Optimal Solid Waste Policy with Centralized Recycling Opportunities

Economic models have demonstrated the efficiency of curbside collection taxes. This paper demonstrates that such efficiencies disappear in economies with centralized recycling options - where recyclable materials can be removed from the waste stream either by households or at a centralized recycling facility. In such economies a curbside garbage tax not only fails to encourage the centralized recycler to internalize the external costs of waste disposal, but introduces inefficiencies to the cost-minimizing mix of household and centralized recycling efforts. The optimal waste policy is a tax assessed further downstream at the landfill rather than at the curb.

The Economics of Residential Solid Waste Management

This paper provides a broad overview of recent trends in solid waste and recycling, related public policy issues, and the economics literature devoted to these topics. Public attention to solid waste and recycling has increased dramatically over the past decade both in the United States and in Europe. In response, economists have developed models to help policy makers choose the efficient mix of policy levers to regulate solid waste and recycling activities. Economists have also employed different kinds of data to estimate the factors that contribute to the generation of residential solid waste and recycling and to estimate the effectiveness of many of the policy options employed.

The Costs of Municipal Curbside Recycling and Waste Collection

This paper estimates cost functions for both municipal solid waste collection and disposal services and curbside recycling programs. Cost data are obtained from a national survey of randomly selected municipalities. Results suggest, perhaps unsurprisingly, that both marginal and average costs of recycling systems exceed those of waste collection and disposal systems. Economies of scale are estimated for all observed quantities of waste collection and disposal. Economies of scale for recycling disappear at high levels of recycling - marginal and average cost curves for recycling take on the usual U-shape. Waste and recycling costs are also estimated as functions of factor costs and program attributes.

Evaluating Bucknell's Waste Stream

This thesis examines three questions regarding the content of Bucknell University‟s waste stream and the contributors to campus recycling and solid waste disposal. The first asks, “What does Bucknell‟s waste stream consist of?” To answer this question, I designed a campus-wide waste audit procedure that sampled one dumpster from each of the eleven „activity‟ types on campus in order to better understand Bucknell‟s waste composition. The audit was implemented during the Fall semester of the 2011-2012 school year. The waste from each dumpster was sorted into several recyclable and non-recyclable categories and then weighed individually. Results showed the Bison and Carpenter Shop dumpsters to contain the highest percentage of divertible materials (through recycling and/or composting). When extrapolated, results also showed the Dining Services buildings and Facilities buildings to be the most waste dense in terms of pounds of waste generated per square foot. The Bison also generated the most overall waste by weight. The average composition of all dumpsters revealed that organic waste composed 24% of all waste, 23% was non-recyclable paper, and 20% was non-recyclable plastic. It will be important to move forward using these results to help create effective waste programs that target the appropriate areas of concern. My second question asks, “What influences waste behavior to contribute to this „picture‟ of the waste stream?” To answer this question, I created a survey that was sent out to randomly selected sub-group of the university‟s three constituencies: students, faculty, and staff. The survey sought responses regarding each constituency‟s solid waste disposal and recycling behavior, attitudes toward recycling, and motivating factors for solid waste disposal behaviors across different sectors of the university. Using regression analysis, I found three statistically significant motivating factors that influence solid waste disposal behavior: knowledge and awareness, moral value, and social norms. I further examined how a person‟s characteristics associate to these motivating factors and found that one‟s position on campus proved a significant association. Consistently, faculty and staff were strongly influenced by the aforementioned motivating factors, while students‟ behavior was less influenced by them. This suggests that new waste programs should target students to help increase the influence of these motivators to improve the recycling rate and lower overall solid waste disposal on campus. After making overall conclusions regarding the waste audit and survey, I ask my third question, which inquires, “What actions can Bucknell take to increase recycling rates and decrease solid waste generation?” Bucknell currently features several recycling and waste minimization programs on campus. However, using results from the waste audit and campus survey, we can better understand what are the issues of the waste stream, how do we go about addressing these issues, and who needs to be addressed. I propose several suggestions for projects that future students may take on for summer or thesis research. Suggestions include targeting the appropriate categories of waste that occur most frequently in the waste stream, as well as the building types that have the highest waste density and potential recovery rates. Additionally, certain groups on campus should be targeted more directly than others, namely the student body, which demonstrates the lowest influence by motivators of recycling and waste behavior. Several variables were identified as significant motivators of waste and recycling behavior, and could be used as program tactics to encourage more effective behavior.

A study of high solids anaerobic digestion of Bucknell University food waste followed by aerobic curing

Anaerobic digestion of food scraps has the potential to accomplish waste minimization, energy production, and compost or humus production. At Bucknell University, removal of food scraps from the waste stream could reduce municipal solid waste transportation costs and landfill tipping fees, and provide methane and humus for use on campus. To determine the suitability of food waste produced at Bucknell for high-solids anaerobic digestion (HSAD), a year-long characterization study was conducted. Physical and chemical properties, waste biodegradability, and annual production of biodegradable waste were assessed. Bucknell University food and landscape waste was digested at pilot-scale for over a year to test performance at low and high loading rates, ease of operation at 20% solids, benefits of codigestion of food and landscape waste, and toprovide digestate for studies to assess the curing needs of HSAD digestate. A laboratory-scale curing study was conducted to assess the curing duration required to reduce microbial activity, phytotoxicity, and odors to acceptable levels for subsequent use ofhumus. The characteristics of Bucknell University food and landscape waste were tested approximately weekly for one year, to determine chemical oxygen demand (COD), total solids (TS), volatile solids (VS), and biodegradability (from batch digestion studies). Fats, oil, and grease and total Kjeldahl nitrogen were also tested for some food waste samples. Based on the characterization and biodegradability studies, Bucknell University dining hall food waste is a good candidate for HSAD. During batch digestion studies Bucknell University food waste produced a mean of 288 mL CH4/g COD with a 95%confidence interval of 0.06 mL CH4/g COD. The addition of landscape waste for digestion increased methane production from both food and landscape waste; however, because the landscape waste biodegradability was extremely low the increase was small.Based on an informal waste audit, Bucknell could collect up to 100 tons of food waste from dining facilities each year. The pilot-scale high-solids anaerobic digestion study confirmed that digestion ofBucknell University food waste combined with landscape waste at a low organic loading rate (OLR) of 2 g COD/L reactor volume-day is feasible. During low OLR operation, stable reactor performance was demonstrated through monitoring of biogas production and composition, reactor total and volatile solids, total and soluble chemical oxygendemand, volatile fatty acid content, pH, and bicarbonate alkalinity. Low OLR HSAD of Bucknell University food waste and landscape waste combined produced 232 L CH4/kg COD and 229 L CH4/kg VS. When OLR was increased to high loading (15 g COD/L reactor volume-day) to assess maximum loading conditions, reactor performance became unstable due to ammonia accumulation and subsequent inhibition. The methaneproduction per unit COD also decreased (to 211 L CH4/kg COD fed), although methane production per unit VS increased (to 272 L CH4/kg VS fed). The degree of ammonia inhibition was investigated through respirometry in which reactor digestate was diluted and exposed to varying concentrations of ammonia. Treatments with low ammoniaconcentrations recovered quickly from ammonia inhibition within the reactor. The post-digestion curing process was studied at laboratory-scale, to provide a preliminary assessment of curing duration. Digestate was mixed with woodchips and incubated in an insulated container at 35 °C to simulate full-scale curing self-heatingconditions. Degree of digestate stabilization was determined through oxygen uptake rates, percent O2, temperature, volatile solids, and Solvita Maturity Index. Phytotoxicity was determined through observation of volatile fatty acid and ammonia concentrations.Stabilization of organics and elimination of phytotoxic compounds (after 10–15 days of curing) preceded significant reductions of volatile sulfur compounds (hydrogen sulfide, methanethiol, and dimethyl sulfide) after 15–20 days of curing. Bucknell University food waste has high biodegradability and is suitable for high-solids anaerobic digestion; however, it has a low C:N ratio which can result in ammonia accumulation under some operating conditions. The low biodegradability of Bucknell University landscape waste limits the amount of bioavailable carbon that it can contribute, making it unsuitable for use as a cosubstrate to increase the C:N ratio of food waste. Additional research is indicated to determine other cosubstrates with higher biodegradabilities that may allow successful HSAD of Bucknell University food waste at high OLRs. Some cosubstrates to investigate are office paper, field residues, or grease trap waste. A brief curing period of less than 3 weeks was sufficient to produce viable humus from digestate produced by low OLR HSAD of food and landscape waste.

Examining the Justification for Residential Recycling

Municipalities in the United States have for the past two decades initiated two policies to reduce residential solid waste generation by increasing recycling. The first policy, implemented in over 4,000 municipalities in the United States, requires households to pay a fee for each unit of garbage presented at the curb for collection. The second policy, initiated in 8,875 municipalities, subsidizes household recycling efforts by providing free curbside collection of certain recyclable materials. Both initiatives serve as examples of incentive-based environmental policies favored by many economists. But before economists can celebrate this wide-spread adoption of incentive-based environmental policies, further examination reveals that potentially inefficient command and control policies have been more instrumental in promoting recycling than might be commonly known. This article examines the empirical lessons gained from studying twenty years of solid waste policy in the United States and argues for the replacement of several state recycling mandates with a system of state and/or national landfill taxes.

Explaining the Growth in Municipal Recycling Programs: The Role of Market and Non-Market Factors

The implementation of thousands of municipal recycling programs in the United States has increased recycling’s portion of solid waste from 10% to 30% over the past decade. But the lack of accurate data has spurred a debate over whether the growth in recycling can be attributed to market or nonmarket factors. To address this issue, this article conducts a benefit-cost analysis of a municipal recycling program. Results suggest recycling is costly. So why, then, does it remain popular? This article suggests that local governments could be responding to households that perceive a benefit from recycling services. These benefits are estimated with a contingent valuation survey.

Landfill Closure and Housing Values

The United States disposes roughly 60% of the municipal solid waste it generates each year in solid waste disposal facilities, commonly known as landfills. Hedonic pricing studies have estimated the external costs of landfills on neighboring housing markets, but the literature is silent on what happens to property values after the landfill closes. Original housing price data collected both before and after a landfill closure are used to estimate how a landfill closure affects neighboring property values. Results of both a hedonic pricing model and repeat-sales estimator are used in the analysis.

Why do Municipalities Recycle?

The disposal of municipal solid waste is believed to emit foul odor, threaten groundwater, and increase road congestion. As remote regional landfills have replaced local town dumps, these costs are no longer internalized by garbage-producing households or their municipalities. Instead, rural property owners located adjacent to large regional landfills and along the roadways accessing those landfills bear the external costs of garbage disposal. This paper uses a comprehensive nine-year panel data set of aggregated state data to empirically examine why 8,937 municipalities continue to operate costly recycling programs designed to reduce the external costs of garbage disposal. Results suggest that local tastes for recycling drive municipal decisions. If household preferences for recycling are short lived, then we can expect a future decrease in the number of municipal recycling programs. Recent data indicate the number of recycling programs in operation in the U.S. has indeed fallen.

The Socially Optimal Recycling Rate: Evidence from Japan

This paper estimates the average social cost of municipal waste management as a function of the recycling rate. Social costs include all municipal costs and revenues, costs to recycling households to prepare materials estimated with an original method, external disposal costs, and external recycling benefits. Results suggest average social costs are minimized with recycling rates well below observed and mandated levels in Japan. Cost-minimizing municipalities are estimated to recycle less than the optimal rate. These results are robust to changes in the components of social costs, indicating that Japan and perhaps other developed countries may be setting inefficiently high recycling goals. (C) 2014 Elsevier Inc. All rights reserved.