Odors from agricultural operations have become a concern to neighboring residents in many locations. As housing developments encroach on what has been traditionally agricultural regions, complaints and calls for government regulation have increased. The preparation of mushroom substrate has the potential for creating odors if the compost piles are not managed properly.
Researchers in the College of Agricultural Sciences at Penn State are investigating methods to reduce the emission and transmission of these odors. The objectives are to determine sources and management of odors, methods for evaluating odor strength, methods for impeding emission and transmission of odors, and assessing the dispersion of odors from preparation facilities.
Several commercial
substrate preparation operations around the world have begun using
aerated floor "bunkers" to reduce odors. Two aerated
floor bunkers have been installed at Penn State to evaluate the
effectiveness of the units for reducing odors. At the same time,
the aeration can change the properties of the material, affecting
the quality of the substrate and subsequent mushroom yields. Research
will help to optimize the odor reduction while maintaining substrate
quality.
Two views of the bunkers, showing the blower and manifold from the rear, and the rear of the bunkers under the new MTDF wharf roof.
This image shows a commercial aerated floor bunker for Phase I substrate processing.
SMS Processing
A project funded by the Pennsylvania Department of Agriculture, investigated use of aeration for reducing odors from the processing of spent mushroom substrate (SMS). The project objectives looked at odor reduction, value of SMS processed as a growing media, and management strategies to best process SMS using aerated floor bunkers. A portable research bunker was developed and used for this purpose. Faculty from Penn State (Agricultural and Biological Engineering, Plant Pathology, and Horticulture) cooperated with researchers at the Monell Chemical Senses Center and Therion, Inc. on this project.
The results showed that aeration significantly reduced odors as measured by a human odor panel, and emission of odorous compounds were also significantly reduced based on quantitative analysis. SMS can be mixed with other materials to provide a nutrient-rich and safe growing media for nurseries and landscaping.
A recent project investigated
the use of microporous membranes to impede the transmission of
odor-producing compounds from the substrate piles. These covers
have the unique characteristic of allowing small gaseous molecules
such as water vapor, oxygen, and carbon dioxide to pass through
the material while impeding transmission of larger molecules.
Therefore, the piles can maintain the desired aerobic conditions
while the covers reduce the odorous compound transmission. Qualitative
(human sensing panel) and quantitative (gas chromotography, thermal
absorption) showed that the covers significantly reduced the intensity
of odors while still maintaining the substrate quality necessary
to grow quality mushrooms.
An understanding of the odor generation and how atmospheric conditions can affect the transport of the odors can help growers alter their management strategies to reduce the impact on neighboring communities. Quantification of odors is a very difficult and subjective task. The compounds that produce odors need to be sampled from the air and levels determined through gas chromatography. This is a time-consuming and expensive process. In addition, the perception of odors by humans is quite variable from one person to the next. To simplify the assessment of odor transport and dispersion, computer models were used.
The three objectives of this effort were to:
1. develop an odor source generation model;
2. develop an odor dispersion model that would be linked with
the odor source generation model;
3. verify the source and dispersion models.
Example Results
The following two figures show some sample results from the models.
Figure 1. Odor dispersion plume under unstable conditions 
Figure 2. Odor dispersion plume under very stable conditions
Publications:
Wahanik, D.A., and P.H. Heinemann. 1994. Odor dispersion modeling for mushroom farm composting facilities. ASAE Paper No. 94-4546. American Society of Agricultural Engineers, St. Joseph, MI. 12 pp.
Heinemann, P.H., and D.A. Wahanik. 1995. Assessment of odors from mushroom composting facilities. ASAE paper NABEC-9506. American Society of Agricultural Engineers, St. Joseph, MI. 11 pp.
Heinemann, P.H., and D.A. Wahanik. 1998. Modeling the generation, transport, and dispersion of odors from mushroom composting facilities. Transactions of the American Society of Agricultural Engineers. 41(2):437-446.
Labance, S.E., P.H. Heinemann, and D.M. Beyer. 1999. A simple olfactometric evaluation of microporous covers for the reduction of mushroom substrate preparation odors. Applied Engineering in Agriculture. 15(5): 559-566.
Heinemann, P.H., R.E. Graves, S. Walker, D.M. Beyer, E.J. Holcomb, C.H. Heuser, G. Preti, C. Wysocki, F. Miller. 2003. In-vessel processing of spent mushroom substrate for odor control and reduced processing time. Applied Engineering in Agriculture. 19(4):461-471.
Heinemann, P.H., S.E. Labance, S. Walker, and D.M. Beyer. 2004. Modeling mushroom substrate temperature during aerated phase I substrate preparation. Transactions ASAE. 47(4):1301-1311.
Sabeh, N., E.F. Wheeler, D.M. Beyer, and P.H. Heinemann. 2005. Environmental control strategies in Agaricus biosporus production rooms and their effects on mushroom quality. Mushroom News, Science and Technology. 53(1): 6-12.
Holcomb, E.J., C. W. Heuser, P.H. Heinemann, and F.E. Miller. 2005. Nutrient changes in spent mushroom compost. Mushroom News. 53(11):6-11. (refereed section).
Labance, S.E., P.H. Heinemann, R.E. Graves, and D.M. Beyer. 2006. Evaluation of the Effects of Forced Aeration During Phase I Mushroom Substrate Preparation . Part 1: Model Development Trans. ASABE. 49(1): 167-174.
Labance, S.E., P.H. Heinemann, R.E. Graves, and D.M. Beyer. 2006. Evaluation of the Effects of Forced Aeration During Phase I Mushroom Substrate Preparation. Part 2: Measurements and Model Results. Accepted in: Trans. ASABE. 49(1): 175-182.
Bechara, M.A., P.H. Heinemann, P.N. Walker, and C.P. Romaine. 2006. Non-composted Grain-based Substrates for Mushroom Production ( Agaricus bisporus ). Accepted in: Trans. ASABE.
Bechara, M.A., P.H. Heinemann, P.N. Walker, and C.P. Romaine. 2006. Agaricus bisporus mushroom cultivation in hydroponics systems. Accepted in: Trans. ASABE.
Sabeh, N., E.F. Wheeler, P.H. Heinemann, and D.M. Beyer. 2006. Environmental Conditions within Small-scale Agaricus bisporus mushroom production rooms. Accepted in: Applied Engineering in Agriculture.