Study On The Advanced Wastewater Treatment In The Cleaner Production Of Tannery

The thesis mainly studies the cleaner production of one tannery factory of Nanhai. Furthermore, it gives a analysis of the process in several aspects, such as technical, environmental, economical, and etc.The aim is to search for a feasible plan that is suitable for tannery at the new situation,in particular to reduce waste water. It is hoped that the corporation will set a good example of launching cleaner production to other brother companies. Therefore, cleaner production is not only a modern running administrative idea, but a green manufacturing method, that is a best way to balance the economic development and environmental protection.Contrapose the tannery's production status,this thesis makes research on the pollution caused by production, then put forward a solution, and its feasibility is validated by the actual engineering project. The biggest challenge of this tannery facing is how to reduce polleution cause by waste water, and this thesis just focus on how to solve this problem, the method that coagulation and sedimentation→hydrolytic acidification +biological contact oxidation→ozone pretreatment +biological aerated filter (BAF) was proposed. After analyze the quality of waste water discharge from every section on the treatment process, the optimum parameters of process operation is determined, then some analysis of how to remove contaminants effectively was carried out. This processes were validated that by test run. When the dosage of PAC was 500 mg/L-750 mg/L by two times, the removal rate of COD was the highest, reaching to 58.5 percent, the removal rate of sulphide and total Cr was 99 percent and 95 percent, but the removal of chroma was not distinct.Hydrolytic acidification +biological Contact Oxidation had good effect on this tannery wastewater, when HRT was 46 hours, the removal rate of COD could be from 80 to 90 percent, the removal rate of ammonia nitrogen could be from 50 to 60 percent. Even if the water quality variable, CODcr from discharge water could be stabilized at between 73 ~ 110 mg/L, it provides stable conditions for subsequent processing.The main influence factors were got by bio-chemical treatment effluent with Fenton reagent. When the dosage of H2O2 was 9.7 mmol/L, the rate ofρ(H2O2) /ρ(Fe2+) was 1.9 and the initial pH was 3, reaction time was 60 min, the removal rate of COD was reaching to 60.61 percent, the chroma could be 8 times. Basing on the experiment, it proved when the dosage of ozone was 25 mg/L~30 mg/L , the chroma of wastewater could decline to 4 or 8, COD and ammonia nitrogen discharge water from BAF which was pretreated by ozone could be stabilized below 50 mg/L and 7 mg/L.After cleaner production, this tannery had remove 95.56 percent COD and 97.78 percent ammonia nitrogen emission every year, COD and ammonia nitrogen emission declined from 13500 kg and 2160 kg to 600 kg and 48 kg respectively.