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 to 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 is used to break down and degrade organic waste and transform them into harmless by-products that do not pollute the water bodies or the environment. These powerful microorganisms, for a long time, have been characterized as plank tonic and freely suspended cells. However, microbes are present in the form of multi-cellular aggregates glued together in surfaces and interfaces known as biofilms. This gives a better understanding of how microbes work in wastewater treatment.

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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 that is surrounded and held together with a protective combination of sugary secreted molecules known as Extracellular Polymeric Substances ( EPS ). It is built through communications among microorganisms and they secrete a glue-like substance resulting in a sticky surface allowing microorganisms to function as a unit. Also, they are present in almost all moist environment 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 are 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 the wastewater treatment process 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 has been conducted over many decades and continues to happen to boost the performance of biological wastewater treatment using biofilms. 

Also Read: The Role Of Clarifiers In Wastewater Treatment Plants

Biofilms in wastewater treatment systems are found to be much more efficient and effective than plank tonic cells. Also, wastewater plants provide a continuous flow of food in the form of carbon and other nutrients present in the waste which is a perfect environment for microbes to survive and thrive. 

One of the major goals of the wastewater treatment process is to remove biological nutrients as they pollute water bodies and cause eutrophication, leading to fish kills and the destruction of the aquatic ecosystem. Moreover, it can damage the natural environment and affect animal life and the human population. Thus, dangerous nutrients are removed through the activated sludge process which are essentially floc. These floc are the same as biofilms having a protective environment formed with EPS and microorganisms. It is known to break down a wide variety of organic compounds, nitrogen and phosphorus compounds etc. Additionally, due to its sticky characteristic, it is capable of capturing pathogens, nano particles and also heavy metals. In situations where wastewater systems receive extensive waste load, biofilms help bacteria to recover faster and boosts the treatment process. 

Developmental Stages of Biofilms in Wastewater Treatment

The development of biofilms is a complex process. It involves mechanisms like physiology, genetic genotype expression and signal molecule induced communication through Quorum Sensing

1)Film Formation: In the first stage, a conditioning surface in the wastewater composed of inorganic solutes and organic molecules is attained. 

2)Initial attachment: In the second stage, bacteria and other microbes use Brownian motion and Chemotaxis to move towards the film surface and thereby establishes a connection. Chemotaxis is the movement that guides several microorganisms toward nutrients for adsorption onto the surface. 

3)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 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. 

4) Replication and Maturation: The fourth stage constitutes cell divisions that result in a three-dimensional growth of bacterial cells on the surface through nutrients obtained from the biofilm surface. As bacteria grows, micro-colonies increase and a surface of it forms on the film. The mature films adapt to the wastewater environment with fluctuating pH levels, nutrients, temperature etc. 

5) 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.

Dispersion stage
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 residing 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 which has developed advanced biological treatment solutions for industrial and sewage treatment after years of dedicated research in the field. Cleanmaxx range of products consists of a robust microbial formulation that helps in the degradation of organic waste and boosts the performance of the biological wastewater treatment process. You can use Cleanmaxx range of products to meet the standards for releasing effluent and protect the environment as well. 

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Post by Lindsey McClure