Use of zeolitized coal fly ash in the simultaneous removal of ammonium and phosphate from aqueous solution  

作　　者：WU Deyi HU Zhanbo WANG Xinze HE Shengbing KONG Hainan 

机构地区：[1]School of Environmental Science and Engineering,Shanghai JiaoTong University,Shanghai 200240,China

出　　处：《Frontiers of Environmental Science & Engineering》2007年第2期213-220,共8页环境科学与工程前沿（英文）

基　　金：This work was supported by the National High-Tech Research and Development(863)Program of China(Grant No.2002AA601013);the Key Technologies Research and Development Program of Shanghai(Grant No.04DZ12030-2).

摘　　要：Discharge of wastewater containing nitrogen and phosphate can cause eutrophication.Therefore,the development of an efficient material for the immobilization of the nutrients is important.In this study,a low calcium fly ash and high calcium fly ash were converted into zeolite using the hydrothermal method.The removal of ammonium and phosphate that coexist in aqueous solution by the synthesized zeolites were studied.The results showed that zeolitized fly ash could efficiently eliminate ammonium and phosphate at the same time.Saturation of zeolite with Ca^(2+)rather than Na+favored the removal of both ammonium and phosphate because the cation exchange reaction by the NH_(4)^(+)resulted in the release of Ca2+into the solution and precipitation of Ca^(2+)with PO_(4)^(3−)followed.An increase in the temperature elevated the immobilization of phosphate whereas it abated the removal of ammonium.Nearly 60%removal efficiency for ammonium was achieved in the neutral pH range from 5.5 to 10.5,while the increase or decrease in pH out of the neutral range lowered the adsorption.In contrast,the removal of phosphate approached 100%at a pH lower than 5.0 or higher than 9.0,and less phosphate was immobilized at neutral pH.However,there was still a narrow pH range from 9.0 to 10.5 favoring the removal of both ammonium and phosphate.It was concluded that the removal of ammonium was caused by cation exchange;the contribution of NH3 volatilization to immobilization at alkaline conditions(up to pH level of 11.4)was limited.With respect to phosphate immobilization,the mechanism was mainly the formation of precipitate as Ca_(3)(PO_(4))_(2) within the basic pH range or as FePO_(4) and AlPO_(4) within acidic pH range.

关 键 词：fly ash ZEOLITE AMMONIUM PHOSPHATE REMOVAL 

分 类 号：X70[环境科学与工程—环境工程]