The influence of sodium hypochlorite on the presence of xenobiotics in model and real wastewater

Povećana upotreba antiparazitika u veterinarske i druge medicinske svrhe, te široka primjena pesticida u poljoprivredi, dovode do kontinuiranog i nekontroliranog ispuštanja ksenobiotika u okoliš. Iako se oni i njihovi razgradni i transformacijski produkti u okolišu nalaze u tragovima, mogu uzrokovati dugoročno visoku koncentraciju tih onečišćivala i tako štetno djelovati na okoliš. Prije ili kasnije ti spojevi ispiranjem ili otjecanjem voda dospijevaju u vodeni okoliš i otpadne vode. Brojna istraživanja pokazuju da je uklanjanje mnogih ksenobiotika u konvencionalnim uređajima za obradu otpadnih voda često nepotpuno te stoga dolazi do onečišćenja prirodnih vodotoka. Poznato je da sredstva za dezinfekciju također uklanjaju i organska onečišćenja stoga je cilj ovoga rada procijeniti utjecaj prisutnosti natrijevog hipoklorita kao dezinfekcijskog sredstva na uklanjanja ksenobitika u otpadnim vodama nakon postupka šaržne biorazgradnje kao konvencionalne i često primjenjivane metode. Provodio se proces biorazgradnje u tri aerirana šaržna reaktora različitih sadržaja. Prvi reaktor je sadržavao aktivni mulj i radnu otopinu ksenobiotika masene koncentracije 10 mg L^-1. Kao kontrolni reaktori, drugi reaktor je sadržavao samo aktivni mulj, dok je treći reaktor sadržavao samo radnu otopinu ispitivanog ksenobiotika iste koncentracije. Uz ispitivanje fizikalnokemijskih parametara biorazgradnje, praćena je koncentracija u vremenskim razmacima uzorkovanja. Nakon procesa biorazgradnje, otopine ksenobiotika podvrgnute su procesu fotolize kao obliku tercijarne obrade otpadnih voda. Fotoliza se provodila u četiri kvarcne posudice s različitim sadržajem. Tijekom procesa fotolize ispitivan je utjecaj prisutnosti natrijevog hipoklorita na uklanjanje ksenobiotika uz usporedno provođenje uklanjanja ksenobiotika s vodikovim peroksidom kao vrlo učinkovitom metodom. Rezultati su pokazali različit postotak uklanjanja šest ispitivanih ksenobiotika. Novonastali razgradni i/ili transformacijski produkti detektirani su tekućinskom kromatografijom visoke djelotvornosti. Također, procijenjena je toksičnost istraživanih otopina ksenobiotika pomoću bioluminiscentne metode određivanja akutne toksičnosti bakterijom Vibrio fischeri.The increased use of antiparasitics for veterinary and other medical purposes, and the widespread use of pesticides in agriculture, lead to the continuous and uncontrolled release of xenobiotics into the environment. Although they and their degradation and transformation products are found in traces in the environment, they can cause a long-term high concentration of these pollutants and thus have a harmful effect on the environment. Sooner or later, these compounds end up in the water environment and waste water through washing or runoff. Numerous studies show that the removal of many xenobiotics in conventional waste water treatment devices is often incomplete and therefore pollution of natural waterways occurs. It is known that disinfectants also remove organic pollutants, therefore the aim of this work is to evaluate the influence of the presence of sodium hypochlorite as a disinfectant on the removal of xenobiotics in wastewater after batch biodegradation as a conventional and often applied method. The biodegradation process was carried out in three aerated batch reactors with different contents. The first reactor contained activated sludge and a working solution of xenobiotics with a mass concentration of 10 mg L^-1. As control reactors, the second reactor contained only activated sludge, while the third reactor contained only the working solution of the tested xenobiotic of the same concentration. In addition to testing the physico-chemical parameters of biodegradation, the concentration was monitored at sampling intervals. After the biodegradation process, the xenobiotic solutions are subjected to the photolysis process as a form of tertiary wastewater treatment. Photolysis was carried out in four quartz vessels with different contents. During the photolysis process, the influence of the presence of sodium hypochlorite on the removal of xenobiotics was examined, with a comparative performance of xenobiotic removal with hydrogen peroxide as a very effective method. The results showed a different percentage of removal of the six tested xenobiotics. Newly formed degradation and/or transformation products were detected by high performance liquid chromatography. Also, the toxicity of the investigated solutions of xenobiotics was evaluated using the bioluminescent method of determining acute toxicity by the bacterium Vibrio fischeri