Waste-to-Energy Biomass Digester with Decreased Water Consumption
The digestion process has several variations, but in each method the animal waste must be diluted with water in order for digestion to occur. Current forms of biomass digester technology require large amounts of water to facilitate digestion. The volume of water required to digest biomass waste into usable resources is not economically or environmentally feasible for most animal feeding operations, especially those in the arid Western United States and other water-scarce regions.
DescriptionResearchers at Colorado State University have created a new digestion process that is particularly well-suited for the treatment of equine, bovine, and poultry waste in arid regions. This digester uses far less water than other digestion methods to process animal waste into useful compost and methane gas. Because this digester uses less water, it is more economically feasible for use in regions where water is scarce, and helps to reduce the environmental impact of large-scale animal feeding operations.
This digester uses multiple stages of both aerobic and anaerobic digestion to break down waste. Specifically, it has multiple leachate bay reactors (LBRs) that can work together or separately. The digestion stages are all separate from each other, so if one LBR becomes contaminated or the bacteria in it die, the digestate can be removed from it while the uncontaminated LBRs continue to process. Furthermore, the digestion process can be scaled back during times of lower waste production by taking one or more of the LBRs offline. Additionally, each stage is monitored to ensure that optimum conditions for the bacteria are maintained; this monitoring ensures that the conditions in the reactor are appropriate for the specific type of bacteria needed in that step.Benefits
- Less water can be used to create methane and compost than in other digestion processes
- Able to digest multiple types of waste, including bovine, equine, and poultry manure
- Methane produced by the digestion process can be used on-site to offset energy needs.
- Compost produced can be used on-site as soil amendment.
- Disposal of solid animal waste and generation of biogas
- Suitable for large-scale animal feeding operations that dry-scrape manure
- Especially well-suited for areas with low water availability and high water and/or energy costs
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DIGESTER FOR HIGH SOLIDS WASTE
A digester with separate stages for hydrolysis and methanogenesis is disclosed. The digester includes a leachate bay reactor, which may be configured as modular, multi-bay units. Waste material is added to the leachate bay reactor. A leachate storage tank is fluidically connected to the leachate bay reactor, which facilitates hydrolysis. Leachate from the leachate storage tank is recirculated through the leachate bay reactor. A high rate methanogenic reactor is fluidically connected to the leachate storage tank to cycle the leachate in a fixed film environment for biogas production from solubilized organic matter. The reactor may be operated in an anaerobic digestion mode, or a dual aerobic-anaerobic digestion mode. The reactor may also include a struvite system having a crystallizer unit and a separation unit to reduce ammonium and phosphate accumulation during operation.
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