Study On The Preparation Of The Slow Releasing Carrier Of Trace Elements And Its Performance

Affected by the production and raw materials, the chemical composition of the industrial waste water is often a single, in which trace elements are often lacked. The existence of trace metals and trace metals bio-effective would solve most of the problem in the biological treatment. However, due to trace elements of biological effectiveness is very low, which determines the dosage of trace elements is a slow and long-term process. Therefore the development of a slow release of trace elements carrier will solve these problems, and there is a very good market prospects and research value.The static adsorption kinetics and thermodynamics of Ni2+, Co2+, Fe2+ ion adsorption onto D113 resin, bentonite, etc. have been reviewed. The speed-control steps of adsorption and thermodynamic parameters have been computed. The study of speed-control steps shows that, the speed-control steps of Ni2+, Co2+, Fe2+ ion adsorption onto D113 resin, Co2+ ion adsorption onto D001 resin are pore diffusion and Fe2+ ion adsorption onto D201 resin is controlled by interface diffusion and pore diffusion. Thermodynamic studies indicate that, Ni2+, Co2+ and Fe2+ adsorption on the resins or bentonite Gibbs free energyΔGθ<0 which indicate the spontaneous nature of the process; adsorption entropyΔSθ>0; Ni2+, Co2+ ion adsorption onto D113, Ni2+ ion adsorption on the bentonite and Co2+ ion adsorption onto D001 resin enthalpyΔHθ>0, indicate endothermic reaction, Fe2+ ion adsorption onto D113 and D201 resin adsorption enthalpyΔHθ<0, show that radiative reaction.The behavior of bentonite, D113 and other macroporous resin release Ni2+, Co2+, Fe2+ ion have been studied by cumulative release experimental. The results show that, D113, D001 and D201 macroporous resin release Ni2+, Co2+ and Fe2+ ion could be descripted by the Weibull equation. The performance of show-release have been studied by change and constantly experiments.Epoxy resin, polyamide resin, starch were used to coat D113 resin which adsorbed the trace elements. We mixed epoxy resin, polyamide resin, starch and D113 resin in best rate of 2:1:2:3 and shaped a columniform slow-release carrier with 1cm high and 0.5cm diameter. The half life of release t50 prolong 4 times than without the coating. The trace elements can promote the growth of aerobic activated sludge without pollution on water quality, and CODCr removal rate are higher.