Researching On Treatment Methods Of Tannery Wastewater Containing Formaldehyde

Leather industry's development created much wealth for the county, but it also caused many serious environmental problems at the meantime. The treatment of tannery wastewater is very difficult because of its characteristic property such as big basicity, deep color, high oxygen consumption, more SS and with many toxic substances. Especially for the formaldehyde wastewater, it is hard to be treated directly with biochemical method due to its toxicity to microbe.This paper is studied the effective pretreatment method to treat formaldehyde wastewater based on broad investigation. PHysical and chemical methods were adopted to lower the concentration of formaldehyde to an acceptable level for microbe.Formaldehyde can be removed by oxidant because itself is a strong reducer. In the experiments Ca(C10)2 was chosen as the oxidant. The result showed that Ca(C10)2 can react with formaldehyde, but the removal rate is not high and the reaction condition is very harsh. So it could not be considered as the effective method to remove formaldehyde in actual wastewater project.According to the characteristic property of aldehyde and making use of its addition reaction, Sulfuric acid hydrogen sodium can remove Formaldehyde. The result showed that the removal rate of formaldehyde was very high with sulfuric acid hydrogen sodium. It has several advantages as follows: (1) Good removal effect, at the ratio of 2:1 in molar, the removal rate of formaldehyde reached more than 99%; (2) No special request to the temperature, the reaction can complete very well in homoiothermy; (3) Reaction speed is fast, and the reaction can complete within 30 minutes; (4) Operation cost is low, and the price of sulfuric acid hydrogen sodium is low, too.So sulfuric acid hydrogen sodium was chosen to deal with formaldehyde wastewater. It has good value in actual wastewater project because of its easy reaction condition, good effect low cost and so on.