CANCELLED - Compost Decomposition and Contaminant Detection Using an Array of Sensors

Background/Question/Methods

Byproducts of organic waste decompose to create compost, a fertilizer used to provide nutrients to and adjust pH of soil. Compost is created by two major groups: individuals who compost their refuse and facilities capable of composting material on a commercial scale. Composting facilities collect compost feedstock from the public and sort plastic and metallic contaminants from the waste stream to sell a uniform, contaminant free product. Feedstock maturation is challenging for composters because of the need to adjust chemical composition to meet facility specific standards for nutrient content for specific crops. Currently, there is no way for composters to know bin contents and decomposition level before receiving compost at their facilities. The integration of compost collection receptacles with inexpensive sensors could provide insight into feedstock composition and presence of contaminants. In order to address this need, fruit, vegetable, and meat waste were placed into a receptacle and decomposed for several weeks while in-situ measurements of gases were taken at regular intervals and contaminants were detected upon waste deposition using cameras and inductive sensors for plastic and metallic waste.

Results/Conclusions

Expected products of compost decomposition included heat, moisture, carbon dioxide, nitrous oxide, trace amounts of methane, ammonium, and Volatile Organic Compounds (VOCs). The receptacle had a volume of 0.3 m3 with 4 kg of refuse and sensor ranges were selected based on literature review of typical compost conditions and outputs. VOCs were an important parameter which were released at specific times and quantities depending on feedstock during decomposition allowing the estimation of decomposition and deposited waste by measuring gases released. The data collected was analyzed to identify level of decomposition and contaminant estimates which could be relayed to composters, providing a tool for advanced knowledge of waste composition. The impact of this research was providing insight into feedstock composition and presence of contaminants.