When dewatered swine manure-derived biochar meets swine wastewater in anaerobic digestion: A win-win scenario towards highly efficient energy recovery and antibiotic resistance genes attenuation for swine manure management

This work explored the feasibility of dewatered swine manure-derived biochar (DSMB) as an additive to facilitate anaerobic digestion (AD) of swine wastewater for energy recovery and antibiotic resistance genes (ARG) attenuation enhancements. With 20 g/L DSMB assistance, the methanogenic lag time of swine wastewater was shortened by 17.4-21.1%, and the maximum CH4 production rate increased from 40.8 mL/d to 48.3-50.5 mUd, among which DSMB prepared under 300 degrees C exhibited a better performance than that prepared under 500 degrees C and 700 T. Integrated analysis of DSMB electrochemical properties, microbial electron transfer system activity, and microbial community succession revealed the potential of DSMB-300 to act as redox-active electron transfer mediators between syntrophic microbes to accelerate syntrophic melba nogenesis via potential direct interspecies electron transfer. Meanwhile, DSMB preparation by pyrolysis dramatically reduced ARG abundance by almost 4 logs. Adding DSMB into AD not only strengthened the attenuation efficiency of ARG in the original swine wastewater, but also effectively controlled the potential risk of horizontal gene transfer by mitigating 74.8% of the mobile gene elements abundance. Accordingly, we proposed a win-win scenario for bio-waste management in swine farms, highlighting the more advanced energy recovery and ARG attenuation compared to the current status. (C) 2021 Published by Elsevier B.V.

Automated summary

This study demonstrated the feasibility of using dewatered swine manure-derived biochar (DSMB) as an additive to enhance anaerobic digestion of swine wastewater for energy recovery and antibiotic resistance gene degradation. DSMB was found to accelerate methane production, reduce antibiotic resistance genes, and mitigate the risk of horizontal gene transfer, presenting a win-win solution for bio-waste management in swine farms.