Treatment plants are not omnipotent
In all large cities, there are sewage treatment facilities sewage waters before releasing them into rivers and ponds. However, it is often old and low-power facilities that do not cope with increasing volume of effluent.
In the same cities and towns, where there is no treatment of domestic wastewater, pollution of waterways is progressing. And most importantly, the principle of operation of the treatment facilities is such that cleaning is only partial – mechanical (from large impurities, suspended solids) and biological (as it would Express natural cleaning). In special constructions – aeration tanks the wastewater is treated with active sludge rich in microorganisms. They destroy organic impurities – products of our life (but not synthetic detergents) and pathogens. Organic substances are decomposed into simple compounds, in particular containing nitrogen and phosphorus. These compounds, acting with the treated effluents in natural water bodies, it is practically harmless for humans and for vegetation, including water, are perfect breeding ground. Their so – called- nutrients. They promote intensive development of algae, primarily blue-green – a kind of weed. The cycle of their short life, they are quickly and massively die off, they grow new. The decomposition processes are growing at an exponential rate, compromising the properties of water ruining higher vegetation and animals, water inhabitants.
We elaborated on the consequences of the treatment of domestic wastewater, because it is this type of cleaning was performed for other categories of wastewater. Of under construction and planned for the coming years, water treatment facilities every fourth will provide only mechanical treatment, and almost all the others involve deeper cleaning than biological.
Agricultural wastewater and stormwater washouts are also sources of pollution. While there are almost no treatment facilities for SEL-hostacov and virtually no cleaning of the storm drains.
Agricultural runoff is a loose concept, it refers to the various waste water generated in the process of agricultural production. This storm water run-off from fields treated with pesticides, runoff of pesticides warehouses, waste water machine-tractor Park, containing oil products and oil. A significant proportion of the contaminants are selkhozstroi containing nutrients: fertilizers, washed from the fields or contained in the effluent of warehouses for agricultural equipment, liquid waste from large livestock farms (1,000 head cattle pollutes natural water as well as a city with a population of 15 thousand people). Finally, that’s what carries the soil, washed into the water bodies by erosion and wind erosion. Thus, the penetration of selkhozstroi in ponds leads to direct pollution.
In modern cities and towns with the highest asphalted or paved area runoff have no opportunity to gradually seep into the soil and undergo natural long-term treatment and only then get into the water. All contaminants are washed from paved urban areas very quickly, almost immediately, and through the storm sewers discharged into rivers, lakes, etc. But qualitative composition of impurities of the city was different than in the days when there was no asphalt. In a modern city settle industrial emissions: soot and carcinogenic soot, corrosive sulfuric acid and nitric acid fumes, oxides and salts of heavy metals, combustibles and lubricating oils, a wide range of chemical compounds are washed off by rains from factories, contaminated wastes, etc.