Changes in the toxicological characteristics of biochars from chicken manure dependent on their chemical modification

Abstract

© 2019 Kazan Federal University. All Rights Reserved. Data on changes in the chemical composition and toxicological characteristics of the biochars modified by nitrogen doping with urea ((NH2)2CO), potassium, and phosphorus using potassium dihy-droorthophosphate (KH2PO4) have been presented. Four variants of doping, differentiated by the sequence of treatment with agents and the multiplicity of pyrolysis processes, have been analyzed. The toxicity has been determined using the protozoa Paramecium caudatum, planktonic crustacean Daphnia magna, and higher plants Hordeum vulgare. The results obtained have been processed by the method of principal components. It has been established that both pyrolysis and chemical modification lead to a significant change in the content of organogenic elements and toxicity. Using the method of principal components, we have identified a variant of the biochar modification, which allows to produce biochar with a high content of organogenic elements and a low increase of toxicity. This variant implies pyrolysis of the raw substrate for 2 h, treatment with regents in dry or dissolved forms, and repeated pyrolysis for 2 h.