SBIR-STTR Award

Fungal inocula are an important component of a soil bioaugmentation technology that relies on the pollutant-degrading abilities of white-rot wood decay (Bioremedy) fungi. Current inoculum production techniques are expensive and cumbersome. Preliminary work on a less expensive, technically superior inoculum formulation based on a pelleted lignocellulosic-based substrate covered with an active mycelial coat of a selected Bioremedy fungus, indicates that pelleted inocula are effective at supporting fungal colonization and pollutant degradation in soil and that they are potentially much less costly to produce than currently inoculum formulations. Equipment and supplies for three key steps in the pelleted inoculum production process require identification before a realistic economic analysis can be conducted. These steps include: pelleted substrate sterilization, fungal biomass fragmentation to produce hyphal fragments for pellet coating, and appropriate packaging to optimize uniform hyphal coat development on the pellets. The objective of the proposed work is to demonstrate the technical and economic feasibility of producing pelleted fungal inoculum, at the pilot scale.

Anticipated Results/Potential Commercial Applications of Research:
As a result of the proposed work we expect to identify an economic method for sterilizing the pelleted lignocellulosic substrates and a method for fragmenting fungal biomass, produced in liquid culture, to produce hyphal fragments which will be applied in an alginate slurry to the surface of the pellets to allow development of a hyphal coat over the pellet surface. In addition, packaging that is robust enough to withstand handling and which is designed to allow uniform hyphal coat development during the grow-out phase will be identified. As a result, fungal-based remediation, an environmentally harmonious soil remediation alternative, will be technically improved and applied more inexpensively.

Fungal inocula are a critical and economically-significant component of a technology that exploits the abilities of white-rot wood-decay fungi to degrade pollutants in soil. This technology involves mixing of a fungal inoculum with contaminated soil and placing this mixture in an aerated pile. Current standard inoculum production techniques are expensive, involving the field pasteurization of substrate, inoculation of this substrate with an appropriate fungal strain under aseptic conditions, and monitoring of the inoculum during a grow-out period of 4 to 6 weeks. Preliminary and Phase I SBIR work demonstrated that a novel alternative to standard inocula, referred to as pelleted inoculum, is effective at supporting fungal colonization and pollutant degradation at a significant cost savings compared to standard inocula. However, before pelleted fungal inocula can be used in fungal-based remediation on a commercial basis, successful demonstration of the technical and economic feasibility of large-scale pelleted inoculum production and application are required. The purposes of this project are to identify appropriate equipment for the large-scale production and bagging of pelleted inocula and to demonstrate that pelleted inocula are technically comparable and economically superior to the use of standard inocula in pollutant degradation. As a result, the technical effectiveness and economic competitiveness of fungal-based remediation, an environmentally harmonious soil remediation technology, will be greatly improved. OBJECTIVES: This project has the following technical objectives: (1) Test identified equipment that has suitable process capacity for large-scale fungal coating of pellets; (2) Investigate the possibility of inoculum grow-out bags that have a capacity to hold up to 34 kg of pellets while providing acceptable hyphal coal development; (3) Conduct a treatability study to determine the most effective pelleted inoculum application rate to decrease concentrations of polycyclic aromatic hydrocarbons in contaminated soil; (4) Conduct a pilot-scale investigation to assess the comparative economic and technical effectiveness of pelleted and standard fungal inocula; and (5) Prepare a refined economic analysis of pelleted inoculum use based on large-scale production and delivery. APPROACH: The approach to this project will involve the following nine tasks: (1) Produce pellets for use in the investigations. Pellets will be toll manufactured using a mixture of hardwood sawdust, soybean meal, lime, and linosulfonate. The pellets will be sterilized using gamma irradiation following production. (2) Test a continuous mixer for its efficiency in applying a uniform coat of liquid fungal inoculum to the surface of the pellets. We have identified the 300 L KM series mixer of Littleford Day as an appropriate candidate. This mixer uses a series of paddles to create a fluidized bed with the capability of processing approximately 120 kg of pellets every two minutes. (3) Design, have produced, and test large capacity grow-out bags. Solid inoculum is typically grown out in polyethylene bags fitted with filters to allow air exchange while retaining moisture. However, standard bags hold only 7 kg. Bags with a 34-kg capacity will be designed and produced to minimize handling under full scale conditions. (4) Identify appropriate equipment for conveying and bagging the pellets. An important factor to consider in equipment selection will be the ease with which the system can be sanitized to maintain the sterility of the pellets. (5) Conduct a bench-scale treatability study to determine the most effective pelleted inoculum application rate to decrease the concentration of PAHs in soil obtained from a contaminated site. It is currently anticipated that this test will be conducted using soil obtained from the Appalachian Timber Services site in Sutton, West Virginia. (6) Produce sufficient pelleted inoculum to conduct a field test to compare pelleted and standard inoculum performance. Primary liquid inoculum will be produced in the EarthFax laboratory, with pelleted inoculum being produced by L.F. Lambert Spawn Company in Coatesville, Pennsylvania. (7) Produce standard fungal inoculum for performance of the field trial. This will involve pasteurization, inoculation, and monitoring of approximately 16 tons of hardwood sawdust at the field site. (8) Perform a field trial to compare the efficacy of standard and pelleted inocula. Approximately 120 cubic yards of contaminated soil will be treated (half with standard inoculum and half with pelleted inoculum). Each treatment biopile will be constructed using the same techniques. The two treatments will be compared on the basis of the time required to decrease contaminant concentrations to below risk-based levels. (9) Perform a comparative economic analysis of pelleted and standard inoculum production and use. Actual costs experienced during the field trial will be used as the basis, with appropriate scale factors applied to estimate the comparative costs of treating larger quantities of soil