Morton A. Barlaz

Bio: Morton A. Barlaz is an academic researcher from North Carolina State University. The author has contributed to research in topics: Municipal solid waste & Leachate. The author has an hindex of 55, co-authored 199 publications receiving 15571 citations. Previous affiliations of Morton A. Barlaz include University of Texas at Arlington & RTI International.

Accumulation and fragmentation of plastic debris in global environments.

Abstract: One of the most ubiquitous and long-lasting recent changes to the surface of our planet is the accumulation and fragmentation of plastics. Within just a few decades since mass production of plastic...

Present and long-term composition of msw landfill leachate: a review

Abstract: The major potential environmental impacts related to landfill leachate are pollution of groundwater and surface waters. Landfill leachate contains pollutants that can be categorized into four groups (dissolved organic matter, inorganic macrocomponents, heavy metals, and xenobiotic organic compounds). Existing data show high leachate concentrations of all components in the early acid phase due to strong decomposition and leaching. In the long methanogenic phase a more stable leachate, with lower concentrations and a low BOD/COD-ratio, is observed. Generally, very low concentrations of heavy metals are observed. In contrast, the concentration of ammonia does not decrease, and often constitutes a major long-term pollutant in leachate. A broad range of xenobiotic organic compounds is observed in landfill leachate. The long-term behavior of landfills with respect to changes in oxidation-reduction status is discussed based on theory and model simulations. It seems that the somewhere postulated enhanced release of accumulated heavy metals would not take place within the time frames of thousands of years. This is supported by a few laboratory investigations. The existing data and model evaluations indicate that the xenobiotic organic compounds in most cases do not constitute a major long-term problem. This may suggest that ammonia will be of most concern in the long run.

Transport and release of chemicals from plastics to the environment and to wildlife

Abstract: Plastics debris in the marine environment, including resin pellets, fragments and microscopic plastic fragments, contain organic contaminants, including polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons, petroleum hydrocarbons, organochlorine pesticides (2,2′-bis(p-chlorophenyl)-1,1,1-trichloroethane, hexachlorinated hexanes), polybrominated diphenylethers, alkylphenols and bisphenol A, at concentrations from sub ng g–1 to µg g–1. Some of these compounds are added during plastics manufacture, while others adsorb from the surrounding seawater. Concentrations of hydrophobic contaminants adsorbed on plastics showed distinct spatial variations reflecting global pollution patterns. Model calculations and experimental observations consistently show that polyethylene accumulates more organic contaminants than other plastics such as polypropylene and polyvinyl chloride. Both a mathematical model using equilibrium partitioning and experimental data have demonstrated the transfer of contaminants from plastic to organisms. A feeding experiment indicated that PCBs could transfer from contaminated plastics to streaked shearwater chicks. Plasticizers, other plastics additives and constitutional monomers also present potential threats in terrestrial environments because they can leach from waste disposal sites into groundwater and/or surface waters. Leaching and degradation of plasticizers and polymers are complex phenomena dependent on environmental conditions in the landfill and the chemical properties of each additive. Bisphenol A concentrations in leachates from municipal waste disposal sites in tropical Asia ranged from sub µg l–1 to mg l–1 and were correlated with the level of economic development.

Methane production from municipal refuse: A review of enhancement techniques and microbial dynamics

Abstract: Methane is recovered from about 100 municipal solid waste landfills in the U.S. in saleable volumes, although yields are 1 to 50% of the methane potential of refuse based on biodegradability data. Studies on the microbiology of refuse decomposition and efforts to enhance refuse methanogenesis are reviewed here. Results of studies on the effects of leachate recycle and neutralization, a reduction in refuse particle size, the addition of anaerobic sewage sludge or old refuse as a seed, nutrient addition, calcium carbonate addition, and moisture on methane production are examined in consideration of new findings on landfill microbiology. A four‐phase description of refuse decomposition with leachate recycle, including an aerobic phase, an anaerobic acid phase, an accelerated methane production phase, and a decelerated methane production phase, is proposed. Mass balances and pumping tests may be used to estimate the methane potential of a sanitary landfill. The use of empirical, zero, and first‐order models t...

Bacterial population development and chemical characteristics of refuse decomposition in a simulated sanitary landfill.

Abstract: Population development of key groups of bacteria involved in municipal refuse conversion to methane was measured from the time of initial incubation through the onset of methane production. Hemicellulolytic bacteria, cellulolytic bacteria, hydrogen-producing acetogens, and acetate- and H2-plus-CO2-utilizing methanogens were enumerated by the most-probable-number technique with media containing oat spelt xylan, ball-milled cellulose, butyrate, acetate, and H2 plus CO2, respectively. Refuse decomposition was monitored in multiple replicate laboratory-scale sanitary landfills. A laboratory-scale landfill was dismantled weekly for microbial and chemical analysis. Leachate was neutralized and recycled to ensure methanogenesis. The methane concentration of the sampled containers increased to 64% by day 69, at which time the maximum methane production rate, 929 liters of CH4 per dry kg-year, was measured. Population increases of 2, 4, 5, 5, and 6 orders of magnitude were measured between fresh refuse and the methane production phase for the hemicellulolytic bacteria, cellulolytic bacteria, butyrate-catabolizing acetogens, and acetate- and H2-CO2-utilizing methanogens, respectively. The cellulolytic bacteria and acetogens increased more slowly than the methanogens and only after the onset of methane production. The initial decrease in the pH of the refuse ecosystem from 7.5 to 5.7 was attributed to the accumulation of acidic end products of sugar fermentation, to the low acid-consuming activity of the acetogenic and methanogenic bacteria, and to levels of oxygen and nitrate in the fresh refuse sufficient for oxidation of only 8% of the sugars to carbon dioxide and water. Cellulose and hemicellulose decomposition was most rapid after establishment of the methanogenic and acetogenic populations and a reduction in the initial accumulation of carboxylic acids. A total of 72% of these carbohydrates were degraded in the container sampled after 111 days. Initially acetate utilization, but ultimately polymer hydrolysis, limited the rate of refuse conversion to methane. Microbial and chemical composition data were combined to formulate an updated description of refuse decomposition in four phases: an aerobic phase, an anaerobic acid phase, an accelerated methane production phase, and a decelerated methane production phase.

Production, use, and fate of all plastics ever made

Abstract: Plastics have outgrown most man-made materials and have long been under environmental scrutiny. However, robust global information, particularly about their end-of-life fate, is lacking. By identifying and synthesizing dispersed data on production, use, and end-of-life management of polymer resins, synthetic fibers, and additives, we present the first global analysis of all mass-produced plastics ever manufactured. We estimate that 8300 million metric tons (Mt) as of virgin plastics have been produced to date. As of 2015, approximately 6300 Mt of plastic waste had been generated, around 9% of which had been recycled, 12% was incinerated, and 79% was accumulated in landfills or the natural environment. If current production and waste management trends continue, roughly 12,000 Mt of plastic waste will be in landfills or in the natural environment by 2050.

Plastic waste inputs from land into the ocean

Abstract: Plastic debris in the marine environment is widely documented, but the quantity of plastic entering the ocean from waste generated on land is unknown. By linking worldwide data on solid waste, population density, and economic status, we estimated the mass of land-based plastic waste entering the ocean. We calculate that 275 million metric tons (MT) of plastic waste was generated in 192 coastal countries in 2010, with 4.8 to 12.7 million MT entering the ocean. Population size and the quality of waste management systems largely determine which countries contribute the greatest mass of uncaptured waste available to become plastic marine debris. Without waste management infrastructure improvements, the cumulative quantity of plastic waste available to enter the ocean from land is predicted to increase by an order of magnitude by 2025.

Accumulation and fragmentation of plastic debris in global environments.

Abstract: One of the most ubiquitous and long-lasting recent changes to the surface of our planet is the accumulation and fragmentation of plastics. Within just a few decades since mass production of plastic...