Pollutant-Eating Sewage Bacteria Offer Hope for Environmental Cleanup

How Enzyme-Driven Microbial Communities are Revolutionising Wastewater Bioremediation

At Bioglobe, we have long championed the use of enzymes for sewage remediation — not just because of their efficiency and specificity, but because they represent a fundamentally organic approach to some of the most pressing environmental challenges of our time. Among the most exciting recent developments in the field is the discovery, highlighted by Chemical & Engineering News, that specific bacteria in sewage sludge are capable of detoxifying harmful chlorinated solvents such as tetrachloroethene (PCE). These bacteria, equipped with powerful enzymatic machinery, offer tremendous promise in transforming highly toxic pollutants into environmentally benign substances.

This article explores the science behind these microbial agents, the enzymatic processes they rely on, and how such discoveries align with Bioglobe’s mission to harness nature’s tools for sustainable sewage and wastewater treatment.

The Problem: Chlorinated Solvents in Wastewater

Chlorinated solvents, particularly tetrachloroethene (PCE) and trichloroethene (TCE), are a class of synthetic chemicals widely used in dry cleaning, degreasing, and various industrial applications. Although effective in their intended roles, these compounds are notoriously persistent in the environment and highly toxic to both ecosystems and human health.

These solvents often make their way into municipal wastewater systems through improper disposal, industrial discharge, or leaching from contaminated soils. Once in the sewage sludge, they pose a significant challenge for conventional treatment plants, which are primarily designed to handle organic waste, pathogens, and nutrients, not complex industrial chemicals.

Exposure to even trace amounts of PCE and TCE is linked to neurological effects, liver damage, and increased risk of cancer. Their presence in effluent and sludge requires urgent attention and advanced solutions.

The Biological Solution: Bacteria That Eat Pollutants

The good news is that nature may already hold the key to detoxifying these stubborn compounds. A growing body of research has shown that certain anaerobic bacteria, found naturally in sewage sludge, possess the remarkable ability to break down chlorinated solvents through a process known as reductive dechlorination.

What Is Reductive Dechlorination?

Reductive dechlorination is a type of anaerobic respiration. Instead of using oxygen as a terminal electron acceptor, these bacteria use chlorinated solvents like PCE. As they “breathe,” they remove chlorine atoms from the solvent molecules, gradually converting them into less chlorinated and less toxic forms — and eventually into non-toxic end-products like ethene or ethane.

For example, tetrachloroethene (PCE) can be broken down step-by-step:

• PCE → TCE → DCE (cis-dichloroethene) → VC (vinyl chloride) → Ethene

Each step is catalysed by specific enzymes known as reductive dehalogenases, which are produced by the bacteria as part of their metabolic activity.

Key Players: The Microbial Communities Behind the Chemistry

Among the most prominent bacteria involved in this process are members of the Dehalococcoides genus. These bacteria have been widely studied for their role in bioremediation of chlorinated solvents in groundwater and soil, and now their presence in sewage sludge is generating new excitement for wastewater treatment applications.

Other bacteria of interest include:

• Desulfitobacterium spp.
• Geobacter spp.
• Dehalobacter spp.

Each of these organisms has been found in anaerobic zones of sewage sludge, where they form part of a broader microbial community that includes methanogens, fermenters, and sulphate-reducing bacteria. These communities often work synergistically, with one group creating favourable conditions for another — for instance, by producing hydrogen, which serves as an electron donor for reductive dechlorination.

Enzymes at the Heart of the Process

The core of this biochemical process lies in specialised enzymes called reductive dehalogenases. These are complex proteins embedded in the bacterial cell membrane and often contain metal cofactors such as iron-sulphur clusters and corrinoids (vitamin B12 derivatives), which are essential for their catalytic activity.

These enzymes enable the bacteria to:

• Recognise and bind chlorinated compounds
• Strip away chlorine atoms through electron transfer
• Stabilise intermediate molecules until full detoxification is complete

Importantly, the genes coding for these enzymes are often clustered in operons, allowing bacteria to quickly adapt to environments rich in chlorinated solvents by switching on relevant genetic pathways.

Implications for Bioglobe and the Future of Wastewater Treatment

At Bioglobe, our goal is to provide nature-based, enzyme-driven solutions for sewage remediation that are both effective and sustainable. The discovery that these bacterial communities can actively detoxify some of the most stubborn pollutants known to modern industry is a validation of our approach.

The benefits of integrating these microbial and enzymatic systems into Bioglobe’s technologies include:

1. Targeted Detoxification of Industrial Waste

Traditional methods often require costly, energy-intensive chemical treatments to neutralise solvents like PCE. By supporting natural microbial processes, we can achieve the same outcomes more efficiently and with fewer secondary pollutants.

2. In Situ Remediation

Rather than removing sludge or soil for off-site treatment, microbial remediation can occur within existing infrastructure. This lowers logistical costs and minimises environmental disruption.

3. Synergy with Enzyme Products

Bioglobe’s proprietary enzyme blends could be enhanced or tailored to support these bacteria — for example, by supplying co-factors, maintaining optimal pH, or removing competitive inhibitors.

4. Enhanced Biogas Production

As an added benefit, these bacteria often coexist with methanogenic archaea, which convert fermentation by-products into methane — a renewable energy source. Cleaner sludge can therefore also mean better biogas yields.

Real-World Applications and Case Studies

The principles of microbial dechlorination are already being applied in environmental cleanup projects around the world, particularly for groundwater remediation. However, their application in municipal wastewater treatment is still emerging.

Example: Groundwater Remediation in California

A well-documented case involved Dehalococcoides-based bioremediation of a PCE-contaminated aquifer in California. Through bioaugmentation (the addition of specific bacterial cultures), researchers successfully reduced PCE concentrations by over 90% within 12 months.

Potential for Adaptation in Sewage Systems

By drawing from these successes, Bioglobe could pioneer the adaptation of such technologies for use in:

• Anaerobic digesters
• Sludge holding tanks
• Effluent polishing systems

Combining microbial detoxification with enzyme-enhanced treatment opens up exciting avenues for comprehensive pollution control.

Challenges and Considerations

Despite its promise, microbial bioremediation of chlorinated solvents comes with challenges:

1. Controlling Environmental Conditions

The bacteria require very specific conditions to thrive: anaerobic environments, stable temperatures, appropriate pH, and sufficient electron donors.

2. Slow Degradation Rates

The breakdown of solvents like PCE may take weeks or even months depending on concentration and conditions.

3. Toxic Intermediates

Some intermediate compounds, such as vinyl chloride (VC), are more toxic than their precursors. Ensuring complete dechlorination is essential.

4. Bioaugmentation vs. Biostimulation

Deciding whether to introduce external bacteria (bioaugmentation) or simply stimulate native populations (biostimulation) requires site-specific research and testing.

At Bioglobe, we are actively developing protocols to overcome these challenges using a combination of enzyme supplementation, microbial community analysis, and process optimisation.

Research Directions and Future Outlook

The field of microbial bioremediation is evolving rapidly, with ongoing research into:

• Synthetic biology to engineer enhanced bacteria
• Genomic sequencing to identify optimal microbial communities
• Metabolic modelling to predict and control reaction pathways
• Enzyme immobilisation to improve stability and reusability

As we deepen our understanding of microbial ecology in sewage sludge, we expect new discoveries to enhance the reliability and scalability of this approach.

Bioglobe’s Role in a Cleaner Future

Bioglobe is uniquely positioned to bring this innovation into mainstream wastewater treatment. By integrating microbial detoxification with our existing enzyme systems, we aim to offer:

• Turnkey solutions for municipalities and industry
• Modular systems for on-site treatment
• Training and support for operational staff
• Ongoing R&D to refine and expand capabilities

We believe that the key to solving complex environmental problems lies not in brute force chemistry, but in listening to and learning from the natural world. These pollutant-eating bacteria are not just passive agents of decay — they are skilled biochemical engineers, quietly cleaning up our mess.

Conclusion

The discovery that sewage-dwelling bacteria can degrade harmful chlorinated solvents using enzymes offers a compelling vision for the future of bioremediation. By harnessing these natural processes and integrating them with cutting-edge enzyme technology, Bioglobe can take another step toward its goal of transforming raw sewage into clean, safe water.

As regulatory standards tighten and environmental awareness grows, such solutions will no longer be optional — they will be essential. At Bioglobe, we are committed to staying at the forefront of this transformation, developing systems that are not only effective and economical but also environmentally respectful.

In the world of wastewater, every molecule matters. With the help of nature’s own detoxifiers, we’re ensuring that each drop we return to the world is purer than it was before.

To learn more about our work or to discuss how Bioglobe can support your wastewater treatment needs, please visit www.bioglobe.co.uk or contact our team directly.

Bioglobe offer Enzyme pollution remediation for major oil-spills, oceans and coastal waters, marinas and inland water, sewage and nitrate remediation and also agriculture and brown-field sites, globally.

For further information:
BioGlobe LTD (UK),
22 Highfield Street,
Leicester LE2 1AB
Phone: +44(0) 116 4736303| Email: info@bioglobe.co.uk