UNIVERSITY OF WISCONSIN SYSTEM SOLID WASTE RESEARCH PROGRAM Student Project Report

Transcription

1 UNIVERSITY OF WISCONSIN SYSTEM SOLID WASTE RESEARCH PROGRAM Student Project Report Characterization of Solid Waste and the Potential to Reduce Solid Waste through Implementation of a Composting Program at the University of Wisconsin-Platteville July 2009 Student Investigators: Katherine Goldberg & Colleen Smith Faculty Supervisors: Dr. Christopher A. Baxter University of Wisconsin-Platteville 1

2 Introduction From July 2008 through May 2009 the University of Wisconsin Platteville generated approximately 640 tons of solid waste. The collection, disposal and recycling fees associated with this waste were over $150,000 (based upon data provided by Ed Faherty, Faherty Inc., June 2009). The University would like to reduce the amount of solid waste generated in order to reduce disposal costs and reduce negative environmental impacts, but since little is known regarding the composition of solid waste, it is difficult to plan strategies for reducing the amount of waste sent to landfills, or the potential for increased recycling. This project was initiated to provide the University a better understanding of the composition of the solid waste generated on campus and to provide recommendations for strategies to reduce the amount of solid waste generated. Methods Sampling of Solid Waste from Campus Buildings Solid waste samples were collected from campus building dumpsters in the spring semester (January-May) of Samples were collected from buildings that primarily house dining services, classrooms, and offices on campus. Samples were not collected from any of the campus dormitories. Therefore, the data presented in this report reflects solid waste production in primarily the dining, classroom, and office buildings on campus, but does not reflect the solid waste from student housing on campus. Because the university does not track total amounts of waste produced from each building on campus, it is impossible to determine the proportion of solid waste that comes from student housing relative to the other campus buildings, but the information does provide a general classification of the waste produced from campus-managed classrooms, offices, and dining services. Samples were separated by hand and weighed using a hanging digital scale to determine the weight proportion in each category described below. Subsamples of biodegradable waste (primarily food scraps) were collected and frozen for later analysis of moisture content and C to N ratio. Description of Solid Waste Categories Solid waste samples were separated into one of seven categories prior to weighing. The categories are described and examples are provided below: 1) Biodegradable non-paper: Includes biodegradable materials that exclude paper or cardboard. Primarily included food waste, discarded plant material, sawdust, and coffee grounds. 2) Biodegradable paper: Includes both recyclable and non-recyclable paper and cardboard. Primary sources were office paper, paper towels, paper cups, bathroom/facial tissue, and wax-coated paper. 3) Recyclable plastics: Includes high-density polyethylene (HDPE) and polyethylene tetrapthalate (PETE) plastics with resin codes 1 through 7. Primary sources were plastic soda bottles and other food containers, table ware, and beverage caps. 4) Non-recyclable plastics: Includes other plastics that had resin codes or did not have a resin code. Primary sources were plastic films, garbage bags, beverage lids, foam cups and plates. 5) Recyclable metals: Aluminum and other metals. Primary sources were aluminum containers and cans, and aluminum foil. 6) Non-recyclable non-plastics: Other non-biodegradable and non-recyclable materials. Primary sources were foil chip bags, electrical components (small wires, circuit boards, etc) and ceramics. 7) Glass: All types of glass. Primary source was glass bottles and discarded laboratory glassware. Chemical and Physical Characterization of Biodegradable non-paper waste. 2

3 To determine the potential for biodegradable non-paper waste to be used as a feedstock for composting, thirteen subsamples of biodegradable non-paper waste collected from buildings having dining services were analyzed for moisture content, total carbon, and total nitrogen. Seven samples were collected from Glenview Commons and six were collected from the Pioneer Student Center. All samples were homogenized using a wet/dry mill before analysis. Total carbon (C) and nitrogen (N) were determined by dry combustion using a Variomax Total Carbon and Nitrogen analyzer (Elementar Americas, Inc, Mt. Laurel New Jersey). Moisture content of samples was determined by drying at 70 C. Results of the analysis are presented in Table 2. Because samples were too small to accurately determine bulk density, these were approximated using book value data for food waste. Compost recipes were determined using the Compost Calc software ver developed by Green Mountain Technologies, Inc.. The software allows users to define physical and chemical properties of feedstocks and build compost recipes from them. Recipes were developed for optimum moisture content (45-65%), bulk density (less than 0.5 kg/l), and carbon to nitrogen ratio (20-35:1). Results Characterization of Solid Waste Samples Approximately 350 lbs of solid waste was sorted to approximate the proportion in the categories defined above. Approximately 200 lbs of the solid waste came from buildings that provide dining services, while the remainder came from buildings that primarily house offices and classrooms. Table 1 summarizes the results of the solid waste characterization portion of the study. Biodegradable paper accounted for the largest proportion of the solid waste sampled; ranging 23-69% of the samples collected and averaged 46% of all samples. Biodegradable non-paper comprised 0-65% of the samples collected, with an average of 22%. The highest proportion of this category came from buildings used primarily for dining services. The highest percentage of biodegradable paper came from samples collected from buildings used primarily for offices/classrooms. Recyclable plastics accounted for 1-14% of the samples, with an average of 10% and were slightly higher in classroom/office buildings compared to the dining services building. Similarly, percentage of non-recyclable plastics was slightly higher in the classroom/office buildings compared to the dining services buildings and ranged from 7-19% with an average of 10%. Recyclable metal and glass represented relatively small portions of the samples collected, averaging 7% and 4%, respectively. Other non-biodegradable and non-recyclable materials accounted for 4-21% of the samples collected, with an average of 13%. As shown in the figure below, on average, biodegradable and recyclable material accounted for 80%, while nonbidegradable materials accounted for 20% of the solid waste of the solid waste samples. 3

4 Figure 1. Waste characterization data summarized into categories of Biodegradeable/Recyclable and Nonbiodegradeable/nonrecyclable. PSC=Pioneer Student Center, GLNVW=Glenview Dining Hall, BOEB/Gardner=Boeble and Gardner Halls, Daodna = Doudna Hall, Russell = Russell Hall, Ullsvik=Ullsvik Hall. Biodegradable Non-paper waste for use as a composting feedstock. Table 2 shows results of the moisture content, total C and total N analysis of the thirteen biodegradable non-paper waste samples collected from Glenview Commons and the Pioneer Student Center (PSC). Moisture content ranged from 56-87% for Glenview samples and 52-70% for PSC samples, with an average of 70 and 60% for the Glenview and the PSC samples, respectively. Carbon to nitrogen ratios ranged from 8.3 to 18.5 for Glenview samples and 15.2 to 21.2 for PSC samples, with averages of 12.1 and 16.8 for the Glenview and the PSC samples, respectively. Four compost recipes were determined for both the Glenview and PSC biodegradable non-paper feedstocks (Table 3). Given the high moisture contents and low C:N ratios of these feedstocks, they will require the addition of other materials (carbon sources) in order to create a successful compost. While a wide range of carbon sources could be used, for the purposes of this study only three readily available sources were selected: 1) Green yard waste (i.e. grass clippings), 2) loose/dry leaves, and 3) paper/card waste. Water was added to recipes as needed to increase moisture contents. The yard waste and leaves can be considered readily available from municipal and campus sources, while the paper/card waste could be available through segregation of the current campus solid waste. The compost recipe scenarios were as follows: 1. Biodegradable non-paper Feedstock + Green yard waste only 2. Biodegradable non-paper Feedstock + loose/dry leaves only 3. Biodegradable non-paper Feedstock + paper/card waste only 4. Biodegradable non-paper feedstock + combination of all three carbon sources The recipes show that both the Glenview and PSC biodegradable non-paper feedstocks could be combined with readily available carbon sources to produce compost in a campus composting operation. If only campus generated waste is to be used for the compost, the biodegradable non-paper feedstocks could be combined with paper/card waste in a ratio of approximately 1:0.375 to produce compost. Potential for Solid Waste Reduction The biggest impact on solid waste reduction could be made by segregating and/or eliminating sources of biodegradable wastes that include food and paper that is not recycled. Making the assumption that the samples collected in this study approximate the proportions in the total solid waste collected from UW- Platteville, there is potential for the University to eliminate up to 80% of the current solid waste stream by using a combination of improved waste segregation, implementation of an on-site composting operation, and elimination of waste sources. Further, replacement of some plastics not currently recycled on campus with biodegradable plastics could reduce the solid waste stream and provide additional feedstock materials for composting. Using a conservative value of 10% biodegradable non-paper waste that is recoverable through segregation, this would amount to roughly 64 tons per year. Based on the compost recipe using biodegradeable paper only, it would require approximately 24 tons of biodegradable paper for use as a carbon source. This is a relatively small portion of the total non-recycled paper waste generated on campus, which is estimated to be between Tons per year. Eliminating sources of excess nonrecycled paper waste on campus is therefore necessary for significant waste reduction. Samples of waste from dining services and office/classroom buildings indicate that a high proportion of biodegradable paper were paper towels that are used in all campus rest rooms. Replacement of the paper towels with high efficiency electric hand dryers would significantly reduce the amount of-non-recycled paper waste generated on campus. 4

5 Based on data from , there is a potential reduction in waste generated at UW-Platteville of nearly 500 Tons, although actual waste reduction would likely be less than this due to an expected lessthan 100% compliance with waste segregation. However, it is not unreasonable to believe a solid waste reduction of 50% is possible, which would amount to a savings of approximately $40,000/year in collection and disposal costs alone. Resources and Actions Needed to Facilitate a Comprehensive Campus Waste Reduction Program Based on the results of this study the following recommendations are made for a comprehensive campus solid waste reduction program: 1. Eliminate the use of paper towels in campus rest rooms and replace with high efficiency electric hand dryers 2. Implement further waste segregation in campus buildings with specialized containers for biodegradable paper and biodegradable non-paper waste. 3. Provide education to students and University Staff on the implementation of the waste reduction/segregation program. 4. Implement an on-site composting operation capable of processing at least 100 Tons of solid waste per year. While there is potential cost savings from the reduction of campus solid waste, the implementation of a comprehensive solid waste reduction program on campus will likely exceed the cost savings during the first years of implementation. However, long term savings from waste reduction should be significant, and it would allow the University to serve as a model for communities and businesses seeking to reduce solid waste. Data Limitations and the Need for Further Research on Waste Characterization It must be noted that the amount of solid waste sampled in this study was relatively small, was collected only over a time period of three months, and was not comprehensive to all the solid waste streams on campus. While the data reported may provide a reasonable characterization of waste produced at dining services and classroom/office buildings, it should only be considered a snapshot of the solid waste produced on campus. It is also likely that the samples collected disproportionately represented the biodegradable non-paper waste fraction of the solid waste stream because two of the six buildings sampled housed dining services. More accurate waste characterization for the entire campus could be obtained by randomly sampling waste from trucks during collection days, over a period of months. However, significant cooperation with the campus waste haulers would be needed to accomplish this. 5

6 Table 1. Results of Solid Waste Characterization of Samples collected from Campus Buildings. Building Primary purpose Pioneer Student Center Dining /Student Services Glenview Commons Dining Boeble - Gardner Doudna Russell Ullsvik Classrooms/ Offices Classrooms/ Offices Classrooms/ Offices Classrooms/ Offices lbs collected Biodegradable non-paper (lbs) 31% 65% 11% 9% 0% 8% 22% Biodegradable paper (lbs) 27% 23% 47% 52% 55% 42% 46% Recyclable plastics (lbs) 8% 1% 14% 9% 12% 8% 10% Non-recyclable plastics (lbs) 8% 7% 7% 8% 14% 11% 10% Recyclable metal (lbs) 0% 0% 5% 6% 6% 13% 7% Non-recyclable non-plastics (lbs) 21% 4% 12% 6% 13% 12% 13% Glass (lbs) 5% 0% 3% 10% 0% 5% 4% Total or Average 6

7 Table 2. Moisture Content, Total N, Total C, and C:N ratio of biodegradable non-paper waste samples collected from Glenview Commons and the Pioneer Student Center (PSC). Sample Moisture Content Total Nitrogen Total Carbon C:N ratio % of wet weight (% of dry weight) Glenview Glenview Glenview Glenview Glenview Glenview Glenview Glenview Average PSC PSC PSC PSC PSC PSC PSC Average

8 Table 3. Compost recipes determined by the Compost Calc software, using Biodegradable non-paper feedstocks from Glenview Commons (G-1 through G-4) and Pioneer Student Center (P-1 through P-4). Other Feedstocks (Green waste, Loose/dry leaves, and Paper/card waste) and all bulk density values were estimated by default values from the software. "Green" Yard Waste Paper and Card Waste Recipe Glenview Food Waste PSC Food Waste Loose/Dry Leaves Water Total Tons Bulk Density 1 Moisture 2 C:N ratio 3 Tons (kg/l) % G G G G P P P P Bulk densities below 0.5 kg/l are considered optimal 2 Moisture contents between 45-65% are considered optimal 3 C:N ratios between 20-35% are considered optimal 8