Problems of Wastewater Pretreatment from the Edible Oils Production
The pretreatment of the wastewater from the edible production based on calcium phosphates precipitation, generates sludge characterized by good sedimenting properties. However, a part of the sludge floats through the surface of the settling tank. Lime added for phosphorus removal simultaneously removes also sulphates to a level of above 2000 mg/l. The liquid associated with floated sludge contains low sulfates concentration – about 370 mg/l. The aim of the research project was to examine the causes of such a low sulphates concentration.