Page Banner

United States Department of Agriculture

Agricultural Research Service

Title: In-Vessel, Mechanical Rotating Drum Composting of Institutional Feed Residuals

Authors
item Smith, Douglas
item Cawthon, D - TARLETON STATE UNIV
item Sloan, J - TEXAS AG EXPER STA
item Freeman, T - TEXAS A&M UNIVERSITY

Submitted to: Compost Science and Utilization
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 18, 2005
Publication Date: July 1, 2006
Citation: Smith, D.R., Cawthon, D.L., Sloan, J.J., Freeman, T.M. 2006. In-vessel, mechanical rotating drum composting of institutional feed residuals. Compost Science and Utilization. 14(2):155-161.

Interpretive Summary: Food waste from large-scale food service providers are commonly disposed of through the wastewater stream. This increases the costs associated with the treatment of wastewater, due to the large amounts of organic materials that must be removed, which may be charged to the food service provider. Alternative management of this waste stream would benefit the wastewater treatment facilities, and the food service provider. This study was conducted to examine composting as a method to reduce the amount of food waste that enters the wastewater stream. A rotating drum composter was used to compost three batches of food waste collected from a prison. Three ratios of wood shavings to food waste were used: 2/1, 3/1 and 4/1. Food wastes were highly variable between batches. Initial compost pH was low in all batches, generally around 4.5. Constant rotation from the composter provided sufficient aeration to initiate aerobic composting. Thermophilic temperatures (> 45 C) were reached within 2-5 days, as pH of the compost biomass increased simultaneously. Over the three batches, the 3/1 ratio reached the desired thermophilic temperatures quicker, and maintained those temperatures longer than the other two batches. The impact of this work is to provide an alternative management strategy to remove food wastes from the wastewater stream. Use of this composting technology could save money charged to food service providers to whom surcharges are added for handling wastewater streams with high amounts of organic matter.

Technical Abstract: Food waste from large-scale food service providers are commonly disposed of through the wastewater stream. This increases the costs associated with the treatment of wastewater, due to the large amounts of organic materials that must be removed, which may be charged to the food service provider. Alternative management of this waste stream would benefit the wastewater treatment facilities, and the food service provider. This study was conducted to examine composting as a method to reduce the amount of food waste that enters the wastewater stream. A rotating drum composter was used to compost three batches of food waste collected from a prison. Three ratios of wood shavings to food waste were used: 2/1, 3/1 and 4/1. Food wastes were highly variable between batches. Initial compost pH was low in all batches, generally around 4.5. Constant rotation from the composter provided sufficient aeration to initiate aerobic composting, and O2 levels in the biomass were rarely below 5%. Thermophilic temperatures (> 45 C) were reached within 2-5 days, while a simultaneous increase in pH to optimal range (5 – 7.5) was occurring. Over the three batches, the 3/1 ratio reached the desired thermophilic temperatures quicker, and maintained those temperatures longer than the other two batches. The impact of this work is to provide an alternative management strategy to remove food wastes from the wastewater stream. Use of this composting technology could save money charged to food service providers to whom surcharges are added for handling wastewater streams with high amounts of organic matter.

Last Modified: 8/21/2014