Water treatment


Wastewater treatment may be defined as the array of physical, chemical, and biological processes involved in the partial or complete removal of contaminants present in the effluents from industrial processes, sewers, drainage or natural sources to deliver water of a suitable quality for its end purpose. 

Wastewaters may be generated by numerous sources or activities, and for reasons of public health they cannot be discharged into lakes, seas or normal watercourses without first being treated. The treatment of wastewaters is a complex and demanding process that ranges from the assessment of the purifying process itself through to the processing of the wate recovered. 


Water is arguably the world’s most important natural resource, as life cannot survive without it and industry is unable to operate. As opposed to numerous other natural resources, there is no substitute for water in numerous applications, which means it needs to be managed carefully.

A safe supply is vital for building communities. However, a community’s liquid and solid wastes have a considerable potential for polluting the environment. 

Over the passage of time, people have gone from using water solely for personal consumption to relying on it for their activity and comfort, whereby water has become the vehicle for removing all kinds of waste. This is the premise underpinning what we now refer to as wastewater.

Water pollution

One of the downsides of globalisation and the population explosion is the higher consumption of water resources and the diversification of contaminating agents. Relentless human activity means that water now includes a huge number of toxic substances, which increase the need to treat polluted waters. 

According to legislation on waters, pollution is understood to be the action and effect of using materials or forms of energy or prompting conditions that either directly or indirectly impair the quality of water in relation to its subsequent uses, people’s health, the aquatic ecosystems or the land directly associated with them; causing damage and deteriorating or hindering the enjoyment and use of the environment. 

Pollution has four basic sources within the economic process:

  • Pollution caused by the harvesting of raw materials, including the environmental damage from the mining and transportation of the non-renewable raw materials and recycled ones required in manufacturing. 
  • Pollution due to the process, arising both during it and as a by-product. 
  • Pollution due to the product; this includes environmental damage caused by its everyday use.
  • Collateral pollution, which includes a product’s final disposal at the end of its useful life. 


According to their composition, we can separate wastewaters into three main groups: white, grey and black. Each one of them requires a specialised treatment.

At QUILTON, we design and manufacture a wide range of customised equipment for providing effective solutions in wastewater treatment. 

Treatment of white waters or rainfall

This is water collected in drains or from surface runoff, characterised by sporadic large volumes and the scarce presence of contaminants. 

The contaminating content is added to the water as it falls through the atmosphere or when flowing across surfaces and lands. 

Treatment of grey waters

This concept encompasses all those waters produced by household activities such as personal hygiene or domestic tasks (dishwashers, washing machines, etc.). They generally contain little contamination and can be easily reused after simple treatment. 

Particular attention needs to be paid today to emerging contamination that may appear in this type of water, and which stems from the use of certain cleaning compounds, medications and other types of substances consumed that may contain major contaminants from both a qualitative and quantitative perspective.

Treatment of black water or sewage

These wastewaters come from the effluents of human and domestic activities, agriculture, industry, etc. 

They have a lower volume, a more constant flow, and produce much higher contamination. 


In 1800, only around 1% of the world’s population lived in cities of more than 10,000 people, by 1960 this proportion had risen to 20%, and this figure is expected to reach 70% by 2030. This concentration of the global population is prompting a steady increase in the complexity of the design of infrastructures, and particularly those related to urban water management, such as the supply of mains water, wastewater management, the drainage of rainwater etc., with increasingly larger investments being required for their building or enlargement, as well as for the financing that needs to be earmarked for their operation and maintenance.

The indirect use of wastewaters is an intrinsic part of the natural water cycle, as through the discharge of these effluents into watercourses and their dilution in the flow they have traditionally been tapped downstream for their urban, agricultural, and industrial use. 

As opposed to this indirect use, their direct or planned reuse has a more recent origin and involves the direct application of purified effluents, with a greater or lesser degree of prior treatment, through their delivery to their point of use via a specific channel. The treatment process required for reusing wastewater is generally referred to as “regeneration”, with the result being called “regenerated waters”. 

Growing health and environmental requirements on the quality of freshwater and seawater, together with increasingly stricter treatment standards imposed on the discharge of wastewaters, have meant that regenerated water has become an economical and safe alternative from a health and environmental perspective. 


There are numerous benefits involved in this reuse, with the following highlights:

  • It leads to a substantial increase in the resources available in those areas where treated effluents are discharged into the sea.
  • It improves the management of resources through the use of regenerated water to replace better quality water, which can then be redirected to more demanding uses (e.g., human consumption).
  • It reduces the volume of contaminants in watercourses.
  • It avoids the need to build costly infrastructures for transporting additional resources over long distances.
  • When this water is reused in agriculture, it means exploiting the nutrients contained in the wastewater, thereby reducing the amounts of fertilisers used in farming. 
  • It is a guarantee of greater flexibility and regularity in water availability, especially at those times of the year in which there may be a shortage of water from other sources.


At QUILTON, we design, and manufacture equipment adapted for rainwater, waste, and industrial water treatment.