Investigation And Research On Operation Situation Of Low Turbidity Raw Water Purification Process

With the increasing of water pollution and situation of water scarcity, a growing number of waterworks uses lake and reservoir water as source of water, due to the long-term effects of static Shen making water turbidity of lakes and reservoirs water generally low, which bring difficulty to the water purification plant; many waterworks are designed in accordance with water quality in the initial construction,so the original process is often difficult to adapt to changing in raw water quality after the source of water switching from river water to lake water; the full implementation of new "drinking water health standards "(GB5749-2006) bring new challenge to water purification plant using traditional craft. These three aspects proposed new requirements to the current waterworks treatment process. To get the current situation of low turbidity water purification processes running in different areas,and to find a more effective treatment of low turbidity source water technology portfolio, firstly by surface survey we collected the northeast, north, northwest, southwest, east, central and southern seven areas water purification plant on the basis of data, including water scale, water type, processing technology, operational status and wastewater disposal.As the study shown, low turbidity water can be divided into three part: low, regular and low turbidity water, low temperature and low turbidity water and slightly turbid polluted water. Three low turbidity water purification process can be divided into six parts: traditional crafts, advection / inclined tube and combined with flotation tank, flotation tank, clarifiers, high density pool, and pre-treatment composition and depth. Conventional treatment processes accounted for 30%, while 63.6% of the water work uses a pre-treatment or advanced treatment process, in which 71.4% water work’s pre and deep water pretreatment process were constructed after 2008.Low turbidity water treatment and new clarification process include single-module and multi-module combination. Single-module form refers to the precipitation unit reconstruction, with the replacement of the new clarification process concluding clarifier sludge with reflux, high-density pools become mainstream technology; multi-module combinations adds depth treatment before coagulation unit increase in pre- or post-filtration unit. Alterations in the clarification process on the basis of the original precipitation unit were part of the transformation, flotation tank is renovated main selection process; the subsequent increase in water depth of treatment also mentions a trend marked transformation of water work. To the traditional process for clarifying water, it is to dig the potential of the existing process by optimizing coagulant, use powdered activated carbon, add sludge reflux and other methods to strengthen the clarification process of processing power. For low turbidity water quality characteristics, survey results show that a single module forms uses more processing conventional low turbidity water or low temperature and low turbidity water; Water treatment plant raw water with low turbidity and micro-contamination use more the general multi-module new programs, particularly the construction of additional depth treatment process. Maintaining the traditional process of waterworks generally use a variety of methods to guarantee water quality and tapping.As the data obtained shown through research, 22 of the whole 33 low turbidity water as raw water purification plants water uses waste water reuse technology, of which only two choose reuse and in 20 direct reuse of wastewater 80% of water choose reuse. 81.8% of the recovery process was built in 2000, mainly in 2006 and 2010, probably because during this time many waterworks response to the technological transformation of the new standards, while improving the wastewater treatment process.In order to further study, this paper selected the raw water on behalf of the three types of low water of four typical waterworks, through information, verification and measurement for further research. The study found that A water plant raw water which belongs to the conventional low turbidity water, using wastewater reuse technology; B water plant raw water belongs to conventional low turbidity water, no waste water reuse; C water raw water belongs to low temperature and low turbidity water; D belonging to micro-polluted raw water waterworks low Turbidity. Depth study found that wastewater reuse can eliminate drug consumption increase due to the problem of low turbidity water, A cloud water at low dosage of PAC was only 10.42mg/L; B average water production load was 56.6 percent, mixing tube mixes the poor, drug use is low; C low temperature and turbidity of raw water, high PAC dosage, up to 70mg/L, wastewater reuse technology built without use; D raw water with low turbidity and water pollution, increased water coagulant dosage to protect water quality, resulting in increased waste water, in 2011 the average water consumption rate of 9.4 percent, the late multi-module combination a+C+b, increasing the depth of the pretreatment and treatment in order to improve water quality.In short, low turbidity water purification process reflux coagulation effect water through building with the clarification process sludge return system to improve water quality can also be improved by optimizing the wastewater; As for the waterwork suffering from raw water pollution,it is better to enhance the removal of contaminants from increasing the depth of the pretreatment and processing unit.