Study on a Real-Time Control Strategy to Cr(VI) Removal with Fluctuation of Influent in Fe-Electrocoagulation-Al-Electroflotation Reactor

The overall goal of this study was to construct a real-time control strategy to Cr(VI) removal with fluctuation of influent using FeElectrocoagulation (EC)-Al-Electroflotation (EF) reactor. Firstly, we used the pH as the indirect indicators to developed mechanism models that could describe the process of Cr(VI) reduction to Cr(III). During the process of Fe-EC, if Delta[pHm]/Delta t <=Delta[pHp]/Delta t, indicating that Cr(VI) was completely removed. Model M2 was more capable of predicting the terminal time of Fe-EC process than Model Ml. To improve accurate of model M2, the effective rate of Fe(II) for Cr(VI) reduction (psi = 28.7%) in an extremely adverse conditions was defined, and the optimal Delta equation was deduced according to monitoring accuracy and stability of pH monitor. Subsequently, the response surface methodology (RSM) was used to develop flocculation-flotation empirical models of suspended particles of Cr(III). The model of response of the residual total Cr and turbidity, temperature, electric quantity per volume (Q) and settling time was constructed. Verification results show the efficiency of the proposed model. Finally, we constructed a real-time control strategy by combined the Fe-EC and Al-EF, which could save 58.8% of anode material and 58.3% of electricity power and reduce 58.7% of sludge production compared to traditional control process. (C) 2018 The Electrochemical Society.