When the City of Danbury decided to renovate its wastewater treatment plant, it incorporated our FOG-To-Biodiesel system to eliminate the economic and environmental costs associated with landfilling and incinerating its waste FOG. The system not only eliminates their FOG disposal costs, but creates a new revenue stream from the sale of biodiesel they produce onsite without interruption to the operation of their plant, through an automated and continuous-flow process.
For this project, we designed an 18,000 GPD FOG receiving station to increase Danbury’s capacity to accept trap grease trucked in by grease collectors. To address concerns about odor emanating from the process of receiving FOG and converting it to biodiesel, odor-control equipment is embedded into our system.
During preprocessing, we eliminate 99% of water content to prepare the brown grease for conversion to biodiesel. Water separated in the this process is fed back into the treatment system, from where it discharges as effluent.
Biodiesel not consumed by Danbury will be sold to a local fuel distributor for a considerable profit through an off-take agreement. Over the past 10 years, B100 biodiesel has been consistently priced higher than most other other alternative fuels.
For municipalities interested utilizing their biodiesel production to fuel their fleets, they can reduce respective carbon emissions by up to 74%. Life-cycle analysis conducted by Argonne National Laboratory concluded emissions for B100 biodiesel to be 74% lower than those from petro-diesel. The California Air Resources Board has also generated similar results for its life-cycle analysis of biodiesel.
FOG is commonly mixed with sludge and utilized as a co-substrate in anaerobic digesters for solids volume reduction and biomethane production. Replacing FOG with glycerin, a byproduct of our FOG-To-Biodiesel system, can increase volatile solids removal and biogas production. With our FOG-To-Biodiesel system, more energy (and value) can then be produced with the FOG that would have otherwise been fed to the digester.
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Biodiesel, which is a renewable and environmentally friendly fuel, has been studied widely to help remedy increasing environmental problems. One of the key processes of biodiesel production is oil extraction from oilseed materials. Switchable solvents can reversibly change from molecular to ionic solvents under atmospheric CO2, and can be used for oil extraction. N, N-dimethylcyclohexylamine (DMCHA), a switchable solvent, was used to extract oil from Jatropha curcas L. oil seeds to produce biodiesel. The appropriate extraction conditions were: 1:2 ratio of seed mass to DMCHA volume, 0.3-1mm particle size, 200 rpm agitation speed, 60min extraction time, and 30 °C extraction temperature. The extraction ratio was about 83%. This solvent extracted the oil more efficiently than hexane, and is much less volatile. By bubbling CO2 under 1atm and 25 °C for 5h, the oil was separated, and DMCHA was recovered after releasing CO2 by bubbling N2 under 1atm and 60 °C for 2h. The residual solvent content in oil was about 1.7%. Selectivity of DMCHA was evaluated by detecting the protein and sugar content in oil. Using the oil with residual solvent to conduct transesterification process, the oil conversion ratio was approximately 99.5%.
