Low Energy Technology to Pasteurize Organic Residuals to Meet Pathogen and Vector Attraction Reduction Requirements
Akrum H. Tamimi[1],1, Richard Miller2
1Department of Biosystems Engineering, The University of Arizona, Tucson, AZ; www.arizona.edu
2Sunstate Environmental Services Inc.& Shincci – USA Inc., Yuma, AZ; www.sunstateinc.com
[1]Corresponding Author: akrumt@email.arizona.edu; +1 (520) 834-2433
We are implementing a new transformative technology for treating organic residuals and sludges to Class A level at a residual treatment facility in New Hampshire. The two-stage technology consists of: i) dewatering liquid or slurry residuals with average total solids ranging from 0.2% to 7% to residual cake with percent total solids ranging from 15% to 25%, and ii) drying the dewatered cake at low temperature utilizing heat pump dehumidification principlesto90% total solids. The final product is a pasteurized organic product that meets pathogen and vector attraction reduction requirements. The low-temperature drying technology keeps caloric and nutrient contents intact and does not change organic residuals’ chemical characteristics. Energy requirements are low; to dry one ton of sludge cake from 20% to 90% total solids requires 160 kWh compared to 700 kWh average requirements of existing drying technologies. This is achieved through hot air recycling within the treatment closed system and due to shaping the treated materials resulting in an increased surface area.
Utilizing this low-temperature dehumidification technology reduces the weight of organic residuals by a factor of at least 4.5, which results in significant reductions of organic materials’ weight and hence hauling cost. For example, utilizing the dehumidification technology in a treatment plant that produces 125,000 tons of 20% residual cake per year would reduce the weight to 27,778 tons of pasteurized pathogen free treated materials per year. This results in significant savings on hauling costs, emissions from trucking, traffic congestion, destruction of roads and bridges due to repeated loading and unloading heavily weighed trucks, in addition to producing the final product that can be beneficially used in agricultural production, creating topsoil, fuel for energy generation and other beneficial uses.
[1]Corresponding Author: akrumt@email.arizona.edu; +1 (520) 834-2433