Urban stormwater carries water from roofs, roads, car parks, footpaths and other hard surfaces into drains, waterways or storage areas. Along the way, it may collect sediment, nutrients, hydrocarbons, metals, litter and other contaminants. Councils commonly manage these risks through practices such as sediment controls, rain gardens, wetlands, swales, gross pollutant traps and treatment systems.
Mycofiltration is an emerging approach that uses fungi, usually through fungal mycelium (the fine network that forms the main body of a fungus), together with a suitable filter or organic growing medium. The fungal material may help capture, transform or support the breakdown of some pollutants as stormwater passes through the treatment area. It is best considered as one possible component of a broader stormwater treatment strategy—not a universal replacement for established controls.
What is the purpose of mycofiltration?
The purpose of mycofiltration is to improve stormwater quality before water reaches a sensitive receiving environment, such as a creek, wetland, lake or coastal waterway. In a practical setting, fungi may be incorporated into a contained filter, a treatment bed, a biofilter or another engineered feature.
Fungi can interact with organic materials and a range of chemical compounds through their growth and metabolic processes. A mycofiltration system may also provide physical filtration, because water passes through a medium that can retain suspended particles. However, the treatment effect depends on the fungal species or material used, the pollutants present, flow conditions, temperature, moisture, contact time and the design of the system.
For this reason, councils should describe mycofiltration as a potential treatment process requiring site-specific assessment and verification. Results from one location should not automatically be assumed to apply elsewhere.
Which urban stormwater problems may it help address?
Mycofiltration may be considered where stormwater contains a mixture of pollutants and where an additional treatment stage could complement existing infrastructure. Potential applications include:
- Suspended sediment: A suitable filter medium may help retain particles, although high sediment loads can quickly block or reduce the performance of a system.
- Hydrocarbon contamination: Stormwater from roads, depots, workshops and parking areas may contain oil-related contaminants. Fungal treatment may be investigated as part of a controlled treatment train, but performance should be tested rather than presumed.
- Nutrients and organic pollution: Fungi may contribute to treatment processes involving some organic materials or nutrient-bearing water, subject to the system design and local conditions.
- Contaminated runoff from redevelopment or remediation areas: A temporary or permanent treatment stage may help manage runoff while other controls are being installed or maintained.
- Small, defined flows: A contained system may be more practical for a monitored discharge point than for an entire urban catchment.
Mycofiltration is less suitable as a stand-alone response to uncontrolled high flows, severe contamination, large volumes of sediment or pollutants that require specialised treatment. It should not be used to justify reducing source controls, spill prevention, erosion management or conventional treatment where those measures are needed.
How could a council plan a simple application?
A council does not need to begin with a large demonstration project. A staged approach can reduce uncertainty and make responsibilities clear.
1. Define the problem and treatment objective
Identify the drainage area, likely pollutant sources, receiving environment and the decision the system must support. The objective might be to reduce suspended solids at a defined outlet, provide an additional treatment stage for runoff from a specific site, or test whether a fungal medium is suitable before considering wider use.
Clear objectives are important because “cleaning the water” is too broad to measure. The project should identify which pollutants matter, what flows need to be treated and what level of performance would justify continuing the approach.
2. Assess the site
Site assessment should cover catchment size, drainage paths, flow rates, flooding, access, available space, soil and groundwater conditions, and the location of workers and the public. Existing water-quality information, spill history and land-use records can help identify likely contaminants.
Consider whether the site can provide pretreatment. A sediment trap, screen or other upstream control may protect a mycofiltration unit from litter and heavy sediment. The system should also have a safe bypass or overflow arrangement so that intense rainfall does not wash treatment media into the receiving environment.
3. Select and contain the treatment medium
The fungal material and supporting medium should be selected for the target pollutants, expected flow conditions and maintenance requirements. The system should keep the media contained and prevent uncontrolled release of fungal material, decaying organic matter or captured contaminants.
Where the approach is experimental or not yet validated for the site, a small pilot or isolated treatment cell may be more appropriate than immediate integration into a major drainage asset. Any proposed design should be reviewed by suitably qualified environmental, hydraulic and safety professionals.
4. Integrate it with existing remediation work
Mycofiltration can potentially be placed as one part of a treatment train. For example, source controls may reduce pollutant generation, a sediment-control stage may remove coarse material, and a contained fungal filter may provide an additional treatment step before discharge. Downstream controls may still be required.
Integration should not create a new maintenance problem for an existing asset. Councils should document ownership, inspection frequency, access arrangements, failure responses and the process for removing and disposing of spent media.
Maintenance and monitoring are essential
Fungal treatment systems are biological systems, so performance can change over time. Routine inspections should check for blocked inlets, ponding, erosion, odour, damaged containment, excessive dryness or saturation, animal disturbance and bypass flows. Maintenance may include removing accumulated sediment, repairing structures and replacing or renewing treatment media.
Monitoring should be designed around the project objective. Depending on the site, it may include:
- flow observations and records of bypass or overflow events;
- visual checks for sediment, litter and changes in water clarity;
- sampling at appropriate points before and after treatment;
- analysis for the pollutants identified during the site assessment; and
- records of inspections, rainfall, maintenance and media changes.
Testing should account for changes in storm intensity and pollutant loads. A single sample cannot establish reliable performance. Councils should set review points in advance and be prepared to modify, pause or remove the system if monitoring shows inadequate treatment, unacceptable risks or impractical maintenance demands.
Safety and responsible handling
Stormwater treatment media may contain concentrated pollutants after use. Spent material should therefore be handled as potentially contaminated until it has been assessed. Workers may need appropriate training, personal protective equipment, hygiene procedures and controls for dust, splashes and direct contact.
Fungal materials should be sourced and managed responsibly. The selected material should not introduce an unacceptable biosecurity, ecological or public-health risk. Avoid releasing untreated media into waterways, parks or soils. Disposal requirements will depend on the contaminants captured and applicable local regulations.
Costs, limitations and decision-making
The cost of mycofiltration is not limited to the filter material. Councils should allow for site investigation, design, hydraulic works, containment, laboratory testing, inspections, maintenance, media replacement and disposal. A small system may be affordable to trial, while a larger installation can require substantial civil works and ongoing management.
Important limitations include variable biological performance, sensitivity to flow and moisture conditions, clogging, uncertain long-term pollutant capacity and the need for site-specific evidence. Fungi may assist with some contaminants but will not remove every pollutant. Treatment may also transfer contaminants from water into sediment or spent media, which then requires responsible management.
For most councils, the soundest approach is cautious and evidence-led: define a local problem, use established controls first, assess whether mycofiltration adds value, test it in a contained setting where appropriate, and monitor the results. Used in that way, mycofiltration may become a useful supplementary tool in urban stormwater remediation without being presented as a guaranteed or universal solution.