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Organochlorines Bulletin 2

December 1995, Ref. INFO 3

Bulletin 1 (July 1995) introduced the Organochlorines Programme with a statement of draft objectives and expected outcomes. This, Bulletin 2, provides an update on:

  • The Organochlorines Consultative Group;
  • Organochlorines in the NZ Environment;
  • National Environmental Standards;
  • Organochlorine Destruction Technologies.

In the past decade, organochlorine contaminants and wastes have generated a high level of awareness, both nationally and internationally, within industry, Governments and communities. New Zealand’s response to these concerns is to determine the status of these contaminants in our country and to set procedures to address them.

The programme focuses on “dioxins” (PCDDs, polychlorinated dibenzo-p-dioxins, and PCDFs, polychlorinated dibenzofurans); PCBs; and the organochlorine pesticides which were widely used in the past within agriculture and industry e.g. DDT, aldrin, dieldrin, chlordane, and pentachlorophenol (PCP).

Organochlorines Consultative Group

The Ministry for the Environment (MFE) has convened an Organochlorines Consultative Group as a source of expert advice and to facilitate effective communication and consultation during the programme. The first meeting of the group was held in October 1995. The membership of the group is listed below:

  • Howard Ellis – Ministry for the Environment (chair)
  • Dr Simon Buckland – Ministry for the Environment
  • Jim Waters – Ministry of Health
  • Dr Bill Jolly – MAF Regulatory Authority
  • Paul Dell – Local Authorities
  • Mark de Bazin – Timber Industry
  • Peter Sligh – Pulp and Paper Industry
  • Dr Jim Barnett – Agricultural sector
  • Bob Moffat – AGCARM, NZCIC
  • Vacant – Incineration Industry [to be appointed]
  • Norm Thom – CAE, IPENZ, NZIC, WMINZ
  • John Hohapata – adviser on iwi
  • Jocelyn Keith – National Council of Women
  • Simon Towle – ECO
  • Michael Szabo – ECO
  • Vacant – Technical specialists as required

The Role of the Consultative Group is to:

  • advise the MFE (which reports to the Minister for the Environment);
  • represent key stakeholders and a diversity of community interests, and contribute individual expertise;
  • advise on programme objectives, directions, priorities, management and progress;
  • guide task-specific working parties;
  • facilitate and coordinate information gathering and dissemination;
  • identify additional resource requirements.

The Ministry for the Environment has undertaken to:

  • work with the Consultative Group to consult effectively with interested parties;
  • take account of current policy and environmental, social and economic factors;
  • widely disseminate key information using non technical language;
  • inform and facilitate an understanding of the issues among interested parties;
  • provide suitable opportunities for, allow time for and take account of, comments and submissions.

The Consultative Group is currently reviewing:

  • the objectives of the programme;
  • the study design for the assessment of the NZ environment;
  • a protocol for destruction technology trials;
  • a communications strategy for the programme.

Assessment of Organochlorine Contaminant Levels in the New Zealand Environment: Study Design

This study is the first stage of a comprehensive three-year programme to assess the significance of organochlorines in the NZ environment. The study design is currently being peer reviewed by NZ and international experts.

The key objectives of this study are to:

  • Provide data on the level of key organochlorine contaminants within New Zealand ecosystems.
  • Enable the level of contamination of the New Zealand environment to be seen in an international context.
  • Support the development and application of national environmental standards or guidelines for these substances.

The first set of environmental samples are timetabled for collection during January 1996 and will continue at intervals over the next twelve months.

To assess the level of organochlorine contamination within New Zealand ecosystems, the approach being proposed is based on the determination of typical or average environmental contaminant concentrations. In developing this study therefore, consideration was given to the following issues:

  • the need to be consistent with international studies in terms of sample collection and analytical procedures;
  • the environments to be sampled (air, soils, rivers and estuaries) need to be representative of NZ with a broad coverage of the country; they will include relatively pristine places (e.g. national parks) and farmland, as well as city, industrial and urban areas.
  • data from previous studies will be taken into account.

[A description of this study will be the focus of Bulletin 3; further study documentation is available on request from Simon Buckland, MFE.]

National Environmental Standards to be Developed

In implementing the Organochlorines Programme, the Ministry intends to develop a suite of National Environmental Standards (NES) for dioxins:

  • these will be promulgated under s.43 of the RM Act 1991; an explicit process of public consultation will be designed.
  • they will apply nationally;
  • they will be used to determine clean-up criteria for contaminated sites and emission standards for RM Act consents, including consents to operate destruction technologies;
  • criteria will be determined for the protection of ecosystems (based on a national protocol) as well as for the protection of human health (based on exposure scenarios for a range of land uses); findings from the assessment of background levels in the environment will be incorporated;
  • experience gained in the development of Health and Environmental Guidelines for Selected Timber Treatment Chemicals (which included criteria for PCP and interim criteria for dioxins) will be carried forward;
  • criteria and standards established in other countries will be examined for their relevance to New Zealand.

The current Government policy on the toxicology of dioxins will be re-examined in the light of the US EPA dioxin reassessment, and any other international reviews of dioxin toxicity.

Organochlorine Destruction Technologies

Organochlorine wastes requiring treatment or destruction may arise from a variety of sources, including contaminated soils, sediments, building materials, chemical stockpiles and materials from treatment ponds and waste dumps. The chemical stability of the organochlorine substances of concern, a feature which contributes to their persistence in the environment, also makes them difficult to destroy.

Internationally the most widely employed means to destroy organochlorine chemicals and contaminated materials is high temperature incineration (HTI).

However in recent years, public opposition to HTI has increased because of uncertainties over its potential for dioxin emissions. After vigorous local opposition to the proposed use of a cement kiln to destroy stocks of PCBs, New Zealand has exported its major holdings of PCBs for destruction in a dedicated hazardous waste HTI facility overseas, principally in France.

The search for alternative means to safely destroy organochlorine substances, particularly PCBs, has involved considerable research and development worldwide. To help identify destruction technologies appropriate to PCP and dioxin contaminated material, the Ministry for the Environment and the Timber Industry Environmental Council contracted overseas consultants to report on all proven or potential technologies. Only three technologies were identified for solid wastes:

  • High Temperature Incineration (HTI)
  • Base Catalysed Dechlorination (BCD)
  • The EcoLogic process

High Temperature Incineration (HTI) is a collective term applied to a range of proven incineration technologies which achieve high destruction efficiencies. HTI's of possible interest to New Zealand include rotary kilns, “plasmox” (plasma arc heated system), fluidised bed combustion, and controlled air incineration (pyrolysis). A high level of treatment efficiency and reliability can be achieved in modern installations that incorporate appropriate pollution abatement systems. Treatment residues in the form of clinker or slag are normally disposed in a landfill.

However any proposal to use HTI for the disposal of hazardous waste could be expected to focus public interest and concern on the possibility of dioxin formation and emission from such a facility.

Base Catalysed Dechlorination (BCD)

The BCD technology is a recent innovation developed and patented by the US Environmental Protection Agency (US EPA) Risk Reduction Engineering Laboratory. BCD involves a reaction which sequentially strips chlorine atoms from organochlorine molecules and substitutes them with hydrogen atoms derived from an oil. The reaction, which requires the addition of a proprietary catalyst, takes place over several hours and at elevated temperatures to yield a completely dechlorinated organic molecule and common salt. Commercial BCD units are now operating under license in the USA and in Australia.

ADI Services, a BCD licensee in Australia, have developed a variation of the BCD reaction (called the “ADOX” reaction) in which the patented BCD catalyst is replaced by an “accelerator”. In the ADOX reaction the nature of the reaction changes dramatically in that PCP molecules, for example, are decomposed completely to carbon. The reaction, which takes place rapidly, can be applied to much higher concentrations of organochlorines than the conventional BCD process and without the requirement for the addition of oil.

In developing technologies of this type, a significant challenge is to destroy the organochlorine contaminants bound up within soil and other solid materials. One approach is to pretreat the contaminated materials within a thermal desorption unit (TDU). The vapourised contaminants are then condensed and destroyed in the BCD reactor. The Ministry for the Environment, in co-operation with the timber industry corporates, recently contracted the Institute of Environmental Science and Research Ltd (ESR) and ADI Services to undertake treatability trials on a sample of PCP and dioxin contaminated soil. The results to date indicate excellent destruction efficiencies from the combined use of TDU and the ADOX reaction. Further trials are to continue in 1996.

The EcoLogic Process

Another technology has been developed by EcoLogic International Inc (ELI). The technology has been successfully demonstrated to completely degrade PCP, dioxins and other organochlorine substances as well as polycyclic aromatic hydrocarbons (PAHs).

When applied to the treatment of soil, the contaminants must first be vapourised by a thermal reduction mill (TRM). The unit adopted by EcoLogic comprises a ball mill (to achieve a finely divided soil) operating at high temperatures on a molten tin bath. The vapourised organics are swept into the EcoLogic reactor with a stream of gas (mainly hydrogen and steam). Chemical decomposition reactions take place in the reactor at 900 C in a hydrogen atmosphere to yield principally methane, carbon dioxide and hydrogen chloride (recovered as hydrochloric acid).

The technology has been successfully audited by both the US EPA during a trial treatment of dioxin contaminated soil, and also by Environment Canada during the treatment of PCB and PAH contaminated harbour sediments. Environmental Solutions International (ESI) and ELI have recently commissioned the first commercial scale EcoLogic plant at Kwinana, south of Perth. This plant is destroying stockpiles of organochlorine pesticides (predominantly DDT) and PCBs. Independent studies indicate a greater than 99.9999 % destruction removal efficiency.

The success of both the BCD/ADOX and the EcoLogic technologies relies on effective materials handling and an efficient TRM pre-treatment phase.

Other Innovative Technologies

  • UV light is being used in conjunction with hydrogen peroxide to successfully treat PCP and dioxin contaminated groundwater at the Forestry Corporation of New Zealand’s Waipa timber processing plant near Rotorua;
  • A number of other technologies can be applied to contaminants dissolved in water but have yet to be seriously considered for the treatment of organochlorine contaminants in soil. These include: “plascon” (in line plasma arc), high energy electron beam irradiation; gamma irradiation; silver II process; and supercritical water oxidation.

Selected fungal or bacterial species may offer the prospect of bioremediating PCP contaminated soils at a lower cost than thermo-chemical methods. However whilst bioremediation has been demonstrated to degrade PCP, it does not appear able to degrade the dioxin microcontaminants of PCP.

Technology Performance Criteria

The introduction to New Zealand of a technology to destroy a hazardous waste or achieve site clean up must address a number of issues:

The technology must be cost effective. There are a number of aspects to this:

  • the technology must be able to meet clean-up or destruction efficiency targets; it must be affordable, yet at the same time it must achieve the required clean up criteria. The development of health and environmental standards are therefore fundamental to the selection of an appropriate technology;
  • the technology must provide value for money. Does it offer a final solution to the contamination problem (e.g. degradation of the contaminants to acceptable end products), or does it transfer the problem to future generations (e.g. containment, immobilisation, landfilling)?;
  • versatility – is the technology effective on a range of contaminants and materials? What is the nature and extent of pre-treatment required? Is the treatment facility small scale and relocatable (i.e. can it be moved from site to site) or would a regional facility be needed?

The technology must be satisfactory and safe to operate from a number of standpoints:

  • occupational, safety and health standards relating to workers and the work place; land use consents concerning the siting, installation and operation of the unit; the transport of hazardous substances to and from the installation;
  • regional council consents for any emissions to air, water or land during its operation;
  • consents to satisfactorily dispose of wastes comprising by-products or end products.

Of underlying importance to technical and performance requirements is the reliability and robustness of the operation. In other words the technology must pass a “warrant of fitness” as tested by certified HAZOP/HAZAN risk assessment procedures.

Acceptance by the general public on the safety and desirability of any technology is a major consideration. The community will need to be satisfied that the technology is safe.

Any technology to destroy organochlorines will therefore need to undergo a considerable degree of technical and public scrutiny before it is judged to be “acceptable” and “safe”.

Full reports available from Ministry for the Environment (publications@mfe.govt.nz).