Method for efficiently removing organic matters in chrome tanning waste liquid and recycling chrome tanning waste liquid

Abstract

The invention provides a method for efficiently removing organic matters in chrome tanning waste liquid and recycling chrome tanning waste liquid. The method comprises the following steps that 1, thechrome tanning waste liquid generated by tanning in chrome tanning equipment is filtered, the filtrate is introduced into a liquid storage tank, if the COD value of the filtrate does not exceed 5000 mg / L, the filtrate in the liquid storage tank is returned to the chrome tanning equipment, the pH value, baume degree and chromium content of the chrome tanning liquid in the chrome tanning equipment are adjusted to meet technological requirements, tanning continues, and if the COD value of the filtrate exceeds 5000 m / L, the filtrate in the liquid storage tank is introduced into a treatment tank, ademulsification coagulant QZ-A02 solution is added into the treatment tank and uniformly stirred and stand, dross is formed by making generated floccules float on the water surface by adopting an airfloatation method, the dross is removed, the clear liquid is returned to the chrome tanning equipment, the pH value, baume degree and chromium content of the chrome tanning liquid in the chrome tanning equipment are adjusted to meet technological requirements, and tanning continues; 2, in the process of continuous tanning, the chrome tanning waste liquid is recycled according to the operation ofstep 1.

Description

technical field [0001] The invention belongs to the technical field of tanning clean production, and relates to a method for efficiently removing organic matter in waste chrome tanning liquid and recycling the waste chrome tanning liquid. Background technique [0002] In the tanning industry, chrome tanning is one of the important leather and fur tanning methods, and the quality of the finished leather has special advantages, so chrome tanning has always occupied a core position in the tanning field. Although chrome-free or chrome-less tanning is being developed globally, more than 90% of leather and fur are still tanned by chrome tanning. In the traditional chrome tanning process, the chrome tanning waste liquid cannot be effectively utilized, and the utilization rate of chromium in the tanning process is only about 60% to 70%. 2 o 3 Total) reached 2 ~ 5g / L (Huo Xiaoping, Liu Cunhai. A review of the status quo of chrome tanning wastewater treatment [J]. "Western Leather",...

AI Technical Summary

Problems solved by technology

The direct recycling method is mainly to recover the chrome tanning waste liquid, filter out the suspended matter or settle naturally, and use it for tanning of pickled hides, pickling and tanning of softened bare hides, or use it for retanning after adjusting the pH value. A large amount of protein and its degradation products, oil and other organic substances will accumulate in the circulating chromium solution. With the increase of the number of cycles, the COD value will increase and microorganisms will grow. Negative Effects

When it is used for retanning, the quality of the finished leather at the early stage of retanning is not significantly different from that of conventional chrome retanning, but as the number of cycles increases, organic matter will continue to accumulate, and the produced leather will have redness and uneven color. Can affect the penetration of chromium

[0005] CN 103663765A discloses a treatment method for repeated use of fur chrome retanning liquor, which is carried out by using plate and frame filter press microfiltration and polyacrylamide flocculation-microfiltration combined treatment in stages, although the method realizes fur chrome Multiple reuse of retanning liquor, but this method uses a plate and frame filter press to perform microfiltration under a pressure of 18-25kg. The price of a large plate and frame filter press is relatively high and needs to be operated under high pressure. The clogging of the filter cloth and the clogging of individual filter chambers will lead to a decrease in the working efficiency of the whole machine, which requires regular cleaning and maintenance. Therefore, this method not only requires high equipment investment, but also consumes high kinetic energy during processing, and also has the disadvantages of high processing and maintenance costs. insufficient

Polyacrylamide is used as flocculant, because chrome tanning liquor is usually acidic, and polyacrylamide has a certain thickening property under acidic and neutral conditions, and its addition is relatively large, which will lead to chrome tanning waste liquor The viscosity increases, which is not conducive to recycling. Polyacrylamide itself contains nitrogen elements. The use of polyacrylamide will cause the ammonia nitrogen or total nitrogen content in the chrome tanning waste liquid to increase, increasing the concentration of organic matter in it, which is also not conducive to Recycling, polyacrylamide will also settle a small amount of chromium while settling organic matter, and there is still a shortage of incomplete chromium recovery