Study On The Application Of Electrosorption In Wastewater Reuse Project

Wastewater reuse provides a useful way to solve the problem of shortage of freshwater resources, which has become an important constraining factor of China's economic development. Wastewater is used for industrial cooling water, ammoniacal nitrogen and salinity are two vital parameters when wastewater is reused for industrial cooling water. Electrosoption is a new water treatment technology aiming to remove the irons in the wastewater via electrifying on both ends of the electrodes below the water decomposition voltage, making ions in raw water moved and then stored in the the double-layer at the surface of electrode. Although eletrosoption technology can achieve good removal effects of ammonia and salinity in theory, at the present time,it is still lack of research especially practice in China.In this paper, the key parameters which affect the removing ability of the electrosoption equipment and the features when different ions are adsorpted combinatorially are studied through laboratory experiments using concocted wastewater. On the other hand, advanced treatment effect of real wastewater using eletrosoption technology is investigated through pilot testing, also demonstration project is trial-operated.The following conclusions are got from the results. The removal effect of ammoniacal nitrogen is stable when pH changes between 6 to 9, while it has a significant decrease when pH is higher than 9. The removal effect of ammoniacal nitrogen and Cl- increase with the increase of the voltage, but the pH decreases and the energy consumption per ton water increases. The appropriate voltage is about 1.5V. When wastewater flow increases, the linearity of the removal rate of chloride ion and energy consumption per ton water declines. At the same time, the removal rate of ammoniacal nitrogen has a more significant decline. When there is only one kind of anion in the water, the absorption amount of anions is proportional to the concentration of influent water, and the proportion has nothing to do with the composition of cations. The absorption amounts of ammoniacal nitrogen and other major cations are also proportional to the concentration of influent water, but the proportions depend on operating conditions such as voltage, influent wastewater flow, etc.Pilot testing and demonstration project shows that electrosorption technology using for advanced treatment of urban wastewater achieves good effects with an average salinity removal rate of 69% and an average water production rate of 79%. What's more, it is feasible from technical and economic aspects, with an unit electricity consumption of 1.1 kWh/m3 and Unit operating cost of 1.68 yuan / m3. In a word, electrosorption technology is of great value and worthy to be promoted.