Organic Value Recovery Solutions LLC Odor Control and Elimination by Using Black Soldier Fly to Digest Swine and Chicken Manure M. Coulibaly, D. C. Sheppard and G. C. Rains, University of Georgia internal report, 2004 Abstract Headspace air was compared for malodorous compounds including acetic acid, propanoic acid, butanoic acid, valeric acid, isovaleric acids, caproic acid, and p-cresol in vials containing swine manure with and without black soldier fly larvae.  The samples were kept in an incubator at 37C and 70% humidity.  Paired samples (vials with and without larvae) were analyzed by static headspace sampling and gas chromatography-mass spectroscopy (HS-GC-MS) each time.  Malodorous compounds were reduced, degraded or eliminated by larval activity over time, and the process was accelerated when the ratio of larvae weight over manure weight was increased.  In vials containing 5 grams of manure and 0.5 gram of larvae, the concentrations of malodorous compounds were 80 to 100% lower than in vials without larvae after three days.  In vials containing 1.7 grams of manure and 0.5 gram of larvae, the concentrations of malodorous compounds were 80 to 100% lower than in vials without larvae after 24 hours. Introduction Production of pork is a major agricultural enterprise in the world especially in countries such as United States, Canada, Japan, the UK, and other parts of Europe. In the United States, the majority of the production occurs in the Midwest from Ohio to Nebraska, Minnesota to Missouri, and North Carolina.  The expansion of pork industries in urban areas, as well as rural areas, causes emissions of offensive odors, which are considered as nuisance pollutants [8,9]. The odor management is often difficult, costly, and sometimes inefficient.  Many approaches such as changing of swine diet, venting of swine manure storage system [2], electron beam treatment of swine manure [3], and others were tested around the world, but they were sometimes time consuming or not cost-effective.  Using black soldier fly larvae digestion is a natural, simple, and inexpensive way to solve the problem. Compared to houseflies, which are vectors of numerous diseases, black soldier flies are not routinely pests, and are attracted neither to human habitation or food [5].  Soldier fly larvae tolerate a wide range of temperatures and are well adapted to the tropics and the warmer temperate .  The last four volatile fatty acids were considered as the major malodorous compounds because they had the most disagreeable odor according to our investigation.  None of the compounds investigated happened to smell like swine manure specifically, so the strong smell related to swine manure is certainly due to the cumulative and synergic effect of the compounds of interest and many others not investigated in this study. All these compounds are more or less destroyed by larval activity. Experiment 2 The importance of the quantity of larvae used in the process of controlling odor in swine manure was investigated by increasing the ratio of the mass of larvae used over the mass of manure to be digested.  The chromatograms obtained during experiment 2 are similar to the ones obtained during experiment 1; the same peaks or compounds were obtained (fig. 1).  As in experiment 1, the effect of larval activity was noticed after just 4 hours with an average of about 47% decrease in concentration of malodorous compounds.  The major decrease in concentration of compounds ranged from 95 to 100%, which is much higher than the one obtained after 3 days in experiment 1 (86 to 100%).  Most malodorous compounds and even p-cresol were eliminated after 48 hours (2 days).  Table 2 shows the average of percent decrease in concentrations for each compound for three replications of experiment 2. Average percent decrease in concentration of malodorous compounds Compounds Initial 4 hours 20 hours 30 hours 48 hours Acetic acid 0 55 60 70 71 Propionic acid 0 47 86 95 100 Butyric acid 0 0 52 87 95 100 Valeric acid 0 0 44 85 95 100 Isovaleric acid 0 36 85 95 97 Caproic acid 0 37 87 100 100 p-cresol 0 47 52 49 100 Furfural 0 55 51 55 60 Table 2. Average percent decrease in concentration of malodorous compounds I vials containing 1.7g of manure with 0.5g of larvae compared to vials without larvae © Organic Value Recovery Solutions 2010 © Organic Value Recovery Solutions 2010