From Waste to Resource: Designing a Campus-Scale Composting System for UCLA

Solid waste management in the US is largely managed by transport via trucks to landfills. The majority of this waste is food waste and compostables. As the suburbs of Los Angeles spread from the city center, landfills too are pushed further out causing more extensive transport requirements, increased greenhouse gas emissions, and growth of the urban footprint. Additionally, landfills give off biogas as a result of the anaerobic degradation of organics as well as produce leachants into the surrounding environment. Although a better alternative, commercial composting facilities are also very far from the producers.

UCLA’s goal to send zero waste to landfill by 2020 is hampered by the lack of organics waste management on campus. By shipping organics to Victorville, the campus’s is generating greenhouse gasses and does not take advantage of the nutrients in the organics waste for on-campus use. This has financial implications where UCLA is paying to get rid of the organics and the revenue from the sale of its nutrients is left to American Organics. Bringing composting to campus poses its own set of challenges including: difficulty of enforcing proper organics separation across campus, dealing with “non-compostable” landscaping waste (pine needles and eucalyptus leaves), space considerations for installation of composters, and pushback from surrounding neighborhoods to any “waste-treatment” projects near their properties.

Our Leaders in Sustainability Project consisted of determining the feasibility of an on-campus composting system. This was conducted in several steps, first by identifying the green waste sources on campus and filtering out the cleaner nitrogen rich food sources, which are more readily processed in a campus scale composting system. From here space consideration as well as machinery and infrastructure for such a system was considered. This presented large challenges because servicing the green waste output of the dining halls alone is a massive undertaking. Once the appropriate space and equipment was identified, a cost benefit analysis involving the actionable reduced CO2 for composting on site as well as reduced fertilizer cost for on campus green spaces could be conducted. Findings were summarized in a comprehensive report and provided to UCLA Sustainability Officer Bonny Bentzin.

Based on the calculations done in this work, approximately 2,400 tons of compost would be produced annually. While we know that a portion of this could be used on many on-campus locations periodically throughout the year, a more detailed audit of the number and type of plants as well as their footprint and water requirements would need to be performed to calculate exactly how much. Additionally, as urban farming efforts increase, its reasonable that compost demand will also. Regardless, additional sites near to campus, including the VA garden, could be locations for compost use. Upon a preliminary search within a 50 mile radius, 6 potential partners were identified: Underwood Family Farms, Boething Treeland Farms, Christmas Tree House, Forneris Farms, McGrath Family Farms, and UCLA Santa Monica Research Station. Follow up analysis would involve determining which of these farms would be most interested in partnering with UCLA for regular compost pickup and the total compost they would require.

On-Campus Composting Solution to Green Waste Disposal at the University of California, Los Angeles

Authors: Mackenzie Anderson & Patricia McNeil

Introduction
Solid waste management in the US is largely managed by transport via trucks to landfills. The majority of this waste is food waste and compostables. As the suburbs of Los Angeles spread from the city center, landfills too are pushed further out causing more extensive transport requirements, increased greenhouse gas emissions, and growth of the urban footprint. Additionally, landfills give off biogas as a result of the anaerobic degradation of organics as well as produce leachants into the surrounding environment. Although a better alternative, commercial composting facilities are also very far from the producers.

UCLA has three primary sources of organic waste: kitchens (dining halls), landscaping, and animal bedding (labs). Presently, organic waste from kitchens is trucked to American Organics in Victorville while landscaping mulch is used as “alternative daily cover” for the landfill in Chiquita Canyon 35 miles east of UCLA. Additional compostables are buried at the landfill along with other non compostables as precise separation of organics, especially in campus-wide compost “trash cans”, is difficult for social and logistical reasons; students don’t sort the waste properly, there is no distinguished container, or distinguished containers are overfilled.

UCLA’s goal to send zero waste to landfill by 2020 is hampered by the lack of organics waste management on campus. By shipping organics to Victorville, the campus’s is generating greenhouse gasses and does not take advantage of the nutrients in the organics waste for on-campus use. This has financial implications where UCLA is paying to get rid of the organics and the revenue from the sale of its nutrients is left to American Organics. Bringing composting to campus poses its own set of challenges including: difficulty of enforcing proper organics separation across campus, dealing with “non-compostable” landscaping waste (pine needles and eucalyptus leaves), space considerations for installation of composters, and pushback from surrounding neighborhoods to any “waste-treatment” projects near their properties.

Herein we present a model of what on campus composting would entail given the current limitations on space, finances, and social impact.

General Composting Facts
Composting is the process via which organic materials are decomposed by microrganisms. Unlike vermicompost or biodigestion, which involve the addition of organisms like worms or particular bacteria to aid in the decomposition process, composting uses the bacteria that exist in the organics sources before decomposition. The ratio of carbon and nitrogen must be maintained at a ratio of around 25-30 parts carbon to 1 part nitrogen to prevent overly slow decomposition, which happens when the C content is too high, or the volatilization of ammonia, which occurs if the C content is too low. Additionally, the presence or absence of elemental oxygen within the decomposing material determines the type of bacteria that will dominate the decomposition process, the most notable difference being that without oxygen, the potent greenhouse gas, Methane, is produced. Aerobic decomposition is a biological oxidation process requiring that the oxygen content in the air not fall below 18%. This can be ensured using pressurized blowing which not only ensures satisfactory oxygen levels but heat transport from hot core of a compost pile outward. The decomposition of organic matter results in the generation of heat by the bacteria while excessively high temperature inhibits the growth of microorganisms. Initially, high T may be useful to reduce pathogens, while cooling to the optimal temperature of about 45-55 oC results in high quality compost.

One way of ensuring these conditions on a large scale is by using forced pressure ventilation with temperature feedback control. Another important handle is the moisture levels in a composting system. High moisture can interfere with aeration by clogging pores while low moisture can lead to biologically unstable compost. optimal between Generally, pH begins to drop at the initiation of the composting process while high values of pH are associated with high temperatures and loss of nitrogen through volatilization of ammonia. The optimal pH is between 5.5 and 8. Lastly, in order to quicken the decomposition process, size reduction and/or initial biotransformation are crucial by increase surface area of the material. Mechanical shredding of the material is beneficial so long as the grain does not inhibit air circulation. This can consist of sorting out inert material after shredding, hammer milling to reduce particle size, followed by screening. For large scale operations, these may be followed up by electromagnetic separation of metals and ballistic or aerated separation. Bio-mechanical processes entail waste be placed in biological reactors for short periods for initial biotransformation and size reduction.
All of these factors must be considered when generating a composting system for an urban campus as they inform the social response if systems fail (foul odors, maintenance disrupting campus services) as well as labor that could be required to maintain a system .

Figure 1: Image of root systems for plants treated with compost (far left) to those not treated with compost. Larger and more dense root zone enables higher soil integrity and increased plant health. Compost acts as a natural fertilizer and improves water retention in soil.

Once the compost has been produced it demonstrates a variety of benefits upon soil integration. Chief among these are weed suppression, water retention, slope stabilization, and restoration of ground nutrients. In the above image, the far right plant was grown with minimal fertilizer, the middle plant was grown with sludge water, and the left plant was grown with compost demonstrating that the compost promoted the greatest growth.

Survey of Urban campuses:
In order to better grasp how other campuses are managing organic waste, apart from sending it to landfills, a survey of campuses with readily available composting information was made. The following table lists the school name and location, the composting technology used and how it can inform UCLA in making the switch to composting.

School Compost Method
Loyola Marymount University, Los Angeles, CA
Somat composing machine Somat composing machine dehydrates any edible fruit, vegetables, grains, dairy, fish, and meat which can be dumped from two of the residence halls. Resident’s put their food waste into a pail, which is then emptied into a communal collection bin. The food is then processes for 14-15 hours before being shipped to Imperial Western Products in the coachella valley to be used as a bioproduct amendment bulking ingredient. This process does not address the transport issue despite dehydrating locally.
Columbia University, New York, New York Rocket in-vessel composter Rocket in-vessel composter/biodigestor stored in Ruggles Residence Hall basement. Ruggles is a vegetarian residence halls where residents are provided under-sink compost bins that students deliver to the composter. Wood chips are added as a the bulking agent. Columbia only puts non-meat waste into the Rocket to avoid reported odor.
University of Salford, Manchester England 2 Rocket composters are at 2/9 campus restaurants 2 Rocket composters are at 2/9 campus restaurants–intent is to put Rockets into all campus restaurants (smallest models), not one central composter. The users report a reduction in vermin that were formerly attracted to garbage bins. Uncooked and cooked meat is disposed of in the Rocket.
The compost is used directly on campus saving the campus money previously spent on compost for landscaping.
Cornell University windrows Has compost trucked 1 mile from campus where compost is processed in massive windrows—not an option for UCLA. Cornell composts: 2,700 tons of animal bedding and manure from research and teaching facilities. 300 tons of plant debris from campus greenhouses, orchards, and farms. 800 tons of food scraps and organic kitchen waste from Cornell dining halls and small eateries. Other waste streams include building-specific compost collection programs and special event.
Loyola University
of Chicago “bucket system” Participating students are given a 1-gallon airtight bucket and a drop-off schedule for locations around campus. The waste from buckets and dining halls are removed by a service
Northern Arizona University, Flagstaff, AZ SOMAT machine Somat machines are installed in dining halls and machine product is let to sit for a few months and is then ready to be used for landscaping on campus and at local elementary schools. Local schools could be good locations to offer locally grown compost given larger play areas with vulnerable turf.
Knox College, Galesburg, IL SOMAT machine Uses SOMAT machine. Formerly did outdoor composting but neighbors started to complain about odors.

Table 1: Summary of college composting programs.

Green Waste sources at UCLA:
In 2016, 44,974 students were enrolled at UCLA. A study done by the Semel institute at UCLA reports that 40% of UCLA students are food insecure, which ranges from not having a diverse or appetizing diet to not having the financial security to ensure regular meals. Despite this, 7,770,518 lbs of green waste is generated on campus per year, approximately 75% of which is food waste. A portion of this waste is certainly comprised of food that could have been diverted for students in need. Therefore, many efforts aside from composting need to be implemented to prevent food waste at the source as well as to enable a larger population access to these sources.

Figure 2 provides the tons of waste produced at each of the addresses where Athens’ Services, UCLA’s waste management servicer, picks up “green bins” from November 2017-October 2018. Most of the clean streams of waste are located near the undergraduate residence halls which consists of waste from dining hall kitchens either from the preparation process or uneaten food from students’ plates. This food waste is pulped before disposal to reduce the volume that it takes up in green bins. Other locations around campus with green bins include the faculty center, which produces a large volume of food as well as biology labs where animal bedding is disposed of on a daily basis. Most of these sites are serviced several days per week with the most frequently used bins emptied 6 days per week.

The map in Figure 3 informs how the organic waste on campus can be most efficiently managed given on-site composters. The contents of the bins (food waste vs. yard trimmings) can be used to determine the ratio of carbon to nitrogen present while the amount of waste produced and its location relative to other sites informs the required infrastructure and manpower.

Using conversion factors, the chart below was generated for the largest producing region of the campus, the residence halls. Based on the C to N ratio, the amount of carbon that must be added in the form of fibrous material is calculated based on the requirements for FOR Solutions in-vessel composting units. Based on surveys of dorm recycle bins as well as the data provided by Athens on the mass of recyclable waste picked up at each site. This requirement is easily met using cardboard waste produced on campus. Although this is not as “high quality” as wood chips in terms of brown additives, it lessens the cost and footprint of composting operations.

Figure 2: UCLA main-campus map with addresses serviced by Athens Services indicated with blue pins and the tons of green waste produced annually at each site.

Figure 3: Breakdown of C:N of compost produced at the circled sites and the calculated mass of bulking agent required for in-vessel composting.

Commercial Technology:

In-Vessel Composting

In order to determine the optimal solution for incorporating composting as a solution for waste management at UCLA, currently available in vessel composters were explored. The premise of the in-vessel composter is that feed can be continually added to the system, then the food waste undergoes a temperature differential where aerobic decomposition is promoted through pressurized aeration and periodic mixing. After decomposition, composted is removed and usually stored for a period of maturation.

Figure 4: Schematic of a tumbler style in-vessel composter. A temperature gradient aids in the decomposition process. Compost is mechanically forced through the system and can then be transported for maturation.

FOR Composting Solutions

All of the FOR in-vessel composters are capable of decomposing all food scraps including dairy and meat as well as bones, napkins, and paper cutlery in a 5-day period. The large grinders can shred most anything including metal cutlery, but high-quality metal cutlery or other pieces of metal will cause the motors to jam. Similar problems will arise if the green waste stream contains large amounts of compostable plastic bags, which are recommended to be shredded beforehand. Pieces of plastic and non-compostable materials can be removed after composting if necessary although there is little to be said about any negative effects the occasional piece of plastic or metal will have on compost or the landscape on which it is used. Plastic disposables made of compostable plastic (PLA or starch-based) cannot be broken down in the composters.

The three pumps that come with the units are standard and can be purchased from companies like McMaster Carr when needed (approx. 10 year lifespan). It is recommended that fittings be re-greased two times per year. Other materials that may be problematic would be paper towels from bathrooms or any waste that may have residues from antibacterial soaps or cleansers that could negatively impact the bacteria in the composter. Due to the large capacity and ease of use, FOR Solutions in-vessel composters were presented as a viable option for use at UCLA

Model Capacity (if loaded 7 days per week) lbs Footprint (LxWxH) Unit Cost (USD)
500 350 26’x5’x11’ 168,000
1000 700 30’x7’x13’ 224,000
2000 1400 36’x7’x13’ 245,000
4000 2800 39’x9’x15’ 427,000
8000 5600 57’x9’x15’ 799,000

Table 3: FOR composters’ specifications by model including unit price.

Dining Hall Average Waste Output (lbs/day) Composter Capacity (lbs/day) Composter Cost ($) Footprint
Covel 1662.75 2800 427K 36’ L x 8’ W x 13’ H
Hendrick 1300.36 1400 245K 30’ L x 8’ W x 13’ H
Feast 1852.82 2800 427K 36’ L x 8’ W x 13’ H
De Neve 908.58 1400 245K 30’ L x 8’ W x 13’ H
Bruin Plate 1545.22 2800 427K 36’ L x 8’ W x 13’ H
Other 190.78 350 168K 26’ L x 6’ W x 11’ H
Table 4: Total cost estimated for FOR Solutions to service dining halls back-of-house.

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EcoRich Commercial Composting System

After evaluating the space and cost for the FOR composting units, it was determined that a smaller, less expensive, and quieter solution would be optimal. Cost estimates and infrastructure requirements were retrieved from EcoRich, a different in-vessel composting manufacturer based in New Jersey.

In addition to the heating and mechanical elements of a standard in-vessel composting system, EcoRich systems also incorporate the use of microbes to facilitate the fast decomposition of organic waste. These microbes are introduced when the composter is first powered on. Microbes come with the system and are self-propagating, needing to be replenished only if the system is shut down. An impressive component of the EcoRich design is the fast turnaround time, boasting an 85 to 90% volume reduction within 24 hours of waste input. Another aspect that is particularly important due to UCLA’s dense campus is the total composter footprint. Compared to a FOR composter that processes 1400lbs of waste per day that has a total footprint of 3120 ft3, an EcoRich composter designed to process 1500lbs per day has a total footprint of 733 ft3.

Model No. Base Price Automatic Compost Removal Crusher De-watering Screw with Stainless Steel Bucket Automatic Loading Attachment Stainless Steel Exteriors
ER-20 $4,935.00 N/A N/A N/A N/A $494.00
ER-50 $10,000.00 $2,000.00 $3,300.00 N/A $4,000.00 $1,000.00
ER-100 $15,000.00 $2,000.00 $3,300.00 N/A $4,000.00 $1,500.00
ER-150 $17,000.00 $1,183.00 $3,300.00 N/A $4,000.00 $1,700.00
ER-200 $18,900.00 $2,000.00 $3,300.00 N/A $4,800.00 $1,890.00
ER-300 $20,895.00 $2,000.00 $3,300.00 N/A $4,800.00 $2,090.00
ER-500 $29,295.00 $2,500.00 $4,000.00 N/A $5,300.00 $2,930.00
ER-1000 $39,900.00 $2,500.00 $4,000.00 $6,900.00 $5,300.00 $3,990.00
ER-1500 $59,000.00 $3,500.00 $4,900.00 $6,900.00 $7,500.00 $5,900.00
ER-2000 $64,900.00 $3,500.00 $4,900.00 $6,900.00 $7,500.00 $6,490.00
ER-2500 $76,900.00 $3,500.00 $4,900.00 $7,900.00 $7,500.00 $7,690.00
Table 5: Price breakdown for EcoRich Composters. Model sizes are comparable to the capacities of corresponding FOR Solutions’model numbers

Dining Hall Average Waste Output (lbs/day) Composter Capacity (lbs/day) Composter& Accessories Cost ($) Footprint
Covel 1662.75 2500 109K 20’ L x 5.8’ W x 8.3’ H
Hendrick 1300.36 1500 88K 18’ L x 5.5’ W x 7.4’ H
Feast 1852.82 2500 109K 20’ L x 5.8’ W x 8.3’ H
De Neve 908.58 1500 88K 18’ L x 5.5’ W x 7.4’ H
Bruin Plate 1545.22 2500 109K 20’ L x 5.8’ W x 8.3’ H
Other 190.78 300 34K 8.45 L x 4.8 W x 5.0 H
Table 6: Total cost estimated for EcoRich units to service dining halls back-of-house.

Figure 5: Schematic of EcoRich in-vessel composter. Incorporates microorganisms to facilitate decomposition in addition to heating, aeration, and continuous mixing.

Return on Investment Analysis:

Calculation of cost of disposal using present methods

Based on the number of bins at each serviced address on campus, the volumes of the bins at each address, the number of times per week each bin is emptied, as well as the cost for having oversized “roll-off” bins requiring weekly service; the amount of money spent of waste disposal on campus can be calculated based on Athens Services’ openly available service fees. In summary, 309 green bins are pulled each week. That means several trips to victorville and $657,889/per year is spent to dispose of organics (not including trash and recyclables) generated at UCLA. Taking into account only the addresses located in the vicinity of the residence halls, $324,000 is spent annually on green waste disposal.

Using the Waste Reduction Model (WARM) developed by the EPA, one can calculate the carbon and energy footprints of waste disposal based on the method used and its distance from the source of generation. In order to use this model, all of the waste tagged as food waste was assigned for disposal at American Organics, 105 miles away while all waste tagged as yard trimmings was assigned for disposal 35 miles away at the Chiquita Canyon landfill. The outputs from this model are summarized in the table below.

Figure 6: Summary of energy consumed and CO2 produced annually as a product of green waste disposal.

Calculation of cost to compost using FOR solutions for Service to Entire Campus

FOR solutions offers a “lease-to-own” offer for its in-vessel composters. This route, compared to paying the values listed above up-front, allows for the buyer to pay off the vessel over a 7 year period with between 5% and 5.25% interest. At any point FOR Solutions can remove the systems it has installed or, after 7 years, there will be no more fee. Additionally, EcoRich offers 24, 36, 48 and 60 month lease-to-own, which would similarly be cheaper than Athens Services.

Based on the tonnage at each campus site, if all of the waste were to be composted on-site, the price for the FOR systems would be less than or comparable to the current amount paid to Athens Services. As regulations continue to tighten regarding the amount of waste required to be diverted from landfills, there is not enough commercial composting infrastructure in CA to accommodate all of the compostable waste generated. Taking into account the relative cost for waste services in more densely populated areas of CA, it is likely that the cost to UCLA for waste services will increase.

Figure 7: Map indicating travel to Chiquita Canyon landfill (35mi. NW) and American Organics (105mi. NE) from UCLA

Service Campus-wide (USD/year) Residence areas (USD/year)
FOR Solutions 648,530 397,692
Athens Services 657,889 328,036

Table 7: Cost comparison between Athens Services and FOR Solutions using the current cost for Athens Services and the 7-year lease-to-own cost for the required FOR Solutions infrastructure to service the entire UCLA campus.

Conclusions:

Based on our analyses EcoRich compost systems purchased using the lease-to-own model implemented in the residential area of UCLA’s campus would be ideal given current projections and without considering a combination of solutions. Given that food-waste reduction efforts will likely diminish the amount of green waste produced at these sites, this will likely be offset by the dramatic rise in population living on the Hill predicted to occur over the next several years. Additionally, as composting infrastructure use matures on campus, green waste from other sites on campus could be re-directed to the composters. On the whole, composting infrastructure, even if eventually used at less than full capacity or with reduced frequency, is a worthwhile investment in the campus’s future.

Future Work:

Based on the calculations done in this work, approximately 2,400 tons of compost would be produced annually. While we know that a portion of this could be used on many on-campus locations periodically throughout the year, a more detailed audit of the number and type of plants as well as their footprint and water requirements would need to be performed to calculate exactly how much. Additionally, as urban farming efforts increase, its reasonable that compost demand will also. Regardless, additional sites near to campus, including the VA garden, could be locations for compost use. Upon a preliminary search within a 50 mile radius, 6 potential partners were identified: Underwood Family Farms, Boething Treeland Farms, Christmas Tree House, Forneris Farms, McGrath Family Farms, and UCLA Santa Monica Research Station. Follow up analysis would involve determining which of these farms would be most interested in partnering with UCLA for regular compost pickup and the total compost they would require.