Phosphorus Recovery From Sewage By Byproduct Of The Extraction Of Potassium Through Seeded Crystallization

Phosphorus is a necessary element of the human body and plant growth,which is used in a large number of industrial applications.Phosphorus is also the main element for eutrophication.There is serious phosphorus pollution of water bodies all over the world.Phosphorus is also considered to be a kind of non-renewable resources.It will be depleted in the coming decades.The recycling of phosphorus pollution in water not only can solve the problem of pollution,but also solve the problem of lack of phosphorus resources.Tobermorite and calcium silicate slag without heavy metals are byproducts produced by the process of extracting potassium,which can provide hydroxide and calcium ions.The experimental results show that tobermorite can be used as seed to recycle phosphorus from the actual sewage.The optimized experimental conditions are the seeds concentration of 3g/L,the pH value of about 8,the reaction time of 4h,the shaking speed of 120r/min and the temperature of 303K.There are still good results for synthetic tobermorite recovery phosphorus in the actual sewage repeatedly.The process follows second-order reaction kinetics.New seed is needed because of the remaining phosphorus concentration in creasedat thelOth times.The remaining phosphorus concentration is below the primary standard in national "emission standards of urban sewage treatment plant" by adding seed several times.The effect of recovery phosphorus by calcium silicate slag in the simulated wastewater is very good.The optimized experimental conditions are the seeds concentration of 1.2g/L and the reaction time of 4h.It is still able to achieve better recovery results in the non-calcium and low pH,but pH is high in the effluent.The characterization results show that the recycled product is crystalline with the low degree of crystallinity.In scale-up experiment,it also gets good recovery results.P2O5 content of recovery products in the eighteenth recovery reach more than 33%,which is up to the standards of rich phosphate mineral.Calcium silicate slag can also accomplish recycling phosphorus effectively from the actual sewage.The optimized experimental conditions is the seeds concentration of 2g/L,the pH value of about 5,the reaction time of 4h,the shaking speed of 140r/min and the temperature of 308K.The phosphorus effluent content of the recycling is below is below the primary standard in national "emission standards of urban sewage treatment plant".The effect of eighteenth recycling phosphorus is revy good.All of the recovery rates are above 50%.The process also follows second-order reaction kinetics.Phosphate impacts the recycling effect of the calcium silicate slag.The more phosphate exists in the actual sewage,the worse of the recycling.Recovery performance is improved significantly without phosphate in the actual sewage.In five repeat times,the phosphorus recovery rates are all more than 94%.The results show that the calcium silicate slag may be an ideal seed for phosphorus recovery from the actual sewage.