Waste to Energy: Harnessing the fuel in organic waste to create a business opportunity for a recycling-based society and system
To generate a feasible amount of methane to support a digester, it is estimated that 10 to 12 tons/d, with 8-10% contamination and 80% of the contamination being bioplastics, can produce about 70 Nm3/h of biogas. This is the amount of biogas needed to produce 200 kg/day of hydrogen, which is the smallest commercially available packaged system. The greenhouse gas emission (GHG) for IngeoTM is currently 1.3 kg CO2 eq./kg polymer compared to approx. 3.2 kg CO2 eq./kg polymer for PET. Therefore, implementing anaerobic digestion for PLA can reduce around 942.5 kg - 1132 kg per day of CO2 equivalent emissions. A total of 1 ton per day of undigested bioplastic with 30% of total solids will be sent to landfills; 3 tons per day of dewatered digestate cake can be utilized for composting, and Class A fertilizer can be produced. The research on anaerobic degradation of biopolymers is still in its infancy. Therefore, this report has discussed different pre-treatment alternatives to treat PLA such as physical, chemical, and thermal treatments. This report suggests on-site segregation benefits of the current solid waste management scenario in the commercial sector of Plano, Texas. Organic waste generated from a cafeteria of the commercial sector in Plano caused an environmental impact on landfills. This report consists of a description of existing scenarios and possible pre-treatment alternatives for bioplastic degradation generated from the commercial sector. Harshada Pednekar was a graduate research analyst in the Hunt Institute while studying for a masters degree in environmental engineering from SMU's Lyle School of Engineering
To generate a feasible amount of methane to support a digester, it is estimated that 10 to 12 tons/d, with 8-10% contamination and 80% of the contamination being bioplastics, can produce about 70 Nm3/h of biogas. This is the amount of biogas needed to produce 200 kg/day of hydrogen, which is the smallest commercially available packaged system. The greenhouse gas emission (GHG) for IngeoTM is currently 1.3 kg CO2 eq./kg polymer compared to approx. 3.2 kg CO2 eq./kg polymer for PET. Therefore, implementing anaerobic digestion for PLA can reduce around 942.5 kg - 1132 kg per day of CO2 equivalent emissions.
A total of 1 ton per day of undigested bioplastic with 30% of total solids will be sent to landfills; 3 tons per day of dewatered digestate cake can be utilized for composting, and Class A fertilizer can be produced. The research on anaerobic degradation of biopolymers is still in its infancy. Therefore, this report has discussed different pre-treatment alternatives to treat PLA such as physical, chemical, and thermal treatments. This report suggests on-site segregation benefits of the current solid waste management scenario in the commercial sector of Plano, Texas. Organic waste generated from a cafeteria of the commercial sector in Plano caused an environmental impact on landfills. This report consists of a description of existing scenarios and possible pre-treatment alternatives for bioplastic degradation generated from the commercial sector.
Harshada Pednekar was a graduate research analyst in the Hunt Institute while studying for a masters degree in environmental engineering from SMU's Lyle School of Engineering
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18<br />
Feeds<strong>to</strong>ck Composition<br />
Food <strong>waste</strong> has a high energy potential <strong>and</strong> an estimated decay rate of 0.14 yr - which<br />
makes it compatible <strong>to</strong> digest with PLA. Feeds<strong>to</strong>ck will be composed of food <strong>waste</strong> <strong>and</strong><br />
PLA/bioplastic. The source of food <strong>waste</strong> is <strong>the</strong> cafeteria <strong>and</strong> canteen food <strong>waste</strong>.<br />
Because of high moisture content (approx. 80% or more) <strong>in</strong> food <strong>waste</strong>, it is suitable <strong>to</strong><br />
comb<strong>in</strong>e with PLAs that are low <strong>in</strong> moisture content. Not all bio-<strong>based</strong> plastics will<br />
biodegrade. Lactic acid is a great source of food <strong>for</strong> microorganisms <strong>and</strong> hence is easy<br />
<strong>to</strong> biodegrade. Biodegradable bioplastics like pure PLA have great potential <strong>to</strong> contribute<br />
<strong>to</strong> material recovery, reduction of l<strong>and</strong>fills, <strong>and</strong> use of renewable resources.<br />
The Ratio of Food <strong>Waste</strong> <strong>to</strong> PLA<br />
There are a variety of ratios of food <strong>waste</strong> <strong>to</strong> PLA recommended, but overall, a very small<br />
percentage of PLA <strong>to</strong> <strong>organic</strong> <strong>waste</strong> is feasible. The ratio of bioplastic <strong>to</strong> kitchen <strong>waste</strong><br />
was kept very low at a compost plant <strong>in</strong> Kassel, Germany: 1 plastic part <strong>to</strong> 99 parts of<br />
<strong>organic</strong> <strong>waste</strong> on a weight basis. It showed no negative effects observed <strong>in</strong> terms of<br />
quality <strong>and</strong> <strong>the</strong> same effect on plants as regular compost. (Song, et al. 2009). SMU faculty<br />
members from <strong>the</strong> Civil <strong>and</strong> Environmental Eng<strong>in</strong>eer<strong>in</strong>g Department <strong>and</strong> professionals<br />
had <strong>the</strong> same op<strong>in</strong>ion that an acceptable ratio is up <strong>to</strong> 10%. It can also work as COD of<br />
kitchen garbage (raw - 230 g/lit) <strong>to</strong> PLA at a 4:1 ratio. (Wang, et al. 2012).<br />
Alternatives <strong>for</strong> Pre-Treatment of PLA<br />
Inconsistencies <strong>in</strong> product label<strong>in</strong>g <strong>and</strong> a lack of accepted def<strong>in</strong>itions <strong>for</strong> <strong>in</strong>dustry terms<br />
confuse consumers upon purchas<strong>in</strong>g <strong>and</strong> discard<strong>in</strong>g products. Improperly sorted<br />
bioplastics can contam<strong>in</strong>ate recycl<strong>in</strong>g streams <strong>and</strong> feeds<strong>to</strong>ck <strong>for</strong> compost<strong>in</strong>g operations<br />
WASTE TO ENERGY<br />
PEDNEKAR, HARSHADA
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