Removal of ammonia as struvite from anaerobic digester effluents and recycling of magnesium and phosphate.
A second order kinetic model was developed to predict the rate and extent of NH(4)(+) removal as struvite from anaerobic digester effluents. Alternative to this, NH(4)(+) can be recovered from struvite and the remaining Mg(2+) and PO(4)(3-) can be recycled back to the wastewater to fix more NH(4)(+). The NH(4)(+) solution was retained and the remaining Mg(2+) and PO(4)(3-) were returned back to be mixed with wastewater. In a five-step process, NH(4)(+) recovery was initially 92% and progressively decreased to 77% in the fifth stage, due to loss of Mg(2+) and PO(4)(3-) at each step in the supernatant. Finally, economic analysis of recycling nutrients was performed and compared to the one step process. The cost of NH(4)(+) recovery was calculated as $0.36/kgNH(4)-N which is lower than $7.7/kgNH(4)-N the cost of one step process without considering the market value of struvite obtained in one step process.
Türker
Mustafa
M
Pak-Food Industries, P.O. Box 149, 41001 Izmit, Kocaeli, Turkey.
Celen
Ipek
I
D000693:Anaerobiosis; D007700:Kinetics; D017616:Magnesium Compounds / Q000032:analysis*; D008956:Models, Chemical; D010710:Phosphates / Q000032:analysis*; D000644:Quaternary Ammonium Compounds / Q000032:analysis*; D000069877:Struvite; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
D017616:Magnesium Compounds; D010710:Phosphates; D000644:Quaternary Ammonium Compounds; D014874:Water Pollutants, Chemical; D000069877:Struvite