Types of Methane Digestion Facilities. Info based on priorities desired in the digestion facility.
Priorities (ranked from highest to lowest)
Environment
Safety
Reduced space requirements in Volume/square feet
Increased composting rate
High Revenue
Reduced operating costs (When all is said and done total costs must be substantially lower than revenue)
Reduced Employee time
Reduced equipment maintenance and ease of needed maintenance
Reduced energy requirements -Use Gravity Flow for waste materials
Reduced nonwaste inputs
Retrofitable, and flexible to change at relatively low-cost
Upfront costs
Lower in priority but must be low enough to make a high return on investment. Payback
Problems to control
Safety
Gas tank leaks
If underground tank might get displaced
Methane corrosion of metal
Environment
Odor
Scum on top (Prevents methane gas from coming up from reactions)
Mehthane-forming bacteria have very needy condtions, reproduce slower than acid-forming
What should the large-scale worm composting facility look like?
The purpose of this paper is to outline what I have been learning about Methane digestion for the past few weeks in order to learn what needs to get done next in order to attain the goal of a rough blueprint of the methane digestion facility that will be built at Sarah Lawrence College. Biogas facilities are seen as the most cost-effective option due to the relatively low-maintenance requirements, low land usage (can even be buried underground), and an additional source of revenue, biogas, a perfectly renewable source of energy. The purpose of drawing and writing up a rough blueprint of the methane digestion facility for food waste at Sarah Lawrence College is to prepare to talk to professional contractors who design and install methane digestion facilities. Professionals are expensive, therefore, it is important to do as much work on our own as possible in order to reduce time necessary to talk to them. In addition, professional designers of methane digestion facilities do not know Sarah Lawrence College very well, therefore, by knowing specific sites for the methane digestion equipment, and having a rough idea of the design, that will save numerous hours, and therefore a lot of money that would have needed to get paid to the experts. Nevertheless, professional, reputable people who have installed successful methane digestion facilities are essential for ensuring that the equipment gets installed correctly and safely. Even the smallest error in the installation of such a large, expensive methane digestion facility could cost thousands of dollars to repair or retrofit. By having a rough blueprint of this facility before asking the professional, I will be able to ask him/her educated questions about overseeing the facility such as, how will this tank be made gas-sealed, will this underground tank have issues with erupting due to flooding or heating, could the tank crack from constant cooling/heating and expansion as a result of the digestion process and/or weather? The other reason for this rough blue print is to make a pilot project that demonstrates the effectiveness of my rough blueprint, gives hands-on experience with day-to day operations, and allows me to perfect my blueprint for any potential errors or unanticipated problems that may occur in a much larger-scale facility, and serves as an educational tool for students, faculty, Avi Staff, and other interested people in the community. Seminar and lecture field trips will be openly encouraged and done. Written material about this facility can and should be published and given as reading material in seminar and lecture settings. Material relating to organisms in the composting process, and its ramifications on the environment should also be recommended for class readings to professors. A pilot scale methane digestion facility will be everything like the methane digestion facility I plan to build except it will be a lot smaller and less costly.
A finished rough blueprint will have thoroughly explored several types of methane digestion facilities, food grinding and separating machines, harvesting machines, and have thorough knowledge about possible sitings of this facility. Thorough knowledge of the types of equipment for each stage of the methane digestion process, and a thorough knowledge of the methane digestion facility are essential. This rough blueprint should be completed no later than December 15 2011. While a finsished blueprint will not necessarily have in-depth knowledge of exactly where the equipment will be, the exact measurements of all the pipes, and tanks etc. it will have an approximate number stating how much food waste it will digest, how much fibrous waste needs to be digested, and will have deduced from that how much methane, finished sludge, and water will be produced. Knowledge of other facilities that have done similar facilities will be essential by this date.
This paper will examine in broad detail digestion facilities with their pros, cons and give in detail possible conference projects that other students and I can do to help install this facility and make this rough blueprint possible. In addition, we will make a rough outline demonstrating how this facility will work.
First, food waste and paper waste gets collected. Hand sorting of discarded material is labor-intensive work, so a possible education campaign to show people where to discard waste is possible. Possible sorting of bottles and sending them in for reclaimment money will at least help offset costs as long as transportation costs to the nearest facility, right now in Stop and Shop, are substantially lower than the revenue gained from sending in assorted plastic bottles. Paper and food waste will be separated, weighed, and added accordingly.
A large shredder will then cut and pulverize the food and paper waste to pieces about 5-10 mm in average size. We are considering purchase of a machine that does both food and paper shredding in order to save on capital costs, and facilitate proper mixture of the materials. Food and paper waste next goes to a mixing machine. Possibly a tumbler similar to the blue tank seen at Cherry Street and Pike Street at Coleman park New York, NY at the lower East Side Ecology Center. Food waste will then either be kept in the same drum-like mixer, or be sent via dumping and other gravity-fed means into a heating tank. There food waste will be heated at 150 degrees Celsius#. Sonar treatment may also be applied for breakage of cell membrane walls and further digestion.
Food waste then proceeds to the biogas facility. Types of facilities are numerous. However, dry digestion methods including, plug-flow, Kompogas, Dranco, and Inclined designs are taken into careful consideration, and wet types of digesters, including the Anaerobic Baffled reactor, the Upflow Anaerobic Sludge Blanket (UASB) and its close relative the Expanded Granular Sludge Blanket (EGSB) are all potential competitors.
Biogas then gets harvested either for heat production, or for electricity generation. Because electricity generators produce heat due to their inherent inefficiencies, a cooling jacket will be used to harvest excess heat either for biogas temperature controls or for college heating needs. Excess water then gets extracted with a pulverizer. Excess water will then either be treated or recirculated for mixture with food waste. This can provide both added microbial boosts, and also drastically reduce costs of ongoing maintenance that otherwise would have gone to water treatment. The digested product, being high in nutrient content may either be sold to contractors, rooftop farms, or other entities in need of large-scale land treatment, or be further composted by a lively worm population. While treated food waste can be applied, due to its partially degraded state, the quality of this soil ammendment, while high in nutrients, still is a lower quality compost. Worm digestion will increase plant-available nutrient content and foster healthy microbial plant populations.
Dry types of digestion
Advantages include reduction of maintenance costs due to reduced water treatment needs, reduced heating needs and other temperature controls. Potential difficulties include pumping of food waste material or moving it through various phases of digestion. A close examination of this is essential.
Wet Types of Digestion
Average retention times are substantially lower sometimes as low as 3 days# while dry types can take approximately 14-30 day retention times. While water treatment costs would be substantially high, and additional water means increased facility size, and therefore, capital costs, much depends on the Hydraulic and Solid Retention times of food wastes. If it can be low enough to make a facility small enough to fit on campus, facilitate transportation of food waste to each stage of the digestion process, and if water can be recirculated for re-use, and if the facility can be insulated enough to minimize additional costs of heating extra water, using a wet digestion process may be worthwhile. In addition, since food waste is composed of 80-90 percent water, a wet process, which is normally solid contents under 20%, may be feasible. However, paper, which contains a relatively lower moisture content, once factored in may substantially reduce water content, and thus, drive up the costs due to the need to add additional water.
Below are a series of potential digestion facilities. They are analyzed in the following terms:
Priorities (ranked from highest to lowest)
Environment
Safety
Reduced space requirements in Volume/square feet
Increased composting rate
High Revenue
Reduced operating costs (When all is said and done total costs must be substantially lower than revenue)
Reduced Employee time
Reduced equipment maintenance and ease of needed maintenance
Reduced energy requirements -Use Gravity Flow for waste materials
Reduced nonwaste inputs
Retrofitable, and flexible to change at relatively low-cost
Upfront costs
Lower in priority but must be low enough to make a high return on investment. Payback
should take five years at most.
Problems to control
Safety
Gas tank leaks
If underground tank might get displaced
Methane corrosion of metal
Environment
Odor
Scum on top (Prevents methane gas from coming up from reactions)
Mehthane-forming bacteria have very needy condtions, reproduce slower than acid-forming
bacteria- therefore, acids may be in greater quantity than methanogens can
handle-causing methane to not get produced.
How to market/use effluent both water (if any) and sludgeWhat should the large-scale worm composting facility look like?
The purpose of this paper is to outline what I have been learning about Methane digestion for the past few weeks in order to learn what needs to get done next in order to attain the goal of a rough blueprint of the methane digestion facility that will be built at Sarah Lawrence College. Biogas facilities are seen as the most cost-effective option due to the relatively low-maintenance requirements, low land usage (can even be buried underground), and an additional source of revenue, biogas, a perfectly renewable source of energy. The purpose of drawing and writing up a rough blueprint of the methane digestion facility for food waste at Sarah Lawrence College is to prepare to talk to professional contractors who design and install methane digestion facilities. Professionals are expensive, therefore, it is important to do as much work on our own as possible in order to reduce time necessary to talk to them. In addition, professional designers of methane digestion facilities do not know Sarah Lawrence College very well, therefore, by knowing specific sites for the methane digestion equipment, and having a rough idea of the design, that will save numerous hours, and therefore a lot of money that would have needed to get paid to the experts. Nevertheless, professional, reputable people who have installed successful methane digestion facilities are essential for ensuring that the equipment gets installed correctly and safely. Even the smallest error in the installation of such a large, expensive methane digestion facility could cost thousands of dollars to repair or retrofit. By having a rough blueprint of this facility before asking the professional, I will be able to ask him/her educated questions about overseeing the facility such as, how will this tank be made gas-sealed, will this underground tank have issues with erupting due to flooding or heating, could the tank crack from constant cooling/heating and expansion as a result of the digestion process and/or weather? The other reason for this rough blue print is to make a pilot project that demonstrates the effectiveness of my rough blueprint, gives hands-on experience with day-to day operations, and allows me to perfect my blueprint for any potential errors or unanticipated problems that may occur in a much larger-scale facility, and serves as an educational tool for students, faculty, Avi Staff, and other interested people in the community. Seminar and lecture field trips will be openly encouraged and done. Written material about this facility can and should be published and given as reading material in seminar and lecture settings. Material relating to organisms in the composting process, and its ramifications on the environment should also be recommended for class readings to professors. A pilot scale methane digestion facility will be everything like the methane digestion facility I plan to build except it will be a lot smaller and less costly.
A finished rough blueprint will have thoroughly explored several types of methane digestion facilities, food grinding and separating machines, harvesting machines, and have thorough knowledge about possible sitings of this facility. Thorough knowledge of the types of equipment for each stage of the methane digestion process, and a thorough knowledge of the methane digestion facility are essential. This rough blueprint should be completed no later than December 15 2011. While a finsished blueprint will not necessarily have in-depth knowledge of exactly where the equipment will be, the exact measurements of all the pipes, and tanks etc. it will have an approximate number stating how much food waste it will digest, how much fibrous waste needs to be digested, and will have deduced from that how much methane, finished sludge, and water will be produced. Knowledge of other facilities that have done similar facilities will be essential by this date.
This paper will examine in broad detail digestion facilities with their pros, cons and give in detail possible conference projects that other students and I can do to help install this facility and make this rough blueprint possible. In addition, we will make a rough outline demonstrating how this facility will work.
First, food waste and paper waste gets collected. Hand sorting of discarded material is labor-intensive work, so a possible education campaign to show people where to discard waste is possible. Possible sorting of bottles and sending them in for reclaimment money will at least help offset costs as long as transportation costs to the nearest facility, right now in Stop and Shop, are substantially lower than the revenue gained from sending in assorted plastic bottles. Paper and food waste will be separated, weighed, and added accordingly.
A large shredder will then cut and pulverize the food and paper waste to pieces about 5-10 mm in average size. We are considering purchase of a machine that does both food and paper shredding in order to save on capital costs, and facilitate proper mixture of the materials. Food and paper waste next goes to a mixing machine. Possibly a tumbler similar to the blue tank seen at Cherry Street and Pike Street at Coleman park New York, NY at the lower East Side Ecology Center. Food waste will then either be kept in the same drum-like mixer, or be sent via dumping and other gravity-fed means into a heating tank. There food waste will be heated at 150 degrees Celsius#. Sonar treatment may also be applied for breakage of cell membrane walls and further digestion.
Food waste then proceeds to the biogas facility. Types of facilities are numerous. However, dry digestion methods including, plug-flow, Kompogas, Dranco, and Inclined designs are taken into careful consideration, and wet types of digesters, including the Anaerobic Baffled reactor, the Upflow Anaerobic Sludge Blanket (UASB) and its close relative the Expanded Granular Sludge Blanket (EGSB) are all potential competitors.
Biogas then gets harvested either for heat production, or for electricity generation. Because electricity generators produce heat due to their inherent inefficiencies, a cooling jacket will be used to harvest excess heat either for biogas temperature controls or for college heating needs. Excess water then gets extracted with a pulverizer. Excess water will then either be treated or recirculated for mixture with food waste. This can provide both added microbial boosts, and also drastically reduce costs of ongoing maintenance that otherwise would have gone to water treatment. The digested product, being high in nutrient content may either be sold to contractors, rooftop farms, or other entities in need of large-scale land treatment, or be further composted by a lively worm population. While treated food waste can be applied, due to its partially degraded state, the quality of this soil ammendment, while high in nutrients, still is a lower quality compost. Worm digestion will increase plant-available nutrient content and foster healthy microbial plant populations.
Dry types of digestion
Advantages include reduction of maintenance costs due to reduced water treatment needs, reduced heating needs and other temperature controls. Potential difficulties include pumping of food waste material or moving it through various phases of digestion. A close examination of this is essential.
Wet Types of Digestion
Average retention times are substantially lower sometimes as low as 3 days# while dry types can take approximately 14-30 day retention times. While water treatment costs would be substantially high, and additional water means increased facility size, and therefore, capital costs, much depends on the Hydraulic and Solid Retention times of food wastes. If it can be low enough to make a facility small enough to fit on campus, facilitate transportation of food waste to each stage of the digestion process, and if water can be recirculated for re-use, and if the facility can be insulated enough to minimize additional costs of heating extra water, using a wet digestion process may be worthwhile. In addition, since food waste is composed of 80-90 percent water, a wet process, which is normally solid contents under 20%, may be feasible. However, paper, which contains a relatively lower moisture content, once factored in may substantially reduce water content, and thus, drive up the costs due to the need to add additional water.
Below are a series of potential digestion facilities. They are analyzed in the following terms:
- Distinguishing features of each facility
- Gross biogas production per Kilogram per day (Environment/revenue)
- Volatile Solids reduction Kg per meter-day (Reduced space requirements/ increased composting rate)
- Usable sludge-compost production KG per meter day. Approximate dollar amount obtained per kg (reduced space requirements/increased composting rates, and revenue)
- Ongoing and maintenance cost per kg of finished product both methane and finished sludge-compost (reduced ongoing and maintenance costs)
- Fixed costs cost ($) per cubic meter/ square meter of used space.
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