Preparation of Acid-Base Composite Modified A1-Fe Flocculants:Phosphorus Removal Performance
ZHANG Chengchen
LI Bolin
YAO Ya
WANG Jun
LIANG Yanan
FAN Hangxu
LI Ye
Abstract：In order to solve the problem about overstandard TP emission in urban sewage,A1-Fe coagulants were improved.In the study,the coagulants were prepared by using monohydrallite (for Fe) and coal ash (from power plant) via constantpressured base leaching before acid leaching at high-temperature.The phosphorus removal performance of the as-prepared flocculant was discussed.Results indicated that the best preparation conditions using single factor control variables are optimized to 4 mol/L NaOH,100 ℃,and 4 h (in base modification),2 mol/L HCl(aq),100 ℃,and 4h (in acid modification),mixture rate of acid and alkali (VB/VA) as 1:16.The removal efficiency of TP in the sewage was 97.73％,and the effluent concentration of TP was 0.132 0 mg/L,which apparently meet the criteria of first level A class specified in GB 18918-2002.The results of characterization test show that coagulant is composed of A1Cl3· 6H2O,NaC1,KMgF3,Na3A1Hx,SrFeO2.5,and main effective component is Al2O3 (13.343％),Fe2O3 (5.497％) and SiO2 (17.920％).After coagulants were added into the water,iron ion and aluminum ion as well as its hydrolysate form unsaturated hydroxyl complexation ion such as Fe3(OH)27+,Aln(OH)m(3n-m)+,which obtain hydroxyl from the solution to complement its unsaturated,thus strong adsorption to the water condensed phosphate and colloid particles is generated.Meanwhile,rough surface,developed porosity,and high surface area also contribute to its high phosphorus removal rate.
Keywords：coal ashmonohydralliteacid modificationalkali modificationA1-Fe coagulants
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：5( 28-32 )