A new idea of disinfection and sterilization treatment of wastewater under the new environmental protection law

Disadvantages of liquid chlorine disinfection:

(1) The safety of liquid chlorine disinfection is poor.

(2) There is secondary pollution in liquid chlorine disinfection. Chlorine reacts with certain organic and inorganic components in sewage to form a series of stable chlorine-containing compounds, most of which are harmful to human health, and some chlorine-containing compounds are carcinogenic.

(3) The chlorinated ammonia produced by the reaction of chlorine and ammonia in sewage will reduce the disinfection effectiveness, and the chlorinated ammonia will have toxic effects on environmental organisms after discharge into the water body.

3, sodium hypochlorite disinfection

Sodium hypochlorite can be produced by electrolysis of seawater or saline solution with sodium hypochlorite generator. The effective chlorine in sodium hypochlorite is about 5-15%. Sodium hypochlorite disinfection depends on the effect of OCI-. Sodium hypochlorite disinfection solution is less toxic and easier to operate than chlorine disinfection system. Less training is required compared to chlorine disinfection systems.

Disadvantages: Sodium hypochlorite is easy to deteriorate, the addition of sodium hypochlorite has the possibility of increasing inorganic by-products (chlorate, hypochlorite and bromate), has a corrosive effect on some substances, is not easy to store compared to other solutions, and the cost of chemical agents is higher than chlorine gas.

4. Ultraviolet light

Ultraviolet is an electromagnetic wave with a frequency higher than that of visible light. It is the use of ultraviolet light generating device to generate strong ultraviolet c light to irradiate water, air and surface of objects. When various bacteria, viruses, parasites, algae and other pathogens in water, air and surface of objects are subjected to a certain dose of ultraviolet c light radiation, the DNA structure in their cells is damaged. To achieve the purpose of disinfection and purification.

Ultraviolet disinfection defect

① does not have follow-up disinfection ability, easy to produce secondary pollution

② Only the microorganisms that absorb ultraviolet light will be inactivated, and the disinfection effect is difficult to guarantee when the sewage SS is large

Bacterial cells are not removed in the UV sterilizer, and the killed microorganisms, along with other pollutants, become food for the surviving bacteria

5, ozone disinfection method

Ozone is a strong oxidizing agent, is the use of the unstable characteristics of the three oxygen atoms composed of ozone, the decomposition of the release of new ecological oxygen, and the new ecological oxygen has a very strong oxidation capacity, a strong lethality to bacteria and viruses, resulting in the death of bacteria and viruses. Ozone disinfection efficiency is high, and can effectively degrade the residual organic matter in the sewage, decolorization and odor removal effect is excellent, and the pH value and temperature of the sewage have little impact on the disinfection effect, and do not produce a pollution.

Disadvantages: The use of ozone to disinfect the effluent of urban sewage treatment plants has disadvantages such as large investment, high operating costs, complex equipment management, and so on. In addition, when the water quantity and water quality change, it is difficult to adjust the amount of ozone added. Therefore, ozone disinfection is mainly suitable for industrial wastewater treatment disinfection and small-scale urban sewage treatment disinfection with high effluent quality requirements, high chroma or difficult to degrade substances in the effluent, and small amount of water, and is not suitable for large and medium-sized urban sewage treatment plants.

6, chlorine dioxide disinfection

Chlorine dioxide disinfection is characterized by oxidation, not chlorination, and therefore generally does not produce carcinogens. The disinfection effect of chlorine dioxide is comparable to that of chlorine gas, but when the concentration of NH3N in sewage is high, the amount of chlorine consumption will increase greatly, but because chlorine dioxide does not react with NH3, its dosage does not increase. In addition, chlorine dioxide disinfection is not affected by pH. Chlorine dioxide is unstable and explosive, so it must be made on site for immediate use. The preparation of chlorine dioxide with low chlorine content is complicated, and the price of raw material (NaClO2) is higher than that of other disinfection methods, so the widespread adoption of this method is limited. Therefore, the chlorine dioxide disinfection process is only used in some small and medium-sized sewage treatment projects in China.

To sum up, the six disinfectant methods introduced in this paper are the most popular technical methods used in sewage treatment systems at this stage. Although they have their own characteristics in the actual application process, they are being recognized by more and more enterprises due to their high operating cost, high risk, difficult to guarantee disinfection effect, difficult to store and poor stability. From another aspect, it also shows that the above toxic sterilization methods are being abandoned. The bactericidal effect is good, easy to store, no harm to people, and a disinfectant that is colorless, odorless, non-toxic and no residue has slowly entered people's vision, that is, the original imported from Germany, food-grade silver hydrogen peroxide ion compound disinfection disinfectant: Oktez.