In a beet-sugar plant numerous sources of wastewaters exist. The cleanest water is from the evaporators (150% calculated on the sugar-beet), which contains ammonium and ammonium carbonate. The waste water used for cooling afterwords is used for beet washing (830% calculated on the sugar-beet). The third kind of waste water is used for washing beets soked with dirt. This water contains some residues, suspended solids, organic compounds. The fourth group is fecal waste water, which is treated in a system designed for recycling the waste. This system is composed of two decanters. Calcium-carbonate, aluminium sulphate could be used as precipitating agents. Sugar factories that manipulate with 500 tonnes of sugar-beet need lagoons with an area of about 30-40ha. Since 2006 the sugar factory near Novi Sad has not been letting the effluent into the chanal Bezdan-Vrbas. The waste water which is let into the lagoons has about 3000mg/l BOD5, and 4-5 months later the level of BOD5 decresed for about 70%