Inhibitory Effect Of Veterinary Antibiotics On Anaerobic Digestion Of Pig Manure

Anaerobic digestion technology is widely used in the treatment of livestock manure and wastewater.With the rapid development of livestock and poultry breeding,antibiotics play an important role in the prevention and treatment of animal diseases,improving feed utilization,and promoting the growth of livestock and poultry.With the extensive use of antibiotics,problems such as bacterial resistance and drug residues have become increasingly prominent.Antibiotics remaining in livestock manure can inhibit the anaerobic digestive flora and affect the anaerobic digestion process.Proven the inhibitory effect of veterinary antibiotics on anaerobic digestion of pig manure,this study selected representative tetracycline antibiotics(tetracycline,chlortetracycline)and sulfa antibiotics(sulfadiazine,sulfamethoxazole) for anaerobic digestion of pig manure,and systematically explored the individual inhibition,using the methanogenesis kinetic model to fit the anaerobic digestion unit mass VS cumulative methanogenesis,and the antibiotic combined inhibition test and anaerobic microbial activity recovery test,etc.The main results are as follows:(1)Study on the individual inhibitory effect of four antibiotics during the process of anaerobic digestion to produce methane.The inhibition rate of cumulative methanogenesis by four antibiotics increased with the increase of concentration,the inhibition rate of TC on cumulative methanogenesis was 14.27%~56.67%;the inhibition rate of CTC on cumulative methanogenesis was 17.39%~62.65%;the inhibition rate of SD on cumulative methanogenesis was 8.26%~56.54%;the inhibition rate of SMZ on cumulative methanogenesis was 10.51%~66.12%.The changes of VFA in the process of anaerobic digestion with the four antibiotics indicated that TC,CTC,SD and SMZ have inhibitory effects on the hydrolysis fermentation and hydrogenproduction phase.(2)Using the methanogenesis kinetics model to fit the anaerobic digestion unit mass VS cumulative methanogenesis,all correlation coefficients R2 are above 0.95,indicating that the kinetic model was feasible to predict the unit mass VS cumulative methanogenesis.By comparing the methanogenic kinetic model to predict the theoretical value of the final cumulative methanogenesis Mmax in the case of adding antibiotics,it is concluded that the inhibitory effect of CTC on the cumulative methanogenesis of anaerobic digestion is stronger than that of TC,and the inhibitory effect of SMZ on anaerobic digestion.Stronger than SD.(3)Study on the joint inhibitory effects of four antibiotics.The antibiotic digestion test showed that the different levels of four antibiotics had an inhibitory effect on the cumulative methanogenesis,and the inhibition rate was 7.56%~63.73%.The results of combined inhibition test were very poor and analysis of variance.The results showed that the effects of four antibiotics on cumulative gas production of anaerobic digestion were CTC>TC>SMZ>SD,and chlortetracycline had significant effect on anaerobic digestion inhibition.According to the range and variance analysis of the joint inhibition test,the effects of four antibiotics on the cumulative gas production of anaerobic digestion were CTC>TC>SMZ>SD,and the effect of chlortetracycline on anaerobic digestion was significant.The first-order interaction analysis showed that the combined inhibitory effect of four antibiotics was antagonistic.(4)Study on the effects of chlortetracycline during the recovery process of anaerobic microbial activity.The microbial activity recovery test showed that CTC was a lethal inhibition,and the inhibition of sludge activity was irreversible.When chlortetracycline was more than 30 mg·kg-1,the lethal amount of methanogens in the anaerobic system was more than half,and it was difficult to restore activity.