Degradation And Removal Characteristics Of Sulfonamides During Swine Manure Anaerobic Digestion

In order to elucidate the sulfonamides(SAs)degradation,adsorption and distribution properties during swine manure mesophilic anaerobic digestion,different swine manure to rice straw ratios on the removal of SAs,and the distribution rate of liquid digestates and solid digestates in CSTR(completed stirred tank reactor)were investigated.Degradation and adsorption chatateristics,and SAs ARGs relative abundance and biotoxity after anaerobic fermentation were researched in the paper.The influence on the removal of SAs in liquid digestates stewing process during different seasons and the removal rates of SAs by hydrothermal biochar explored.The main results were shown as follows:(1)It shows good removal efficiency of SDZ,SMZ and SCP during anaerobic digestion with swine manure or straw as main material,the longer HRT(hydraulic retention time),codigestion of manure and straw have positive effect on the removal of SAs.The removal rate of SDZ and SMZ reach 95%and 90%when HRT was 20 d and 15 d,However,in comparion with SDZ and SMZ,SCP was more recalcitrant,the reamoval was only 90.3%and 72.8%at HRT was 20 d and 15 d.(2)Treatment(T5 and T6)with 20 mg·L-1 SAs has 7 d lag behind normal fermentation treatment(T7),but the addition of SAs didn't reduce accumulative biogas productivity and methane proportion.The adsorption of SAs was rapidly,and adsorption contents was 24.05 and 27.58 ?g·g-1 at equilibrium.Removal efficiency of SDZ and SMZ was 41.8%and 63.4%.Meanwhile,we found biodegradation was main route for SAs elimination,which has the proportion about 83.3%and 85.5%.The degradation charateristics follows the first order kinetics,degradation half-time was 32.91 and 17.83 d for SDZ and SMZ,co-digestion of SAs and SCOD was found in the experiment.(3)After 25 d anaerobic digestion no significant difference was observed in solid digestates of each treatment for SAs ARGs sull and sul2,which shows less ARGs selective pressure under this concentration of SAs.In a word,sull and sul2 relative abundance was higher in solid digestates than in liquid digestates,which shows sul3 selective mechanism was different to sull and sul2.(4)Through 90 d natural storage in summer and winter two seasons,SAs removal efficiency(75%?95%)was significantly higher(45%-60%).Six different kinds of hydrothermal biochar was applied to adsorb two different concentration of SAs in wastewater.We found the adsorption contents is 4.2-4.8 ?g·g-1 and 1.1?3.1 mg·g-1.250-R hydrothermal biochar has the highest removal rates,and reach 99.0%and 65.1%at 5 ?g·L-1 and 5 mg·L-1 of SAs.