Wastewater is the liquids resulting from common domestic, industrial or agricultural activities. Their uncontrolled disposal can cause environmental damage, which is why there is a strict regulation that provides for effective purification treatments aimed at removing pollutants within them. The first phase of purification involves the separation between solids and liquids, the chemical treatment removes unwanted substances. Biological purification involves living organisms.
The waste water are nothing more than an inevitable by-product of human activities. By their nature they cannot be used by man, at least not before having been subjected to a purification treatment. Both to avoid risks to human health and damage, even quite significant, to aquatic ecosystems. In this article we are concerned with deepening the concept and understanding what wastewater contains and how it is purified.
What is waste water?
Let’s start from What is meant by waste waterand we do so by relying on the definition provided by the Treccani dictionary.
“In technique, waters r., the same as waste waterthat is, the waters which, after domestic, industrial or agricultural use, are sent, more or less polluted, for disposal”.
In essence, it is “water that has been used,” which means it includes liquids from a variety of sources, including urban settlements, industry, and agriculture. It is not just sewage, either: wastewater comes from homes (showers, sinks, dishwashers), businesses (laundries, car washes, clinics), industries (such as food processing or manufacturing plants), and schools (canteens, toilets). But it also includes storm runoff. As such, it can contain chemicals, nutrients, pathogens, and other pollutants that require proper treatment before being discharged into the environment.
What does domestic wastewater contain?
The domestic waste water are those coming from daily activities carried out in homes related to kitchens, bathrooms, laundries, etc. The waste from sinks, showers, toilets and washing machines are the main source. Therefore, they can contain a wide range of contaminants such as organic substances from food waste and detergents, nutrients such as nitrogen and phosphorus, pathogenic microorganisms from human feces as well as urea, fats, proteins, cellulose. They contain, in different concentrations, the same substances present in domestic waste as well as micropollutants such as pesticides, rubber debris, hydrocarbons.
Wastewater purification treatments
Let’s start from the assumption that wastewater purification treatment consists, as we read on Wikipedia, in the “process of removing contaminants from wastewater of urban or industrial origin, or from an effluent that has been contaminated by organic and/or inorganic pollutants”.
The treatments that are carried out inside a purification plant are divided into mechanical, chemical and biological. The former include, among others, preliminary operations of removal of undissolved solids. In wastewater, in fact, there are solids of organic and inorganic nature that can be sedimentable (i.e. heavier than water and therefore easily accumulate on the bottom) and non-sedimentable.
In the field of chemical treatments, on the other hand, substances are added to trigger certain chemical reactions (to modify the pH of the water, or to disinfect it). Finally, biological treatments exploit technologies based essentially on natural phenomena but made to occur in artificially created environments. Biological purification has as protagonists living organisms that, in collaboration with each other, cause the degradation of the polluting substances present in the water.
Why is wastewater dangerous to the environment?
If used without first being treated, they can trigger a series of environmental problems. Starting with the possible contamination of groundwater and waterways, which can give rise to public health problems as well as significant damage to ecosystems. Any toxic substances can in fact damage aquatic organisms and impact the food chain. The presence of bacteria and viruses in wastewater can spread diseases and compromise the safety of the water supply.
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Source: www.greenstyle.it
