Coagulating agent for treatment of leather-making waste water and leather-making waste water treating method

Abstract

The invention discloses a coagulant used for treating tannery wastewater, which consists of pickling waste liquid, calcium aluminate, additive and catalyst; quality percentages of each component are 60 percent - 90 percent of the pickling waste liquid, 8 percent - 37 percent of the calcium aluminate, 1 percent - 3 percent of the additive and 0.01 percent - 0.03 percent of the catalyst.The invention also discloses a method for treating the tannery wastewater which includes the steps: preparing the coagulant, balancing water quality and water quantity of the wastewater, a coagulation reaction, a biochemical treatment, effluent discharge etc. The invention uses steel pickling waste liquid to prepare the coagulant for treating the tannery wastewater so as to reduce the load of treating the pickling waste liquid for the steel deeply-processing industry as well as reduce the treating expense.The invention improves the treatment effect of the wastewater from the tannery industry; removal rate of CODcr content of organic pollutants in the tannery wastewater increases by over 20 percent than the removal rate of common aluminum salts coagulant or ferric salts coagulant; the removal rate of a plurality of toxic substances in the wastewater such as sulfide, chromium etc. reaches over 95 percent; the following ordinary operation of a secondary biochemical treatment system of the tannery wastewater is guaranteed; and the treatment cost is reduced.

Description

【Technical field】 [0001] The invention relates to wastewater treatment, in particular to a coagulant for treating tannery wastewater. 【Background technique】 [0002] In recent years, my country's raw hide imports have continued to grow. In 2004 alone, my country imported USD 1.25 billion of raw hides, a year-on-year increase of 38%. The world's leather industry began to transfer to Asia, especially China, in the 1980s, and now China has become a major leather country in the world. [0003] However, the leather industry is a high-pollution industry. With the increase of the output of the leather industry, the pollutants discharged by the tannery industry are also increasing, and the environmental problems of tannery wastewater pollution have become increasingly prominent. Most tanneries in my country adopt lime depilation and chrome tanning technology, and the resulting tannery wastewater is characterized by high alkalinity, deep color, high oxygen consumption, high suspend...

AI Technical Summary

Problems solved by technology

According to preliminary statistics, more than 20,000 tons of steel pickling waste liquid are produced every year in Pinghu City, Zhejiang Province and its surrounding areas alone. Due to the serious corrosiveness of pickling waste liquid, it has been included in the "National List of Hazardous Wastes". The traditional lime neutralization method is very costly to treat the liquid, and the generated sludge is difficult to dehydrate and dry, so the post-treatment is difficult. At the same time, this treatment method wastes a lot of acid and iron resources

Images