The disposal of solid wastes in Mexico

 Excerpts from Geo-Mexico  Comments Off on The disposal of solid wastes in Mexico
Oct 252010

The disposal of solid wastes has become a serious problem almost everywhere in the world. In general the more affluent a society, the more solid waste it generates. Technologically-advanced civilizations tend to produce many wastes that are not biodegradable, further complicating the disposal problem. With each succeeding decade, Mexico faces greater and more complex challenges in managing its solid waste.

Garbage recycling at Oaxaca City dump

Garbage recycling at Oaxaca City dump. Photo: Conrad Fox, World Vision Report

In terms of weight, the vast majority of solid waste is produced by the agricultural sector. Fortunately most of this waste in readily biodegradable and is produced in areas of relatively low population density. However, agricultural wastes in the form of fertilizers and pesticides which are carried into steams and rivers have significant impacts on water quality. Animal wastes from concentrated feed lot operations are another major concern particularly because they are often located relatively close to densely populated areas.

Municipal solid waste includes waste from most commercial establishments and many small industrial operations. Mexico’s urban waste exceeds 36 million tons a year, three times the equivalent figure for Canada. Many municipalities in Mexico have initiated recycling programs, primarily focused on aluminum, glass, certain plastics and paper. However, in 2008 only 3.3% of Mexico’s total urban waste was recycled. Waste from larger towns and cities, about half of the total, is deposited in properly operated sanitary landfills. Waste from smaller communities often ends up in dumps, two thirds of which are uncontrolled.

The management (treatment or recycling) of hazardous wastes has improved greatly in recent years, particularly in the states of Nuevo León, Tamaulipas, Mexico, Tabasco and the Federal District. About half of all hazardous waste originates either in the state of Chihuahua (31% of the total) or in Mexico City (17%).

See also:

This is an excerpt from chapter 30 of Geo-Mexico: the geography and dynamics of modern Mexico. Buy your copy today, and learn more about Mexico’s fascinating geography.

Air quality improving in Mexico City but not in Monterrey

 Mexico's geography in the Press, Other  Comments Off on Air quality improving in Mexico City but not in Monterrey
Aug 102010

A recent short piece in The Economist, “A breath of fresh air” (31 July 2010) echoes Geo-Mexico’s contention that air quality has been improving in Mexico City in recent years, but declining in other large cities, especially Monterrey.

The improving air quality in Mexico City is attributed to:

  • relocation of heavy industry away from the city
  • closure of the Azcapotzalco oil refinery (1991); part of this area is now a public park
  • vehicle emissions standards, and enforcement
  • “Día sin coche” (Day without a car) policy for all but the newest vehicles
  • improvements to public transport, such as introducing Metrobus; starting in 2011, taxi owners have incentives to use hybrid or electric vehicles
  • on-going, effective monitoring of air quality since the mid 1980s
The IMECA scale for urban air quality

The IMECA scale for urban air quality

Air quality still exceeds environmental norms in Mexico City many days each year, but far fewer than during the late 1980s and early 1990s when air pollution was at its peak. Even low-level ozone measurements are showing improvement. Ironically, ozone in the lower atmosphere rose immediately after the introduction of a new unleaded gasoline, designed to  ensure that the major source of brain-damaging lead pollution was removed. The new gasoline, it emerged, simply traded one serious pollutant for another.

Latest pollution values for Mexico City.

Mexico’s other big cities still face enormous challenges with regards to air pollution. Monterrey’s air regularly has very high concentrations of microparticulates (PM10); the levels now exceed Mexico City’s peak readings from twenty years ago.  The air in Guadalajara is improving, but not as rapidly as in Mexico City.

Geo-Mexico: the geography and dynamics of modern Mexico examines the trends in air quality (ozone, microparticulates and carbon monoxide) for Mexico’s three largest cities and also asks whether the air pollution from maquiladora plants in Ciudad Juárez raises public health issues.

Ask your library to buy a copy of this handy reference guide to all aspects of Mexico’s geography today! Better yet, order your own copy…

Previous post on this topic: Mexico City air quality continues to improve

Is the BP Deepwater Horizon accident the biggest Gulf of Mexico oil spill in history?

 Mexico's geography in the Press  Comments Off on Is the BP Deepwater Horizon accident the biggest Gulf of Mexico oil spill in history?
Jun 042010

Judging from the recent coverage in the US and world media, most people would immediately respond “Yes!”, citing the current BP spill resulting from the April 20 explosion of the Deepwater Horizon offshore rig.

Ixtoc-1 blow out

However, at present this would not be the correct answer.  The largest oil spill in the Gulf of Mexico followed the June 3, 1979 blowout from the PEMEX Ixtoc I exploratory well in the southern part of the Gulf of Mexico 100 kilometers from the Campeche Coast. Though the well was in only 160 feet of water, the leak was very difficult to plug.  The flow started at an estimated 30,000 barrels a day (b/d); but was reduced in July by pumping mud into the well.  In August PEMEX pushed steel, iron and lead balls into the well to further reduce the flow.  Though PEMEX drilled two relief wells to reduce the pressure, the leak continued for 295 days until March 23, 1980.  An estimated total of 140 million gallons oil escaped making the Ixtoc I the largest oceanic accidental oil spill in history.

The next largest accidental oceanic spill was that same year when in July, 1979 the two tankers, the Atlantic Empress and the Aegean Capitan, collided off Trinidad and spilled about 90 million gallons.  The largest oil spill ever was during the Gulf War Gulf when the Iraqi Army intentionally sabotaged the oil fields in 1991 spilling about 525 million gallons.  The second largest was the Lakeview Gusher which occurred on land near Bakersfield, California in 1909 and spilled an estimated 370 million gallons.

BP oil spill approaches the US coast

The current BP leak south of Louisiana spilled an estimated 19 to 39 million gallons during its first six weeks.  At this rate, it could surpass the Ixtoc I spill between by September or October.  Everyone hopes that the leak is stopped long before then…

Update (16 July 2010). BP has capped the well, and no more oil is leaking into the ocean. The total volume of oil that has already spilled from the BP well is estimated at between 90 and 180 million gallons, comparable to, and possibly even exceeding, the Ixtoc I spill.

Update (16 August 2010). A team of US scientists now estimates that BP’s Macondo oil well, which exploded on 20  April 2010 spewed 170 million gallons of crude into the Gulf of Mexico during the 87 days before 15 July, when it was  finally capped. A further 34 million gallons of oil were captured by BP during efforts to cap the well. This makes the BP disaster the world’s largest accidental offshore oil spill ever.

More details? Wikipedia’s extensive account of the Deepwater Horizon oil spill.

Reducing pollution from the making of corn tortillas

 Mexico's geography in the Press  Comments Off on Reducing pollution from the making of corn tortillas
Mar 202010

The traditional way of turning corn (maize) into tortillas pollutes large volumes of water and uses copious amounts of energy. Researchers at the biotechnology department of the Autonomous Metropolitan University of Mexico (UAM) are developing a greatly improved “greener” way of  making tortillas.

Tortilla-making. Photo: krebsmaus07 (Flickr)

Tortillas cost less than a dollar a kilo in Mexico, but price rises for corn (and therefore tortillas) in recent years have caused the consumption of tortillas to fall to about 80 kg per person each year. According to the National Institute of Nutrition, tortillas account for about 45% of all the  calories consumed in Mexico.

Conventional tortilla mills cook the corn in a solution of calcium hydroxide (limewater) and then ground it into a dough. The process, known as nixtamalization, was originally developed in pre-Hispanic times. A ball of dough is then flattened into a round which is cooked on both sides on a hot comal to produce a tortilla. Residue from the nixtamalization proces contains starches, cellulose and calcium and is discarded into local drains.

About 54% of all the tortillas consumed in the country are made this way. The remainder come from a ground corn-flour mix to which water must be added to form a dough, marketed by giant commercial producers such as Maseca and Minsa.

Processing a single kilogram of corn for tortillas the conventional way requires two liters of water. There are 20,000 corn mills in Mexico; each one can pollute more than 1,000 liters of water every day. The UAM researchers were able to reduce pollution by conventional mills by 80% simply by introducing a more efficient filtering system for the cooked mass, allowing more dough to be extracted.

The researchers have now turned their attention to energy usage. Using solar energy to help heat the water should reduce the amount of natural gas required by as much as 40%. This could save mills a considerable amount of money. Each mid-sized mill (supplying dough to an average of 10 tortilla factories) spends about 2,300 dollars a month on energy.

Mar 172010

Geo-Mexico looks in some detail at air quality issues in several Mexican cities, focusing on trends in carbon monoxide, ozone and microparticulates (PM10) from 1995-2008. Among other things, it concludes that,

“As a result of aggressive government efforts, the quality of air in Mexico City has improved significantly. Since 1990 the number of hours that air pollution exceeded the city’s quality standard has declined by about two-thirds. Ozone continues to be a problem as do minute particulates under 10 microns (PM10), both of which can have serious health consequences.”

Mexico City air quality in 1980. Credit: Tony Burton

In the two years since 2008, the trend towards improvement of the air quality in Mexico City has continued according to this article which has appeared in numerous newspapers including the online version of The Independent, a UK daily.

That is very good news indeed. Hopefully air quality in all Mexico’s major cities will improve over the coming decade. When last we looked, Monterrey’s air pollution statistics were still headed in the wrong direction.