Treating wastewater. The efficiency of wastewater treatment in sewage treatment plants depends on many factors, among them is the presence of toxic substances in wastewater which affect activated sludge.
Typically, a pharmaceutical substance (medicine) is a mixture prepared by treating natural materials by synthesis or chemical treatment. These chemicals are released into sewage in micro concentrations, but some of these chemicals have an extremely negative effect, which in many cases exceeds the effect of known contaminants entering the drains in large quantities. Traces of pharmaceutical drugs were found in wastewater, surface water, activated sludge, oceanic sediments and annual rainfall and also in filters in municipal landfills in countries such as France, Germany, Great Britain, Denmark, the Netherlands, Sweden and the United States.
Wastewater from residential areas, medical institutions and pharmaceutical companies are discharged into municipal sewage, and then into treatment plants for the biological treatment. But even after the treatment the purified water that goes into natural waterways contains pharmaceutical drugs or their derivatives. This is explained by the fact that biological wastewater treatment in most cases is not intended to remove micro contaminants.
Chemical drugs poison the activated sludge microorganisms of treatment plants. The examination of toxic effects of pharmaceuticals show the negative change in the biological nature of the activated sludge organisms, which changes the results of wastewater treatment.
The negative effects of pharmaceutical pollutants on the active sludge are various. Some of the pollutants slow down oxygenation of activated sludge, reducing its productivity, while others become food.
The remains of pharmaceuticals, after passing through biological treatment are discharged into surface waters and accumulate in the natural environment. They reduce the quality of water, violate the life-cycle of organisms and cause their abnormal development.