Leather wastewater treatment method. The leather industry is one of the high water consuming and high polluting industries in the light industry. Currently, leather industryThe annual discharge of wastewater into the environment by the industry reaches 8.0x 107~1.2x 108 tons, accounting for about 0.3% of the national industrial wastewater discharge. These wastewater contain approximately COD substances1.8x 105t, BOD substance 7.0x104t, suspended solids 1.2x105t, chromium 3500t. This wastewater not only pollutes the surface water system, soil, and crops, but alsoSerious threat to human physical health.

Aiming at the characteristics of high sulfide, high COD, and high ammonia nitrogen in comprehensive wastewater, a combined process of pre aeration desulfurization and denitrification → primary physical and chemical precipitation → A-O process → secondary physical and chemical precipitation → aerated biological filter is proposed to treat this type of wastewater. The process starts from the overall perspective: first, pre aeration is used to treat comprehensive wastewater, with aeration intensity controlled at 5m3/m2 · h. On the one hand, aeration blows off NH3-N from the wastewater, and on the other hand, aeration oxidizes S2- in the wastewater into elemental S and SO2. SO2 is released from the water and captured by the deodorization system, reducing the inhibitory effect of S2- on the biochemical system. The large-scale removal of S2- and NH3-N will reduce the load of subsequent treatment systems and improve treatment efficiency; The anaerobic section of A-O process adopts HABR composite anaerobic reactor, which is installed on the upper part of the tank bodyCombination biological fillerPlacing granular biological carriers at the bottom can significantly increase the concentration of anaerobic microorganisms and increase their spatial distribution, thereby improving the degradation efficiency of organic matter; The end of the combined process adopts an aerated biological filter, which integrates biological treatment and filtration, has high microbial activity, low organic load, and good effluent quality, ultimately ensuring that the wastewater meets the discharge standards.

Based on the above analysis, the project adopts the processing technology flow shown in Figure 1.