Bioremediation efforts at Pemex sites in Mexico
Crédito: Courtesy of Pemex
Biological Remedy for Sickened Soil
Por Emilio Godoy
Biological remediation costs
80 to 150 dollars per cubic meter of soil in Mexico,
where such methods are increasingly studied and
applied to clean up contaminated land.
MEXICO CITY, Aug 24 (Tierramérica).- Mexico is beginning to fight the hefty
environmental debts left by the oil industry,
applying biological techniques to break down
alcohols, solvents, glycerines, gasoline, benzene
and acetone, turning them into carbon dioxide and
Known as bioremediation, it involves a process in
which bacteria or mold "degrade hazardous
chemicals into less toxic or nontoxic substances,"
according to the U.S. Environmental Protection
Agency. The chemicals are food to certain
In 1933, El Águila fuel refinery began operating
its 18 de Marzo plant in Azcapotzalco, northwest
of Mexico City, and was nationalized in 1938 by
President Lázaro Cárdenas (1934-1940) along with
the rest of the petroleum industry.
Since 1976, the company processed 105,000 barrels
of oil per day, and reached a total of 14
refineries, three petrochemical units, 218 storage
tanks and loading and distribution terminals.
The government ordered its closing in March 1991
because it was located in an urban area. What
remains is a fuel storage and distribution
terminal, which still needs to be razed.
The federal government decided to turn the former
industrial site, property of the government-run
Petróleos Mexicanos (Pemex), into the Bicentennial
Ecological Park, covering 55 hectares. It is to be
inaugurated in 2010 as part of the celebrations of
200 years of Mexico's Independence from Spain.
But the first step is to eliminate the residues
inherited from the oil operations, contamination
which has gradually diminished on its own over
time. One of the techniques used to speed up the
process is biological remediation, using a variety
One is to dig out portions of the contaminated
soil and then treat it with microorganisms.
Another is to aerate sections to stimulate
biological activity and, if needed, add nutrients
like nitrogen, phosphorous or potassium.
"The increase in petroleum and natural gas
activity brings with it a great deal of waste,
from drilling the wells and from spills of the
fuel itself, which is why soil treatment has
intensified," researcher Patricio Rivera told
Tierramérica. He works at the public Autonomous
University of Tamaulipas, in the eastern state of
the same name, where the Madero refinery is
Rivera works on a bioremediation project around
former well drilling operations in the natural gas
zone of the Burgos oil fields. The work centers on
eliminating mixtures of petroleum-based substances
in the soil using native bacteria. The research is
slated to conclude in December.
Although these techniques are being applied in
many places around the world, local studies are
needed in order to find the most appropriate
native microorganisms. In Mexico, scientists have
identified at least 22 native bacteria and 26
native molds that would be effective in this type
of clean-up effort.
"The biodiversity we have gives us great
potential. We are still only working with a small
number of microorganisms; more research is
needed," said expert Katiushka Arévalo, of the
public Autonomous University of Nuevo León, in the
eastern state of the same name, where the
Cadereyta refinery operates.
The growing popularity of this approach lies in
its simplicity, effectiveness, environmental
sustainability and relatively low price, which
runs 80 to 150 dollars per cubic meter of soil -
cheaper than other decontamination methods, like
incineration or washing.
In Mexico there are vast areas contaminated with
petroleum derivatives, which tend to accumulate in
marine ecosystems and in soils.
More than half of the country's oil drilling
industry is situated in the southeastern states of
Tabasco and Veracruz, where spills are frequent.
In 2003, the Environmental Projects and Services
Group was created, made up of researchers from the
Autonomous Metropolitan University, to provide
remediation services, especially with
microorganisms, in areas contaminated by fossil
So far, the entity has signed more than 200
contracts with Pemex to clean up contaminated
Furthermore, there are at least 15 companies whose
services include bioremediation. This technique is
also used in other Latin American countries, such
as Cuba and Argentina.
The decontamination of the former Azcapotzalco
refinery, which will conclude in December at a
cost of about 80 million dollars, is entrusted to
seven university institutions from across Mexico.
Observers believe bioremediation will keep
expanding over the next few years as successful
techniques continue to be developed.
In February, Mexico hosted the 14th Symposium of
the Latin American Biological Sciences Network,
which emerged in 1975 to promote these disciplines
throughout the region. The central theme of this
year's meet was bioremediation.
"The country faces a serious situation. In some
places there are oil spills in mangroves and in
bodies of water. That is why these methods are so
necessary," said Rivera.
"The application of bioremediation is going to
increase; it is a science that is increasingly
important. Today there is more knowledge and I
predict a long future for it," said Arévalo, who
works with molds that produce enzymes for
eliminating dyes or derivatives of aromatic
In October 2006, the Secretariat (ministry) of
Environment and Natural Resources and the Mexican
Institute of Petroleum and the National Institute
of Ecology published a technical manual for soil
analysis to be applied in remediation of