Environmental Engineering Reference
In-Depth Information
3
Use of Nanomaterials in Water Remediation
by a Subc
ritical Water Process
Guy Baret
42TEK S.L., Voiron, France
CONTENTS
3.1 Introduction .......................................................................................................................... 55
3.2 Water Remediation in Supercritical Conditions .............................................................. 56
3.2.1 Supercritical State .................................................................................................... 56
3.2.2 Supercritical Water and Organic Compounds .................................................... 57
3.2.3 Sequestration of Toxic Elements in Nanoparticles of Complex Oxides ........... 57
3.2.4 Process ....................................................................................................................... 58
3.2.5 Energetic Aspects ..................................................................................................... 60
3.3 Water Remediation in Subcritical Conditions ................................................................. 61
3.3.1 Use of a Nanocatalyst .............................................................................................. 61
3.4 Conclusion ............................................................................................................................ 61
3.1 Introduction
In the ield of water remediation, most of the processes focus on the wastewater from
houses and industry. These two origins are the most important sources of pollution of
water owing to the high quantity of water used in private houses and in the industry.
Speciic processes have been developed to treat thousands of cubic meters of water per day
at a very low cost by using iltration, settling, and bacterial treatment. Although there are
exceptions, most of the polar solvents, apolar organic solvents (light solvents or heavy oils),
and organic compounds are rather eficiently removed by these processes.
However, some very stable molecules cannot be degraded by these particular treat-
ments, even the bacterial treatment. This is mainly the case for complex organic mol-
ecules. This is, for instance, the case of molecules used in medical treatments, such as
animal or human proteins, hormones, blood residues, and some drugs. Among these
products, hormones and anticancer drugs have been increasing very quickly for 10 or
20 years without particular attention to the effect on the environment. These classes of
molecules go through the water remediation plants and end up in the rivers and, inally,
the ocean.
In the rivers, downstream to the wastewater plants where the concentration of such
molecules can be high, these molecules are highly suspected to interact with the living
bodies, modifying natural equilibria such as the sex distribution of aquatic species, par-
ticularly ish. The danger comes from the activity of such molecules on the operation of
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