Advances in Solid Waste Management Technology: The Way Forward

Although landfill disposal of municipal solid waste is an integral part of any waste management system, most people identify the landfill as a key factor in the mismanagement of finite resources and as a source of greenhouse gas emissions. The landfill is being considered a “liability” requiring solutions to each associated individual problem. Various governmental agencies throughout the developed and developing world have responded to these concerns by adopting new policies, regulations, and guidelines. For example, the European Union (EU) has adopted the Landfill Directive, which requires member states to achieve a staged reduction of 65% in the amount of biodegradable municipal waste directed to their landfills by 2016. Most governments are attempting to reduce greenhouse gas emissions, either directly by adopting new landfill technologies or indirectly by reducing waste directed to landfills.

With the changing regulatory environment, the way forward for the waste management industry is becoming increasingly clear. First, continuing a trend started a couple of decades ago, there is heavy emphasis on diverting biodegradable and recyclable waste from landfills, via physical and biological processing of waste. Second, holistic and sustainable approaches to landfill design are emphasized over the conventional dry-tomb landfill approach. Recent advances in solid waste research have indicated that the operation of landfills as bioreactors for enhanced waste biodegradation and energy recovery could be viable. Various government agencies are in the process of adopting the landfill bioreactor concept as the preferred option.

The emphasis is on simultaneously solving the three most important problems with landfills: groundwater contamination with leachate, atmospheric release of greenhouse gases, and loss of resources/space. Rather than treating landfill cells as long-term waste repositories, as in the case of the dry-tomb landfill approach, future cells may be designed and operated as energy and resource recovery facilities for minimal environmental impacts. Such initiatives have the potential to solve the waste management problem in a sustainable manner, but a number of technical obstacles may prevent their implementation. This special issue of the Practice Periodical of Hazardous, Toxic, and Radioactive Waste Management presents a collection of papers dealing with current research around the world, focused on removing these technical obstacles.

Despite widespread interest in operating landfills as bioreactors, a number of areas related to bioreactor operation require close scrutiny. Two papers on leachate collection and recirculation systems provide additional information to the practitioners to ensure that such systems achieve the stated objective of efficient collection of leachate and distribution of leachate evenly throughout the waste matrix. VanGulck et al. provide design tables and a new approach to designing horizontal leachate recirculation piping systems in bioreactor landfills. New approaches to evaluating and designing leachate collection systems are presented by Soh and Hettiaratchi. Elagroudy and coworkers provide details of early laboratory research into determining waste biodegradation in lysimeters operated in anaerobic bioreactor mode. An analysis of waste biodegradation kinetics is provided by Kumar et al. for aerobic composting of municipal solid waste under tropical climatic conditions in India.

With system optimization as the central theme, there is a renewed interest in applying operation research approaches to solid waste management. Two papers by Vidanaarachchi et al. and Filipiak et al., focusing on waste management situations in developing countries, discuss resource optimization for environmental improvements at waste disposal sites and the use of an optimization approach for municipal waste collection, respectively. One other area receiving greater attention from researchers is the application of soil methanotrophy to control fugitive methane emissions from landfills. There are two potential approaches of soil methanotrophy application at landfills: biocaps to control area source emissions across landfill final covers, and biofilters to control point source emissions. Albanna and Fernandes discuss the importance of temperature, moisture content, and fertilizer addition to increase methanotrophic activity in biocaps. Yuan and coworkers present details of a mathematical model for predicting behavior of a biofilter capable of methane oxidation using methanotrophic bacteria.

Overall, the papers exhibit the changing focus of the solid waste management industry. As the guest editor, I appreciate the opportunity to work with these authors and sincerely thank them for their efforts in preparing interesting manuscripts. I am grateful to the numerous reviewers who donated their time and insight to the peer review process. Finally, I am grateful to Dr. Rao Surampalli, editor in chief, for inviting me to be the guest editor of this special issue and for his valuable guidance in facilitating the completion of this special issue.