Reuse of the spent sorbent mixture for wastewater treatment

Abstract

Much of the sorbent used in the food industry is not re-used because it is difficult to regenerate and expensive. Also, the reuse of used sorbents involves their biological cleaning, which is due to the specificity of adsorbed materials. As a result, they are often stored off-site or disposed of in landfills, usually without authorization. It is more promising to use such sorbents in waste water treatment, especially in the same food industry and in other industries where wastewater contains bioorganic substances. Studies have been made on the reuse of a used sorbent mixture, consisting of activated carbon and kieselguhr, for the treatment of wastewater from food processing plants. It has been determined the efficiency of the regeneration of the used sorbents, when it is successively cleaned from organic impurities after purification of technological solutions by its successive treatment with an alkali solution and then with a solution of hydrochloric acid, with the recovery of the sorption capacity of such a sorbent to 97–100%. The activity of the regenerated mixed sorbent with respect to the main components of the wastewater from dairy has been studied. The research results show that the mixture of sorbents has a higher sorption capacity regarding to lactic acid with a higher cleaning efficiency; however, when removing the protein pollutant, it is possible to pump more effluent before the first traces of the pollutant appear. It is shown that the sorption of components - pollutants of the milk processing industry by affordable sorbents, which include regenerated ones, is among the most promising due to their high efficiency, low cost of cleaning, and the possibility of further use of used sorbents in agriculture.