Industrial wastewater treatment technology

1. Problems and development prospects China's sewage treatment industry started late but developed rapidly, now has made gratifying achievements, which is a fact for all to see, but in the face of the rapid development of China's industry, the amount of industrial production wastewater is also growing year by year, although the current scale of sewage treatment plant construction can basically meet the industrial sewage treatment. However, there is still a long distance from deep purification and recycling. Sewage treatment is a worldwide problem, the sewage treatment capacity of developed countries can reach 70% ~ 80%, China's sewage treatment capacity can only reach 50% ~ 60%, the rest of the treatment can not still rely on direct discharge.

1.1 Construction and operation of sewage treatment plants In order to meet the needs of industrial development, in recent years, the state has built more than 500 standardized sewage treatment plants, sewage treatment capacity can not meet the current stage of sewage production, regional economic development of different sewage treatment plants investment scale is also different, most of the sewage treatment industry belongs to public institutions. It is not a profit-oriented industry, and its main role is reflected in public welfare and environmental protection, so the construction and operation of sewage treatment still needs to rely on the support and macro-control of the state and local governments. Affected by the economic development of local enterprises, the government's tax revenue will also fluctuate, if the construction and operation of sewage treatment plants can not be perfected and developed, the direct discharge of sewage will cause incalculable harm to the local living environment.

1.2 Upgrading of sewage treatment equipment Most of the equipment installed and operated in the existing sewage treatment plant tends to be aging and traditional, a large number of operating equipment is imported from abroad, and the economic costs caused by equipment aging, treatment efficiency decline, equipment damage and other problems in the operation process are huge, and the introduction cost of new equipment is high due to the influence of intellectual property rights. In the face of the annual growth trend of industrial sewage volume, China's independent development will be imminent, which is a more severe challenge, the development of domestic sewage treatment technology has been tested, training professional and technical personnel to develop China's independent sewage treatment technology has become the first issue, in the continuous learning of foreign peer experience, Independent innovation and development of independent intellectual property rights of sewage treatment equipment, fully complement the pressure of sewage treatment. Equipment transformation: The traditional sewage treatment equipment has achieved considerable results in recent years in our country, and gained rich experience through actual debugging operation. However, with the shortage of water resources in China, the deterioration of the environment, the perfection of the national law, the sewage treatment requirements are becoming more and more strict and meticulous, and the development and introduction of new technologies will gradually replace traditional equipment. Membrane technology, ultrafiltration, electroadsorption salt removal technology, chitosan derivative technology, biochemical bed, electrocatalytic oxidation, mvr and other parts of the modern technology with energy saving, green, recycling, efficient is the goal of our future reform.

1.3 Sewage deodorization In the process of sewage treatment, the sewage itself has a strong volatility will produce different kinds of odor, in the process of entering the physicochemical and biochemical system, the change of temperature promotes the dispersion of odor. For example, when sewage enters the aerobic and anaerobic sections, because the metabolic temperature of activated sludge is generally above 20 ° C or even higher, coupled with the aeration of Roots fan directly affects the Brownian motion of harmful gases, resulting in serious damage to the air environment of residential areas and working areas around the factory.

1.4 Sludge treatment Sludge mainly exists in the biochemical system, and the bottom of the other process section pool will regularly produce sludge with higher concentration. The traditional treatment method is to collect this part of sludge into the sludge thickening tank, and then add flocculant and other agents to treat it into the mud press filter and bag for preservation. The traditional mud press is mainly plate and frame type mud press, which has low operation difficulty and low automation, and the water removal of sludge needs to be improved. Gradually, it will be replaced by a spiral sludge filter press, because it has a more efficient water removal effect, convenient operation, time-saving efficiency, but the price is more expensive.

There are two main ways to treat sludge: incineration and deep burial. In essence, it has not reached harmless, and the development of new technologies is concentrated in the direction of natural and harmless sludge cultivation by loach method and plant absorption. Although the distance from actual industrialization is still far away, we must make efforts to green and harmless.

1.5 Sewage recycling Energy saving and environmental protection is the theme of China's current sustainable development, if the use of water treatment technology to recycle industrial waste water to other ways will save a considerable part of the water consumption, bring economic benefits at the same time to save China's water resources. The recycling of sewage has achieved remarkable results in foreign countries, and more and more enterprises are applying the treated sewage to other fields. With the development of sewage treatment technology, the feasibility of industrial sewage as a secondary energy is getting higher and higher, the development of water treatment technology has promoted the production efficiency of enterprises, and the recycling of sewage has been paid more and more attention by enterprises. Conforming to the national policy and conforming to the people is the fundamental of industrial development.

1.6 Application after sewage treatment The demand for water in industrial production is different in different sections. Under the requirement of ensuring safe production, the workshop wastewater can be reasonably classified according to the demand standard by using sewage treatment technology to form the next level of workshop water. In the workshop through the sewage diversion water (including circulating cooling water, boiler water, overflow water, auxiliary water and cleaning water, etc.), ground collection of rainwater, living area water and other less polluted wastewater, after preliminary treatment can be widely used in brick factories, cement factories, mines, construction and other factories. BOD5 and COD indicators can be reduced to identify the biological and chemical oxygen demand consumed by the complete decomposition of organic substances in sewage to form water and carbon dioxide. The higher the content of unsaturated organic matter and inorganic matter in wastewater, the greater the values of BOD5 and COD. BOD5 /C index is an important indicator of the biodegradability of sewage, and it is usually stipulated that BOD /COD > 0.45 has the best biochemical effect. The sewage is mainly organic pollution, and the biochemical effect is the best when BOD /COD= 0.58. BOD5/T index is an important indicator of biological nitrogen removal requirements, because the hydrogen donor for denitrification in the biological nitrogen removal system mainly comes from the substrate in sewage, and the greater the ratio, the more obvious the nitrogen removal effect. BOD5 /TP index is an important reference to the production water consumption of biological phosphorus removal requirements, so that the problem of water shortage can be alleviated. Industrial sewage contains a large amount of salt, unreacted raw materials and valuable intermediate products. Recycling devices are used to process and extract valuable components in sewage, turning waste into treasure and harm into benefit. On the one hand, the cost of raw materials required for production is saved, and on the other hand, the concentration of sewage is reduced. The waste acid and alkali generated in the production process of chemical plants can be applied to the neutralization and regulation of sewage, saving the cost of sewage treatment and creating secondary value by waste treatment.

1.7 Water and stolen discharge industrial parks are big polluters generally far away from urban areas and developed areas, located in relatively remote desert, suburban and other places, stealing sewage behavior is widespread but difficult to be found and punished. With the increase of the state's requirements for special new indicators related to sewage treatment, the cost of sewage treatment and sewage treatment faced by enterprises is getting larger and larger, the increase of tap water, steam and electricity, the increase of industrial production raw material costs and the reduction of enterprise product sales have a certain degree of impact on China's industrial development. More and more enterprises are listed, the competition between peers, and the sluggish international economic situation make the survival and development of enterprises weak. Some areas adopt the "one enterprise one pipe" management model, that is, an enterprise one pipeline first through the enterprise's own sewage treatment station to treat the polluted water to a certain index after centralized collection of standardized sewage treatment plants for centralized treatment.