[Influencing Factors for Phosphorus Removal by Modified Bio-ceramic Substrates Coated with ZnAl-LDHs Synthesized by Different Modification Conditions].

Under different pH conditions, the hydrothermal and co-precipitation method was used to synthesize layered double hydroxides (LDHs) coated on bio-ceramic substrates with three different Zn/Al molar ratios. Applying the original and six kinds of modified bio-ceramic substrates coated with ZnAl-LDHs (bio-ceramic/ZnAl-LDHs) in simulated vertical-flow constructed wetlands, experiments for phosphorus removal and isothermal adsorption were conducted to analyze the mechanism and effect of each synthesis factor. The results showed that ZnAl-LDHs (pH=11) had a more obvious effect on phosphorus removal, especially for bio-ceramic/ZnAl-LDHs (pH=11, 1:1), whose average removal rates of TP, TDP and SRP were enhanced over 70%. Its maximum adsorption capacity for phosphorus was three times higher than that of the original bio-ceramic. Both pH and Zn/Al molar ratio affected the configuration and coating properties of bio-ceramic/ZnAl-LDHs at the time of synthesis, and pH was the main synthesis factor for phosphorus removal efficiency of bio-ceramic/ZnAl-LDHs. Through reasonable regulation of pH and Zn/Al molar ratio when bio-ceramic/ZnAl-LDHs was synthesized, the phosphorus removal efficiency could be improved effectively.