Possible Ways for Post‐treatment of Biologically Treated Wastewater From Yeast Factory/Galimi Papildomi Mielių Gamyklos Biologiškai Valytų Nuotekų Valymo Būdai/Возможные Пути Доочистки Биологически Очищенных Сточных Вод Дрожжевого Завода

Abstract

Abstract. The effluents, which are formed from the waste in the process of production of yeast and molasses, contain a large amount of colouring substances (melanoidins, etc.) and can give dark brown painting to the effluent leading to high organic load on the wastewater treatment plant. The purpose of this study was estimation of the process of coagulation as possible method for the post-treatment of effluents of yeast industry. The experiments on the coagulation were carried out using biologically purified effluents of Salutaguse yeast factory. This effluent had relatively high residual content of COD (with the effectiveness of treatment -90%) and brown colour. Different coagulants and flocculants were studied under laboratory conditions. The most effective coagulants FeCl 3 ·6H 2 O and Al 2 (SO 4 ) 3 were studied additionally. The results of this experiment showed a significant decrease of colour and also concentration of COD. Economic analysis for the possible application of coagulants and ozone for the post-treated effluents of yeast factory was also made. The obtained data showed that coagulants and ozone could be used in the process of the post-treatment of effluents of yeast industry for the purpose of decreasing the colour and general concentration of pollutants, however, these processes are very expensive.