Home Health Best practices for environmental health : environmental pollution, protection, quality and sustainability
SUB-PROBLEMS INCLUDING LEADING TO IMPAIRMENT AND BEST PRACTICES FOR SOLID WASTE DISPOSAL FOR MUNICIPAL LANDFILLS
(See endnotes 73, 74, 75)
There always will be a need for landfills that are properly constructed, operated, maintained, and closed in an appropriate manner when the landfill is full. With growing populations, there is an increase in waste production and necessary waste disposal. The use of waste minimization techniques reduces the immediate need for additional large amounts of land, but over time the land areas will be filled up. The function of the sanitary landfill is to completely degrade biologically, chemically, and physically the material within it. The composition of the wastes varies with the type of waste deposited. Domestic waste which comes from household activities includes food wastes, plastics, paper, ash, broken pottery, metal, glass, rubber, textiles, etc., and unfortunately may contain some of the household hazardous waste. Commercial waste comes from stores, offices, restaurants, hotels, etc., and is composed mainly of packing materials, office supplies, food wastes, and then some of the same waste as domestic waste. Street sweepings are primarily dust and soil and may also contain paper, metal, and other types of street litter including the residues of drains and culverts. Waste from sewage treatment plants may include dried biosolids, and chemical wrappers and containers. Industrial non-hazardous waste, depending on the industry, includes packaging, plastics, paper, metal, and food waste from the cafeterias, etc.
There are six major site restrictions. They are airports where a landfill cannot be located within 10,000 feet of the end of the runway; 100-year floodplains where the solid waste would reduce temporary water storage or allow a wash-out of the material; wetlands with a few exceptions for states or tribes in certain situations; fault areas where landfills are prohibited within 200 feet; seismic impact zones where a landfill can exist if the liners and leachate collection systems can resist ground motion; and unstable areas such as sinkholes, rock falls, or where the soil may become liquefied during extreme wetting and drying cycles.
A special problem for landfills and metal recyclers is the household appliances that contain refrigerants. These units include window air conditioners, motor vehicle air conditioners, water coolers, vending machines, icemakers, and refrigerators. The common refrigerants which are ozone-depleting chemicals are typically chlorofluorocarbons and hydrochlorofluorocarbons.
Landfill gas is a mixture of many different kinds of gases. The gases are produced by bacterial decomposition of the material deposited, volatilization of certain organic compounds, and chemical reactions between different compounds present in the waste. The gases produced include typically 45-60% methane, 40-60% carbon dioxide, 2-5% nitrogen, 0.1-1% oxygen, 0.1-1% ammonia, 0.1-0.6% non-methane organic compounds, 0-1% sulfides, 0-0.2% hydrogen, and 0-0.2% carbon monoxide. The amount and type of gas production is affected by the composition of the waste, age of the waste, presence or absence of oxygen in the landfill, moisture content, and the temperature of the landfill. The landfill gases can move from under the surface through spaces in the refuse and soils depending on the ability of the gas to defuse in a given area, the pressure of the gases, and the permeability of the waste and soil.
Landfill gases can be captured, treated, and converted into a source of energy. Solid waste can be turned into cellulosic gasoline and diesel fuels.
Reducing the use of energy and recovery of energy from the solid waste helps control the cost of operating the landfill, helps reduce pollutants of air and water, and assists in controlling global warming.
Modern landfills are properly engineered facilities where the remains of the solid wastes are deposited after recycling and further processing of the solid waste has been utilized. The landfills are designed, operated, and monitored to meet the requirements of federal regulations and therefore the following essential practices are utilized: restriction to locations in areas where the waste will not contaminate the groundwater or essential land areas; proper use of landfill liners; collection and removal of leachate for treatment; modern operating practices; groundwater monitoring wells; proper closure of landfills; and long-term evaluation and correction of problems in closed landfills.
Bioreactor landfills help to reduce the amount of landfill space needed and make the waste less hazardous by rapidly transforming and degrading organic waste. This is accomplished by injecting liquid, which may be leachate from the landfill which is recycled, wastewater, or sludge from sewage treatment plants and thereby maintains the moisture content at approximately 35-65%. The landfill may be aerobic, anaerobic, or a hybrid of both. The bioreactor produces additional landfill gas such as methane, which when captured and treated may be used as a source of energy.
Landfills are the least expensive method of solid waste disposal. Major controversies have occurred in local areas because there were increasing quantities of solid wastes and decreasing areas for disposal of this material. Existing landfills were filling up, and the sites of new landfills, incinerators, and recycling centers were complicated by citizen complaints and the typical response of not placing a new landfill, incinerator, and/or recycling center in my backyard. The cost of taking the solid waste to areas away from municipalities has grown considerably and the amount of funds available for doing this has decreased sharply. The choosing of a facility site is complicated by a variety of issues: environmental and health risk to groundwater, air, and land; economic concerns related to the effect on property values and cost to the taxpayer; social issues related to aesthetics, community image, and current and future land use patterns; and political issues related to special interests, community groups, local elections, and who profits from the facility.
Landfill facilities, which are utilized for the concentration and containment of wastes and waste byproducts, are rapidly running out of room for the placement of new materials. Major concerns include insect and rodent problems, odor problems, leachate potentially surfacing or entering the groundwater supply, hazardous gases, heat-trapping gases with methane being 20 times as potent a greenhouse gas as carbon dioxide, and injuries and potential illness to the people working with the solid waste.
Best Practices in Disposal of Solid Waste in Municipal Landfills
Best Practices for Disposal of Household Appliances Using Refrigerants
Construction and Demolition Waste Landfills
(See endnotes 26, 77)
Construction and demolition waste comes from the construction, renovation, repair, and demolition of all types of structures, roads, and bridges. It is mostly composed of various types of wood, asphalt, drywall, masonry, metals, earth, shingles, plastics, insulation, paper, and cardboard. It may also contain excess construction materials and containers such as adhesives, paint, and roofing cement cans. It may contain waste oils, grease, other fluids, batteries, appliances, carpet, and treated wood. The bulky material of construction and demolition waste allows moisture to easily infiltrate and therefore be available for production of hydrogen sulfide gas. Where the gypsum drywall is reduced to smaller pieces, there is an increased surface which creates greater amounts of hydrogen sulfide gas.
The composition of any given project varies tremendously from other projects. Most of the construction and demolition wastes are sent to either municipal solid waste landfills or specialized construction and demolition landfills. Some are dumped illegally or go to incinerators.
Two very serious problems are leachate and the production of landfill gases, especially hydrogen sulfide. The leachate may contain hazardous substances such as 1,2-dichloroethane, methylene chloride, cadmium, iron, lead, manganese, and excess total dissolved solids. Hydrogen sulfide can be produced in substantial quantities from landfills that accept gypsum drywall. Hydrogen sulfide is a poisonous, irritating, flammable, colorless gas which may cause substantial odor problems or damage the landfill gas collection system. It is also very harmful to the health of humans. The scope of the problem depends on the duration of exposure and concentration, and whether or not the individual already has upper respiratory problems of either an acute or chronic nature. It also may depend on the concentration. It can paralyze the olfactory system, cause respiratory distress, and at high enough levels cause death. The gypsum is a source of reducible sulfur in the landfill and combined with moisture, organic matter, anaerobic conditions, a pH of 6-9, and a variety of temperatures will produce hydrogen sulfide gas. (See endnote 78.)
Another serious problem in both construction and demolition landfills and municipal solid waste landfills is subsurface heating events such as chemical reactions, including spontaneous combustion, hot waste being deposited, or oxidation of cellulose and plastics which form peroxides, etc. This can lead to fires, explosions from gases, odors, smoke, toxic emissions, contamination of ground or surface water, and damage to various parts of the landfill management system.
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