Istraživano je začepljivanje membrana u membranskom bioreaktoru pri filtraciji aktivnog mulja. Izmjereni kritični fluks sustava iznosio je 20 L m-2 h-1, ali i pri provođenju pokusa ispod te vrijednosti, fluksom od 10 L m-2 h-1, došlo je do umjerenog začepljivanja membrana. Do najjačeg začepljivanja membrana došlo je filtracijom s većim fluksom od 32 L m-2 h-1 gdje je relaksacija membrana bila nužna kako bi se filtracija održala stabilnom. I samim uranjanjem membrane u aktivni mulj izmjereno je začepljivanje membrana. Iz izmjerenih i izračunatih vrijednosti otpora filtraciji može se zaključiti da na porama membrana nije došlo do stvaranja filtracijskog kolača što je uzrokovano radom ispod kritičnog fluksa pri kojem su se nataložene čestice i flokule aktivnog mulja aeracijom odvajale od membrane. Najznačajniji mehanizam začepljivanja bila adsorpcija otopljenih tvari i koloidnih čestica. Fizičkim pranjem nije postignut značajniji porast permeabilnosti, a pri kemijskom pranju otopinom hipoklorita kroz 48h postignuta je početna vrijednost permeabilnosti.

Fouling of membrane in the membrane bioreactor during the filtration of the activated sludge was investigated. The measured critical flux of the system was 20 L m-2 h-1 but during the experiment below that value (10 L m-2 h-1) mild fouling membrane was observed. The strongest fouling membrane was achieved by the filtration with the higher flux of 32 L m-2 h-1, where the membrane relaxation was necessary to keep the filtration stable. Fouling of the membrane was measured by the membrane immersion in activated sludge. From the measured and calculated values of the filtration resistance it can be concluded that the filtration cake was not formed on the membrane pores, which was caused by the functioning below the critical flux during which the sediment particles (deposit matter) and flocs of the activated sludge parted from the membrane due to aeration. The most important mechanism of fouling was the adsorption of the soluble and colloid matter. Physical cleaning did not cause the permeability growth, and by washing the membranes with the hypochlorite solution, initial permeability was restored.