The Study of the Influence of Tetracycline and Sulfadiazine on Biomethane Production from Manure and Apple Pomace

Chlortetracycline and sulfadiazine are commonly used in animal husbandry, which can be found in cow manure. Anaerobic digestion is the most popular technic for obtaining biomethane from substrates like cow manure and other organic materials. However, the presence of an antibiotic in the feedstock can adversely affect biomethane yields. In this paper, the influence of chlortetracycline and sulfadiazine affecting biomethane yield for 21 days lasting co-fermentation of cow manure and apple pomace was determined. The doses between 10-1000 mg×kg-1 of chlortetracycline and 10-500 mg×kg-1 of sulfadiazine were studied. The kinetics parameters of biomethane production were determined according to the modified Gompertz model. The experiments showed that chlortetracycline had an inhibitory effect on biomethane production, even at high doses, e.g., 1000 mg×kg-1 can completely stop biomethane production after 6 days of the process. In this case, the biomethane yield had been reduced by 32.3%. In contrast, sulfadiazine did not affect biomethane production. However, the kinetics study revealed that the highest dose of sulfadiazine 500 mg×kg-1 decreased the maximum biomethane potential by 13.9%. Obtained results showed that anaerobic digestion performance may be affected by high doses of antibiotics, therefore the proper screening of the manure source before entering the biogas plant is recommended. Lack of the influence of low doses of antibiotics may indicate the development of antibiotic-resistant genes in the activated sludge of biogas plants. This phenomenon should be studied both as it may have importance for biogas plant performance and spreading these genes in the environment after digestate field application.