74 / 2021-06-30 15:50:01

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

Dewatered swine manure-derived biochar,Anaerobic digestion,Swine wastewater,ARG attenuation,Sustainable swine manure management

This work explored the feasibility using dewatered swine manure derived biochar (DSMB) as an additive to facilitate anaerobic digestion (AD) of swine wastewater, with particular focus on energy recovery and antibiotic resistance genes (ARG) attenuation enhancements simultaneously. With 20g/L DSMB assisted, the methanogenic lag time of swine wastewater were shortened by 17.4-21.1%, and the maximum CH₄ production rate increased from 40.8 mL/d to 48.3-50.5 mL/d, among which DSMB prepared under 300℃ (DSMB-300) showed better than the ones prepared at 500℃ and 700℃. Integrated analysis of DSMB electrochemical properties, microbial electron transfer system activity, and microbial community succession uncovered that DSMB-300 potentially acted as the redox-active electron transfer mediator between syntrophic microbes to accelerate the methanogenesis of VFA by potential direct interspecies electron transfer. Besides that, the resistant genes attenuation benefits of DSMB preparation and DSMB-assisted AD were evaluated. DSMB preparation by pyrolysis greatly reduced ARG concentration in DSM by almost 4 logs. Meanwhile, adding DSMB into AD not only strengthened the attenuation efficiency of ARG in original swine wastewater, but also controlled the potential risk of horizontal gene transfer effectively by mitigate 74.8% mobile gene elements abundance. Accordingly, we proposed a win-win scenario for bio-waste management in swine farms, which highlighting more advanced energy recovery and ARG attenuation strategies than the current status.