Water quality in the water before entering the PVC pipeline, can reach the national standard. But because it is not pure water, water generally contain some metal elements, compounds and microorganisms. When the water flows in the pipe, some of the compounds will break down, so that the water and the inner wall of the pipe material to produce chemical action. At the same time, the residual bacteria in water may reproduce again, so that the water quality in the tube can be changed. And a conduit due to corrosive action generated sediments, formation of fouling layer, about the thickness of the pipe to be used for a number of years, it decreases with the increase of time continues to expand, fouling layer is bacterial reproduction, the formation of the "membrane", also known as "growth rings". The water quality of the effluent from the PVC pipeline is found as many as 28 kinds of bacteria and 16 kinds of metal elements, mainly iron, manganese, zinc, lead, mercury, etc., the water quality directly affects people's health. Pipe is the main cause of water pollution: the effect of internal corrosion and scaling on water quality. The formation mechanism of water on the inner wall of the metal pipe is dirty, and the formation mechanism of the water is mainly three kinds of explanations. A called oxidation theory, is due to the action of water carbonate and iron into ferrous carbonate, then it is oxidized by the oxygen in the water and become the ferric hydroxide; second is called oxidation theory, namely iron first combine it with water for ferrous hydroxide, to produce hydrogen and water oxidation synthesis of hydrogen peroxide and ferrous hydroxide and hydrogen peroxide of synthetic iron hydroxide.
Fe+2H2O (Fe) 2+H2 (OH)
H2+O2 - H2O2
2Fe (OH) 2+H2O2 (2Fe) 3 (OH)
The third theory is the theory of micro corrosion cell. Because of the metal itself contains many impurities, between the metal and the impurities exist potential difference, in the medium of water formed numerous micro corrosion cell, in a part of the surface of the pipe, because iron is etched into iron ions into the water and the formation of anode, released by electronic transfer to pipe surface of another part of the cathode is formed. In the pH<7. At the cathode occurred reaction to losing hydrogen ions and increases the hydroxide ion, when reaching a sufficient number of water and iron to form ferrous hydroxide, be dissolved ferric hydroxide formation of rust, deposited on the tube surface, rust is uneven, in the distribution pipe network at the end of the pipe diameter is small, and the flow velocity is low, rust will intensify. The water calcium carbonate precipitation (mg) to form scale. In all natural water, almost all contain calcium and magnesium ions. And water carbonate ion decomposition of carbon dioxide and carbonate ions, and calcium magnesium ion combination will generate calcium (magnesium), it is difficult to dissolve in water into sediment. Biological blockage in the pipeline. General water after purification, disinfection, in the pipe network is generally no possibility of organic and biological reproduction, but iron bacteria is a special kind of chemical nutrition fungi. It relies on ferric oxide, in the organic matter content is extremely clean water, successfully using bacteria itself survival survival of energy generated in the process. So addicted to iron bacteria attached to the inner wall of the tube, absorption of ferrous salt in the process of survival, discharge of ferric hydroxide, thus forming bulges, so that the smaller diameter.
The above conditions are the main causes of the precipitation and scaling in the tube. According to the condition and time difference, it can be roughly divided into hard and soft deposits. And the main reason of hard scaling is the corrosion of the metal pipe itself and biological fouling. It is a metal pipe. Soft precipitation may exist in the metal or nonmetal pipe. So it is seen that scaling is one of the main factors of water quality change. And the metal tube is the main reason for the formation of the hardness. The formation of water pollution again.
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