Identification and evaluation of VOCs evolved from warm season swine mortality composts

Abstract

<p>The intensive production of swine in Iowa (28.4 % of the U.S.A production) inevitably results in high amounts of piggery waste including animal carcasses. Composting is an environmentally sound and relatively inexpensive method to dispose swine mortalities especially when the carcasses are diseased. Measurement of VOC emissions is an alternative to test progress and completion of the process. In this study, diseased swine mortalities are composted in summer conditions of Central Iowa. Corn silage, oat straw and corn stalks are used as envelope materials. Once a week, air samples are collected from the center of test units and sampled with 85 µm Carboxen/ polydimethylsiloxane (CAR/PDMS) solid phase microextraction (SPME) fiber. Samples were analyzed using gas chromatography (GC) - mass spectrometry (MS). The objective of the study is to investigate the potential usage of VOCs as indicators of swine mortality degradation. It is found that nitrogen and sulfur containing compounds can be used as indicators of the composting process. Sulfur-containing compounds are detected from all test units. Nitrogen-containing compounds are detected from only corn silage test units. It is concluded that carcass degradation is incomplete in all of the test units. Carcass degradation in corn stalks and oat straw test units is better than corn silage test units. These results are supported with respiration rate results. Respiration rates of the remaining swine carcasses are found to be between 5-7 mg CO2-C g VS-1d-1 and swine carcasses are categorized as moderately unstable composts.</p>