Mexico City's Water Supply Improving the Outlook for Sustainability (1995) / Chapter Skim
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4 Water Supply, Distribution, and Disposal
4 Water Supply, Distribution, and Disposal
Pages 19-38
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From page 19... ...
In this chapter, information is presented on the quantities of water derived from the various sources, the treatment and distribution of this water, wastewater treatment, the drainage system, and water reuse. In many respects, this effort represents the first time that water resource information of this nature has been integrated for the MCMA.
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From page 20... ...
Authorities have been attempting to restrict urbanization in this southern portion of the district because of the difficulties in providing basic services, and because it represents an important natural ground water recharge zone. According to the Water and Sanitation Commission of the State of Mexico, the metropolitan area extends to the east, north, and west of the Federal District into 17 counties of the State of Mexico, having a total area of 2,269 square kilometers.
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From page 21... ...
Domestic Industrial Commercial and Urban Services State of Mexico Federal District 1504 2269 667 620 8.3 364 67 17 16 6.8 230 80 17 3 Sources of information: Departamento del Distrito Federal, 1992b; Comision Estatal de Aguas y Saneamiento' 1993; INEGI, 1991a. An important aspect of water service is the amount of unaccounted water lost due to leaks within the distribution system.
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From page 22... ...
The quantities provided by each of the water sources are shown in Table 4.2. Except in the case of the Magdalena River and Madin Dam, the same raw water sources supply the metropolitan service areas of both the Federal District and the State of Mexico (Departamento del Distrito Federal, 1 992b; Comision Estatal de Agua y Saneamiento, 1993~.
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From page 23... ...
Lerma Basin over the SierTa de las Cruces divide to Mexico City and the Basin of Mexico. In 1982, a more ambitious project was initiated that delivered surface water from the Cutzamala River Basin, a distance of 127 kilometers and a net rise in elevation of 1,200 meters.
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From page 24... ...
The Federal Distnct operates the Magdalena River treatment plant, which provides alum coagulation/flocculation, gravity sedimentation, rapid sand filtration, and chlorine disinfection. The National Water Commission operates a surface water treatment plant at Madin Dam, which supplies the State of Mexico service area and uses a similar treatment process as the Magdalena plant.
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From page 25... ...
As mentioned, and shown in Table 4.2, the Federal District and the State of Mexico service areas share water from all sources, except for the Magdalena River serving the Federal District, and Madin Dam serving the State of Mexico. The Federal District and the State of Mexico service areas within the MCMA are each divided into five water service districts, and water enters the distribution system at designated "entrance points" at one or more locations in each service district.
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From page 26... ...
\ Xotepingo S ,, 1 FIGURE 4-2 Water service districts within the Federal District and names of associated entrance points where water enters the distribution system. describe water distribution for both the Federal District and State of Mexico service areas in a combined approach.
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From page 27... ...
Bold numbers are quantities from ground water sources; plain numbers identify surface water sources. Ground water is extracted within each service district.
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From page 28... ...
The approximately 10 percent of wastewater treated in the MCMA is for local reuse projects such as ground water recharge and agricultural and urbanlandscape irrigation. There are 13 wastewater treatment plants in the Federal District and 14 in the State of Mexico service area treating a total flow of 2.62 and 1.69 ems respectively (Departamento del Distrito Federal, 1992b; Comision Estatal de Agua y Saneamiento, 1993~.
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From page 29... ...
Source: Departamento del Distrito Federal, 1982.
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From page 30... ...
Tables 4.4 and 4.5 list the treatment plants serving the Federal District and the State of Mexico service areas, together with their design and current opera
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From page 31... ...
The current flow of the 13 treatment plants within the Federal Distnct service area (Table 4.6) is only 55 percent of design capacity, i.e., 2.621 versus 4.623 ems (Departamento del Distrito Federal, 1992b)
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From page 32... ...
Because some ofthe treatment plants are operated by either an industry or the county in which the plant is located, information on the operation and performance of all the plants was not available from the State of Mexico water and sanitation department. The handling, treatment, and disposal of the residual or sewage sludge solids normally generated at wastewater treatment plants is a major consideration.
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From page 33... ...
ever, because wastewater treatment in the MCMA is performed for water reuse, rather than for disposal purposes, the sludge produced is apparently returned directly to the sewer system without any treatment. WATER REUSE AND RECYCLING Water reuse refers to the practice of reclaiming waters of impaired quality and using them, after suitable levels of treatment, for beneficial purposes.
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From page 34... ...
The program goals include the development of feasibility studies for the construction of additional treatment systems and a distribution network for delivering reclaimed wastewater for reuse; the promotion of water reuse projects within both the public and private sectors; the rehabilitation of existing wastewater treatment plants; the preparation of operation and maintenance manuals and other documents for improved management of wastewater treatment and reuse systems; and a quantification of the potable water now being used for various purposes which could potentially be replaced with reclaimed wastewater. Under this program, potential water reuse activities including agricultural irrigation, industrial use, urban landscaping, and aquifer recharge have been identified within specific service districts of the State of Mexico service area.
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From page 35... ...
Total dissolved solids, nitrates, and pathogens in reclaimed Wastewater Health concerns of bacteria and viruses; Eutrophication due to N and P in receiving water; Toxicity to aquatic life. Constituents in reclaimed wastewater, especially trace organic; chemicals and their toxicological effects; Aesthetics and public acceptance; Health concerns about pathogen transmission, particularl viruses Y
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From page 36... ...
A portion of the treated wastewater from eight of the Federal Distnct's wastewater treatment plants is used for this purpose. One of the more significant projects is using reclaimed municipal wastewater to improve the lacustrine ecosystem of the historic canals of Xochimilco.
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From page 37... ...
The Federal District is also developing a system of ditches along a slope of the Magdalena Contreras hills with the intention of collecting stormwater and promoting natural infiltration. The Federal District constructed two pilot treatment plants in 1983 to study the potential for the advanced wastewater treatment of secondary effluent for potable reuse, and to examine the potential for treating contaminated ground water.
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From page 38... ...
See AIC-ANIAC (1995) for further water reuse guidelines and examples.
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