David J. Tonjes

Quantitative assessments of municipal waste management systems: Using different indicators to compare and rank programs in New York State

The primary objective of waste management technologies and policies in the United States is to reduce the harmful environmental impacts of waste, particularly those relating to energy consumption and climate change. Performance indicators are frequently used to evaluate the environmental quality of municipal waste systems, as well as to compare and rank programs relative to each other in terms of environmental performance. However, there currently is no consensus on the best indicator for performing these environmental evaluations. The purpose of this study is to examine the common performance indicators used to assess the environmental benefits of municipal waste systems to determine if there is agreement between them regarding which system performs best environmentally. Focus is placed on how indicator selection influences comparisons between municipal waste management programs and subsequent system rankings. The waste systems of ten municipalities in the state of New York, USA, were evaluated using each common performance indicator and Spearman correlations were calculated to see if there was a significant association between system rank orderings. Analyses showed that rank orders of waste systems differ substantially when different indicators are used. Therefore, comparative system assessments based on indicators should be considered carefully, especially those intended to gauge environmental quality. Insight was also gained into specific factors which may lead to one system achieving higher rankings than another. However, despite the insufficiencies of indicators for comparative quality assessments, they do provide important information for waste managers and they can assist in evaluating internal programmatic performance and progress. To enhance these types of assessments, a framework for scoring indicators based on criteria that evaluate their utility and value for system evaluations was developed. This framework was used to construct an improved model for waste system performance assessments.

A Review of the Hyporheic Zone, Stream Restoration, and Means to Enhance Denitrification

The hyporheic zone is the subsurface area below and adjacent to a stream where groundwater mixes with stream water, through vertical, lateral, and longitudinal flows. The hyporheic zone connects the stream to uplands and other terrestrial environments. It is a zone of distinct faunal communities, high biological diversity and ecological complexity, and is the site of chemical processing and transformations of ground- and stream waters. The hyporheic zone is important to the overall ecosystem ecology of the stream, and it can influence stream water chemistry. Flows, reactions, and biota in the hyporheic zone are heterogeneous and patchy, making it difficult to clearly describe the ecotone in a straightforward, general way. Nitrogen processing, especially denitrification, appears to be widespread in the hyporheic zone. The hyporheic zone, as with most aquatic systems, is often impacted by human activities. Stream restorations rarely consider potential effects on the hyporheic zone, but careful project choices can enhance the condition of the hyporheic zone, and so increase uptake of nitrogen by stream-associated environments as partial mitigation of continuing and increasing releases of reactive nitrogen, potentially reaping short-term benefits to estuarine environments that may not be as quickly realized from source control measures.

Quantification of Food Waste Disposal in the United States: A Meta-Analysis

Food waste has major consequences for social, nutritional, economic, and environmental issues, and yet the amount of food waste disposed in the U.S. has not been accurately quantified. We introduce the transparent and repeatable methods of meta-analysis and systematic reviewing to determine how much food is discarded in the U.S., and to determine if specific factors drive increased disposal. The aggregate proportion of food waste in U.S. municipal solid waste from 1995 to 2013 was found to be 0.147 (95% CI 0.137-0.157) of total disposed waste, which is lower than that estimated by U.S. Environmental Protection Agency for the same period (0.176). The proportion of food waste increased significantly with time, with the western U.S. region having consistently and significantly higher proportions of food waste than other regions. There were no significant differences in food waste between rural and urban samples, or between commercial/institutional and residential samples. The aggregate disposal rate for food waste was 0.615 pounds (0.279 kg) (95% CI 0.565-0.664) of food waste disposed per person per day, which equates to over 35.5 million tons (32.2 million tonnes) of food waste disposed annually in the U.S.

A review of national municipal solid waste generation assessments in the USA

Municipal solid waste (MSW) is generated in very large quantities (probably between 200 and 400 million tonnes per year) in the USA. MSW is generated at millions of places and there is no one precise, general definition for MSW that is generally applied—despite US Environmental Protection Agency efforts. As an element of both commerce and politics, reporting may be framed towards particular ends. Therefore, the two best known assessments of the quantity of US MSW production differ by approximately 50%. The assessors understand some of the reasons for the differences, but our analysis suggests that there are profound factors, not openly discussed, that affect estimates of waste stream size. Many regulators propose that strict, universal formats be adopted so that there is consistency in waste reporting; we note that this will not change the materials requiring management, only what is counted. Therefore, the most accurate assessments may be those where controllable errors are minimized but which suffer from differing definitions of ‘MSW’.

Cost effectiveness of recycling: a systems model.

Financial analytical models of waste management systems have often found that recycling costs exceed direct benefits, and in order to economically justify recycling activities, externalities such as household expenses or environmental impacts must be invoked. Certain more empirically based studies have also found that recycling is more expensive than disposal. Other work, both through models and surveys, have found differently. Here we present an empirical systems model, largely drawn from a suburban Long Island municipality. The model accounts for changes in distribution of effort as recycling tonnages displace disposal tonnages, and the seven different cases examined all show that curbside collection programs that manage up to between 31% and 37% of the waste stream should result in overall system savings. These savings accrue partially because of assumed cost differences in tip fees for recyclables and disposed wastes, and also because recycling can result in a more efficient, cost-effective collection program. These results imply that increases in recycling are justifiable due to cost-savings alone, not on more difficult to measure factors that may not impact program budgets.

A Management Framework for Municipal Solid Waste Systems and Its Application to Food Waste Prevention

Waste management is a complex task involving numerous waste fractions, a range of technological treatment options, and many outputs that are circulated back into society. A systematic, interdisciplinary systems management framework was developed to facilitate the planning, implementation, and maintenance of sustainable waste systems. It aims not to replace existing decision-making approaches, but rather to enable their integration to allow for inclusion of overall sustainability concerns and address the complexity of solid waste management. The framework defines key considerations for system design, steps for performance monitoring, and approaches for facilitating continual system improvements. It was developed by critically examining the literature to determine what aspects of a management framework would be most effective at improving systems management for complex waste systems. The framework was applied to food waste management as a theoretical case study to exemplify how it can serve as a systems management tool for complex waste systems, as well as address obstacles typically faced in the field. Its benefits include the integration of existing waste system assessment models; the inclusion of environmental, economic, and social priorities; efficient performance monitoring; and a structure to continually define, review, and improve systems. This framework may have broader implications for addressing sustainability in other disciplines.

Modeling an Improvement in Phosphorus Utilization in Tropical Agriculture

Studies of Terra Preta soils have generated interest in recreating their fertility elsewhere. Much of the research has focused on soil amendment charcoal (“biochar”). Terra Preta also contains bone fragments, producing a high concentration of phosphorus. Some forecast worldwide declines in phosphorus supplies, and better agricultural system management is required to improve phosphorus use efficiency. A conceptual model is offered to consider the influence of charcoal on bioavailability of phosphorus. The model describes a system where improvements in the chemical and biological condition of the soil result in increased phosphorus availability and cycling. Mechanisms of phosphorus/charcoal interaction are considered, and an assessment is made of the potential impact on African subsistence agriculture from the incorporation of biogenic, allogenic phosphorus through biochar.

Biogas potential on Long Island, New York: A quantification study

Biogas is the product of anaerobic digestion of waste, whether occurring spontaneously in landfills or under controlled conditions in digesters. Biogas is viewed as an important energy source in current efforts to reduce the use of fossil fuels and dependency on imported resources. Several studies on the assessment of biogas potential have been made at regional, national, and global scales. However, because it is not economically feasible to transport biogas feedstock over long distances, it is more appropriate to consider local waste sources for their potential to produce biogas. An assessment of the biogas potential on Long Island, based on the review of local landfills, wastewater treatment plants, solid waste generation and management, and agricultural waste, found that 234 × 106 m3 of methane (CH4) from biogas might be harvestable, although substantial barriers for complete exploitation exist. This number is equivalent to 2.52 TW-h of electricity, approximately 12% of fossil fuel power generation on ...

The hidden gender effect in online collaboration

Controlled experiment of gender composition on team performance under anonymity.Female-dominated teams are more productive than male-dominated teams.Female students are no more productive than male students.Female students act more collaboratively. It has been argued that the generally positive effect that female participation exerts on team performance ceases to exist under conditions of anonymity. We evaluate this thesis in the context of an online learning environment in which the gender of fellow student team members was not disclosed to subjects. To circumvent selection effects in the composition of teams we employed an experimental design in which female and male students were randomly assigned to teams of varying gender composition. Against expectations, we find that under anonymity gender composition continues to impact team performance, with all-female teams being most productive. Counter-intuitively, this team effect occurred in our study without female students individually being more productive than their male counterparts. These findings indicate that the presence of females on anonymous teams can have a hidden effect on the productivity of other team members. Our results underscore that despite face-to-face interaction in higher education increasingly being substituted by Internet-enabled communication, a students social environment continues to impact academic learning in important ways.

Degradable Plastics And Their Potential ForAffecting Solid Waste Systems

Plastic waste forms a substantial part of municipal solid waste and has caused environmental concerns, particularly due to the chemical contamination of the environment and effects from persistent litter. Plastics also complicate waste management processes, such as by having poor recovery rates through recycling and causing contamination in composting operations. One potential means of addressing some of these challenges is through degradable plastics, which unlike conventional plastics, are designed to decompose at an accelerated rate in specific environments. Degradable plastics aim to address the end-of-life of plastic products and are intended to reduce the environmental impacts associated with their use and management. The first generation of degradable plastics did not meet marketing claims; some of the more recent formulations, partly as a consequence of third party certifications, are more compliant. However, many plastics that are labelled as degradable do not decompose very readily, and it is not clear that litter will be diminished to any great degree through their use. In addition, user confusion regarding degradable definitions is common. Multiple formulations mean that not all degradable plastics address compost contamination and most degradable plastics do not address other problems associated with plastics waste management. Therefore it is not clear that degradable plastics constitute a major technological advance. In fact, they may be more harmful than helpful to waste management systems at this time. Here we discuss how these materials perform in different aspects of solid waste programs: recycling, composting, WTE incineration and landfills, as well as the potential for these plastics to reduce litter problems, both on land and at sea.