Fundamental Research Of Packed Bed Electrochemical Reactor

Packed bed electrochemical technology is a feasible and effective approach for high concentration organic wastewater treatment with large colority and salinity. However, lack of the kinetics for the coupling of electrodes, fillings and concentration prediction of organics in the bed electrode hinders the transfer of this technique. Therefore, it is necessary for thorough research of the process. At the same time, the achievement obtained through varied means such as theoretical analysis, modelling, laboratory and pilot-scale experiment are as follows:(1) the concept of"multiphase control"was proposed for description of the transition of reaction and diffusion controlled processes, which is a complete supplement for the reaction theory based on sufficient analysis of current researches.(2) a new equation, which is accordance to the experimental data, was obtained for the calculation of current efficiency in packed bed electrochemical reactor (PBER) on the basis of Faraday's law.(3) a"step-reaction kinetics", which is related to the charactristics of different reaction stages, was achieved through the determination of reaction, multiphase and diffision controlled processes by the relation between limiting current density and operating current density. The new theory could be employed for the quantized description of the relevance of the organics oxidation and operation conditions, physi-chemical behaviors of solution and configuration of the reactor. Meanwhile, the integrated, sufficient and accurate prediction of the concentration distribution of organic matters in the bed electrode is acquired using this theory.(4) a global energy model was established through the application of laws of the conservation of energy, momentum and electron. The values of characteristic parameters, K1 and K2, which are related to the essence of organics in wastewater, could be obtained when linearized the complex expression of energy equation. Simultaneously, the parameters could be employed for the optimization of inter-electrode distance and the overall kinetic behaviors under reaction, multiphase and diffusion controlled phases also could be described by this model. The accurate design and operation are acquired by the introduction of global energy model and"step-reaction kinetics"through the lab-scale experiments.(5) an effective and precise prediction of potential distribution in bed electrode could be conducted using"step-reaction kinetics"coupled with Poisson's equation. The results for starch wastewater, auxiliary wastewater, DSD acid wastewater from reduction and oxidation processes treatment revealed that the experiments was consistent with the theoretical ones and the potential, over-potential, current and reaction velocity of the bed electrode during the oxidation could be estimated by the kinetics proposed in this research. All in all, the optimization of the reaction and design parameters and management of the technology are easily achieved by the integrated theory.(6) the experimental results for the four kinds of different industrial wastewater treatment were in good agreement to the step-reaction kinetics on the prediction of concentration distribution, current efficiency and energy consumption of the bed electrode. Moreover, the successful fitting between these theories and experiments in glycine wastewater treatment using the engineering scale-up bed electrode indicates that the kinetics proposed in this study could be used for the accurate design of the PBER.The research demostrates that the PBER is wide-adaptable in environmental protection engineerings: it not only can be employed as a kind of pretreatment measure to improve the biodegradability of regular wastewater, but also for the final handle way of high salinated wastewater. However, the competitive advantages are noticeable in the application of solution with high salinity. Concomitantly, the development and improvement of kinetics for the PBER provide some significant possibility on its technical spread, rational design and optimal operation.