Modelling of chloride influence upon activated sludge community growth

Abstract

Growth kinetics, i.e. the relationship between specific growth rate and the concentration of a substrate, is one of the basic tools in the modelling of activated sludge community growth. The above-described conventional growth kinetics derived from single-substrate-controlled laboratory experiments have invariably been used for describing both growth and substrate utilization in wastewater treatment. After technological processes various mineral substances, such as chlorides, get into water bodies. These substances are not removed from wastewater by the biological treatment method. The purpose of this study is to determine the concentrations of chlorides, investigate the influence of enzyme preparations upon wastewater treatment quality during biological process modelling. Kinetics of microbial growth was designed using the model of Monad. To analyse the chloride influence on the biooxidation process a series of laboratory tests was carried out: biochemical oxygen consumption (BOD), activated sludge concentration and other indexes. It is found experimentally that a 400 mg/l concentration of chlorides disarranges the activity of microorganisms and activated sludge is no longer suitable for biological treatment. Also, we investigated the effect of enzyme preparation on effluence on sewage treatment. As chloride concentrations are increased in a tank without an enzyme, bacterial spores contained in the enzyme preparation produce a renewing effect upon active sludge.

Darbe modeliuojama veikliojo dumblo mikroorganizmų biocenozės dinamika, atliekant aerobinį nuotekų valymą. Nagrinėtas atvejis, kai nuotekų užtarša yra didesnė chloridų koncentracija. Veikliojo dumblo biocenozės dinamikai modeliuoti pasirinktas Monodo modelis. Atlikus eksperimentą nustatyti degradacijos koeficientai kd. Gautas Monodo diferencialinės xdfxdfd A. Skaisgirienė et al. Modelling of chloride influence upon activated sludge community growth 120 lygties sprendinys, nusakantis veikliojo dumblo dinamiką. Skaitiniais metodais išspręsta veikliojo dumblo augimą bei substrato biodegradaciją nusakanti diferencialinių lygčių sistema. Įvertinus eksperimentų rezultatus nustatyti veikliojo dumblo sistemos degradacijos koeficientai įdėjus fermentinio preparato. Rezultatai parodė, kad fermentinis preparatas teigiamai veikia mikroorganizmų augimą t. y. veikliojo dumblo koncentracija mažėja lėčiau.