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Nanoremediation: Information for Decision Makers from NanoRem

Thematic Page 7: Risk Benefit Appraisal

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:
 

FAQs




THEMATIC PAGES
 

 

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Taking Nanotechnological Remediation Processes from Lab Scale to End User Applications for the Restoration of a Clean Environment.
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