Transcript Waste Water Treatment in Mexico

Hugo Fernando Palacios González
Introduction
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Hydrologic resources in Mexico
780 mm of pluvial precipitation (1 532 million m3)
Superficial runoffs of an annual average volume of
410,164 million m3.
Runoffs distributed in 320 drainage basins
Some of the most important rivers: Yaqui, LermaSantiago, Balsas, Bravo, Pánuco, Grijalva, Usumacinta.
Yaqui
Lerma
Bravo
Grijalva
 Water distribution problem- 80% of hydrological
resources under 500 m (over sea level). 70% of total
population over this level, 80% of industrial activity as
well.
 55% of industrial activity is developed in the valley of
Mexico at more than 2000 m over sea level.
Water Quality
 3 main pollution sources classified as follows:
 Social sector. Mexico 23%, Monterrey 4.1%,
Guadalajara 4%. Only 50% of the population has
sewerage infrastructure.
 Industrial sector. Generates 43% of waste water in the
country.
 Agricultural sector. 92 500 million m3 are used in this
sector. Produces 12% of waste water. Water with high
levels of particles in eutrophication state.
Waste Water Treatment
 361 municipal WWT plants. Installed capacity of 25
m3/s. (Unfortunately they only have capacity to treat
24%)
 282 industrial WWT plants. Capacity of 20 m3/s.
(Only treats 25%)
 It’s been estimated that only 50% of these plants
operate regularly
 There’s an index of water quality used by scientists to
classify treated water.
 It’s known as the ICARen (Índice de Calidad de Agua
Renovada) which would literally mean Quality Index
of Renewed Water
 ICARen of 0- drinkable water
 ICARen >38- useless water
ICaren
Uses
<3
Drinkable water
16
Industrial: vapor production
22
Industrial: Cooling
25
Fishing
26
Recreation: swimming
26
Commerce, Services, industrial processes
27
Livestock
28
Agriculture
30
Municipal, undrinkable
34
Agriculture: plantations and vines
35
Agriculture: Industrial crops/ Green areas
36
Recreation with secondary contact: navigation
38
Not recommended for use
Water Purification Stations
 Conventional treatment methods
 Basic Physical and chemical procedures, such as
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decantation, sedimentation and coagulation
Elimination of wastes, oils, greases, sand
Elimination of inorganic and organic materials by
decantation
Elimination of biodegradable organic matter
Stabilization and disposition of sludge extracted in the
processes
Reverse Osmosis
 Membranes made out of synthetic materials
Coagulation
 Addition of electrolytes (Alum or Lime)
 Charged particles of waste water combine with ions
neutralizing the charges
 The neutral particles combine to form greater particles
 E.G. Ca(OH)2 -> Ca(aq)2+ + 2 OH(causing pH change)
Flocculation
 Use of starch or multiply charged ions to attract or trap
the particles and settle down together.
 Other salts such as iron sulfates Fe2(SO4)3 and FeSO4,
chromium sulfate Cr2(SO4)3, and some special
polymers are also useful
Sedimentation
 Used after coagulation and flocculation
 A settling tank with inlets and outlets is used
 The settled particles and sludge must be removed
Settling tank
Filtration
 Removal of solids from water, passing them by a
porous medium
 Artificial membranes, nets, sand filter and high
technological filter systems
Aeration
 Main purpose: Oxygenation
 Removal of volatile organic substances , hydrogen
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sulfide, ammonia and volatile compounds
Diffused aeration- air bubbles through water
Spray aeration
Multiple tray aeration- water flows through many trays
to mix with air
Cascade aeration
Air stripping- combination of multiple tray and
cascade techniques
Bioaugmentation
 Introduction of a group of natural microbial strains or
a genetically engineered variant
KB-1
Dechlorinator.
Used to
introduce
Dehalococcoides
to sites where
they are absent
Activated Sludge
 Atmospheric air or pure oxygen is bubbled through
sewage combined with organisms to develop a sludge,
which reduces the organic content of sewage.
Industrial Effluent Recycling
 Clonal poplar as recycling engine
 Transpiration function driven by weather
characteristics
 Plantation supplied with water according to needs
 Monitoring of parameters every 10 minutes:
1. Solar radiation
2. Air temperature
3. Air relative humidity
4. Wind speed
5. Rainfall
 Parameters monitored by a station equipped with a
micrologger (environmental data logger)
 Data is retrieved and evapotranspiration is calculated
for every 10 min. interval
 These amounts are summed until they reach the
amount of a watering (Pre-established based on soil
water)
Poplar plantation
Effluent recycling
plant
Sewerage Infrastructure
 Old infrastructural designs
 Old facilities
 New Projects:
“Túnel Emisor Oriente” (Mexico city). Interior diameter
of 7 meters. Extension of 62 kilometers at more than
200 meters under ground level. Investment of 13
million pesos (19.5 million Kč approximately). Avoid
Future floods.
Present Day Problems
 In the Valley of Mexico only about 6% of their waste
water is treated (against legislation)
 Immediate response to the problem:
1. Permits for the construction of 6 new WWT plants
in Mexico city
2. Investment of 37 million pesos (55.4 million Kč
approx)
Leading WWT companies
 ACS Medio Ambiente (Monterrey, NL)
 Aguas Latinas México S de RL de CV (México, DF)
 Alianza con la Biosfera (AliBio) (México, DF)
 Bio-Ingenieria Ingeniería SA de CV (La Paz, BCS)
References
 www.sagan-
gea.org/hojared_AGUA/paginas/8agua.html
 http://www.imacmexico.org/ev_es.php?ID=17461_201&
ID2=DO_TOPIC