Characterization of biochar derived from water hyacinth, rice straw and sewage sludge and their environmental implications
The conversion of organic residues to biochar through pyrolysis has proved to be an effective way in improving the environmental quality of soil and water while reducing the release of greenhouse gas.However,the application of biochar in the environment may simultaneously pose a range of eco-toxicological risks.Therefore,it is essential to analyze and evaluate the key chemical properties of biochars before their application in field.In this study,water hyacinth (Eichhornia crassipes),the most aggressively invasive species,rice straw,the most prominent crop residue in China,and municipal sewage sludge have been chosen as three typical feedstocks and slowly pyrolyzed at 250,350,450 and 550 ℃.The resultant biochars were characterized for surface morphology,element composition,mineral constituent,and a set of chemical properties pertinent to their potential use in soil improvement,remediation of heavy metal contamination and eutrophication control.According to the results,water hyacinth biochar (WBC) contained the highest amount of water-soluble K,Ca,Na and Mg but lowest P in water extraction,indicating its potential in mitigating soil acidification with minimized risk of eutrophication.Rice straw biochar (RBC) exhibited the most prominent CEC (33.7 cmol· kg-1) among tested samples,which was useful to enhance minerals retention in soils while decreasing heavy metal bioavailability.As shown by SEM-EDX,bundled tube structure was developed in W-BC and R-BC,which could be used with priority to improve soil aeration.However,water-soluble Cd and As in some biochar samples exceeded the safety threshold,highlighting the necessity of pre-screening of both feedstocks and biochar products for their safe application in environment and agriculture.
invasive plantbiocharenvironmental chemical propertiesmineral crystalsenvironmental risks
NETL
NSTL
万方数据
维普
