Analysis of future development trend of leather wastewater treatment

Core Tip: The United Nations designates June 5 as World Environment Day every year, and issues a warning of "only one Earth" to draw attention to global environmental issues, remind people to protect the environment and cherish the planet. Environmental protection and ecological balance have become a worldwide social problem that governments and people all over the world pay close attention to. It is closely related to people's health and living standards, economic and social development and the happiness of future generations. Since the 1950s, with the development of the economy, the people have developed a large number of industries, and large factories have sprung up in many parts of the world.

The United Nations designates June 5 as World Environment Day every year and issues a warning of "only one earth" to draw attention to global environmental issues and remind people to protect the environment and cherish the earth. Environmental protection and ecological balance have become a worldwide social problem that governments and people all over the world pay close attention to. It is closely related to people's health and living standards, economic and social development and the happiness of future generations.

 

                  

Since the 1950s, with the development of economy, people have developed industry in large numbers, and large factories have sprung up. The production and living environment in many parts of the world have been increasingly polluted and destroyed. According to statistics, for every ton of raw leather produced in China, the wastewater produced is about 50-150 tons, and the annual discharge of wastewater from the tannery industry to the environment is more than 8 million tons, accounting for about 0.3% of the total industrial wastewater discharged in China; the discharge of 10000 yuan output value of the leather industry ranks third in the light industry, second only to the paper and brewing industry.

Nowadays, environmental pollution has become a serious social hazard, the sky is full of smog; inland waters are dirty and dirty; the vast sea has become a garbage dump and so on, so that the health and life of the broad masses of people are greatly threatened. In an era when environmental problems have become so serious, the leather industry, known for its dirty, messy, smelly and tired properties, is facing unprecedented pressure.

Hazards of Tannery Wastewater

1. In the process of leather manufacture, it is necessary to dye animal fur, so the leather wastewater will contain a large number of dyes, but the color of wastewater is higher, if not treated directly, it will affect the surface water quality.

2. It is necessary to depilate animal fur in the process of leather processing. There are a lot of sulfides in the depilation fluid. The sulfur-containing waste liquid is easy to produce H2S gas when it encounters acid. The sulfur-containing sludge also releases H2S gas under anaerobic conditions, which is harmful to water and human beings.

3. in the process of peeling, a lot of lime, caustic soda and Na2S will be used. High alkaline without treatment will affect the surface water pH and crop growth.

4. Chloride and sulfate are used in the preservation, pickling and tanning of raw hide. When the sulfate content exceeds 100mg/L, the water will be bitter and diarrhea will occur after drinking.

5. Because of the high content of protein and some reducing substances in leather wastewater, COD and BOD are very high. If the wastewater is discharged directly without treatment, it will cause water pollution and promote bacterial reproduction. At the same time, the wastewater discharged into the water will consume dissolved oxygen in the water body. When the dissolved oxygen in the water body is lower than 4mg/L, fish and other water will be consumed. The respiration of living organisms will become difficult or even death.

According to incomplete statistics, China has more than 500 industrial-scale leather factories, more than 15,000 small leather factories, and numerous small workshops can not be counted. The annual processing capacity is about 10000000 leather, 75 million pigskin and 10 million sheepskin. Nearly 150 domestic tanneries have built environmental protection facilities, but few of them have reached the national discharge standards and operated normally. Most of them can not operate normally because of unreasonable treatment process, high operating costs and troublesome operation and management. Most of the tannery wastewater is discharged directly after simple precipitation or untreated. Some rivers or lakes even discharge from seepage pits.

In view of the actual situation of enterprises in various regions, we should seriously consider, study and fully demonstrate, in line with the principle of saving investment, occupying less land and operating costs, draw up a sewage treatment scheme for the experts to demonstrate.