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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15<br />
Digestate<br />
Ideally, bioplastics would biodegrade <strong>and</strong> dis<strong>in</strong>tegrate dur<strong>in</strong>g <strong>the</strong> anaerobic phase <strong>in</strong> an<br />
anaerobic digestion plant, just as a major part of “natural” bio<strong>waste</strong> does. However, if<br />
bioplastics dis<strong>in</strong>tegrate dur<strong>in</strong>g <strong>the</strong> anaerobic phase, <strong>the</strong>y later can biodegrade completely<br />
dur<strong>in</strong>g <strong>the</strong> aerobic stabilization phase or with <strong>the</strong> use of digestate or compost <strong>in</strong> <strong>the</strong> soil.<br />
Usually, <strong>in</strong>dustrial digestate is sieved through a 2 mm mesh, <strong>and</strong> if <strong>the</strong> result<strong>in</strong>g biomanure<br />
is not 100% PLA, it can be dangerous. The feeds<strong>to</strong>ck of pure PLA can produce<br />
Class A sludge <strong>and</strong> be used as fertilizer on farms.<br />
No significant amount of chemicals (PLA, Accelerant, etc) were found <strong>in</strong> <strong>the</strong> compost<strong>in</strong>g<br />
process, but daily lab test<strong>in</strong>g is required. Seasonal variation <strong>in</strong> <strong>the</strong> <strong>waste</strong> can <strong>create</strong><br />
obstacles <strong>in</strong> <strong>the</strong> process. A sampl<strong>in</strong>g at various stages is recommended. The undigested<br />
matter would go <strong>to</strong> <strong>the</strong> l<strong>and</strong>fill, <strong>and</strong> it is assumed that <strong>the</strong> residual untreated PLA from <strong>the</strong><br />
AD process will not cont<strong>in</strong>ue <strong>to</strong> emit biogas when l<strong>and</strong>filled <strong>and</strong> will offset emission via<br />
carbon sequestration. Generally, one <strong>to</strong>n per day of <strong>organic</strong> matter produces<br />
approximately 33 <strong>to</strong>ns of bio manure per year.<br />
A <strong>to</strong>tal of 1TPD of undigested bioplastic with 30% of <strong>to</strong>tal solids will be sent <strong>to</strong> <strong>the</strong><br />
l<strong>and</strong>fill; about 3TPD dewatered digestate cake can be utilized <strong>for</strong> compost<strong>in</strong>g, <strong>and</strong><br />
Class A fertilizer can be produced.<br />
Gas Production<br />
Gas from anaerobic digestion conta<strong>in</strong>s about 65 - 70% CH4 by volume, 25 <strong>to</strong> 30% CO2,<br />
<strong>and</strong> small amounts of N2, H2, H2S, water vapor, <strong>and</strong> o<strong>the</strong>r gases. PLA was degraded<br />
us<strong>in</strong>g dry digestion with high solids under <strong>the</strong> mesophilic condition up <strong>to</strong> 60% over 40<br />
days (Itavaara, et al. 2002). It was found that approx. 90% degradation occurs <strong>in</strong> 60 days<br />
WASTE TO ENERGY<br />
PEDNEKAR, HARSHADA
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