About: Leachate is a(n) research topic. Over the lifetime, 11751 publication(s) have been published within this topic receiving 197005 citation(s).
TL;DR: Today, the use of membrane technologies, more especially reverse osmosis (RO), either as a main step in a landfill leachate treatment chain or as single post-treatment step has shown to be an indispensable means of achieving purification.
Abstract: In most countries, sanitary landfilling is nowadays the most common way to eliminate municipal solid wastes (MSW). In spite of many advantages, generation of heavily polluted leachates, presenting significant variations in both volumetric flow and chemical composition, constitutes a major drawback. Year after year, the recognition of landfill leachate impact on environment has forced authorities to fix more and more stringent requirements for pollution control. This paper is a review of landfill leachate treatments. After the state of art, a discussion put in light an opportunity and some results of the treatment process performances are given. Advantages and drawbacks of the various treatments are discussed under the items: (a) leachate transfer, (b) biodegradation, (c) chemical and physical methods and (d) membrane processes. Several tables permit to review and summarize each treatment efficiency depending on operating conditions. Finally, considering the hardening of the standards of rejection, conventional landfill leachate treatment plants appear under-dimensioned or do not allow to reach the specifications required by the legislator. So that, new technologies or conventional ones improvements have been developed and tried to be financially attractive. Today, the use of membrane technologies, more especially reverse osmosis (RO), either as a main step in a landfill leachate treatment chain or as single post-treatment step has shown to be an indispensable means of achieving purification.
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.
Abstract: The literature has been critically reviewed in order to assess the attenuation processes governing contaminants in leachate affected aquifers. Attenuation here refers to dilution, sorption, ion exchange, precipitation, redox reactions and degradation processes. With respect to contaminants, focus is on dissolved organic matter, xenobiotic organic compounds, inorganic macrocomponents as anions and cations, and heavy metals. Laboratory as well as field investigations are included. This review is an up-date of an earlier comprehensive review. The review shows that most leachate contamination plumes are relatively narrow and do not in terms of width exceed the width of the landfill. The concept of redox zones being present in the plume has been confirmed by the reported composition of the leachate contaminated groundwater at several landfills and constitutes an important framework for understanding the behavior of the contaminants in the plume as the leachate migrates away from the landfill. Diverse microbial communities have been identified in leachate plumes and are believed to be responsible for the redox processes. Dissolved organic C in the leachate, although it appears to be only slowly degradable when the volatile organic acids are gone, apparently acts as substrate for the microbial redox processes. Several xenobiotic organic compounds have been found to be degradable in leachate contaminated groundwater, but degradation rates under anaerobic redox conditions have only been determined in a few cases. Apparently, observations in actual plumes indicate more extensive degradation than has been documented in the laboratory. The behavior of cations in leachate plumes is strongly influenced by exchange with the sediment, although the sediment often is very coarse and sandy. Ammonium seems to be subject to anaerobic oxidation, but the mechanisms are not yet understood. Heavy metals do not seem to constitute a significant pollution problem at landfills, partly because the heavy metal concentrations in the leachate often are low, and partly because of strong attenuation by sorption and precipitation. Although complexation of heavy metals with dissolved organic matter is significant, the heavy metals are in most cases still strongly attenuated in leachate-polluted aquifers. The information available on attenuation processes has increased dramatically during the last 15 a, but the number of well-documented full scale leachate plumes are still few and primarily from sandy aquifers. Thus, the diversity of attenuation processes in leachate plumes is probably not yet fully understood. Apparently, the attenuation processes in leachate plumes may for many contaminants provide significant natural remediation, limiting the effects of the leachate on the groundwater to an area usually not exceeding 1000 m from the landfill.
•17 Dec 1996
Abstract: Preface Composting: A Prospective Composting and Recycling History Philosophical Aspects and the Future of Composting in the United States Advantages and Disadvantages of Composting Conclusion References Basic Concepts Introduction Oxygen and Aeration Moisture Temperature Nutrients: Carbon, Nitrogen, pH Summary References Microbiology Introduction Microbial Populations Temperature Moisture Nutrients Inoculants Summary References Biochemistry Introduction Organic Matter Biochemical Manifestations Occurring during Composting Biochemical Manifestations Occurring When Compost Is Applied to Soil Humus Formation Summary References Stability, Maturity, and Phytotoxicity Introduction Stability and Maturity: Chemical Methods Carbon/Nitrogen Ratio (C/N) Nitrogen Species pH Cation Exchange Capacity (CEC) Organic Chemical Constituents Humification Parameters Humification Index Relative Concentrations of Humic Acid to Fulvic Acid Humic Substance Functional Groups Optical Density Physical Methods Temperature and Heat Output Color, Odor, Structure and Specific Gravity Plant Assays Microbiological Tests and Activities Respiration-Carbon Dioxide Evolution Respiration-Oxygen Uptake Microbial Changes Enzyme Activity Phytotoxicity Summary References Trace Elements, Heavy Metals, and Micronutrients Introduction Essentiality and Toxicity Arsenic (As) Boron (B) Cadmium (Cd) Copper (Cu) Lead (Pb) Mercury (Hg) Molybdenum (Mo) Nickel (Ni) Selenium (Se) Zinc (Zn) Occurrence in the Environment Environmental Consequences Leachate Characteristics of Compost Soil-Plant Interactions Type of Trace Element and Chemical State Soil Acidity Organic Matter Cation Exchange Capacity (CEC) Reversion to Unavailable Forms Other Aspects Effect of Compost on Trace Element Uptake Summary References Organic Compounds Introduction Organic Compounds in Various Compost Materials and Feedstocks Fate of Organic Compounds during Composting Reactions and Movement of Toxic Organics in Soil Uptake by Plants and Potential Entry into the Food Chain Conclusion References Pathogens Introduction Primary Pathogens in Wastes and Compost Worker Health Risks of Solid Waste Composting The Effect of Composting on Pathogen Destruction Survival of Pathogens in Soils and on Plants Conclusions References Bioaerosols Introduction Aspergillus Fumigatus Morphology Pathogenicity Occurrence in the Environment Occurrence in and Around Composting Facilities Dickerson, Maryland Site II, Maryland Westbrook, Maine Windsor, Ontario Hampton Roads, Virginia Beltsville, Maryland Camden, New Jersey Yard Waste Composting Facilities MSW Composting Facility Other Studies Endotoxin and Organic Dusts Conclusions References Odors and Volatile Organic Compounds Introduction Odorous Compounds and Odors Emitted by Composting Facilities Volatile Organic Compounds Air Dispersion Modeling for Composting Facilities Regulatory Models Model Parameters Gassian Dispersion and Dispersion Parameters Treatment of Terrain Reliability of Model Results Peak-to-Mean Conversion for Assessing Odor Impacts Examples of Dispersion Modeling for Composting Facilities Conclusion References Soil Physical and Chemical Manifestations Introduction Effect of Compost Application on Soil Physical Properties Soil Structure Bulk Density Soil Strength Water Relations-Soil Water Retention and Available Water to Plants Runoff and Soil Erosion Soil Temperature Effect of Compost Application on Soil Chemical Properties Cation Exchange Capacity Soil pH Electrical Conductivity (EC) Nitrogen Availability in Soil Nitrogen Leaching Summary References Utilization of Compost Introduction Horticulture Ornamental Flowering and House Plants Sod Production and Turf Grass Establishment Agricultural Crops Field Crops Vegetable Crops Silviculture Conclusion References Compost Utilization II Introduction Plant Pathogen Destruction during Composting Plant Disease Suppression Biofiltration Basic Concepts Moisture Content pH Nutrients Temperature Microbiology Application Summary References Regulations Introduction Concepts and Approaches to Regulations United States Federal Regulations State Regulations in the United States New York Tennessee Composting Facility General Requirements Facility Design and Construction Compost Standards California Canada Europe Austria Denmark Germany Italy Netherlands Criteria for Compost Quality and Facility Design: Compost Quality Criteria Facility Design Criteria Conclusion References Index
Abstract: Inevitable consequences of the practice of solid waste disposal in landfills are gas and leachate generation due primarily to microbial decomposition, climatic conditions, refuse characteristics and landfilling operations. The migration of gas and leachate away from the landfill boundaries and their release into the surrounding environment present serious environmental concerns at both existing and new facilities. Besides potential health hazards, these concerns include, and are not limited to, fires and explosions, vegetation damage, unpleasant odors, landfill settlement, ground water pollution, air pollution and global warming. This paper presents an overview of gas and leachate formation mechanisms in landfills and their adverse environmental impacts, and describes control methods to eliminate or minimize these impacts.