Purifiers: transforming wastewater into pure water resources

How water purification plants work and why they are increasingly essential

Sewage treatment plants are specific systems designed to treat wastewater. It is a particular process through which the various procedures of decontamination of water, from civil and/or industrial discharges, take place. 

Modern applications play an increasingly crucial role in transforming “waste” water into valuable resources, thanks to advanced purification technologies that allow water to be recovered and reused, reducing environmental impact. Indeed, it is becoming increasingly important to carry out wastewater treatment consciously in order to save as much water consumption as possible-especially when, as is increasingly the case, long periods of drought occur.

Water is an increasingly precious resource, and wastewater purifiers make it possible to sanitize it, clean it up and put it back into circulation, avoiding unnecessary waste.

What is wastewater and why is it increasingly important to treat it properly?

Water that enters homes, offices, and industrial facilities clean and ready for use comes out dirty and needs to be cleaned before it can be returned to the cycle. 

Wastewater" or "wastewater" is the water used in human activities - domestic, industrial, agricultural - that, after use, contains organic and inorganic substances that can be harmful to health and the environment.

After use, this type of waste water cannot be discharged directly into the environment (soil, rivers, lakes or seas) without first undergoing carefully monitored purification measures regulated by precise national and EU legislation.
 
The process of purification and disinfection of waste water must be carried out in accordance with Italian and EU regulations, which provide for the necessary measures to achieve or maintain the good quality status of surface or deep waters, protecting them from pollution. The recovery of purified water, as already mentioned, is essential to reduce waste and can be particularly useful in various sectors, such as industry and agriculture.

How does a wastewater treatment plant work?

A wastewater treatment plant is a complex and increasingly technologically advanced system used to treat wastewater. Once the wastewater arrives at the treatment plant through the sewer system and intermunicipal sewers, it undergoes a lengthy purification process. 

This process consists of several stages during which toxic and polluting substances are removed from the liquid waste, transforming it into sludge. The sludge, which is still not completely free of waste and pollutants, is then treated. Only at the end of this process can the sludge be disposed of in special landfills, sent to composting plants or reused in agriculture, as is the case with wastewater. 

The activated sludge system is the most popular biomass system for treating organic compounds in wastewater. They are very versatile and are suitable for individual users as well as for medium and large communities. The process that takes place in these plants mimics the biological mechanisms that occur in nature: this is thanks to the presence of aerobic microorganisms that "feed" on organic compounds, transforming them into smaller, more easily disposable and less harmful compounds for the environment. 

But let us discover together and in more detail the different stages of purification.

The stages of purification

1.Screening
Wastewater collected from individual sewer systems is conveyed through collectors to the treatment plant. Primary screening of the wastewater removes coarser materials such as pieces of plastic, wood, sanitary products, rocks, paper, and anything else that could clog pipes and pumps. The "screenings," or material collected by the screen, are then washed, compacted, and hauled to the landfill. 

After this first step, the black water is lifted by special pumps and conveyed to a collection canal. Here, as it flows downstream, it is again filtered through progressively smaller screens. "Secondary screening allows the retention of smaller solid waste, but larger than 3 millimeters. 

2.De-oiling and desanding
In this step, the water treatment plant ensures that sand, grease and oil are removed from the water by insufflation. Air is injected into the system, causing turbulence and eddies that prevent particles from settling to the bottom. Instead, they rise to the surface, ready to be removed.

In fact, de-oiling is based on the lower specific gravity of fats and oils compared to water, which allows them to rise to the surface. The process takes place in open rectangular tanks. Compressed air is blown from the bottom of these tanks through porous diffusers. This air forms a kind of emulsion with the fats in the wastewater, which causes them to float to the surface. The emulsified fats are then pushed to the end of the tank, where they are removed manually in small plants, or by mechanical means in larger ones, and discharged into a special collection tank. 

Oils and fats in the effluent can also be recovered by de-oiling for future reuse. However, in ordinary plants, the amounts of grease and oil are small and modest and are therefore generally retained by the backwaters at the inlet of the primary clarifiers. 

Wastewater also generally contains sand and clay. These elements, which tend to settle to the bottom due to their weight, are sucked up and deposited in special containers; this is the desanding stage.

3.Decantation
The final stage of the treatment plant is the sedimentation stage. In the primary settling tank, the solids are separated by gravity.

This is the case with sludge, for example, which requires special treatment. The individual bacterium, which is very light, floats in the water, while the sludge floc, which is heavier, falls to the bottom. Settling tanks are important because they separate the clean water from the sludge, which contains the pollutants. The heavier sludge that settles to the bottom is sucked up and separated from the water, which is then purified and sent for disinfection. 

In terms of size, the tanks are neither too short, to avoid confusion and possible mixing between the inlet and outlet of the waste water, nor too wide: the risk would be to create dead and stagnant water spaces that would cause mold or rot.

Wastewater treatment plants built by IDRO Group

IDRO Group is a benchmark in the design and construction of civil and industrial wastewater treatment plants.

The wastewater treatment plants built by the Group collect large quantities of water and, through treatments such as biological systems, are able to return clean water with organoleptic, chemical, physical and biological characteristics that comply with legal standards and allow its reuse for multiple purposes.

They are the ideal solution for the reuse of wastewater in agriculture, for the reuse of purified water in various sectors such as industry, but also for the new transition to the civil sector.

Plants can also be designed for specific industry needs and precise contamination problems: as you can imagine, domestic wastewater is very different from industrial wastewater, which contains a wide range of by-products and contaminants, often related to specific manufacturing processes or industrial activities.  For this reason, customized systems are required. Also possible are compact, mobile containerized treatment plants designed by Idro to purify water from conventional and unconventional sources where the raw water quality is unknown.

Thanks to its long experience in the field, IDRO Group is able to advise and guide customers in choosing the right treatment plant for their needs. To learn more, please contact us.