What Can Microbes Do for You? Part I

Speeding Up Mother Nature with Microbiology

After more than 20 years working in the environmental industry, one of the most common questions I have been asked is:

“What can microbes do for me?”

A better question may be: What treatment objective do you want microorganisms to accomplish?

Microorganisms play an essential role in natural biological processes. Different microbial populations can break down a wide range of organic materials and contaminants when the appropriate organisms and environmental conditions are present.

Using Microorganisms for Environmental Remediation

In environmental cleanup and wastewater treatment, microbial performance depends on several important factors, including:

  • Microbial population

  • Microbial diversity

  • Temperature

  • pH

  • Available nutrients

  • Oxygen conditions

  • Treatment time

Biological treatment is not always an immediate solution. Some microbial processes require days, weeks, or even months to achieve the desired result.

However, when sufficient treatment time is available, biological remediation can provide a practical and potentially cost-effective alternative to more intensive mechanical or chemical treatment methods.

Bioaugmentation and Biostimulation

Natural microbial communities have been breaking down organic material for millions of years.

Modern biological treatment strategies can help accelerate these natural processes through bioaugmentation and biostimulation.

Bioaugmentation

Bioaugmentation involves introducing additional or specialized microorganisms into a wastewater or environmental system.

This approach can help increase the population or diversity of microorganisms needed for a specific treatment objective.

Biostimulation

Biostimulation focuses on improving conditions for microorganisms already present in the system.

This may involve supplying carbon, nutrients, oxygen, or other materials that help indigenous microbial populations grow and perform more effectively.

Both strategies can be used to support biological wastewater treatment, environmental remediation, and contaminant degradation.

Sources of Bacteria in Wastewater Treatment

Wastewater treatment systems naturally contain many microorganisms, but the existing microbial population may not always be sufficient for every treatment objective.

Human waste contributes significant microbial populations to municipal wastewater. Inflow and infiltration (I&I), industrial discharges, soil, runoff, and other sources can introduce additional microorganisms.

However, complex wastewater treatment processes often depend on specialized microbial communities.

These processes may include:

  • Nitrification

  • Denitrification

  • Phosphorus accumulation

  • Cellulose degradation

  • Petroleum hydrocarbon degradation

  • Food-based oil and grease degradation

  • Breakdown of certain fertilizers, pesticides, and herbicides

Relying solely on the microorganisms naturally entering a wastewater system may not always provide the abundance or diversity needed to maintain efficient treatment.

Specialized Microbiology for Emerging Wastewater Contaminants

Modern wastewater can contain a wide variety of chemicals and organic compounds from households, businesses, agriculture, industry, pharmaceuticals, and personal care products.

These compounds may include:

  • Pharmaceutical residues

  • Personal care product compounds

  • Hydrocarbons

  • Pesticides and herbicides

  • Fertilizer-related compounds

  • Sterols and other organic contaminants

Because different microorganisms perform different biological functions, maintaining a diverse and active microbial community can be important for treating increasingly complex wastewater.

Bioaugmentation and biostimulation provide wastewater operators with additional tools for supporting microbial populations when natural biology alone is not meeting treatment objectives.

Figure 1. A close-up image of microbial bacteria that is responsible for reducing compounds in wastewater systems. Image retrieved from https://www.conservationmagazine.org/2013/12/10-ways-microbes-save-world/

What Microorganisms Need to Succeed

Selecting the right bacteria for a wastewater treatment or bioremediation process can be challenging.

Different microorganisms perform different biological functions, so maintaining a diverse microbial community can be important for effective treatment. In many cases, a single bacterial species cannot complete the entire degradation or nutrient-removal process.

This is why microbial diversity plays such an important role in biological wastewater treatment.

Microbial Diversity in Nitrification and Denitrification

The nitrification and denitrification process is a good example of why multiple microbial populations are needed.

During nitrification, specialized bacteria convert ammonia into nitrite and then nitrate under aerobic conditions.

During denitrification, other microorganisms convert nitrate into nitrogen gas under anoxic conditions.

These processes require different:

  • Microbial populations

  • Oxygen conditions

  • Nutrient sources

  • Environmental conditions

  • Contact times

Managing these variables adds complexity to biological nutrient removal and wastewater treatment.

Biological Phosphorus Removal

Biological phosphorus removal also depends on specialized microorganisms known as phosphorus-accumulating organisms (PAOs).

PAOs are exposed to alternating anaerobic and aerobic conditions as part of the treatment process.

During the anaerobic phase, PAOs release stored phosphorus while taking up readily available carbon compounds. When they later enter an aerobic environment, they absorb phosphorus in amounts greater than what they previously released.

This process allows phosphorus to become concentrated within the biomass, where it can be removed from the wastewater through solids wasting.

Managing Contaminants and Biological Byproducts

The goal of biological wastewater treatment is to maximize the degradation or removal of unwanted compounds while managing the byproducts produced during microbial metabolism.

Different contaminants follow different biological pathways.

For example, microorganisms can help break down:

  • Fats, oils, and grease (FOG)

  • Petroleum hydrocarbons

  • Cellulose and other organic solids

  • Proteins and carbohydrates

  • Ammonia

  • Nitrogen compounds

  • Phosphorus

  • Other biodegradable organic materials

Some compounds are relatively easy for microorganisms to metabolize, while more complex contaminants may require greater microbial diversity, longer contact times, or carefully controlled environmental conditions.

Understanding the Role of Bacteria in Wastewater Treatment

Wastewater treatment plants are essentially engineered environments designed to provide microorganisms with the conditions they need to perform biological treatment.

Activated sludge basins, biofilm systems, lagoons, digesters, and other treatment processes provide habitats where microorganisms can grow and break down wastewater contaminants.

Without microbial activity, many wastewater treatment processes would provide only physical separation rather than true biological degradation and nutrient removal.

What Are Microorganisms Treating in Wastewater?

Wastewater contains a complex mixture of organic and inorganic materials.

These may include:

  • Cellulose and paper products

  • Human waste

  • Food residues

  • Fats, oils, and grease

  • Dead microbial biomass

  • Nutrients

  • Industrial chemicals

  • Other biodegradable organic compounds

Many of these materials contribute to biochemical oxygen demand (BOD), nutrient loading, and solids accumulation.

Microorganisms help convert biodegradable organic matter into simpler compounds, additional biomass, and metabolic end products.

Creating the Right Environment for Wastewater Bacteria

Successful biological treatment depends on having the right microorganisms in the right environment at the right time.

Microorganisms generally require:

  • An appropriate food source

  • Adequate nutrients

  • Suitable temperature and pH

  • The correct oxygen