Study On The Novel Technology Development Of Electroplating Wastewater & Liquid Treatment And Utilization

In this paper, we investigated the possibility of electroplating wastewater treatment by modified activated sludge. There are three main contents as following: the first section is adsorption thermodynamics of modified activated sludge to heavy metal ions in real wastewater, and the models of heavy metal ions adsorption on modified activated sludge in complex wastewater system were obtained. In the second section, we considered the process of heavy metal wastewater by modified activated sludge. And sludge concentration, contact time, the pH value of system, reaction temperature and addition of S2- on the treatment effect were investigated. In the third section, we studied the leaching process of heavy metal ions containing in sludge by sulfuric acid. The pH value of system, liquid to solid ratio and reaction time on the leaching effect were discussed. Meanwhile, we researched the possibility of countercurrent leaching process.The adsorption of Cu2+, Ni2+, Zn2+ and Cr3+ on activated sludge pretreated by saturated lime solution was investigated. Under the given condition, the saturated adsorption capacity of Cu2+, Ni2+, Zn2+ and Cr3+ on activated sludge are up to 8.9, 10.3,9.8 and 2.0mg/g. The adsorption isotherm of Cu2+ and Zn2+ are in keeping with Freundlich model, and Langmuir model is better coincidence of Ni2+ while Cr3+ agrees with Henry model. Under the experimental condition, the inhibition effect of high concentration metal ions to low was observed.We studied the possibility of heavy metal wastewater(liquid) treatment by activated sludge pretreated by lime. For high concentration electroplating wastewater(liquid), sludge concentration, contact time and the pH value of system have notable influence on the treatment effect, while the influence of reaction temperature and addition of S2" are weaker. Under the certain factor, the highest removal rate of Cu2+, Ni2+, Zn2+ and Cr are up to 89.0,94.08,95.98 and-100%. For the low concentration electroplating wastewater, the highest removal rate of Cu2+ Ni2+, Zn2+ and Cr are 88.58,97.13,99.31 and 99.88%. The concentration of the above mentioned ions in the effluent have been reduced to 5.1,2.0,0.06 and 0.15mg/L, and the pH value is 8～9. We also investigated sludge settling characteristics, and the possible mechanism of heavy metal ions removal by modified activated sludge was discussed, too.We considered the leaching process of metal ions containing in sludge by sulfuric acid. It is observed that the pH value of leaching solution and liquid to solid ration have notable influence on leaching rate while the reaction time get weaker influence. Under the fixed condition, the leaching rate of Cu2+, Ni2+, Zn2+ and Cr are up to 98.07,99.08,98.80 and 95.63%. When the countercurrent leaching was applied, the reactor should not be more than three, and it is necessary that at least two of the three reactor should hold the pH value of their reaction solution under two.At last, we developed the novel technology of electroplating wastewater (liquid) treatment and utilization based on the obtained data in experiments.