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reportEnvironment
6.1 Executive summary
Maintaining and restoring the quality of air, water and soil is one of the great challenges of our time. Many countries face serious environmental problems such as availability of drinking water, treatment of waste and wastewater, air pollution, contamination of soil and groundwater etc. The scarcity of water, both in terms of quantity as well as quality poses a significant threat to the well-being of people – especially in developing countries. There is thus considerable commercial potential in environmental technologies. According to Boehm (Boehm, 2006) the projected world market for applications of environmental nanotechnologies by 2010 is approximately $6 billion. Claire (Claire in (Rickerby and Morrison, 2007)) even expects the market for soil and groundwater remediation to grow to around €23.6 billion worldwide with the UK and Japan as expanding near-term markets and central and eastern Europe as important mid-term markets.
Conventional remediation technologies have so far shown only limited effectiveness in reducing the levels of pollutants - especially in soil and water (Rickerby and Morrison, 2007). Nanomaterials will be able to perform significantly more effectively than larger particles because of the much greater surface area (Rickerby and Morrison, 2007). Most effective will probably be a combination of more than one (nano)technology in a hybrid system and membrane technologies are expected to play a role in this (Rickerby and Morrison, 2007).
So far only few industrial companies consider environmental technologies as a core business, even though there is obvious potential for market applications (e.g. drinking water purification) (Morrison, 2006). A large hurdle are the initial costs for the material, pilot run and facilities (Morrison, 2006). Morrison (Morrison, 2006) suggests to link environmental issues with public health as a driver for creating markets.
Various applications have been successfully demonstrated at the laboratory scale but most of them still require verification of efficacy and safety in the field and are thus still far from market. Further research is also needed to assess the environmental impact of the nanoparticles released. There are serious concerns about the release of free nanoparticles in the environment also for remediation purposes. One way of minimizing the probability of exposure is to encapsulate the nanomaterial within an inert barrier (e.g. silicon can be used to coat quantum dots) or – as employed by the CONCORDE project – to immobilize nanostructure onto a surface (Morrison, 2006). Employing such methods can maintain the activity and functionality of the nanomaterial while minimizing the probability of nanoparticle dispersion.
Methods for environmental remediation can be divided into adsorptive vs reactive and into in situ vs. ex situ techniques, see Table 1 (Tratnyek and Johnson, 2006). Ex situ remediation is often very costly whereas in situ remediation cost less but the delivery of the treatment to the contaminated site is challenging. Further more, the NP released will stay in the environment and have thus to be nontoxic. For in situ treatment it is necessary to create either an in situ reactive zone with relatively immobile NP or a reactive NP plume that migrate to contaminated zones (NP must be mobile).
Table 1: Classification of remediation methods applying nanoparticles into in-situ and ex-situ methods and adsorptive and reactive methods.
|
|
In situ |
Ex situ |
|
Adsorptive |
Sequestration by addition of binding agents
|
Treatment of wash solution ex-situ with adsorbents |
|
Reactive |
Zero valent iron injection/ addition |
Treatment of wash solution ex-situ with TiO2 photoxidation |
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