Study And Application Of Chromium Wastewater Treatment By Reduction And Sedimentation Process

Chromium is a main pollutant in the environment. It mainly comes from the electroplating wastewater. With the development of science and technology and the scale of electroplating industry becomes larger, the chromium wastewater discharge amount also increases. If the chromium wastewater does not deal with efficiently, it will do fatal damage to the environment.Chromium has more valences in the water environment, with a valence of three or six mainly. Hexavalent chromium is more toxic, and it is known as a carcinogen. Trivalent chromium is less toxic, and it is a necessary trace element for humen beings and animals.For the present home and abroad accumulate many efficient methods for the electroplating chromium wastewater treatment, such as physical method, chemical method, physical-chemical method and biological method. The chemical method is the main one, and it is a very important part in engineering practice.This paper adopts deoxidization and sedimentation process to deal with the electroplating chromium wastewater. For the different deoxidization effectiveness, it compares the three main reducing agents with Na2SO3, FeSO4 and NaHSO3, including pH for reduction reaction, the reducing agent quantity and reduction reaction time. And then to confirm the reducing agent for the chromium wastewater of Harbin Bearing Factory's Electroplating Workshop. In order not to increase the sludge quantity, it chooses NaOH as the sedimentation agent, and then to confirm the pH and sedimentation time.In accordance with the water quality, the testing result and the electroplating workshop's real situation, I design the reasonable technology process and analyze the economic and technical for the engineering example in order to produce favorably, discharge wastewaters qualified and mitigate environmental pollution.