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Waste Milk Remediation and Hydrogen Gas Production Using a High-Temperature Anaerobic Digestor

Principal Investigator/Project Leader: 
Department of Project: 
Microbiology Dept.
Project Description: 

Nearly all food and agricultural waste in the U.S. enters landfills, making it the largest contributor of material entering these sites. Biological pre-treatment of large organic molecules by fermentative organisms lowers the high organic carbon load in waste, lowers wastewater treatment costs, and can produce bioenergy to partially offset costs. Conceivably, microbes that grow best above 80°C, or so-called ‘hyperthermophiles’, could be used to consolidate wastewater heat treatment and organic remediation in a single step to decrease costs while producing H2 as an energy product.

This proposal seeks to make fundamental advances in waste milk remediation and bioenergy generation using a hyperthermophilic microbe. We will study the ability of Thermococcus paralvinellae to degrade waste milk at 80°C, including milk from cows treated for mastitis and containing the bacterial antibiotic Ceftiofur, kill the bacteria present in the waste, remove the Ceftiofur, and produce hydrogen gas as an end product in an anaerobic digestor. Previous research by the PI showed that T. paralvinellae can perform all of these tasks when grown on a small scale in sealed bottles. The next phase of the project is to determine the conditions necessary for maximum organic compound removal and hydrogen gas production in a bench-scale continuous flow anaerobic digestor. This research will provide insight into ways to rapidly treat waste milk specifically and food and agricultural wastes in general, the largest contributor to municipal solid waste in the U.S., with concomitant decontamination and bioenergy production. 

In 2014, the Massachusetts Department of Environmental Protection enacted a ban on disposal of commercial organic wastes by businesses and institutions that dispose of one ton or more of these materials per week. The materials must be composted, converted, recycled or reused prior to disposal as solid waste or raw sewage. Waste milk is a growing part of commercial organic waste, and waste milk from cows treated for mastitis is particularly problematic due to the presence of antibiotic in the milk that cannot be sold, sent for disposal, or dispersed onto fields and preferably should not be fed to calves to prevent antibiotic resistance. This project explores waste milk conversion to energy using high-temperature anaerobic digestion. Its goal is sustainability, as it relates to solid waste management, focused on utilizing waste as a resource. It will facilitate the development of new and existing technologies/practices prior to the landfilling option and evaluate ‘next generation’ technologies for processing or converting discarded materials into energy or beneficial products. The project is also a pilot for the digestion of other food and agricultural waste streams that might all be degraded in a centralized processing facility.