Study On Phosphorus Recovery From Sewage Sludge

With the rapid development of national economy,the issue of phosphorus recovery has been widely concerned.Phosphorus is the essential element of human existence,which is a state of one-way cycle in the nature.Because of the excessive use of phosphorus,the natural phosphorus resources are declining and difficult to regenerate.However,a number of phosphorus are present in the sewage,through the discharge of sewage formation of eutrophication.If people choose the technology of recovering phosphorus from sewage properly,it can not only reduce the water pollution,but also make up the problem of phosphorus shortage in nature,and has the important significance in real life.The main research of this paper is to recover phosphorus from sewage sludge by adsorption.First of all,the research object of this experiment is corn straw,which is modified carbonization,and finally the adsorbent with good performance,by studying the efficiency of the removal of phosphate group in solution,the optimal conditions of the carbonized corn straw adsorbent is obtained.Using different chemical modifier to modify corn straw,it was found that the removal effect of phosphate group was the best by using zinc chloride as modifier to modify corn straw.Using chlorination corn straw modifier,the modified carbonized corn straw adsorbent was prepared,the effects of the concentration of modifier,impregnation ratio,activation time and activation temperature on the adsorption efficiency and yield of adsorbents were analyzed.The experimental results show that the removal rate of phosphate group in solution reached 99.52% and the yield is 21.75 %,when the concentration of the modifier is 50 g / L,impregnation ratio is 2: 1,activation time 2h,activation temperature 400 ?.Secondly,the best modified carbonized corn straw adsorbent is used to adsorb phosphate group in solution.the effect of the adsorbent dosage,p H value,reaction time and initial concentration of phosphate group on the removal of phosphorus in solution were studied by equilibrium adsorption.The experimental data show that when the concentration of phosphorus in the solution is 50 mg / L and the dosage of adsorbent is 0.2 g,the removal rate of phosphate group reached the best,which can reach 99.52%,and the adsorption process is rapid,the reaction is 20 min,the adsorption process has been basically completed.The p H value of solution has great effect on the removal of phosphate group,when the p H is 2,the removal rate of phosphate group is 42.89 %;When the p H of the solution is 8,the removal rate of phosphate group was 99.52%.When the p H value of solution exceeds 8,the removal rate of phosphate group shows a slow downward trend,so the p H of solution is adjusted to weak alkalinity,which is conducive to the adsorbent for phosphorus recovery.At the same time,different concentration of chaff was added into solution,the effect of chaff on the adsorption of phosphate group in solution of modified carbonized corn straw adsorbent was analyzed.The experimental results show that when the solution contains different concentration of COD and NH4+,the effect of the absorbent recovery solution is very small.Finally,the adsorption process of phosphorus in solution by different temperature the modified was described in detail by Langmuir and Freundlich isotherms,the results showed that the reaction temperature had little effect on the adsorbent capacity.Through the adsorption kinetic model,the process of phosphorus removal by modified carbonized corn straw adsorbent is closer to the pseudo second kinetic model.In conclusion,the problem of the shortage of phosphorus resources andlarge amounts of phosphorus in sewage should be paid more attention.The technology of recovering phosphorus from sewage sludge is being perfected as people study.In this paper,the use of corn straw to prepare adsorbent not only realizes waste utilization,protection environment,but also has high efficiency adsorbent.Therefore,the content of this paper provides a reference for the related technology of phosphorus recovery in sewage sludge,and is important to solve the problem of shortage of phosphorus resources.