Rehabilitation and Remediation of POPs

Transcription

1 and of POPs

2 Module 3 and Overview of the course This module will cover various remediation and rehabilitation strategies. Contents Strategies (and part of ) Summary technologies Summary Learning outcomes Understand the main strategies to deal with POPs contamination. Understand the differences between rehabilitation and remediation n and where these may be appropriate. Pre-requisites requisites Introduction to POPs Chapter 1 of the manual or e-learning e Module 1 Risk Assessment Chapter 5 of the manual or e-learning e Module 2 Follow-on on Course None Download the course as a pdf Related information Chapter 6 of the Manual Approximate time for this module 45 mins 1 hour

3 Introduction POPs problems are addressed using and procedures. POPs are Persistent Organic Pollutants which are long lasting in the environment and can be harmful to health. For more details click here. POPs are Persistent Organic Pollutants which are long lasting in the environment and can be harmful to health. For more details click here. cleans-up a contaminated site. For more details click here.

4 Introduction The purpose of a rehabilitation strategy is to reduce the exposure of an environmental receptor to POPs to an acceptable level. The purpose of a remediation strategy is to clean-up a site that has been contaminated, to levels determined to be health protective for its intended use. of soil and waters is likely to form at least part of the strategies to deal with most discrete POPs problems. Example of remediation: Soil washing

5 Introduction - Strategies The rehabilitation of POPs fall into 3 main categories. breaking the linkage between source and receptor mitigating the effects of POPs re-engineering engineering the impact at the point of use or treatment to remove/ reduce the concentrations of POPs at the source (remediation). Each potential strategy will have its place and preference within n the range of possible rehabilitation options. This should be based upon a detailed or generic risk assessment or a hazard assessment.

6 Introduction - Strategies of POPs contaminated soil or water generally involves Containment Oxidation or Reduction Extraction can be much more expensive than other rehabilitation methods, but is a better long term solution. This image shows in-situ solidification, containing the chemical within the soil.

7 Strategies The exposure pathways identified previously fall into 3 distinct rehabilitation groups: General population Via food chain or water resource Not monitored No mitigation General population Exposure route known Can be monitored / mitigated Workers and operatives Should have assessment and mitigation to risks as part of Health and Safety.

8 Strategies The main problematic area is in dealing with exposure where there is: No monitoring of the POPs within the food-chain, No appreciation of the potential risks of the population at risk,, or mitigation of the risks of exposure. The traditional Source reduction approach to mitigating the exposure to POPs has limited benefit to the population. A point of exposure methodology can be employed and can be many times less expensive. Alternatively, exposure levels can be reduced by manipulation of the pathway in the Source-Pathway Pathway-Receptor scenario. strategies can be categorised in order of their invasiveness upon the population.

9 Strategies Group A Group B Group C

10 Least Most Invasive Strategies (& some of B) Monitor soil, animals, fish, plants and water resources for POPs and check against set standards or guideline values available. Rehabilitate food and water supply by filtering, mixing and blending to lessen the impact of POPs. Rehabilitate soil and water resources by filtering, mixing and blending to dilute the concentrations of POPs. Remediate soil and water resources found to be contaminated with POPs. Monitoring of water resource

11 Strategies (& some of B) Other strategies for this group limit exposure to POPs by limiting some natural resources available to the population. These strategies can generally only be seen as temporary solutions to acute problems. If circumstances change these strategies are unlikely to remain in place.

12 Strategies (& some of B) Exclude and replace soil and water resources found to be unacceptably contaminated with POPs. Exclude/ limit and replace certain crops, livestock or fish from the agricultural resources. Recommend maximum daily intake of impacted food and water supply. Exclude certain foods and animal products/ water supply from the population and replace with similar alternatives. Control infants breast milk from nursing mothers and replace with formula milk.

13 Strategies Group A Group B Group C

14 Strategies This is very widespread at a low level, but less common at a level of sufficient quantity to represent a direct health risk. The public is generally alert to the production of these POPs, especially from incineration processes. strategies are again categorised in order of their invasiveness upon the population and the requirements of the individual to undertake action.

15 Least Most Invasive Strategies Mitigation of POPs released from the source. Monitor soil and water resources against standards. of soil and water resources, contaminated with POPs downstream of the source. Exclude access to areas of contaminated soil or water bodies. Targeted health monitoring of the population affected by POPs and undertake specific measures to counteract these effects. Restrict the movement of the population in respect of exposure to POPs in the environment.

16 Strategies Group A Group B Group C

17 Strategies Workers and operatives that are likely to be exposed to POPs as part of their normal activities and covers workers employed in: Incinerator and industrial process industries Crematorium operators Power workers Waste site operatives Plant decommissioning personnel Soil and water remediation engineers Operatives of the limited use of DDT to control malaria mosquitoes. Incineration is a source of POPs

18 Strategies As part of Health and Safety Risk Assessment risk associated with exposure to POPs will be assessed and actions taken to mitigate the risks. In general the appropriate actions are to avoid and limit exposure by a change to the work process. Use of Personnel Protective Equipment (PPE) to prevent exposure is the last line of defence.

19 Strategies Most Preferred Typical measures to protect workers from exposure to POPs are listed below, in order of preferred mitigation top to bottom. Substituting less toxic compounds. Eliminate/ reduce the production and release of POPs. Automating production process or shielding the operations. Monitor the exposure of POPs in the workplace. Warn workers and visitors by labelling, training and refuge rooms.

20 Strategies Most Preferred Toxic chemical screening of workers and operatives exposed to POPs. Limit exposure of workers and operatives to exposure by limiting time exposure, the use of specific Personnel Protective Equipment and staff rotations, coupled with regular health check. Exclude workers from exposure to POPs by reassignment of their duties where high levels of exposure have occurred.

21 Strategies Summary The applicability of a rehabilitation strategy is highly dependent on: the nature of the exposure the intensity of exposure time of exposure availability of alternative resources ability to mitigate the exposure and the socio-economic costs of mitigation

22 Strategies Summary How effective a rehabilitation strategy is will often depend on the rigour with which individuals can adhere to a strategy. The choice of an appropriate rehabilitation strategy may be limited by what can be achieved within the target population. Manipulation of the targets at the points of exposure, is increasingly gaining favour.

23 Strategies In the long term rehabilitation strategies would most likely result in either: exclusion of an area of land or water supply whilst natural biological and physical processes slowly break the POPs contaminant down remediation to return the groundmass to a useable resource. Various techniques have been outlined to give an overview of the technologies available.

24 Strategies This section examines a range of remediation technologies that have been comparatively assessed by authoritative sources such as the US EPA. This is a non-exhaustive list of technologies split into three generic groupings: Containment Oxidation or Reduction Extraction

25 Strategies

26 Strategies Seal the POPs contamination within a protective casing to limit or prevent their release. Examples: Soil excavation/sediment dredging with Encapsulation/ Landfilling. Solidification and Stabilisation Soil, sediment and some groundwater. Encapsulating contaminated material in a landfill site.

27 Strategies They are used for: soil and sediment contaminants most pollutant releases into the environment They can treat: large and small volumes low and high grade waste a wide variety of POPs highly toxic and radioactive compounds concentrated sources or dispersed sources Entombment of highly contaminated material.

28 Strategies Encapsulation, Reactive Permeable Barriers and Solidification and Stabilisation: large scale treatments low/medium unit cost low energy/low CO2 release Suite most geographic situations. relatively low start-up costs are therefore sustainable Entombment and Vitrification high cost could result in sterilization of the land Statements 1 to 5, outline the salient features relating to POPs.

29 Strategies

30 Strategies Designed to either destroy the POPs by: converting them to another chemical in a de-halogenations or de- chlorination process; or oxidising the POPs at very high temperatures (incineration), to convert the POP compounds to primarily CO2, methane and water, with limited residues waste streams. Examples: Monitored Natural Attenuation In- situ for soil, sediment and water. Ex-situ Anaerobic Bioremediation and Bio-Reactors Soil and sediment. Monitored Natural Attenuation

31 Strategies These technologies range from: very passive low cost low energy/ low CO2 treatment of large volumes of low grade impacted soils and silts with little impact on the wider environment to aggressive and destructive technologies small volumes of very high grade waste high energy incinerator with a very large carbon footprint per unit of contaminated media treated. Enhanced Bioremediation by addition of selected materials.

32 Strategies The extent of treatment is often dependant on statutory limits set for the concentrations of contaminants, rather than any risk based site specific remedial targets. Centralised waste processing facilities are both expensive and energy hungry with a large carbon footprint but, once built, afford economies of scale in dealing with contaminated media. Statements 6 to 19,, detail the various processes currently available.

33 Strategies

34 Strategies This group covers extraction technologies, designed to recover the POPs from the contaminated matrix by either a concentration process or stripping process. The concentrated recovered POPs contaminated media itself requires treatment by a or Y technology. High temperature oxidation in an incinerator.

35 Strategies Examples: Ex-situ Soil Washing Soil and sediments. In-situ Soil Flushing Soil and groundwater. Water and Waste Water Treatment Ex-situ treatment to remove contaminants from surface water and groundwater streams. In-situ soil washing to dissolve organic compounds.

36 Strategies These are often used in conjunction with other processes. The contaminants are concentrated or otherwise liberated, so they can be recovered and are encapsulated, decomposed or oxidized. Achieving very low levels of residual contamination can lead to protracted and often costly remediation process. A more realistic risk based approach increases cost- effectiveness.

37 Strategies These technologies are designed to enable the risks to be managed and controlled, and to achievable levels at a reasonable cost in terms of money, energy, resources and timescale. statements 20 to 26 detail the various processes currently available.

38 Strategies Summary A technology is available that is suitable for almost any POP problem that will present itself. The objective must be to protect human health and the environment. A balanced strategy will have the best benefits to the wider community and overall environmental protection.

39 Glossary de-halogenations removing a halogen atom from the molecule de-chlorination removing a chlorine atom from the molecule invasiveness