Biodegradability of anthelmintics with activated sludge

Povećanjem uporabe antihelmintika u veterinarske i druge medicinske terapijske svrhe dolazi do njihovog kontinuiranog i nekontroliranog ispuštanja u okoliš. Iako se farmaceutici i njihovi metaboliti u okolišu nalaze u tragovima mogu dovesti do visoke dugoročne koncentracije i time štetno djelovati na okoliš. Obzirom da njihova kemijska postojanost, mogućnost akumulacije, otpornost na mikrobe i sinergistički učinci još uvijek nisu u potpunosti poznati potrebno je razvijati i primjenjivati analitičke i bioanalitičke metode detekcije antihelmintika i njihovih razgradnih i/ili transformacijskih produkata. Cilj ovog rada bio je ispitati učinkovitost biorazgradnje antihelmintika mebendazola, albendazola i febantela te njihove smjese. Proces biorazgradnje provodio se u tri aerirana šaržna reaktora različitih sadržaja. Prvi reaktor je kontrolni reaktor koji je sadržavao samo radnu otopinu ispitivanog farmaceutika masene koncentracije 3 mg L^-1. Dodatak drugom reaktoru je aktivni mulj, dok je u treći uz sve prethodno navedeno dodana i poznata masa mikroplastike. Uz ispitivanje fizikalno-kemijskih parametara biorazgradnje, praćenje koncentracije antihelmintika u definiranim vremenskim razmacima uzorkovanja, procijenjen je i ekotoksični utjecaj pojedinačnih komponenti i njihove smjese. U ovom radu je postignuta biorazgradnja antihelmintika s aktivnim muljem masene koncentracije 4 - 5 g L^-1. Pretpostavka je da se uz glavni mehanizam uklanjanja antiparazitika - biorazgradnju, javljaju i hidroliza i adsorpcija na pahuljice mulja. Praćeni parametri tijekom biorazgradnje bili su pH-vrijednost, temperatura okoline, temperatura svakog reaktora i preostali radni volumen otopine u reaktoru. Novonastali razgradni i/ili transformacijski produkti detektirani su tekućinskom kromatografijom visoke djelotvornosti. Također je procijenjena toksičnost odabranih istraživanih antihelmintika i njihove smjese nakon provedene biorazgradnje pomoću bioluminiscentne metode određivanja akutne toksičnosti bakterijom Vibrio fischeri.Increasing the use of anthelmintics for veterinary and other medical therapeutic purposes leads to their continuous and uncontrolled release into the environment. Although pharmaceuticals and their metabolites are found in traces, they can lead to high long-term concentrations and therefore have a detrimental effect on the environment. Since their chemical resistance, accumulation potential, microbial resistance and synergistic effects are not yet fully known, it is necessary to develop and apply analytical and bioanalytical methods for the detection of anthelmintics and their degradation and/or transformation products. The aim of this study was to examine the biodegradation efficiency of the anthelmintics mebendazole, albendazole and febantel, and their mixture. The biodegradation process was carried out in three aerated batch reactors of different contents. The first reactor was a control reactor containing only the working solution of the test pharmaceutical at a mass concentration of 3 mg L^-1. The addition to the second reactor is activated sludge, while in the third, in addition to all the above, a known mass of microplastics was added. In addition to examining the physicochemical parameters of biodegradation, monitoring the concentration of anthelmintics at defined sampling intervals, the ecotoxic effect of individual components and their mixture was assessed. In this study, biodegradation of anthelmintics with activated sludge with a mass concentration of 4 - 5 g L^-1 was achieved. It is assumed that in addition to the main mechanism of antiparasitic removal - biodegradation, hydrolysis, and adsorption on the floculae of activated sludge are also occuring. The parameters monitored during biodegradation were pH-value, room temperature, temperature of each reactor and the remaining working volume of the solution in the reactor. The newly formed degradation and/or transformation products were detected by high performance liquid chromatography. The toxicity of the selected investigated anthelmintics and their mixture after biodegradation was also assessed using the bioluminescent method of determining acute toxicity with bacteria Vibrio fischeri