【 Weak current College 】 supply materials and equipment for water quality impacts and solutions (1)

With the development of science and technology and improve people's quality of life, water quality requirements are also getting higher and higher. Although water factory factory water targets to achieve the national water quality standards, however tap water by transmission and distribution network to the user group leader, has gone through dozens of kilometers to hundreds of kilometres of the journey, are often subjected to secondary pollution, caused to the household water quality deterioration. Guarantee to the household water key factor depends more on the pipe material and equipment selection and maintenance.
1 pipe and equipment effects on water quality
1.1 corrosion
Broken pipe body and corrosion is an important cause of water quality incidents. 97 year on domestic large and medium cities water company of survey data show that end water turbidity, total bacteria, total coliforms and free residual chlorine as a comprehensive rate lower than the factory water 3.05 per cent, with total coliforms rate decline 7.3%, close to the standard threshold. Chloroform, carbon tetrachloride 47.91% respectively and 38.78% permanganate index increase 35.0%, reflecting the net increase of organic pollutants and the effects of chloride. Our many cities in the 1990s before the laying of the pipeline had not adopted measures, both within and outside the anti-corrosion rust has now become quite serious "red water", "black water", and other incentives for water quality incidents.
1.1.1 metal materials
Metal pipe corrosion caused by turbidity, color, iron, manganese and other content increased, General corrosion of inner surface of the pipe pollution increases volume is large, the increase in small pipes of large diameter greater than. Rust soluble in causing odour and taste. Other metal tube formation rust, corrosion, scale layer is the germ of the workplace, biofilm growth thus biofilm formation, the United States in pipes checked out 28 biofilm bacteria. Biofilm of aging and peeling caused a user of olfactory and taste and color of increase, and these micro-organisms began to disinfectants produced the resistance, not killing, but also increased the number of microorganisms in the terminal of tap water. The thickness of the pipe and scale will be as time continued to increase, the effective sectional area of pipeline is shrinking, thereby seriously affecting the ability of water transmission pipelines.
1.1.2 cement materials
Use a pipe cement materials have concrete pipe, asbestos cement pipes, cement lining pipe. Water and the tube wall contact part of corrosion are for the same mechanism. Water consumption of cement in acidic ingredients, alkaline constituents and OH decomposing induced Ca2, drinking water quality deterioration.
China has gradually after 1988 on the application of metal pipe cement mortar lining anti-corrosion coating, excavated from the maintenance of the pipeline inspection, internal coating effect is good, but there are certain disadvantages, for pipe construction backfill after deformation caused by mortar burst, partial loss, as well as cement mortar with long-term immersion, erosion, the loss of the cement constituents that cause exudative cement mortar loosely, part peeling mortar flow to the users table, some even lead to valve does not close.
1.2 piping and equipment damage to water quality and contamination
1.2.1 pipeline was buried, contaminated groundwater or water immersion, if pipeline perforation, gate leakage, seepage, interface has not been timely repair, once decompression or water, wastewater may be inhaled, causing pollution inside the tube.
1.2.2 pipe drainage sluice export below the riverbed water level or add to the water pipe, if the gate is closed, you will cause the dirty water poured in, causing pollution inside the tube.
1.2.3 pipeline burst water leakage, closing the formation of negative pressure, dirty water suction tube, pipe repair after failing to hedge row forming pollution.
1.2.4 user-end storage (used) water device communicates with the water supply pipe, no separate measures, process all the result of the suspension or other causes outside water back into the water distribution pipe, causing pollution. At present, China's general use ordinary check valve to prevent backflow of water, but the effect is not good.
1.3 piping and equipment for material selection of water pollution caused by improper
As the transportation of pipes and equipment for drinking water and water contact parts should be non-toxic, this is a selection of pipes and equipment of the most basic requirements. In the current market, pipes and equipment of variety, how to get to the identification of pipes and equipment of health status?
1 October 1998 the State Bureau of technical supervision issued jointly with the Ministry of health was "drinking water transmission and distribution equipment and protective material safety evaluation standards" (GB/T17219-1998), which is currently evaluating transport drinking water pipes an important basis for health and safety.
1.3.1 plastic piping and equipment
According to the national standard of water quality monitoring stations in Chengdu (GB/T17219-1998) on different manufacturers of PVC-u pipe and fittings for safety inspection, there are four immersion fluid serious excess of lead in a time of chloroform, carbon tetrachloride available. Monitoring station technician stated that lead is a serious cumulative toxins, is a carcinogenic substance becomes, whether due to short-term or long-term ingestion of lead, the human body will cause serious damage to health or death; chloroform, carbon tetrachloride or are highly carcinogenic risk of organic toxins, since the production costs and other factors, many manufacturers use low-cost lead sulfate tribasic sexual or dibasic lead phosphite sex as a product of heat stabilizers, products containing lead, product high chlorine water immersion, the water naturally appear large amounts of lead. And chloroform, carbon tetrachloride is exceeded due to pipe fittings and pipes used for bonding adhesive solvent.
1.3.2 FRP pipe
FRP tube on impervious layer of resin with clear requirements to non-toxic, cutoff, wear-resistant, thickness should 2mm. such an impervious layer should use a more expensive room benzene of unsaturated polyester resin, but some manufacturers use a low-resistance of unsaturated polyester resin, thickness is quite thin, if this layer crack, fiber easy immersed. The centrifugal process pipe comes from Austria; winding process pipe from Italy. However, Vienna, Rome and developed by metropolis of tap water pipe network, there is no or very little use of such material. ThisSome countries, some manufacturers are continually developing the dumping of such pipe equipment in a large amount of water supply network, you should think twice.
1.3.3 for cement pressure pipe, lined with cement mortar for ductile iron pipe and steel pipe on the health situation is there are two points to note:
1. cement production often infiltrate slag, this cement has no radioactive indicators exceeding a problem worthy of attention, some pipe factory samples marked their selection of cement, radioactive indicator inspection is proof of competency should welcome.
2. the pipe surface should not exist within the floating pulp, pipeline cleaning after grey powder layer also tends to make the water process suspended solids increase.
In addition, pipe and equipment problems within the coating should be careful to avoid pollution from toxic paint.