Water pre-treatment in wastewater treatment

a. What is water pretreatment

Water pre-treatment is a process designed to remove impurities, which can be found in raw water, mainly those in suspension. These impurities are of different sizes and natures. We can find them as tiny particles of matter, sometimes at the nanometric scale, sometimes they are even living organisms.
The purpose of this manipulation is to ensure that the population has sufficient water quality, without industrial pollutants and whose quality does not depend on abiotic factors, such as the weather, or even the seasons.
Water pre-treatment refers to the phase prior to the membrane separation process in wastewater treatment. This way, all risks of obstruction in the pipes are avoided and subsequent treatments are facilitated.

b. What are the wastewater treatment technologies in water pretreatment?

Water pre-treatment technologies are mostly focused on coagulation-flocculation processes. Filtration only comes later in the wastewater treatment process.

  • Coagulation-flocculation is a physico-chemical process, intended to treat wastewater, by removing colloidal particles (small negatively charged particles, which have a very small diameter and do not sediment) present in the water.
  • Coagulation involves the addition of metallic salts to the water. This will reduce the electronegative character of the particles and thus their repulsive capacity. This way, they will come into contact with each other. Flocculation is the addition of polymers that act as glue between the colloids. Therefore, when they come into contact, the colloids will form aggregates called flocs, which can be easily eliminated afterwards.
  • Elimination of the flocs is done by settling to separate the water from the impurities.
  • Another process, called reverse osmosis, allows the removal of particles of different sizes, up to the ionic scale.

Of course, the drum filter has its place in water pre-treatment technologies. With its mechanical water treatment system, it can perform the coagulation-flocculation steps. This only applies to particles whose diameter exceeds the pore size of the filter.

Coagulation-floculation pour le traitemnt des eaux usées municipales et industrielles
Coagulation-flocculation for the treatment of municipal and industrial wastewater

c. What are the advantages of using a filter for the pre-treatment of municipal and industrial wastewater?

There are many advantages in using a filter for water pre-treatment:

  • The assurance of a continuous and reliable water supply;
  • Optimizing the overall life cycle of the plant, thereby reducing costs;
  • Compliance with required quality standards.

Tertiary treatment

a. What is industrial wastewater treatment?

Generally, wastewater requires purification before it can be released into the environment. This is especially relevant in the case of industrial wastewater treatment, which requires a high quality of purification. To remove contaminants and ensure that industries are fully compliant with regional standards, it is important to have an adequate purification system in place. Furthermore, this type of approach presents a real economic advantage, linked to the reduction of waste treatment costs.

b. What technologies are used for tertiary treatment?

The technologies used for tertiary treatment are extensive and diversified. Evaporation, filtration, clarification, aerobic and anaerobic biological treatment technologies are used. This flexibility is essential in order to meet all requirements. These requirements may come from regulatory standards applied in the territory. They can also be linked to the sector of activity (food industry, automotive, pharmaceutical industry, energy, etc.)

c. Advantages of industrial wastewater treatment with a drum filter ?

The treatment of municipal and industrial wastewater has the virtue of drastically reducing the overall production of waste while recycling the wastewater, transforming it into clean and reusable water. Therefore, we have:

  • Reduced water loss through pollution control;
  • contaminants which present a risk to the environment which are disposed of ;
  • a revalorization of mud allows :
    • Methane production through methanization;
    • recovering fertilizer for agriculture.
  • waste is treated and its disposal is no longer necessary. As such, this results in considerable savings.
  • a clear view of the water quality, allowing to respect and maintain the conformity to the standards of the territory.
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