title: Optimization of struvite crystallization protocol for pretreating the swine wastewater and its impact on subsequent anaerobic biodegradation of pollutants.
abstract: Higher contents of NH(4)(+) and SS in wastewater hamper the anaerobic digestion; necessitating its pretreatment to reduce them. This study reveals optimization of struvite/MAP precipitation protocol followed by anaerobic digestion of pretreated swine wastewater for pollutants removal. Levels of different treatments: stirring speeds, 400 and 160 rpm; pH values, 9.0, 9.5, 10.0, 10.5, 11.0 and 11.5; and P:Mg:N ratios, 1:1:1.2, 1:1:1.7, 1:1:2.2, 1:1:2.7, 1:1:4.0 and 1:1:5.0 were evaluated for MAP crystallization. Among various combinations, protocol comprising of initial 10 min stirring at 400 rpm followed by 160 rpm for 30 min, pH 10.0, and P:Mg:N ratio 1:1:1.2 rendered the best removal efficiency for NH(4)(+), PO(4)(3-), COD, TC and TOC. Subsequent anaerobic biodegradation revealed superiority of MAP supernatant over raw swine wastewater for methane yield and NH(4)(+)-N, PO(4)(3-)-P, COD, TC and TOC removals. It suggests that struvite precipitation as pretreatment to anaerobic digestion is highly effective and advantageous in wastewater treatment.
authors.affiliation: Ministry of Agriculture Key Laboratory of Non-point Source Pollution Control, Institute of Environmental Science and Technology, Zhejiang University, Hangzhou 310058, PR China.
authors.forename: Dong-mei
authors.initials: DM
authors.lastname: Zhang
authors.forename: Ying-xu
authors.initials: YX
authors.lastname: Chen
authors.forename: Ghulam
authors.initials: G
authors.lastname: Jilani
authors.forename: Wei-xiang
authors.initials: WX
authors.lastname: Wu
authors.forename: Wen-li
authors.initials: WL
authors.lastname: Liu
authors.forename: Zhi-ying
authors.initials: ZY
authors.lastname: Han
mesh_terms: D000641:Ammonia / Q000032:analysis; D000693:Anaerobiosis; D000818:Animals; D001673:Biodegradation, Environmental; D056804:Biofuels / Q000032:analysis; D057919:Biological Oxygen Demand Analysis; D002244:Carbon / Q000302:isolation & purification; D011232:Chemical Precipitation; D003460:Crystallization; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000032:analysis; D017616:Magnesium Compounds / Q000737:chemistry*; D008697:Methane / Q000032:analysis; D009584:Nitrogen / Q000302:isolation & purification; D009930:Organic Chemicals / Q000302:isolation & purification; D010710:Phosphates / Q000032:analysis / Q000737:chemistry*; D010758:Phosphorus / Q000032:analysis; D000644:Quaternary Ammonium Compounds / Q000302:isolation & purification; D012995:Solubility; D000069877:Struvite; D034421:Sus scrofa; D014835:Volatilization; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
chemical_list: D056804:Biofuels; D017616:Magnesium Compounds; D009930:Organic Chemicals; D010710:Phosphates; D000644:Quaternary Ammonium Compounds; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D002244:Carbon; D000641:Ammonia; D000069877:Struvite; D008274:Magnesium; D009584:Nitrogen; D008697:Methane