title: Struvite Precipitation as a Means of Recovering Nutrients and Mitigating Ammonia Toxicity in a Two-Stage Anaerobic Digester Treating Protein-Rich Feedstocks.
abstract: Accumulation of ammonia, measured as total ammonia nitrogen (TAN), a product of protein decomposition in slaughterhouse wastes, inhibits the anaerobic digestion process, reducing digester productivity and leading to failure. Struvite precipitation (SP) is an effective means to remove TAN and enhance the buffering of substrates. Different Mg and P sources were evaluated as reactants in SP in acidogenic digester effluents to reduce its TAN levels. In order to measure impact of TAN removal, a standard biochemical methane potential (BMP) test was conducted to measure methane yield from treatments that had the highest TAN reductions. SP results showed 6 of 9 reagent combinations resulted in greater than 70% TAN removal. The BMP results indicated that SP treatment by adding Mg(OH)₂ and H₃PO₄ resulted in 57.6% nitrogen recovery and 41.7% increase in methane yield relative to the substrate without SP. SP is an effective technology to improve nutrient recovery and methane production from the anaerobic digestion of protein-rich feedstocks.
authors.affiliation: College of Engineering, University of Georgia, Athens, GA 30602, USA. wshl2000@uga.edu.
authors.forename: Shunli
authors.initials: S
authors.lastname: Wang
authors.affiliation: College of Agricultural and Environmental Sciences, University of Georgia, Athens, GA 30602, USA. ghawkins@uga.edu.
authors.forename: Gary L
authors.initials: GL
authors.lastname: Hawkins
authors.affiliation: College of Agricultural and Environmental Sciences, University of Georgia, Athens, GA 30602, USA. bkiepper@uga.edu.
authors.forename: Brian H
authors.initials: BH
authors.lastname: Kiepper
authors.affiliation: College of Engineering, University of Georgia, Athens, GA 30602, USA. kdas@engr.uga.edu.
authors.forename: Keshav C
authors.initials: KC
authors.lastname: Das
mesh_terms: D000003:Abattoirs; D000641:Ammonia / Q000032:analysis*; D000693:Anaerobiosis; D011232:Chemical Precipitation; D017616:Magnesium Compounds / Q000737:chemistry; D017553:Phosphorus Compounds / Q000737:chemistry; D062611:Solid Waste / Q000032:analysis*; D000069877:Struvite / Q000737:chemistry*
chemical_list: D017616:Magnesium Compounds; D017553:Phosphorus Compounds; D062611:Solid Waste; D000641:Ammonia; D000069877:Struvite
keywords: ammonia; anaerobic digestion; precipitation; protein-rich wastes; struvite