Contents
1. Aim
2. Overview
3. Benchmarking against key competing remediation
technologies
4. Additional Resources on the NanoRem Web Site
5. Feedback and Opinion
1 Aim
The aim of this page is to place in context the relative
risks associated with nanoremediation compared to other technologies, in particular
those with the closest treatment niche. More detailed information is available
from the NanoRem Tool Box (http://www.nanorem.eu/toolbox/index.aspx#TB1).
2 Overview
Nanoremediation may offer notable advantages in some
remediation applications for example their relative speed of action and
potential applicability to source term problems. These benefits are site specific and niche
rather than representing some kind of over-arching step change in remediation
capabilities, although this over-arching potential may remain a possibility,
for example treatment of recalcitrant problem compounds such as fuel
oxygenates. The principal constraints to
these opportunities remain perceived treatment costs and availability of cost
and performance data from “real” applications, as opposed to pilot deployments
in the field. Nonetheless, NanoRem has
achieved a major shift in the technical discussion of nanoremediation across
many practitioners in the international contaminated land management market, in
that it is now seen as a viable option, albeit it at the “early adoption” stage,
rather than being seen as an emerging approach of fringe interest. There has always been a minority interest in
the technology, but NanoRem has succeeded in making it worthy of consideration
by the majority of contaminated land remediation service providers.
The perception of risk-benefit balance has also
shifted. Niche benefits are now more
strongly recognised, and some (if not most) of the concerns, for example
relating to environmental risks of nanoremediation deployment, prevalent when
the project was proposed and initiated have been addressed. Indeed, these now appear overstated. However, it appears to remain the case that
in some jurisdictions the use of NPs remains less attractive owing to
regulatory concerns and/or a lack of awareness, meaning that regulators may
demand additional verification measures compared with technologies with which
they have a greater level of comfort.
NanoRem has demonstrated and improved the market readiness
of a number of NPs and provides a tool box containing application guidance,
safety datasheets and tools for them, making available field scale deployment
test outcomes in a series of independently peer reviewed technical bulletins.
NanoRem also shown that nanoremediation can be deployed in a targeted way and
has substantive evidence that the ecological risks of NP deployment in the
subsurface have been greatly overstated. Indeed, the NanoRem project has
developed a range of supporting deployment risk assessment and sustainability
assessment tools to ensure that nanoremediation is safe, effective and
sustainable, with a level of scrutiny that far exceeds that which has been
required for many of the subsurface amendments required to initiate competitor
technologies such as in situ bioremediation or in situ chemical reduction using
conventional reducing agents such as micro scale iron or sodium dithionite.
Based on NanoRem’s work the main selling points for
nanoremediation are:
·
Increasing regulatory confidence, facilitated in
large part by NanoRem
·
Broad source and pathway management applications
·
Rapid effectiveness compared with in situ biological remediation (ISBR)
and conventional approaches to in situ
chemical reduction (ISCR)
·
Resilient to conditions inhibitory to ISBR and
can facilitate ISBR / Synergistic with ISBR and ISCR
·
Portable and more rapidly deployed compared to
options like pump and treat
·
Reduced risk of taint of sensitive aquifers
·
Ecological and aquifer impacts now relatively
well understood compared to ISCR and ISBR
·
Rapid initiation of treatment by nZVI can also
support faster initiation of ISBR.
However, several substantial market barriers remain:
productising NPs and their deployment so that it is no longer so bespoke, the
perceived cost of nanoremediation and increasing the number of well documented
commercial deployments of nanoremediation.
These represent the major gaps remaining after the conclusion of
NanoRem, which, to some extent remain a “work in progress”.
Many variants of nanoremediation are viable remediation
options for niche applications in many European jurisdictions. However, market
inertia remains owing to a lack of cost and performance reporting or real,
practical deployments of nanoremediation at scale. Market inertia also persists because of
concern over costs and concern over risks of an additional higher level of
regulatory scrutiny compared with more regularly used alternatives. Hence, for
ongoing development the following areas of effort are suggested.
·
Continuing productisation of nanoremediation
technologies to make them more easily deployable and with less effort.
·
Development of nanoremediation alternatives with
a more competitive pricing (for example via integrated approaches such as
linkage to use of micro-scale iron and/or ISBR).
·
Providing information that is packaged in a way
that it can readily support nanoremediation deployment, building on the
information already consolidated in the NanoRem toolbox.
In the medium term there continues to be an interest in the
possibility of nanoremediation addressing recalcitrant contaminants or emerging
contaminants, or contaminants seen both as emerging and recalcitrant. There is a large body of research evidence
related to nanoremediation for its current niche applications (chlorinated
solvents and heavy metals). Future
research and innovation could usefully address nanoremediation for dealing with
emerging / recalcitrant contaminants.
More detailed information is available from DL9.2 “Final Exploitation Strategy, Risk
Benefit Analysis and Standardisation Status” which can be downloaded from the
NanoRem Tool Box (http://www.nanorem.eu/toolbox/project-deliverables.aspx).
3 Benchmarking against key competing
remediation technologies
The main competing in
situ remediation alternatives to nanoremediation for these contaminants are
in situ bioremediation (ISBR) and
conventional forms of in situ chemical reduction (ISCR) using reducing
agents such as micro-ZVI sodium dithionite or calcium polysulphide. The table below
benchmarks
costs, risks and benefits of nanoremediation against ISBR and ISCR
|
|
|
Nanoremediation
|
Conventional ISCR
|
ISBR
|
|
Risks
|
Human health
|
Some NPs are hazardous, some are air stable and safer
to handle.
No exposure once successfully deployed.
|
Some reagents, such as dithionate, are potentially
hazardous.
No exposure once successfully deployed.
|
Materials are safe to handle.
No exposure once successfully deployed.
|
|
Aquifer
ecology
|
Injections are typically in highly disturbed
environments. No NP specific ecotoxicity found by NanoRem. Ultimate fate is
as iron oxides which are plentiful in soils.
|
Injections are typically in highly disturbed
environments. Ecological impacts unstudied, but assumed minimal.
|
Injections are typically in highly disturbed environments.
Ecological impacts unstudied, but in the long terms assumed minimal.
|
|
Water
|
Injected materials have limited lifetimes and limited
travel distance, and are not associated with taint of the subsurface
|
Lifetimes and travel distance of injected dithionite
has not been widely studied, may be extensive. The travel distance of mZVI is
essentially zero.
High levels of sulphate and low pH remaining after
dithionate or polysulphide reduction
|
Injected substrates to stimulate bioremediation are
soluble or release soluble substrates possibly causing taint for water
supplies.
|
|
Supporting
measures
|
Pre-deployment risk assessment available and published.
|
No pre-deployment risk assessment tool.
|
No pre-deployment risk assessment tool.
|
|
Benefits
|
Breadth of solutions
|
Wide range of treatable contaminants.
Source term and pathway management applications.
Suitable for situations inhibitory to microbial
dehalorespiration processes.
|
Wide range of treatable contaminants.
Tendency to pathway management applications.
Suitable for situations inhibitory to microbial
dehalorespiration processes
|
More restricted range of treatable contaminants.
Potential for stall (e.g. TCE --> DCE)
Tendency to pathway management applications.
May be prevented by toxic or other inhibitory conditions
|
|
Speed and
completeness of action and synergies
|
Rapid treatment effects owing to nanoscale processes.
Moderate migration in the subsurface.
Tendency to complete degradation of contaminants.
Synergistic with ISBR and ISCR.
|
Slower treatment effects.
Microscale ZVI does not readily move in the subsurface.
Tendency to complete degradation of contaminants.
Synergistic with ISBR and nanoremediation
|
Slower treatment effects.
Soluble substrates migrate rapidly in the subsurface
Tendency to stall for some problems (such as DCE stall).
Synergistic with nanoremediation and ISCR.
|
|
Ease of
deployment
|
Portable systems (not requiring fixed infrastructure).
Some systems require specialised deployment
interventions.
NanoRem is addressing the issue that deployment knowhow
is not widespread.
|
Portable systems (not requiring fixed infrastructure).
Widespread know-how and systems.
|
Portable systems (not requiring fixed infrastructure).
Widespread know-how and systems.
|
|
Track record
|
Limited track record, relatively few suppliers.
|
Well established technology, many vendors, moderate
track record.
|
Well established technology, many vendors, substantial
track record.
|
|
Costs
|
Cost
estimating
|
Bespoke costings needed for each deployment option
appraisal.
|
Many consultants have a good knowledge of relative
treatment costs.
|
Many consultants have a good knowledge of relative
treatment costs.
|
|
Cost levels
|
See DL9.2
|
More detailed information is available from DL9.2 “Final Exploitation Strategy, Risk
Benefit Analysis and Standardisation Status” which can be downloaded from the
NanoRem Tool Box (http://www.nanorem.eu/toolbox/project-deliverables.aspx).
4 Additional Resources on the NanoRem Web Site
Comprehensive resources are available from the NanoRem Tool
Box, shown below (http://www.nanorem.eu/toolbox/index.aspx):
Additional summary information is also available on the following online pages:
