What are the most appropriate practices for waste management?
This discussion ranged over the improvement of landfill liners, development of PFOS and PFOA separation techniques from the wastewater streams and the identification of ambiguities in the waste exemption permit.
Phil Henderson (Coffey International) promoted the use of more insulative liners, less prone to seepage in landfills, such as those used in New York or Germany. In those countries, their guidelines place a higher value on groundwater with quantity and quality approval requirements for any leachate which leaks through the liners. With his Victorian background on landfill design and auditing process, Henderson explained how composite, double composite liners with geomembrane layers may be better suited to some conditions rather than the conventional basal liner design. However, they require immediate containment and confinement. Overall, the key to the success of any landfill liner is quality assurance with the importance placed on a Construction Quality Assurance plan during installation. The use of geosynthetic liners require constant contact with the waste being contained. Leakage detection can be installed for a relatively low cost using voltage across the liner to observe any holes. Such liners have been used in Australia as both geomembrane or clay liners can be effective if utilised under conditions suited to their qualities.
Current research on the separation Poly-fluorinated Per- and poly-fluoroalkyl substances (PFAS) from wastewater and solid waste streams is underway. Focusing on Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) separation, Professor William Clarke (University of Queensland) explained possible techniques for trapping PFOA at wastewater plants. One research project at the University of Queensland involves mixing Iron oxide (Fe2O3) nanoparticles with the waste such that the nano-magnetite absorbs PFOA into the thickened sludge. This can then be mixed in water and collected with a magnet, for separation from the waste stream. Other techniques such as incineration were also discussed and there is some research focusing on the destruction of PFAS through non-thermal and thermal plasma (similar to the methods used for the destruction of Perfluorinated compounds (PFCs) in its early stages).
The waste exemption was discussed with regard to unclear definitions and criteria which may be of concern to those wishing to utilise it. After identifying a series of observable ‘gaps’ in the waste exemption, Louise Cartwright (PSK Environmental) queried the Department of Environment and Science (DES) for clarification. The Environmental Protection Act (EP Act) defines ‘earth’ as sand, soil, silt or mud and the definition in the Waste Reduction and Recycling Act (2011) considers natural materials such as clay, gravel, sand, soil and rock. Therefore, this reference to “natural” earth in the Waste Reduction and Recycling Act (2011) does not incorporate fill material? Furthermore, there is no definition for “natural” provided in the legislation potentially causing misinterpretation within the industry. With fines and penalties for the misuse of the waste exemption, these definitions may require further distinction. Further ambiguities were identified in the eligibility criteria for the waste exemption. For the exemption to be applied earth must be reasonably treated by bioremediation. There is no clear consideration of different remediation techniques and expects that earth solely contaminated by petrol hydrocarbons to be treated on site. Furthermore, DES reported that ‘reasonably treated’ is what is cost effective? The overall feedback from DES regarding this and the presence of contamination prior to 1992 is that it is up to the waste exemption declaration signatory to provide evidence of all criteria.
The outcomes of this discussion were that there should be some workshopping with DES to clarify the definition of earth, develop some consideration for the contaminants present and potentially develop a suitable waste management guideline document for the waste exemption. Furthermore, training for the applications of bioremediation and the utilisation of other remediation techniques may be required and discussed with DES to reduce the likelihood of miscomprehension and misuse of the waste exemption.
|Presenter Name||Presenter Company|
|Phil Henderson||Coffey International|
|Professor William Clarke||University of Queensland|
|Dr Louise Cartwright||
19 September 2019 New Zealand Branch report by Lauren Reynolds – Graduate Environmental Engineer - WSP
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