Catalan scientists have shown that using mud from waste water treatment
plants as a partial alternative fuel can enable cement factories to reduce
their CO2 emissions and comply with the Kyoto Protocol, as well as posing
no risk to human health and being profitable. These are the results of an
environmental impact assessment.
Dependency on oil and coal could be coming to an end. Researchers from
the Rovira i Virgili University (URV) have analysed the environmental and
human health impacts of an alternative fuel that solves various problems
simultaneously. This is the solid waste from the water treatment plants of
large cities.
The scientists have carried out the first study into this method at a
cement plant in Vallcarca (Catalonia), which has been producing cement for
more than 100 years, and they confirm in the latest issue of the journal
Environmental Science and Pollution Research that it is "the best option
for getting rid of mud that would have had to be dumped elsewhere, while
also powering the plant".
"As this mud is already waste, burning it does not enter into the
atmospheric CO2 emissions assigned to each country under the Kyoto
Protocol", José Luis Domingo, lead author of the study and director of the
Toxicology and Environmental Health Laboratory at the URV, tells SINC.
This would enable plants producing cement, one of the most
contaminating industries in terms of CO2 as well as emissions of dioxins,
furans and heavy metals, to consume energy in a more
environmentally-friendly way. Up to 20% of the fossil fuel energy used at
the Catalan plant has now been substituted for the fuel from waste water
treatment plant mud.
From an economic point of view, the scientists will not say that cement
plants could increase their profits by using this method, but "they will
not have to pay anything to exceed their agreed emissions", the researcher
points out. The economic benefits of this system also depend on the price
of fuel.
One of the most important issues for the URV scientists is the
reduction in environmental impact, and consequently the health risks for
people living near the plants. The experiment with the mud has led to a
140,000 tonne reduction in CO2 emissions between 2003 and 2006, and will
have limited the potential deaths from exposure to chemical pollutants. In
addition, the study shows that using this green fuel would reduce the
cancer rate by 4.56 per million inhabitants.
The researchers say it is essential to carry out separate studies for
each plant because "we still don't know whether this will be positive for
the whole cement industry", according to Domingo. However, if the
conditions are right, using mud from waste water treatment plants in
cement factories is "a very good solution", he concludes.
SOURCE: FECYT - Spanish Foundation for Science and Technology