Enzymes for Cleaner Rivers

Cutting Sewage Pollution with Nature-Based Technology

Executive Summary

The United Kingdom has committed to halving sewage pollution by 2030, with the introduction of “Open Monitoring” designed to give the public transparent access to discharge and water quality data. This commitment, coupled with the growing ecological and regulatory urgency surrounding river pollution, has created a new window of opportunity for water companies, regulators, local authorities and innovation partners to adopt more agile, nature-based interventions.
Among these emerging tools, enzyme-based treatments stand out as a promising route for reducing nutrients, fats‑oils‑grease (FOGs), and organic pollutants in both the sewer network and the natural environment. Unlike conventional chemical dosing or mechanical interventions, enzymes use catalysis — a biological process that accelerates natural biochemical reactions — to convert pollutants into biodegradable forms, supporting native microbial populations and restoring ecological balance downstream.

This article explains how enzymatic biocatalysis can be integrated into UK catchment strategies and statutory programmes such as the Water Industry National Environment Programme (WINEP), the Catchment Based Approach (CaBA), and local River Basin Management Plans. It discusses pilot‑ready dosing strategies for Combined Sewer Overflow (CSO) impacted reaches, describes how enzymes can enhance reedbed and wetland performance, and introduces the role of bespoke BioGlobe blends in accelerating compliance while protecting biodiversity. In doing so, it places the technical rationale within the wider policy and data landscape shaped by The Rivers Trust, the Environment Agency, and government targets.

1. Why Enzymes Are Gaining Attention

Enzymes are naturally occurring biological catalysts found in all living organisms. They enable life by speeding up chemical reactions that would otherwise proceed too slowly under environmental conditions. In the context of river and wastewater management, this property offers a powerful advantage: enzymes can help to break down organic pollutants, FOGs, and nutrients in situ, without introducing toxic or persistent chemicals.

Traditional interventions such as aeration, chemical dosing, or physical removal of pollutants can be effective but are often energy‑intensive and expensive. By contrast, enzymatic treatments operate at ambient temperatures and neutral pH — conditions typical of temperate UK water systems. They can therefore be applied directly into sewer networks, storm tanks, CSOs, reedbeds, and ponds with minimal infrastructure and a low carbon footprint.

The overarching concept is to work with nature’s existing pathways rather than impose new ones. Enzymes accelerate the rate at which organic matter decomposes, turning complex chains of molecules into smaller, more degradable fractions that can be metabolised by the resident microbial community. In practical terms, this can translate into measurable reductions in BOD (Biochemical Oxygen Demand), COD (Chemical Oxygen Demand), phosphorus and nitrogen compounds, and visible build‑up of fat or grease.

2. The Policy Context in the UK

Recent years have seen growing public and political focus on sewage discharges and water quality. The Storm Overflow Reduction Plan and the government’s target to halve such pollution by 2030 have established a clear regulatory expectation on water companies. “Open Monitoring” — a commitment to making overflow and quality data accessible in near real‑time — is also reshaping the landscape of accountability.

Alongside these measures, the statutory Water Industry National Environment Programme, or WINEP, lists thousands of actions aimed at improving ecological status in rivers and coastal waters. Water companies must plan and deliver these measures within the regulatory price review cycles. The next cycle (AMP8) places emphasis on innovation, resilience, and outcomes‑based metrics rather than fixed outputs. That shift creates room for biological and pre‑treatment technologies like enzymes to play a complementary role.

The Rivers Trust and other non‑governmental organisations have compiled extensive Event Duration Monitoring (EDM) data, revealing the scale and frequency of sewer overflow events across England and Wales. Many stretches of water now have associated “spill counts” running into hundreds of hours per year. While capital upgrades such as storage tanks and tunnel systems will address some issues, they cannot be built fast enough or affordably enough to deliver the 2030 targets alone. Interim and nature‑based solutions are needed — this is where enzymatic technologies can offer immediate relief.

The regulatory framework therefore demands fast, cost‑effective, low‑carbon measures that show quantifiable improvement and work alongside traditional civil engineering. Enzymes align strongly with each of these criteria.

3. The Science Behind Enzymatic Remediation

At its core, enzymatic remediation relies on biochemical hydrolysis and oxidation. Specific enzyme classes act on defined substrates. The most relevant for sewage and river management include:

• Lipases – Break down fats, oils and greases into glycerol and fatty acids, reducing “grease cap” formation and FOG blockages.
• Proteases – Hydrolyse proteins into peptides and amino acids; useful for degrading organic solids in sewage.
• Amylases – Convert starches and complex carbohydrates into soluble sugars, lowering BOD/COD concentrations.
• Cellulases and Hemicellulases – Target fibrous materials such as plant debris, toilet paper and wipes, helping to decompose rag and fibrous scum.
• Phosphatases – Convert organic and condensed forms of phosphorus into orthophosphate, which can subsequently bind to reactive media or precipitate naturally.
• Oxidases and Peroxidases – Break down aromatic and phenolic compounds in urban runoff and agricultural effluent.

Each enzyme family operates optimally under specific temperature and pH ranges. However, by blending multiple enzymes together and stabilising them within carriers, modern formulations can maintain broad effectiveness from around 5°C to 45°C — spanning seasonal fluctuations typical of UK catchments.

By applying these blends at the right points, such as upstream of a CSO chamber or into a reedbed inflow, operators can initiate controlled hydrolysis. Solids become more bioavailable, oxygen demand is reduced, and the microbial community structure shifts towards aerobic decomposition rather than anaerobic septicity. The result is cleaner effluent, fewer odours, and less ecological stress downstream.

4. Addressing Key Pollution Challenges

Fats, Oils and Grease (FOG)
FOGs are a persistent problem in combined sewer systems. They congeal into thick caps that float on water, obstructing flow and creating anaerobic pockets where hydrogen sulphide (H₂S) gas develops. Enzyme blends rich in lipases and biosurfactants can solubilise and emulsify these fats, dramatically reducing the accumulation rate. Field monitoring often shows visible thinning of grease layers within two to four weeks of consistent dosing.

Organic Load (BOD/COD)
High BOD/COD values reflect the oxygen required to break down organic material. During storm events or CSO spills, sudden release of untreated sewage can deplete dissolved oxygen in receiving rivers, suffocating aquatic life. Enzymatic pre‑hydrolysis breaks complex molecules into forms that microbes degrade more rapidly, smoothing out oxygen demand peaks and lowering pollutant concentrations at outfalls.

Nutrients – Nitrogen and Phosphorus
Nutrient pollution drives eutrophication, algal blooms, and loss of biodiversity. Enzymes like phosphatase cleave organic phosphorus compounds, while ureases and deaminases assist conversion of organic nitrogen to forms amenable for nitrification and denitrification. When paired with reactive wetland media, these reactions accelerate nutrient capture and minimise release during high flows.

Odour and Septicity
Where stagnant conditions prevail, organic matter decomposes anaerobically, producing volatile sulphur compounds and methane. Enzyme‑enhanced hydrolysis favours aerobic pathways, reducing odour and corrosion risk in rising mains and pumping stations.

5. From Sewers to Streams: Integration in Catchment Plans

The catchment-based approach, promoted by Defra and delivered through CaBA partnerships, encourages holistic solutions that treat pollution sources, pathways, and receptors. Enzymatic dosing can sit comfortably within this framework. It can be used not as a replacement for infrastructure investment but as a complementary layer of natural bio-conditioning within the wider water system.

Diagnostic Stage

Before any deployment, baseline data are collected to identify hotspots — locations with recurring blockages, odour complaints, or high EDM spill frequency. Laboratory analysis of samples provides BOD, COD, nutrients, grease fraction, and microbial activity profiles. Remote sensing and digital twins can be used to model how pollution loads move through the system.

Formulation and Planning

Once target issues are defined, a bespoke BioGlobe enzyme blend can be designed. For instance, a CSO prone to greasy deposits may need a lipase-heavy mix, while a reedbed receiving agricultural runoff could benefit from phosphatase and cellulase. The formulation’s carrier medium can be liquid, granulated, or encapsulated for slow release, depending on the hydraulic conditions.

Deployment Strategy

Dosing systems are installed upstream of target sites. These may be simple gravity-fed dispensers, pump-controlled systems linked to telemetry, or storm-activated injectors that respond to level sensors. Dosing schedules can be continuous, pulsed, or event-triggered.

Monitoring

Performance metrics are collected regularly: reduction in FOG depth, improved flow rates, fewer blockages, better BOD/COD ratios, and fewer odour complaints. In catchment trials, ecological indicators such as dissolved oxygen, macroinvertebrate scores, and periphyton coverage are also tracked.

Reporting and Scaling

Results feed back into WINEP or CaBA documentation and Open Monitoring portals. Positive pilots can then be extended across multiple sites or scaled up to catchment level.

6. Pilot-Ready Dosing Strategies

In‑network preventive dosing
This involves applying enzyme solutions within wet wells, siphons, or pumping stations where FOG and rag build‑up occurs. The goal is to precondition material before it reaches overflow points. Low-dose continuous or pulsed systems work best. Measuring success involves tracking pump current draw, energy consumption, frequency of blockages, and CCTV inspection results.

During storm events (CSO chamber dosing)
Here, the focus is on reducing the immediate organic load discharged to rivers during high rainfall. Dosing is triggered when CSO levels rise, activating a concentrated enzyme pulse to dissolve solids and fats before they can congeal. Once water levels recede, a smaller “tail dose” maintains residual activity. This approach directly minimises the pollutant impact of each spill.

Downstream buffering and outfall protection
In sensitive reaches with important habitats or bathing waters, enzyme dosing at the outfall can help degrade any remaining organics quickly. It can be coupled with floating aerators, microbial rafts, or sorbent materials to polish effluent before it enters open water.

Data and telemetry integration
To maximise performance, these systems can tie into existing telemetry platforms. Weather forecasts and radar nowcasting trigger pre‑dosing ahead of expected events, while feedback loops optimise consumption rates.

7. Enhancing Reedbeds and Constructed Wetlands

Reedbeds and constructed wetlands are a cornerstone of nature-based water treatment. However, under cold or heavily loaded conditions, they can experience clogging, sludge accumulation, and reduced efficiency. Enzymes can reinvigorate these systems by pre‑digesting particulates and supporting microbial activity.

Mechanistic benefits:

• Enzymatic pre‑treatment transforms particulate matter into dissolved forms that are easier for wetland biofilms to metabolise.
• Lipase and cellulase activity reduces grease and plant fibre accumulation, preserving hydraulic conductivity.
• Phosphatase activity enhances phosphorus turnover, enabling better capture by reactive media like steel slag, alumina or modified sands.

Practical integration:

• Dosing can occur in the forebay or distribution zone, ensuring pollutants are conditioned before entering the main reed channels.
• Seasonal adjustment of the enzyme formulation maintains activity in winter when natural microbial rates are low.
• Monitoring includes inflow/outflow sampling for BOD, COD, ammonia, nitrate, and soluble reactive phosphorus, plus periodic checks of flow distribution and plant health.

Case results:
Pilot sites in northern Europe have shown that enzyme dosing ahead of wetland cells can improve overall BOD and nutrient removal efficiency by 10–25%, especially during cold months. Such interventions require minimal operational adjustment once optimised.

8. BioGlobe Blend Design and Delivery

Every catchment presents unique challenges, influenced by land use, infrastructure, and seasonal flows. BioGlobe enzyme blends are tailored accordingly, offering modular combinations of targeted enzymes with stabilisers, carriers, and non‑toxic co‑ingredients.

Blend architecture:

• Core enzymes: Lipase, protease, amylase, and cellulase form the base.
• Optional modules: Phosphatase for nutrient control; oxidase for trace organics or hydrocarbons.
• Carriers: Biodegradable granules for slow release; liquid emulsions for dosing pumps; encapsulated gels for reedbed zones.
• Adjuncts: Biosurfactants for wetting FOG layers; mineral cofactors for structural enzyme stability.

Operational integrity:
All components are food or industrial grade with established environmental safety. Formulations avoid allergens, synthetic biocides and heavy metals.

Deployment modes:

• Sewers and rising mains: liquid concentrates dosed by peristaltic or diaphragm pumps.
• CSO chambers: solid gel blocks or event-activated dispensers.
• Wetlands: slow-release carriers placed in forebays or flow paths.

Cost efficiency:
Compared to civil upgrades, enzyme programmes require low OPEX and negligible CAPEX. Savings accrue through reduced jetting, fewer callouts for blockages, longer pump asset life, and lower odour complaints. Operational carbon footprints are minimal because no external energy or compressed air is needed.

Governance and compliance:
BioGlobe treatments can be reported under existing WINEP deliverables and CaBA initiatives. Telemetry data can be shared through Open Monitoring to demonstrate transparency and outcomes.

9. Monitoring, Verification and Open Monitoring

Transparency is now a central requirement for environmental interventions. For enzymatic pilots to gain regulatory acceptance, robust monitoring and verification are essential.

Measurement strategy:

• Water quality indicators: Regular sampling for BOD, COD, TSS, ammonia, nitrate, orthophosphate, pH and DO.
• Operational KPIs: Frequency of blockages, jetting events, energy use, H₂S complaints, FOG cap thickness (via sonar or CCTV).
• Ecological response: Macroinvertebrate indices, fish monitoring, and macrophyte surveys to track biodiversity recovery.
• Data transparency: Sync measurement data with public dashboards, ideally consistent with the Open Monitoring ethos.

Validation and QA/QC:
Samples should be processed by accredited laboratories with clear chain-of-custody protocols. Field sensors must be calibrated quarterly, and independent audits recommended for significant pilot projects.

Communication:
Publishing the findings of enzymatic trials not only satisfies regulatory expectations but also builds community trust. Public perception of sewage pollution is heavily influenced by transparency; demonstrating measurable improvement reinforces confidence in nature-based solutions.

10. Risk Management and Limitations

Despite their promise, enzymatic treatments must be applied with care and understanding of their limitations.

• Temperature Sensitivity: Activity may decline below 5–8°C. Seasonal dosing regimes or cold-active enzyme variants mitigate this.
• Hydraulic Retention Time: Too rapid flow may reduce contact time. Engineering modifications or pre‑conditioning upstream can extend effectiveness.
• Nutrient Dynamics: Hydrolysis can initially release dissolved nutrients before capture; coupling with reactive wetlands prevents net release.
• Overdosing and Aerosols: Excessive dosing is wasteful and may create air‑borne enzyme particles; enclosed systems and PPE prevent operator exposure.
• Compatibility: Some cleaning chemicals or high salinity may denature enzymes; product stability checks ensure coexistence.

Risk assessments, including COSHH compliance, should accompany all pilot deployments.

11. Implementation Roadmap: Pilot to Scale

Month 0–1:
Select pilot sites using EDM and River Trust data to flag priority CSOs and catchment reaches. Conduct baseline sampling and hazard analysis.

Month 2–4:
Install dosing equipment, calibrate systems, and begin initial dosing. Record operational and quality metrics weekly. Adjust dosage based on response curves.

Month 4–6:
Analyse early data for KPI trends. Commission independent verification. Capture qualitative stakeholder feedback (operators, local groups).

Month 6+:
Optimise formulation and dosing frequency for site conditions. Launch Open Monitoring dashboard for transparency. Extend programme to other high‑risk sites.

Ongoing:
Feed data into WINEP and catchment planning cycles; publish outcomes annually.

By following such a structured approach, authorities can validate enzyme technology scientifically and scale it responsibly across regional catchments.

12. Broader Value Streams

Adopting enzyme treatment unlocks co‑benefits beyond pollution control.

• Asset performance: Lower grease and rag build-up means fewer emergency callouts and longer pump life.
• Operational safety: Reduced H₂S generation decreases worker exposure risk.
• Energy efficiency: Less reactive jetting and mechanical cleaning.
• Community goodwill: Visible improvements in river appearance and reduced odour incidents.
• Biodiversity gain: Faster recovery of aquatic flora and fauna, improved dissolved oxygen regimes, and better habitat connectivity.
• Climate resilience: As climate change increases rainfall frequency and intensity, enzyme dosing offers flexible, low‑carbon resilience between large infrastructure upgrades.

13. Case Illustrations

In an urban utility pilot, lipase‑centred enzyme dosing in a high‑risk sewer catchment reduced grease cap thickness by more than half within three months. CCTV inspections verified a noticeable reduction in ragging, and pump efficiency improved by around 15%.

In a semi‑rural catchment with CSO discharges into a small tributary, using an amylase‑protease blend during storm events reduced COD loads by roughly one third. Dissolved oxygen downstream no longer dropped below 6 mg/L in post‑event sampling.

Another project trialled phosphatase‑based blends at a constructed wetland treating combined municipal and farm run‑off. During winter, when plant activity is low, phosphorus removal efficiency improved from 55% to around 70%, demonstrating that enzymatic catalysis can bridge seasonal gaps in biological performance.

Such examples reinforce that tangible water quality gains are achievable within a few weeks to months, without capital-intensive works.

14. A Holistic Catchment Strategy

Enzymes should not be viewed in isolation but as part of an integrated package of nature‑based measures. In policy alignment terms:

• Within WINEP: They can be recorded under innovation or interim compliance measures.
• Within CaBA: They provide a practical demonstration of partnership delivery, linking NGOs, community monitoring and utilities.
• Under Biodiversity Net Gain frameworks: Enhanced ecological conditions can contribute to measurable net gain credits.
• In Corporate ESG reporting: Enzymatic pilots can evidence operational decarbonisation, circularity and community engagement.

This systems thinking ensures that each intervention contributes to multiple policy outcomes at once.

15. Future Outlook

As the UK water sector navigates AMP8 and the 2030 milestones, interest in biotechnological solutions will continue to rise. Future developments may include:

• Smart enzymatic blends with on‑demand activation triggered by pH or temperature, reducing waste.
• Enzyme‑microbe synergies, pairing catalytic activity with targeted bio‑augmentation where regulators permit.
• Modelling tools to predict kinetic rates and optimise dosing regimes through digital twins.
• Circular sourcing, using enzymes derived from waste biomass or food processing by‑products to enhance sustainability.
• Local manufacturing under circular bioeconomy models, creating regional supply resilience.

Innovation partnerships between utilities, SMEs, research institutions and environmental NGOs can accelerate these trends, grounded in transparent data-sharing through Open Monitoring.

16. Conclusion

The drive to halve sewage pollution by 2030 demands a mix of pragmatic engineering, proactive regulation, and natural intelligence. Enzymes embody all three. They originate from nature, yet they bring precision and controllability comparable to engineered systems.

When integrated thoughtfully into catchment plans — alongside reedbeds, wetlands, and civil investments — enzyme treatments can deliver rapid, measurable and verifiable improvements to water quality. They help water utilities move beyond crisis response towards adaptive, data‑driven, and transparent stewardship of the environment.

Bespoke BioGlobe blends exemplify how this approach can be operationalised: targeted, safe, and tailored to each catchment’s unique fingerprint of FOG, nutrient and organic stress. Deployed smartly, they transform the unseen biochemical workings of rivers and sewers into allies of restoration rather than sources of pollution.

The next five years will be decisive. Open Monitoring will shine an unfiltered light on every outfall. Communities will expect evidence of change, not intentions. For water companies and local authorities, embracing enzyme‑based, nature‑compatible solutions offers not only compliance and cost savings but also the rare opportunity to align ecology, technology, and trust.

If rivers are the nation’s circulatory system, enzymes are the system’s natural healers — microscopic yet mighty, catalysing recovery one bond at a time.

Frequently Asked Questions

1. How do enzymes differ from microbial additives?
Enzymes are proteins that speed up chemical reactions immediately upon contact, requiring no incubation or colonisation phase. Microbial additives introduce living organisms that may or may not thrive depending on conditions. Enzymes act more predictably, degrading pollutants directly and leaving no residual population to manage.

2. Are enzyme treatments environmentally safe?
Yes. Enzymes used in environmental applications are typically food‑grade or industrial‑grade proteins that quickly denature into amino acids once their task is complete. They are non‑persistent and non‑toxic to aquatic life when properly dosed. BioGlobe formulations avoid harsh stabilisers, metals or synthetic surfactants, prioritising ecological compatibility.

3. Can enzymes help with nutrient as well as organic pollution?
They can. Phosphatase and nitrogen‑cycling enzymes liberate nutrients from complex organic matrices, enabling downstream wetlands or reactive media to capture or transform them. When enzymatic action is integrated with these natural systems, overall nutrient reduction improves significantly.

4. How quickly do results appear?
Early indicators can often be seen within weeks — for instance, thinning of FOG layers, fewer pump alarm triggers, or measurable drops in odour. Quantitative improvements in BOD, COD and nutrient levels usually appear within two to three months, depending on system hydraulics and dosing strategy.

5. How do enzymatic treatments fit within regulatory compliance plans?
They serve as low‑capex, low‑carbon interim measures that support compliance with WINEP and catchment objectives while major capital projects are being planned or delivered. Results can be published under Open Monitoring, demonstrating transparency and progress to regulators and the public.