoring instrument of water quality; the activemaintenance of network based on the reduction of turbidity risk via pipeline.