title: Properties of plant nutrient: Comparison of two nutrient recovery techniques using liquid fraction of digestate from anaerobic digester treating pig manure.
abstract: Anaerobic digestate has valuable potential as organic fertilizer or soil amendment, given that it typically contains high amounts of plant nutrients, such as nitrogen, phosphate and plant hormones. In this study, ammonia stripping and vacuum evaporation were tested to compare their technical feasibilities and their effects on plant nutrient properties in the liquid fraction of digestate. Results of the batch experiments showed that the nutrient characteristics of liquid digestate, including total ammonia nitrogen (TAN), soluble P, gibberellic acid (GA), indoleacetic acid (IAA) and abscisic acid (ABA), were strongly dependent on the initial pH in both ammonia stripping and vacuum evaporation processes. A low plant nutrient concentration (TAN 137 mg · L(-1), soluble P 1.5 mg · L(-1), GA3/ABA 0.04) in the liquid digestate was achieved in the ammonia stripping process with Ca(OH)2 addition of 12 g · L(-1), whereas a high nutrient concentration (TAN 2998 mg · L(-1), soluble P 178.3 mg · L(-1), IAA 60.9 mg · L(-1) and GA3/ABA 0.4) was achieved in vacuum evaporation at a pH level of 6. According to the results, both ammonia stripping and vacuum evaporation can be used as an alternative of nutrient recovery techniques, which should be chosen based on the potential different applications of liquid digestate (e.g., soaking seed, increasing plant tolerance, and nutrients transportation).
authors.affiliation: College of Engineering, China Agricultural University (Key Laboratory for Clean Renewable Energy Utilization Technology, Ministry of Agriculture), Beijing 100083, People's Republic of China.
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.affiliation: College of Engineering, China Agricultural University (Key Laboratory for Clean Renewable Energy Utilization Technology, Ministry of Agriculture), Beijing 100083, People's Republic of China. Electronic address: jianbinguo@cau.edu.cn.
authors.forename: Jianbin
authors.initials: J
authors.lastname: Guo
authors.affiliation: College of Engineering, China Agricultural University (Key Laboratory for Clean Renewable Energy Utilization Technology, Ministry of Agriculture), Beijing 100083, People's Republic of China.
authors.forename: Renjie
authors.initials: R
authors.lastname: Dong
authors.affiliation: Bioproduct Sciences and Engineering Laboratory, BSEL, Washington State University, 2710 Crimson Way, Richland, WA, USA.
authors.forename: Birgitte K
authors.initials: BK
authors.lastname: Ahring
authors.affiliation: College of Engineering, China Agricultural University (Key Laboratory for Clean Renewable Energy Utilization Technology, Ministry of Agriculture), Beijing 100083, People's Republic of China.
authors.forename: Wanqin
authors.initials: W
authors.lastname: Zhang
mesh_terms: D000693:Anaerobiosis; D000818:Animals; D019149:Bioreactors / Q000382:microbiology*; D008372:Manure; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D013552:Swine; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D008372:Manure; D010758:Phosphorus; D009584:Nitrogen
keywords: Ammonia stripping; Nitrogen; Phosphorus; Plant hormones; Vacuum evaporation