According to experts, today in Ukraine a quarter of sewage treatment plants and networks worked in value term depreciation. As a result, a large number of cleaning stations decommissioned and wastewater that must be disposed of at these sites, get into the environment completely untreated, causing serious concern because they pose a potential threat to health and life.
This article describes the results of the technical and economic calculations and analysis of the economic efficiency of the project of reconstruction of waste water treatment plant. Lviv and construction of biogas plants for the production of electricity and thermal energy from sludge and excess activated sludge resulting from waste water treatment. The main elements of the technological scheme of biogas is methane tanks, and electrical and thermal energy – cogeneration units.
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.