Phosphate adsorption from sewage sludge filtrate using zinc-aluminum layered double hydroxides.
A series of layered double hydroxides (LDHs) with different metal cations were synthesized to remove phosphate in waste sludge filtrate from a municipal wastewater treatment plant for phosphorus recovery and to help control eutrophication. The highest phosphate adsorption capacity was obtained by using Zn-Al-2-300, that is LDHs with Zn/Al molar ratio of 2 and calcined at 300 degrees C for 4h. Circumneutral and mildly alkaline waters appeared suitable for the possible application of Zn-Al LDHs due to the amphoteric nature of aluminum hydroxide. Phosphate adsorption from the sludge filtrate by the LDHs followed pseudo-second-order kinetics, and the adsorption capacity at equilibrium was determined to be approximately 50 mg P/g. Adsorption isotherms showed that phosphate uptake in this study was an endothermic process and had a good fit with a Langmuir-type model. The absorbed phosphate can be effectively desorbed (more than 80%) from LDHs particles by a 5 wt% NaOH solution. The regeneration rate of used LDHs was approximately 60% after six cycles of adsorption-desorption-regeneration.
Cheng
Xiang
X
School of Municipal & Environmental Engineering, Harbin Institute of Technology, 150090 Harbin, China.
Huang
Xinrui
X
Wang
Xingzu
X
Zhao
Bingqing
B
Chen
Aiyan
A
Sun
Dezhi
D
D000327:Adsorption; D000535:Aluminum; D005374:Filtration; D006878:Hydroxides; D010710:Phosphates / Q000302:isolation & purification*; D012037:Refuse Disposal / Q000379:methods*; D012722:Sewage / Q000737:chemistry*; D015032:Zinc
D006878:Hydroxides; D010710:Phosphates; D012722:Sewage; D000535:Aluminum; D015032:Zinc