Citation: Lysytsya A., Mandyhra Yu., Kryvoshyia P., Lukyanyk I., Shevchuk A. (2026) Antibiotics in livestock farm wastewater: risks for activated sludge and possibilities for using polyhexamethyleneguanidine. Veterinary Biotechnology, 48, 132-145. https://doi.org/10.31073/vet_biotech48-10
LYSYTSYA A., Doc. Sci. (Biol.), Prof. This email address is being protected from spambots. You need JavaScript enabled to view it. https://orcid.org/0000-0001-9028-8412
MANDYHRA YU., Cand. Sci. (Agric.), This email address is being protected from spambots. You need JavaScript enabled to view it., https://orcid.org/0000-0002-8671-6442
KRYVOSHYIA P., Cand. Sci. (Vet. Med.), This email address is being protected from spambots. You need JavaScript enabled to view it.? https://orcid.org/0000-0002-8671-6442
LUKYANYK I., This email address is being protected from spambots. You need JavaScript enabled to view it., https://orcid.org/0009-0005-8640-2071
SHEVCHUK A., Postgraduate Student, This email address is being protected from spambots. You need JavaScript enabled to view it., https://orcid.org/0009-0007-8266-2065
Research Station of Epizootology of the National Scientific Center "Institute of Experimental and Clinical Veterinary Medicine"
ANTIBIOTICS IN LIVESTOCK FARM WASTEWATER: RISKS FOR ACTIVATED SLUDGE AND POSSIBILITIES FOR USING POLYHEXAMETHYLENEGUANIDINE
Introduction. The intensive use of antibiotics in the livestock industry results in significant environmental release, as 70–90% of these substances are excreted unchanged. Aquatic ecosystems act as reservoirs, facilitating the development of antimicrobial resistance (AMR). Livestock wastewater is a key source of antibiotics and antibiotic resistance genes (ARGs), which can reach concentrations of 10⁸–10¹⁰ copies/mL. These contaminants negatively impact biological treatment, particularly by inhibiting nitrifying bacteria and heterotrophic microorganisms within activated sludge systems.
The goal of the work. This study aimed to analyze the environmental risks associated with antibiotic contamination in livestock farm wastewater and to determine the potential of polyhexamethylene guanidine (PHMG) as a practical mitigation strategy.
Materials and methods. The study utilized standard microbiological methods alongside theoretical analysis. Wastewater samples were collected from livestock farms to evaluate microbial indicators. To assess risk reduction, PHMG was applied as a disinfectant at a concentration of 5.0 mg/L during the post-treatment stage. The efficiency was measured by the reduction in pathogenic microflora and biochemical oxygen demand (BOD₅).
Results of research and discussion. Antibiotic concentrations in local environments typically range from 0.38 to 3.12 μg/L, with tetracyclines identified as the dominant group. Experimental data indicated that elevated concentrations significantly inhibit microbial activity and nitrification processes. The application of PHMG (5 mg/L) proved highly effective, reducing the total microbial count by 98.5%, Escherichia coli by 97.9%, Enterococcus spp. by 97.8%, and Pseudomonas aeruginosa by 97.4%. Additionally, BOD₅ levels decreased by 30.5%. While PHMG does not degrade antibiotic molecules, it significantly mitigates biological risks by inactivating resistant strains and reducing the spread of ARGs.
Conclusions and prospects for further research. PHMG is an effective agent for reducing biological risks in livestock wastewater, provided it is applied at the post-treatment stage to avoid inhibiting the beneficial microbiota of activated sludge. This approach aligns with the "One Health" framework. Future research will expand to a wider range of facilities and test various concentrations of PHMG and polyhexamethylene biguanide (PHMB). The scientific novelty of the study lies in substantiating PHMG application at the post-treatment stage for mitigation of antimicrobial resistance dissemination risks.
Keywords: antibiotics, livestock wastewater, activated sludge, antimicrobial resistance, polyhexamethylene guanidine.
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