Bacteria and micro-organisms involved in water treatment

What are they used for?

The biological method purifies wastewater and remains the most widely used treatment process worldwide. This technology relies on the action of bacteria and other microorganisms to decontaminate polluted water. These organisms feed on organic waste, converting it into energy to grow and reproduce.

This process is essential for human health and environmental protection. Wastewater treatment plants, by concentrating bacteria in a small area, can treat pollution much more efficiently than a natural environment such as a river. By controlling this biological process, we can prevent eutrophication and the spread of disease.

Domestic wastewater and industrial discharges are the main sources that need to be treated. Thanks to microorganisms, these effluents can be recycled, making environmentally friendly sanitation possible. These bacteria are the true invisible agents behind the cleaning of our water.

In summary: a wastewater treatment plant operates like a microbe farm, cultivating these organisms to clean water on a large scale. This process highlights the vital role of microorganisms in our modern world.

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Where are bacteria present?

Bacteria are present at every stage of wastewater treatment. Depending on their environment, they form specific structures such as flocs or biofilms, which play a key role in breaking down pollutants. The table below summarizes where they are found, in what form, and what function they serve.

Où ?Comment ?Rôle
Bassins d’aérationFlocs (amas visibles dans les cultures libres)Dégradation de la matière organique en suspension
Milieux fixés (biofiltres, disques biologiques)Biofilms (couches adhérentes sur support solide)Traitement continu des polluants sur les surfaces
Sortie de traitementPrésence résiduelle de microbesÉliminés par UV ou chloration avant rejet
bactéries sur site 2 x 1m3 bacteries bacteria - 1H2O3
Culture batch bacteria on site 2 x 1m3 bacteria - 1H2O3

Who are these micro-organisms?

Production bactéries mésophiles 1 souche pure par bouteille bacteries bacteria - 1H2O3
Mesophilic bacterial production 1 pure strain per bottle bacteries bacteria - 1H2O3

Parameters influencing the growth of micro-organisms

First of all, before we can understand the different types of micro-organisms, we need to understand the parameters that influence their growth. In microbiology, we study how bacteria and microbes react to these factors, which are important for their effective development. Firstly, geographical location plays a crucial role in the composition of the polluted water treated by the plant. Secondly, the type of tank in which the cleaning bacteria are grown has a significant impact on their growth. Thirdly, the characteristics of the domestic wastewater influence the microbial composition and the decontamination processes required. Finally, the operating parameters of the system, such as aeration and agitation, modify the growth of the micro-organisms. These factors cause quantitative changes between autotrophic and heterotrophic bacteria, influencing the extent of treatment. For example, grey water recycling depends on the effectiveness of these well-balanced and controlled microbiological processes. It is useful to outline the names of the methods used to better understand their specific application.

Bacteria present in wastewater treatment plants

In municipal wastewater treatment plants, Gram-negative bacteria, particularly proteobacteria, predominate, accounting for between 21 and 65% of micro-organisms. Microbiology shows how the abundant Betaproteobacteria class plays a major role in the elimination of organic elements and nutrients. Other important phyla include Bacteroidetes, Acidobacteria, Chloroflexi, and contribute to the decontamination of polluted water. The most numerous types of bacteria, considered to be microbial cleaners, are Tetrasphaera, Trichococcus, Candidatus Microthrix, Rhodoferax, Rhodobacter, and Hyphomicrobium. Each name of these bacteria illustrates their importance and crucial role in the recycling of domestic wastewater. These examples show how micro-organisms contribute to the purification of grey water, demonstrating their usefulness for the environment.

Other micro-organisms: fungi and archaea

Among the fungi studied in microbiology, Ascomycetes are the most abundant, accounting for 6.3 to 7.4% of micro-organisms. It is interesting to note how these fungi react to polluted environments. Archaeobacteria, often seen as natural cleaners, particularly Euryarcheota, make up around 1.5% of the micro-organisms present. The importance of these micro-organisms is crucial in different environments and during decontamination processes. These microbes play a vital role, especially in the presence of ammonia and oxygen, where Nitrosomonas is very present. Among the examples of specific micro-organisms, the name Nitrosomonas often comes up because of its key role in recycling. These micro-organisms also contribute to the treatment of grey and domestic water in a variety of contexts. It is useful to outline these processes to better understand their ecological importance.

The impact of temperature and location

Temperature influences the presence of certain species, and geographical location also affects species composition. In microbiology, it is important to understand how these factors influence polluted water and its treatment. In industry, the dominance of specific micro-organisms is explained by their ability to biodegrade components of industrial wastewater. These micro-organisms act as natural cleaners, which are crucial to the decontamination of polluted water. Their ability to adapt to different environments enables these microbes to recycle grey water effectively. Domestic species exposed to these conditions are proving their usefulness in the treatment of industrial wastewater. For example, understanding the names of adapted species can improve decontamination processes.

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Classification of bacteria according to how they obtain oxygen

In microbiology, bacteria are classified according to how they obtain the oxygen they need to survive in polluted water. In wastewater treatment, there are three types of bacteria: aerobic, anaerobic and facultative. These bacteria act as biological cleaners, essential for effective decontamination and recycling of domestic grey water. Their importance lies in their ability to adapt to different environments to eliminate harmful microbes. Among the examples of these bacteria, each name reflects their specific function in the purification process. It is useful to outline these processes to better understand their crucial role in wastewater purification.

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Impact of microbial imbalances on treatment systems

The presence of bad bacteria or the absence of good strains can cause problems in polluted treatment systems. These problems include:

  • Low biogas yield from the anaerobic digester: Bad bacteria can reduce the efficiency of biogas production, compromising the recycling of organic matter.
  • Poor flocculation and sedimentation: This can lead to poor separation of solids and liquids, affecting the overall decontamination of the system.
  • Excess of filamentous bacteria: Can cause flotation problems and equipment clogging, exposing installations to the risk of breakdown.
  • Excess phosphorus: Can lead to eutrophication of receiving waters, compromising the importance of environmental prevention measures.
  • Low nitrogen removal efficiency (NH4, NO3) : Causes water pollution with high levels of nutrients, affecting treated grey and domestic water.
  • Production of unpleasant odours: Generated by undesirable bacteria, illustrating how a microbial imbalance can impact the environment.
  • Excess consumption of chemical reagents: To compensate for microbial imbalances.
  • Production of foam in an anaerobic digester: Can lead to malfunctions and loss of capacity, limiting the treatment of domestic wastewater.

Solutions for restoring effective treatment

There are generally three ways to restore good treatment:

  1. Modification of operating settings: By adjusting the parameters, we can allow the right strains to naturally recolonise the polluted environment.
  2. Complete elimination of micro-organisms in place: When the first solution fails, this method can be considered. However, it is not recommended, as the biomass will take several days to develop, delaying treatment.
  3. Injection of selected bacteria: This solution involves introducing bacteria that have been cultivated and multiplied to take advantage of the undesirable bacteria present. This decontamination process is essential to guarantee the effectiveness of treatment systems and environmental protection.
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Frequent applications

Microbial biotechnology offers innovative scientific applications of great ecological and economic interest. It makes effective use of natural decontamination processes to treat polluted water. This method is much less costly than conventional physico-chemical or mechanical techniques, demonstrating the importance of sustainable solutions.

How bacteria differ from conventional treatment methods lies in their ability to use simple natural processes. They act as natural cleaners, treating pollution without creating new contamination. Most of the time, they require a bioreactor and the nutrients they need to multiply in large numbers. Dosage is easy and requires only a short operating time, useful for rapid treatment of domestic wastewater. These systems can also be adapted to recycle grey water, thus preventing future contamination problems. Explaining these advantages is essential to understanding the importance of integrating such technologies into modern infrastructures.

Accelerate plant startup / Get a quick start on bacterial seeding for a mobile plant

The colonization of a medium by the necessary bacteria and microorganisms required for depollution generally takes between 4 and 8 weeks. Once again, it is the temperature that has the greatest impact on this growth time.

There are some solutions to reduce this delay to about a week, thanks to the seeding with selected and multiplied bacteria. There are two major benefits here:

  • Reduce the start-up time of a wastewater treatment plant
  • Accelerate the start-up of a mobile processing unit (e. g. in case of accident at the main plant)

The technique is based on the recirculation of a clever mixture of adapted substrate and bacteria selected so that they settle in very quickly. Under these favorable conditions, bacteria rapidly form flocs or biofilms. After a few days, the environment is ready for wastewater discharge.
We’ve selected a range of bacteria to get your plant up and running in a week under normal conditions, with water temperatures between 12 and 30°C.

The design is available on the microbiological optimization page.

Solving the presence of undesirable bacteria

In activated sludge plants, the presence of filamentous bacteria is a real problem. First, the solution is to remove as much mud as possible, and to increase aeration. The recuperation of the environment by the good bacteria can put back several days. If this does not work, then it is possible to destroy these bacteria with chlorine. The problem is that this kills all the bacteria. Und dann wird es ein paar Wochen dauern, bis wieder normale Bedingungen herrschen.

While most operators continue to inject chlorine, we suggest the injection of dedicated bacteria. Like accelerated factory starting, the massive addition of these good populations quickly restores the balance in the ponds.

For example, here is an illustration of the removal of floats in a clarifier.

The design is available on the microbiological optimization page.

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Elimination of pathogenic germs

The microbiological quality of treated water is crucial to public health and environmental protection. When treating wastewater, the elimination of pathogenic germs, such as bacteria, viruses and protozoa, is an essential step in ensuring that the water is safe for reuse or discharge into the environment.

Pathogenic germs in waste water can cause serious illness if the water is not treated properly. Here are some of the methods commonly used to eliminate these dangerous micro-organisms:

  • Chlorination: Adding chlorine to water destroys pathogenic germs. However, this method can leave behind chemical residues and generate potentially harmful by-products.
  • UV disinfection: The use of ultraviolet (UV) light is an effective method of destroying micro-organisms without leaving chemical residues. UV disinfection systems, such as those offered by 1h2o3, use the germicidal effect of UVc rays to eliminate microbes, viruses, bacteria, fungi and algae present in water.
  • Ozonation: Ozone is a powerful oxidising agent that destroys micro-organisms by oxidation. This method is effective but requires complex management and higher operating costs.

How to improve treatment efficiency:

By eliminating the fats and oils responsible for the habitat degradation

Lipophilic bacteria are specialized in the degradation of animal and vegetable fats and oils in urban WWTPs and industrial treatment plant. These bacteria are easily adaptable to all current treatment systems.

On the market, there are products such as completely natural bacteria and enzymes, designed and selected for their ability to solubilize and digest grease and mud. Some bacteria are so specialised in fat degradation that they are capable of degrading high loads, up to 300,000 mg/L of COD.

The design is available on the microbiological optimization page.

By increasing the presence of good bacteria

As expected, the technique of injecting a mixture of suitable substrate and selected bacteria is still the most effective. Therefore, the rapid adsorption of these products in the environment allows to improve the efficiency of the following systems:

  • Activated sludge (fine-bubble aeration)
  • Natural and artificial lagoons and ponds
  • Biofiltres
  • Thrickling filter
  • Rotating biological contactors

The design is available on the microbiological optimization page.

By adding bacteria for the treatment of cold or hot water

The majority of micro-organisms generally develop more rapidly at high temperatures, up to 38°c max. However, their development becomes very slow below 12 ° C, or almost nul below 5 ° C. These low temperatures are often reached when sewage treatment plants are located in geographic areas such as Canada or northern Europe. When the snow melts, these bacteria have to deal with the pollution in cold water. The main solution is to significantly increase the size of the plant to compensate for the lack of microbial activity. However, this solution, which is still widely practiced, is very expensive.

On the contrary, some industrial processes generate water temperatures in excess of 38°C. The most common bacteria cannot survive in these conditions.

That’s why there are mixtures of bacteria that are effective in treating different types of water. In this way, before a cold event for example, it is possible to inoculate the biological reactor with bacteria specially selected for these conditions. They will then overtake the existing populations, and ensure effective treatment of these difficult conditions.

We have a selection of bacteria for these difficult conditions:

  • cold waters (between 1°C and 12°C),
  • warm waters (between 30°C and 50°C or more)

The design is available on the microbiological optimization page.

Design tools

In the Tools section, you will find all the mathematical and cost information that will allow you to estimate a project.

FAQ

What are the main types of micro-organisms?

There are several families of micro-organisms: bacteria, which are widespread living cells; viruses, infectious particles that need a host cell to multiply; microscopic fungi, such as yeasts and moulds; protozoa, which are often mobile and found in aquatic environments; and micro-algae, which are capable of photosynthesis. Each plays a specific role in the environment or in technical processes such as water treatment or energy production.

A micro-organism is the scientific term for any living thing that is invisible to the naked eye: bacteria, yeast, fungi, etc. The word microbe is more common and is often used to designate these same beings, but with a connotation of nuisance. Finally, germ is a medical term for any infectious agent, whether bacterial, viral or parasitic. These words therefore refer to similar realities, but in different contexts.

Not at all. While some are pathogenic, such as those responsible for food or respiratory infections, the majority of bacteria are harmless or even essential. In water treatment plants, they are chosen for their ability to break down organic pollutants. Others live in our intestines, helping us to digest or being used to produce yoghurt, cheese or medicines. Bacteria are therefore both allies and threats, depending on their nature and use.

Synthetic biology is a branch of science that involves designing or modifying micro-organisms to give them specific functions. For example, bacteria can be reprogrammed to produce insulin, bioplastics or to clean up an environment. This is a fast-growing field that offers innovative solutions, drawing on and optimising the natural capabilities of micro-organisms.

Because each type of micro-organism has a precise and complementary role. Aerobic bacteria transform organic matter in the presence of oxygen, while anaerobic bacteria do so in a closed environment. Protozoa regulate the bacterial population and improve water clarity. In some advanced processes, fungi or algae are also used. This biological diversity means that the treatment is more effective, stable and adapted to the type of pollution encountered.

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