Final Report: Comprehensive Assessment of Mycofiltration Biotechnology to Remove Pathogens from Urban Storm WaterEPA Contract Number: EPD12010
Title: Comprehensive Assessment of Mycofiltration Biotechnology to Remove Pathogens from Urban Storm Water
Investigators: Stamets, Paul
Small Business:Fungi Perfecti LLC
EPA Contact: Manager, SBIR Program
Project Period: March 1, 2012 through August 31, 2012
Project Amount: $80,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2012) RFA Text | Recipients Lists
Research Category:SBIR - Water and Wastewater , Small Business Innovation Research (SBIR)
This Small Business Innovation Research project developed the principle of mycofiltration—the use of fungal mycelium as a biologically active filter for removing pathogens from storm water. As pollution from pathogens is the leading cause of critically impaired waters nationwide, with storm water strongly linked to this contamination, this cutting-edge research was a timely response to EPA's focus on safe and sustainable water resources. Although there is substantial evidence that many fungi consume bacteria and secrete antibacterial metabolites, mycological research has remained largely isolated to ecological and pharmaceutical explorations. The mycofiltration research expanded knowledge of the application of fungal biotechnology in an innovative and interdisciplinary way by tying together the fields of public health, environmental engineering, and mycology.
The research identified physically durable and biologically resilient fungal species and low-cost cultivation methods that can be implemented to produce a fungal biofilter, known as a MycoFilterTM, that is capable of filtering E. coli from flowing water under laboratory conditions. Working with Washington State University, the research demonstrated the initial proof-of-concept that fungal mycelium can remove E. coli from flowing water, and that mycofilters can be developed that are not significantly impacted by excessive heat, cold, saturation or dehydration.
Six fungal species that were expected to demonstrate antibacterial activity and resilient growth characteristics were grown on five different substrate combinations. Of the 30 batches of mycofilters initially produced, 19 batches demonstrated the rate of growth needed to proceed to the resiliency testing portion of the project. Following resiliency testing, one species clearly stood out as far more resilient than the others. When this freshly tested mycofiltration media was analyzed for its ability to remove E. coli from flowing water, there was a statistically significant difference compared with the controls, and there was no significant difference between the vigor tested and the non-vigor tested MycoFiltersTM. As this bench-scale test was conducted with the more difficult to remove dissolved bacteria as opposed to the more common sediment-bound bacteria, this innovative water quality solution demonstrated its potential. Subsequent trials with influent containing both sediment and E. coli achieved some additional reductions.
Several conclusions may be drawn from the research results. The first is that there are fungal species that are appropriate candidates for the concept of mycofiltration. Of eight fungal strains that were tested over the course of the research, one clearly demonstrated resilience to harsh environmental conditions and a second showed promising characteristics. The second notable conclusion is that the permeability of mycofiltration media was generally in the range of 0.07 to 0.10 cm/sec roughly equivalent to medium grain sand, indicating applicability for field-relevant hydraulic loading. Additionally, mycofilters demonstrated some capability to remove dissolved E. coli from flowing water, likely through an antibacterial mechanism. The final conclusion is that, as with other stormwater best management practices (BMPs), mycofiltration may be more effective against sediment-bound bacteria, and possibly achieve 100 percent E. coli removal. The natural conclusion from these sets of tests is that specific fungal strains are resilient enough to be considered for stormwater treatment applications against a variety of targets including pathogens, but that more research is needed to clearly define treatment design and operating parameters.
The commercial applications for mycofiltration of bacteria in surface waters are diverse, global, and represent a significant business opportunity. When pathogens are considered as the only target pollutant, opportunities include filtration of stormwater, agricultural runoff, and rural and international wastewater treatment. If activity against other pollutants is considered, additional opportunities include industrial wastewater filtration, contaminated water remediation, managing nutrient runoff from greenhouses and nurseries, and a broader customer base in the stormwater and wastewater management industries. As additional field-scale data validate the bench-scale findings, Fungi Perfecti will bring MycoFiltersTM and other mycofiltration technologies to market both directly and through a network of regional manufacturers.
Supplemental Keywords:Mycofiltration, fungal mycelium, stormwater filtration, E. coli, pathogen, SBIR, wastewater treatment
The intentional use of the vegetative growth of mushroom-forming fungi on wood mulch substrates as a biologically active filtration media, a process known as mycofiltration, is a promising new technology for enhancing biofiltration of stormwater, graywater, and agricultural runoff. Recent trials have documented that Escherichia coli can be selectively removed from contaminated water approximately 20% per cubic foot more effectively by mycofiltration than by wood mulch alone. This improvement in bacteria removal was consistent even after exposure of the mycofiltration media to harsh environmental conditions such as -15 to 40 °C (5 to 140 °F) temperature extremes. This article reviews the historical context, discusses the current state of research, describes best implementation practices, and highlights promising areas for future study to bring the cultivation of fungi in constructed ecosystems into common practice as a new ecological engineering tool for enhancing biological water treatment systems.