The study of the influence of tetracycline and sulfadiazine on biomethane production from manure and apple pomace

Anaerobic digestion is the most popular technic for obtaining biomethane from substrates like cow manure and other organic materials, however, chlortetracycline (CTC) and sulfadiazine (SDZ) which are commonly used in animal husbandry and present in cow manure can adversely affect biomethane yields. In this paper, the results of the influence of an increasing dose of CTC between 10 and 1000 mg×kg−1 and dose of SDZ between 10 and 500 mg×kg−1 on biomethane yield and kinetics for co-fermentation of cow manure and apple pomace experiment was presented. The obtained data during 21 days of lasting batch tests performed under mesophilic conditions allowed the determination of kinetics parameters of biomethane production according to the modified Gompertz model. The biomethane yield for the experiment with CTC differs from 233 to 353 mlCH4, while for the experiment with SDZ from 396 to 455 mlCH4. The kinetics parameters varied in a broad range. The ymax, λ, and Rm were 232–531 ml, 18–66 ml d−1, and –2.9-(–1.7) d for CTC, and 533–653 ml, 20–21 ml d−1, and –4.5-(–0.8) d for SDZ, respectively. With the high antibiotics dose, the biomethane yield decreased due to the inhibitive effect on microorganisms. The experiment showed that antibiotics had an inhibitory effect on biomethane production, at high doses. The biomethane yield had been reduced by 32.3 % at 1000 mg×kg−1 of CTC and by 13.9 % at 500 mg×kg−1 of SDZ. Interestingly, small doses (<100 mg×kg-1) did not affect significantly methane yield and sometimes increased it. Obtained results showed that the co-fermentation of apple pomace and manure performance may be affected by high doses of antibiotics. Depending on the dose and the antibiotic type it affects the biomethane yield, production rate, or lag phase differently.