June 20, 2021
Wastewater
Harnessing the Power of Microorganisms in Wastewater Treatment Using Biofilms
Water contamination is one of the major challenges worldwide.
Several factors, such as rapid urbanization, industrialization, population explosion, and changing lifestyle habits, have contributed to the pollution of water bodies and health problems for humans.
In this context, wastewater treatment is of great importance to prevent water contamination and protect the environment.
Biological wastewater treatment has gained much attention in recent years as a powerful method to treat wastewater and its release into the environment.
In this process, the bacterial population breaks down organic waste, transforming it into harmless by-products that do not pollute water bodies or the environment.
For a long time, these powerful microorganisms have been characterized as planktonic and freely suspended cells.
However, microbes are present as multicellular aggregates glued to surfaces and interfaces, forming biofilms.
This gives a better understanding of how microbes work in wastewater treatment.
Understanding Biofilms
Initially, biofilms were identified as physical objects or deposits of microorganisms on surfaces or as homogenous cells in slime.
By the 1960s, scientists and researchers defined it as “a structured community of microorganisms encapsulated within a self-developed polymeric matrix and adherent to a living or inert surface.”
In simple terms, a biofilm is a community of microorganisms or a cluster of microbial cells attached to a surface.
It is a very basic protective environment surrounded and held together by a protective combination of secreted, sugary molecules known as Extracellular Polymeric Substances (EPS).
It is built through communication among microorganisms, which secrete a glue-like substance that creates a sticky surface, allowing them to function as a unit.
Also, they are present in almost all moist environments where they can find enough nutrient flow and achieve surface attachment.
Biofilms in Wastewater Treatment
The wastewater treatment process started in the UK in the late 19th century after it was found that harmful pathogens in the wastewater were causing various dangerous diseases in the country.
The biological plants at that time used biofilms.
Interestingly, the principles of biofilms were established even before the invention of the Activated Sludge Process, which is one of the most prominent forms of wastewater treatment in the world.
Therefore, by the first half of the 20th century, modified biofilms were used in ASP of wastewater treatment.
Various studies and research have been conducted over many decades and continue to be conducted to improve the performance of biological wastewater treatment using biofilms.
Biofilms in wastewater treatment systems are found to be much more efficient and effective than planktonic cells.
Also, wastewater plants provide a continuous flow of food, carbon, and other nutrients in the form of waste, which is a perfect environment for microbes to survive and thrive.
One of the major goals of wastewater treatment is to remove biological nutrients that pollute water bodies and cause eutrophication, leading to fish kills and the destruction of aquatic ecosystems.
Moreover, it can damage the natural environment and affect animal life and the human population.
Thus, harmful nutrients are removed through the activated sludge process, which essentially involves floc.
These flocs are similar to biofilms, with a protective environment formed by EPS and microorganisms.
It is known to break down a wide variety of organic compounds, nitrogen and phosphorus compounds, etc.
Additionally, due to its stickiness, it can capture pathogens, nanoparticles, and heavy metals.
In situations where wastewater systems receive a heavy waste load, biofilms help bacteria recover more quickly and improve treatment.
Developmental Stages of Biofilms in Wastewater Treatment
The development of biofilms is a complex process.
It involves mechanisms such as physiology, genetic expression, and signal-molecule-induced communication through Quorum Sensing.
- Film Formation: In the first stage, a conditioning surface in the wastewater composed of inorganic solutes and organic molecules is attained.
- Initial attachment: In the second stage, bacteria and other microbes use Brownian motion and Chemotaxis to move toward the film surface and thereby establish a connection. Chemotaxis is the movement that guides several microorganisms toward nutrients, enabling them to adsorb to the surface.
- Irreversible Attachment: Extracellular Polymeric Substances start to form in the third stage. Also, EPS successfully binds the bacterial cells to the surface. EPS plays an important role in enhancing the protection and gathering of nutrients for the growth of the bacterial community. Different forces, such as hydrogen bonding, electrostatic forces, and Van der Waals forces, bind bacteria and film together, resulting in an irreversible bonding in the absence of chemical stress.
- Replication and Maturation: The fourth stage involves cell divisions that result in three-dimensional growth of bacterial cells on the biofilm surface, with nutrients obtained from the biofilm. As bacteria grow, microcolonies increase, and some form on the film. The mature films adapt to the wastewater environment, which features fluctuating pH levels, nutrient levels, temperature, etc.
- Dispersion: The last stage occurs when conditions of the wastewater treatment system become very adverse. Consequently, bacteria from the current biofilm community detach themselves and look for more favourable communities.
Advantages of Biofilms in Wastewater Treatment
- Biofilm acts as a shelter for bacteria and protects them from environmental stress and antimicrobial agents.
- Allows for operational flexibility and low retention times
- Increase in the residence time for biomass concentrations
- Lower sludge production due to slower microbial growth rates
- Microbes in the biofilm can tolerate extreme changes to the wastewater environment.
Organica Biotech is one of the leading companies that has developed advanced biological treatment solutions for industrial and sewage treatment after years of dedicated research in the field.
Cleanmaxx’s product range includes a robust microbial formulation that helps degrade organic waste and boost the performance of the biological wastewater treatment process.
You can use Cleanmaxx’s range of products to meet the standards for releasing effluent and for protecting the environment.
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