"During heavy precipitation, chemical and biological pollutants from urban and agricultural areas enter the waters from storm overflows as a result of infiltration and inflow, as well as via uncontrolled outflows from water treatment plants.
Infiltration and inflow of rainwater into sewers is an especially popular and major worldwide problem. Climate forecasts indicate changes in climatic conditions towards an increase in the intensity and frequency of torrential rainfalls.
It may therefore be assumed that the negative impact of rainwater on water quality will increase. impact of pollution from wastewater introduced into water during rainy weather to the receiver. The assessment of the impact of rainfalls on a receiver was carried out on the basis of a simulation of pollution loads from sewage introduced into a river by storm overflows based on data from monitoring the amount of rainfall and simulating the operation of storm overflow s using Environmental Protection Agency Storm Water Management Model (EPA SWMM).
The obtained results were compared with the pollutant loads discharged at the same time from the sewage treatment plant (STP). In addition, the article assesses possible improvement solutions to reduce the negative impact of storm overflows on water." This explained the researchers of the study Influence of storms on the emission of pollutants from sewage into waters, published on the Scientific reports.
The type of water pollution can be of a chemical, physical or microbiological nature and the consequences can compromise the health of the flora and fauna involved, including humans, harming the ecosystem and water reserves for drinking.
There are two main routes through which pollutants reach the water: either directly or indirectly. Direct pollution occurs when polluting substances are poured directly into water courses without any purification treatment.
The indirect route, on the other hand, occurs when pollutants arrive in watercourses via air or soil. In the case of sewers that release water polluted by viruses and bacteria in places where contact with humans can be created, diseases such as viral hepatitis, salmonellosis or typhoid fever can be determined.
Furthermore, the discharge into the water of non-biodegradable detergents or those containing phosphates, determine the covering of a thick layer with their complex chemical structure with branched chains and are hardly attacked and degraded by bacteria into simpler or less harmful compounds; these substances alter the physical characteristics of the water, modifying its surface tension and causing the disappearance, among other things, of the aquatic flora, of the plankton and, with them, of the components of the entire trophic pyramid.
A very serious consequence, in addition to the extension of large surface layers of decomposing materials, with related miasmas and various colors, is the diffusion in both fresh and marine waters of bacteria and viruses and the absorption of these pathogenic microorganisms by molluscs destined for feed (such as mussels and oysters) and reared near drainage outlets with the consequent danger of serious epidemics.