Leachate

PermeOx is also used to improve the bioremediation of soils contaminated with creosote or kerosene (see Bioremediation (Supplement)), to deodori2e sewage sludges and wastewater (see Odormodification), and to dechloriaate wastewater and effluents. A special formulation of calcium peroxide, made by FMC and sold ia the United States under the trademark Trap2ene, is used for removing metal ions from acidic waste streams such as coal ash leachate and acid mine drainage (see Wastes, industrial). 

Fig. 3. pH Dependence of total organic carbon (TOC) decay during the photooxidation of a landfill leachate using H2O2/uv. Initial TOC concentration,... 

The goal of most scrap tire utilization projects is to find markets for scrap tires so that they do not end up in landfills or on stockpiles. Ironically, one potentially significant use of tires is in the constmction and management of landfills. Both shredded and whole scrap tires have been approved in various states for use in constmcting leachate beds in landfills. Approval has also been given in some states for the use of shredded tire material as a partial replacement for required daily cover (42). 

These include wastewater cleanup for electroplating (75—78), radioactive processing (79—82), landfill leachate (76,83), and municipal wastewater (84—87) ultrapure water production for electronics-grade (88,89), laboratory-grade (90), and pharmaceutical-grade (91) materials and food processing (qv) (9). 

In landfills, vinyl wastes, like all plastics, are extremely resistant to decomposition. In fact, high technology landfills are often lined with thick-gauge vinyl and use PVC pipe to handle Hquid leachate and methane gas for environmental protection. 

Prevents the potential contamination of surrounding soil by leaking filter leachate... 

Good bed drainage characteristics are necessary to ensure that reaction products are easily transported out of the filter media. The leachate is generally recycled through the humidification process to reduce the wastewater stream. 

LandtiUing of Solid Wastes Landfilling involves the controlled disposal of solid wastes on or in the upper layer of the earth s mantle. Important aspects in the implementation of sanitary landfills include (1) site selection, (2) landfimng methods and operations, (3) occurrence of gases and leachate in landfills, (4) movement and control of landfill gases and leachate, and (5) landfill design. The landfilling of hazardous wastes is considered separately. 

Landfills in wet areas. Because of the problems associated with contamination of local groundwaters, the development of odors, and structural stabihty, landfills must be avoided in wetlands. If wet areas such as ponds, pits, or quarries must be used as landfill sites, special provisions must be made to contain or ehminate the movement of leachate and gases from completed cells. Usually this is accomplished by first draining the site and then lining the bottom with a clay liner or other appropriate sealants. If a clay uner is used, it is important to continue operation of the drainage facility until the site is filled to avoid the creation of uplift pressures that could cause the liner to rupture from heaving. 

Leachate in landfills. Leachate may be defined as hquid that has percolated through sohd waste and has extracted dissolved or suspended materials from it. In most landfills, the liqiiid portion of the leachate is composed of the liquid produced from the decomposition of the wastes and liquid that has entered the landfill from external sources, such as surface drainage, rainfall, groundwater, and water form underground springs. Representative data on chemical characteristics of leachate are reported in Table 25-72. 

Gas and Leachate Movement and Control Under ideal conditions, the gases generated from a landfill should be either vented to the atmosphere or, in larger landfills, collected for the production of energy. Landfills with >2.5 miUion cubic meters of waste or >50 Mg/y NMOC (nonmethane organic compounds) emissions may require landfill-gas collection and flare systems, per EPA support WWW, CFR 60 Regulations. The leachate should be either contained within the landfill or removed for treatment. 

TABLE 25-72 Typical Leachate Quality of Municipal Waste... 

From McGinely, P. M. and Kmet, P, Formation Characteristics, Treatment, and Disposal of Leachate from Municipal Solid Waste Landfills, Bureau of Solid Waste Management, Wisconsin Department of Natural Resources, Madison, 1984. 

MAIN LEACHATE COLLECTION LINE, USE OF PERFORATED LATERALS will depend on topography AND EXTENT OF LANDFILL. MAINLINE AND LATERALS SHOULD BE GRAVEL-PACKED. 

FIG. 25-74 Use of an impermeable liner to control the movement of gases and leachate in landfills, (a) Without gas recovery, (h) With gas recovery. (From G, Tchohanoglous, H. Theisen, and R. Eliassen, Solid Wastes Engineering Principles and Management Issues, McGraw-Hill, New York, 1977.)... 

Control of ga.s movement by recovery. The movement of gases in landfills can also be controlled by instadhng gas-recovery wells in completed landfills (see Fig. 25-74b). This is considered an active venting system. Clay and other hners are used when landfill gas is to be recovered. In some gas-recovery systems, leachate is collected and recycled to the top of the landfill and reinjected through perforated lines located in drainage trenches. Typically, the rate of gas production is greater in leachate-recirculation systems. 

TABLE 25-73 Landfill Sealants for the Control of Gas and Leachate Movement... 

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