Treatment Of Dye Wastewater By Microelectrolysis Process

China is one of the dominating countries which produce dye. The yield of dyes in china reaches 20% in the world. But the dye production mills in China are small and sporadic, and their technology is not good as that in the developed country. Because of the low efficiency in raw material use, the wastewater has high concentration of organic compounds and salts. Dye production process discharges a large quantity of wastewater with high concentration of CODcr and salt and, complicated composition and unbiodegradable pollutants. To adapt to the demand, producer changes the product line constantly. This induces that the quality of the wastewater from dye production process usually unstable. So it becomes a focus of environmental research to find a way to treat dye wastewater effectively and economically.In my thesis wastewater with high concentrations of dyes and salts from dye production process was treated by a microelectrolysis system with iron and coke granules. The effects of pH, concentrations of CODcr and color in the wastewater and mass transfer conditions on the removal results of color and CODcr were discussed. The effects of pH, the type of scrap and the rate between scrap iron and coke on the dissolution of scrap iron were also discussed. Synchronously, the change of bed character of iron scrap and granular coke and treatment mechanism of microelectrolysis were seeing about.The results indicated that(1) Microelectrolysis is an efficient way to treat the wastewater. When pH was about 3, the removal rates of color are above 90% and the removal rates of CODcr are between 40% and 60%.(2) pH of the wastewater effects removal rates remarkably. The lower pH, the better results. When pH was about 1, the removal rates of color and CODcr reached 94% and 60% respectively in 30 minutes; when pH was about 3, the removal rates of color and CODcr are 63% and 30% respectively in 30 minutes; but when pH was about 5, the removal rates are only 36% and 26% respectively in 30 minutes.(3) Concentration of CODcr affects removal rates evidently. In the same time, when concentration of CODcr change from 3000mg/L to 6000mg/L, the removal CODcr increase over 2000mg/L and the removal rates also increase 8%~20%. When Original concentration of CODcr changed from 6000mg/L to 8000mg/L, the removal rates reduced about 20%(4)The process of iron dissolution shows that pH effects iron dissolution markedly. When original pH is about 1, the concentration of iron in solution is 2.5 ~ 6 times to that when original pH is about 3. Carbon content of iron is also an influencing factor of iron dissolution. When carbon content of iron is about 3% is above 3.5 times to the speed of iron dissolution when carbon content of iron is about 0.2% in 75 minutes.(5) pH effect frame of iron-carbon bed remarkably. When pH was about 1, the height of bed decline about 25.40% and the rate of lacuna also decline about 24.07%. The reactor approach Plug flow reactor after running 24h. When pH is about 3, the height of bed and the rate of lacuna changed a little.The innovative viewpoints of this article are: (1) Influencing factors of iron dissolution in the Microelectrolysis process were allround study; trait of iron-carbon bed and running state of liquid were also meticulous studied. (2) The relationship between redox reaction and configuration of dye molecule was studied and analyzed.The main research work of the thesis was not reported in literature at presenttime. Results from the study offer a theoretic basis not only to master the Microelectrolysis process, but also to practical use.