Wastewater is any type of water whose quality is adversely affected by anthropogenic influence and includes waste domestic and urban waters, and liquid industrial or mining waste, or water that has been mixed with the above (rainwater or natural waters).

To ensure health and sustainability, this wastewater must be properly treated. This consists of a series of physical, chemical and biological processes that aim to eliminate pollutants present in both industrial and urban effluents.

There are 3 main types of wastewater treatment: primary or physicochemical treatment, secondary or biological treatment and tertiary treatment. There are those who consider a fourth type of treatment before the primary one that includes the preliminary stages for the correct processing of the water.

 

Physical-chemical or primary treatment

It aims to reduce the elements suspended in the liquid by precipitation or chemical oxidation. It is of common application in purification of waters of industrial origin. Among the most common methods of this treatment are flotation and coagulation-flocculation.

When matter suspended in water has a density less than or equal to that of water, such as oils, fats, or non-sedimenting emulsions, the flotation method is applied. It consists of generating a large number of air bubbles that will move the suspended elements to the surface leaving them concentrated and easily removable.

If the size of the particles mixed with the water is very small and does not sediment or does so too slowly, the coagulation-flocculation process is used, which consists of adding chemicals that generate the coagulation of the particles to be removed, favouring their flocculation and sedimentation.

Other options for removing harmful substances from wastewater are precipitation, ion exchange or UV treatment.

 

Biological or secondary treatment

It is applied often, but not necessarily, after physicochemical treatments. It uses microorganisms that are responsible for actively degrading organic matter or other biological waste, so that it can be separated from the aqueous environment. Two different processes are distinguished, aerobic and anaerobic. They differ in the use of oxidants (oxygen) in the former in the purification process.

Aerobic processes consist of a process of aeration by means of compressed air diffuser plates, which incorporate oxygen into the reactor, which is consumed by microorganisms in their process of oxidation of organic matter. Dissolved biodegradable substances serve as food for incorporated microorganisms by converting them into biomass of aerobic conditions, carbon dioxide and water. Some treatment plants also remove other nutrients such as nitrogen or phosphorus. In the case of nitrogen, this process is known as nitrification and denitrification. Nitrification uses microorganisms to convert ammonium from wastewater into nitrates, denitrification reduces nitrate to nitrogen allowing the product to escape in a gaseous state into the atmosphere.

On the other hand, anaerobic processes, also considered fermentative or degrading, are characterized by converting the processed organic matter into compounds of methane and carbon dioxide by bacteria that are responsible for the degradation of solids that reach this stage. In this there is no compound based on oxidants, so the chemical reactions resulting from these processes release a small part of the energy while the remaining energy remains in the methane compound.

 

Tertiary treatment

 

In some cases, there is a third treatment called tertiary, which can be physicochemical or biological in nature. To refine the result of the composition of the effluent, the applied methods will be very variable depending on the origin and destination of the water to be treated.

In all the specified treatments the formation of foam in the liquid is common both by the agitation of the environment due to hydraulic or mechanical processes as well as intentional ventilation. This foam if uncontrolled can generate irregularities in the processes as well as damage the machinery used or produce alterations in the biological purification systems increasing the associated costs and decreasing the productivity of the processes. For this reason, the use of antifoaming agents is common.

Antifoaming agents are chemicals that allow us to control and, if necessary, remove the foam in the treated water to avoid the negative consequences of its appearance or excess in stages where it is not desired. Antifoaming agents are only partially compatible with the medium to be defoamed, so that they spread rapidly at the liquid-gas interface of the bubbles but at the same time are incompatible enough to generate defects in this interface, breaking it and causing the collapse of the bubbles.

Antifoaming agents for water treatment may be needed in a wide variety of industrial sectors. Their composition and formulation will depend on the processes to which the water is subjected and the physicochemical or biological treatments used such as agitation or ventilation, biological reactors, control boxes and collectors, distillation and vacuum systems, etc. The selection of the most suitable antifoam will be made on the basis of the foaming agent, the engineering of the treatment plant and the final quality required in the treated water.

Concentrol has developed the range of antifoaming agents EMULTROL DFM, which includes products designed specifically for wastewater treatment in different industrial sectors.

With decades of experience in a wide range of sectors, Concentrol has extensive knowledge of the wastewater treatment sector. Concentrol’s technical team works together with experts from each industry to get to know their requirements in depth and to be able to propose the solution that best suits their needs.

The EMULTROL DFM range of antifoaming agents is formulated from mineral oils, vegetable oils or silicones. They are formulated with high percentages of active matter, being very effective in the control of foam with very small dosages.

An optimal operation of the facilities and processes is achieved thanks to the technical support, which allows us to configure a solution according to the particularities of each case, and thus achieve considerable economic savings.

 

ReferenceComposition% SolidProperties
Emultrol DFM DV-1 T Antifoam in emulsion with 10% silicone content15Very stable, including dilution with 50% water (1:1)
Emultrol DFM DV-8 PAntifoam in emulsion with 5% silicone content8“Ready-to-use”. Due to the concentration / dilution, it is incorporated very quickly.
Emultrol DFM DV-25 SSilicone-based concentrated antifoam25Needs dilution before use (1:1).
Emultrol DFM AFO-5Antifoam in emulsion based on vegetable oils22100% biodegradable. It does not seal membranes..
Emultrol DFM OLM-14Antifoam based on hydrocarbons100Does not seal membranes.
Emultrol DFM OLM-12 Antifoam based on mineral oils (contains silicone)100Used when silicone antifoaming agents do not work.
Emultrol DFM CP-20Antifoam based on silicone100It is used in dilution, to make antifoaming agents with 5-10% silicone

Concentrol’s extensive track record in additives and experience in antifoaming agents for wastewater treatment enable the company to offer individualized solutions for each situation, based on studies, tests and piloting carried out in Concentrol’s laboratories.