Migration of phosphorus in pig manure during pyrolysis process and slow-release mechanism of biochar in hydroponic application

• Published in: The Science of the total environment Vol. 915; p. 170116
• Main Authors: Jiang, Ru-Qing, Yu, Guang-Wei, Yu, Lin-Hui, Wang, Yu, Li, Chang-Jiang, Xing, Zhen-Jiao, Xue, Xi-Mei, Wang, Yin, Yu, Cheng
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10.03.2024
• Subjects: Animals; Biochar; Charcoal - chemistry; Hydroponic; Hydroponics; Manure; Phosphorus - chemistry; Phosphorus transformation; Pig manure; Pyrolysis; Swine; Pig manure; Pyrolysis; Biochar; Hydroponic; Phosphorus transformation
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2024.170116

Pyrolysis is an effective method for treating of livestock and poultry manure developed in recent years. It can completely decompose pathogens and antibiotics, stabilize heavy metals, and enrich phosphorus (P) in biochar. To elucidate the P migration mechanism under different pig manure pyrolysis temperatures, sequential fractionation, solution 31P nuclear magnetic resonance, X-ray photoelectron spectroscopy, X-ray diffraction, and K-edge X-ray absorption near-edge structure techniques were used to analyze the P species in pig manure biochar (PMB). The results indicated that most of the organic P in the pig manure was converted to inorganic P during pyrolysis. Moreover, the transformation to different P groups pathways was clarified. The phase transition from amorphous to crystalline calcium phosphate was promoted when the temperature was above 600 °C. The content of P extracted by hydrochloric acid, which was the long-term available P for plant uptake, increased significantly. PMB pyrolyzed at 600 °C can be used as a highly effective substitute for P source. It provides the necessary P species (e.g. water-soluble P.) and metal elements for the growth of water spinach plants, and which are slow-release comparing with the Hogland nutrient solution. [Display omitted] •Preparation of pig manure biochar via pyrolysis is an important way to quickly recover P.•As pyrolysis temperature increased, abundance of calcium phosphate and long-term available P for plants increased.•Pyrolysis at 600 ℃ reduces P loss by converting biochar into stable, slow-release nutrient source.•P and other elements leached from 600°C biochar can be absorbed by plants in hydroponics, supporting water spinach growth.