Research On Water Supply Engineering Design Of Small Town In Southwestern Mountainous Area

The number and size of small towns have increased because of a rapid urbanizationprocess in mountainous areas in South-western China. Both the increasing quantity andhigh-quality water are demanded. People are increasing the demand of water supplyscale and effluent quality. It is characterized with complex topography, water levelvariation, water quality significant seasonal variation in Southwest MountainousSmall-towns. Both the industrial water and residents living water are usually providedby a common water supply system, which is born with some defects, such as complextechnology, high cost, lower degree of intelligence. Therefore, it should be paid moreattention on exploring some water supply techniques to achieve adaptable,highefficiency, hi-intellectualized.Taking a water supply project as a case study, a series of water supply craft andtechnology was demonstrated systematically. The project is located in HechuanPrefecture, Chongqing Municipal，aimed to satisfy both the habitat drinking water andthe industrial consuming water of a certain town. The raw water is extracted fromJialing River, which is one of the largest branches of Yangtze River. The water level ofwater intake varies at a scope of30m, and there is a periodic variation in water qualityannually. In addition, the most of water will be supplied to industrial enterprises. Basedon save the construction and operating costs, a great effort was probed into water-intakeway, water purifying technology, intelligent control. The results are expected to achieveintegration,intelligentize and energy-saving by way of real time water-intaking, dualwater purification, auto-control.The main contents and corresponding conclusions are as follows:(1) water-intake by pump vessel technologyWater-intake by pump vessel is one kind of commonly used and economicalwater-intake way, since it is suitable for a great water level，the high average watertemperature, ice free all year round. The mobile steel floating ship was selected as thewater platform, submersible pump installed inside. Based on the hydraulic calculation,it determines the pump flow, head, quantity, power, and through the water pipe to thewater purification facilities.(2)Dual water purification craft1) Train of thoughtThe water plant provide4500m3water for industrial production and urban residents each day，wherein, the industrial-consuming and dring water are3000cubic meters and1500per day respectively. When the turbidity of raw water is less than15NTU, the partof the industrial water is directly transferred to production water supply tank. When theturbidity of raw water is relatively high, after coagulating and precipitating, theindustrial water is transferred to production water supply tank. Regardless of the levelof turbidity, the part of living water is required to pass the water treatment strictly.2) The production processMixing process：PAC will be injected into tubulanr static mixer by100L/hdiaphragm. The amout of PAC can be automatically adjusted by automatic controlsystem, through which the speed of pump should be varied accurately with the qualityof water and the amount of water. Because the liquor can be mixed well with the rawwater, it will ensure the effect of coagulation.Flocculation and Sedimentation: grid reaction inclined tube sedimentation tank isintegrated with flocculation and sedimentation equipment. A sedimentation tank issurrounded by20Flocculation reaction tanks on both sides. The raw water flows intoFlocculation reaction tanks, perforated wall, incline-tube sedimentation tank. Then，thewater goes into the canal by6sets sink.Filter: gravity valveless filter tank was adopted to remove the suspended solids inwater. It contains2filter material layer of anthracite and quartz sand. And smallresistance plate hole type filter plate was selected as water distribution system. TheFiltration process is completely automatic, highly reliability, simplify operation, and agood treatment effect.Disinfection: ClO2is added into the pure water by flocculation, sedimentation andfilter.2Chlorine dioxide generators were installed, in which one is intended to usenormally, and another is prepared to deal with faults. ClO2is produced by Chlorinedioxide generators with tap water and industrial salt.(3)Intelligent control systemAn intelligent control system, developed with PLC programming language, wasintroduced to the water supply project. It is the intelligent control system that realizeboth the water-intake on demand and dual water purification.The intelligent control system can run smoothly and automatically, especially onthe follow2key procedures.1)A kit of "general converter+PLC+liquid level sensor" was applied to stipulatethe water-intaking. The static pressure type liquid level instrument is installed in the supply tank. Sensors in the liquid level instrument timely transfers the signal to thecontroller. After receiving signals, PLC control device automatically and accurately sentdrive or stop command to the inverter.2)The raw water quality are detected by on-line turbidity analyzer，which can beused to judge industrial water need to purify or not. The different water quality of rawwater can be distributed by the control valves.The paper explored several key techniques to suitable for a large variation of waterlevel, dual water purification engineering efficient economy，and remote control systemof intelligent management. It has a certain theoretical and practical reference value forthe optimization of water supply engineering of small towns in Southwest MountainArea.