Biological treatment
A key to successful wastewater filtration
Biological wastewater treatment is an ecological and effective method of purifying water using natural processes. This technique involves the transformation of dissolved and suspended organic pollutants into :
- biomass
- and emitted gases (CO2, CH4, N2 and SO2), which can be separated from treated water.
These gases can then be separated from the treated water, guaranteeing cleaner, less polluted water. In addition, it is designed to break down the pollutants dissolved in the effluent by the action of micro-organisms. These micro-organisms then use these substances to live and reproduce with the pollutants as nutrients.
So not only do they purify the water, they also contribute to a healthy aquatic ecosystem.
What is the purpose of biological treatment?
First of all, you need to know the meaning of the acronym MBBR. This is the Moving Bed Biofilm Reactor.
It is a biological process for the treatment of pollutants through a modular system of fixed cultures. The process is therefore compartmentalised in the same way as our digestive system, so that the water to be treated can be treated in stages.
These steps include:
- denitrification
- carbon elimination
MBBR purification in various stages is based on the distribution of bacteria in different compartments. In addition, MBBR can be used for the treatment of carbon and nitrogen pollution in :
- municipal environments
- and industrial settings
How does biological treatment work?
MBBR is a simple, effective technique for treating municipal or industrial wastewater from :
- biological matter (BOD)
- ammonia and nitrogen
Biological treatment is advantageous because it optimizes treatment capacity while using less energy. The consequence is that not only the environmental impact but also the price of such an operation is reduced.
This technology then uses a compartmentalisation system to treat the water in a fragmented way:
- Micro-organisms (often bacteria) transform the chemical pollutants in the water.
- The water passes through a raw sewage system that filters out the major pollutants.
- The water, freed from its macro-waste, will then be sent to a tank (equalization tank).
- In this tank, the water is mixed to achieve a uniform consistency. This facilitates rapid processing in subsequent stages, thanks to the bacteria present.
Biological treatment operating step 1
Once the water has been thoroughly mixed, it is directed into the first tank. This is where the key micro-organisms in MBBR technology come in. are involved.
Moreover, to be active and functional, these micro-organisms require three essential needs.
Support
A support or substrate will serve as a medium for the bacteria where they can survive and grow. Also called media, this support can be of several natures.
At 1h2o3, we prefer activated carbons, as they offer many advantages.
This is because they can support many bacteria and therefore have a faster action at large scales. In addition, these charcoals provide energy space savings, but also money.
Food requirement
They also need food to ensure their survival and development. This will therefore be the organic matter present in the water.
In fact, it will be consumed by our bacteria to proliferate and have a more efficient action, while guaranteeing purification of the water to be treated.
Oxygen demand
To ensure the degradation of organic matter (BOD), aerobic bacteria must have access to a source of oxygen. This is in order to achieve the right chemical reaction. This means aerobic cellular respiration. There is therefore a “blower” capable of sending air into tank 1. His action will have a double purpose. It will :
- renew the oxygen present in the treated water
- allow the bacteria to carry out their purification
- to encourage mixing of the water inside the tank
- increase the interactions of bacteria with their environment.
The quantity of air injected into the tank must be correctly assessed and will depend on the number of active bacteria and therefore the quantity of water to be treated.
Biological treatment operating step 2
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MBBR 2N-M.N-S
Biological treatment
After prolonged exposure to the action of the bacteria in tank 1, the bacteria will be transferred to tank 2. This tank n°2 will then have a very similar action to that of tank n°1. The water then passes through a lamella column, separating sludge and water for final purification.
After treatment, the sludge is transferred to a special tank. If they meet certain standards, they can be recycled as soil improver or land application sludge. If not, they are incinerated, and the treated water then passes through a sand filter to eliminate any remaining residue.
The treated water is sent to a pressurised sand filter to remove the last residues.
It will be sent directly to an activated carbon filter. The activated carbon will then absorb a wide variety of pollutants present in the wastewater.
To ensure optimum water purification, a final filtration stage targets key elements such as :
- COD and BOD
- mineral oils
- hydrocarbons
- pesticides
- persistent organic pollutants, etc.
Finally, to eliminate any pathogens that may be present in the water, a UV disinfection unit is used. These rays destroy the DNA of germs, neutralizing them.
After this final stage, the water is stored in a tank for reuse. The major advantage of this method is its flexibility. It is adapting to the growing need to treat increasingly polluted water.
What is bioremediation
Bio-remediation is a technology based on the use of micro-organisms to purify various media. It has proved effective time and again in a variety of situations and fields. Actually, it allows to decontaminate :
- soils
- groundwater
- environmental disasters in the oceans
The micro-organisms used in the bio-remediation process can be of several kinds, in order to ensure the widest possible range of action.
What are the two types of bioremediation?
Microbial bioremediation uses microorganisms to break down contaminants using them as a food source.
- Phytoremediation uses plants to capture and eliminate various pollutants, such as pesticides or metals.
- Mycoremediation uses fungi to break down harmful substances with their enzymes.
There are several organizations that specialize in the remediation of environmental pollutants.
As we explore bio-remediation further, it is important to note that the domains affected are not limited to the environmental domain, but also to the health and safety domain.
Which bacteria are used for bioremediation
Biodiversity offers a variety of micro-organisms that can treat a wide range of pollutants using biological treatment. Substances such as arsenic, cadmium and mercury lose their harmfulness thanks to these organisms. It’s the power of nature at the service of pollution control.
However, it is first necessary to identify these different organizations and find the function they perform. Their function varies according to environmental conditions, such as temperature or pH. Drawing up a complete list of these organisms is a challenge, given their diversity and adaptability.
