The Preparation Of Gelatin From White Wet Leather Waster And Treatment Of The Mixied Wasterwater

The leather industry is one of the pillar industries of China's light industry,but a lot of wastewater and waste leather were produced in its production and processing.The wastewater quality of leather wastewater is unstable and it has complex pollutant components which belongs to high concentration refractory organic industrial wastewater.The traditional biochemical treatment cannot meet the requirement of the existing emission standards of?Water Pollutant Emission Standard for Tannery and Fur Processing Industry?(GB 30486-2013).The leather wastewater treatment process is facing the problem of optimization and transformation.Disposal of used leather as solid waste increased the cost of the enterprise and caused a huge waste of biomass resources.Gelatin is widely used in many industries such as food processing,health care,medicine,cosmetics,and chemical industry.It is necessary to use gelatin products without chrome tanning to prepare gelatin products to achieve effective use of resources.This project takes the treatment of tannery wastewater from a tannery in Shandong Province as an example.The tannery has a large amount of waste leather materials to be treated;the effluent CODcr and ammonia nitrogen after the treatment of the tannery wastewater can not reach the current emission standards requirements.Therefore,this topic realizes the resource utilization of leather by preparing gelatin from white wet leather waste,screens the preparation process and conditions of gelatin,optimizes the original wastewater treatment process of tannery,and replaces the original biochemical treatment with A/O-MBR process.The process and the effect of HRT on the biochemical treatment were investigated.Use a split process to treat the tannery and gelatin wastewater to make it meet emission standards.The results have shown that the quality of gelatin prepared by acid-base method is better than acid method and alkali method.The optimum conditions for preparing gelatin are:1.5 mol/L hydrogen hydroxide,alkali treatment time is 12h,acid treatment time is 3h.The viscosity and extraction rate of gelatin products are 6.95 mPa·s and 35%.After the coagulation pretreatment of the glue wastewater,the water quality CODCr is 2048mg/L,the ammonia nitrogen is 15.05 mg/L,and the total nitrogen is 254.9 mg/L.When the A/O pool HRT is adjusted to 12 h,the influent water quality requirements of the MBR pool can be reached.The average CODcr removal rate is 82.4%,the total nitrogen removal rate is 46.09%,and the ammonia nitrogen removal rate is 51.04%.When the MBR pool regulates the hydraulic retention time to 24 h,the CODcr removal rate reaches 91.13%,the total nitrogen removal rate reaches 77.78%,and the ammonia nitrogen removal rate reaches 81.73%,which can ensure the final effluent water quality CODCr?65 mg/L,ammonia nitrogen ?25 mg/L and total nitrogen ?40 mg/L,meet the emission requirements of the existing GB30486-2013 tanning industry emission standards.Based on this,the design of the A/O pool and MBR pool structure is carried out.The operating costs of the process were accounted for and the economic environment gains and losses were analyzed.