- Title
- Strategies to reduce, remove and build resilience to microplastics in the whole of water supply cycle
- Creator
- Senathirajah, Kala
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2024
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- With increasing global awareness of the issues plastics pose, even if new materials replace plastics and all manufacturing of new plastics is to cease, the 8,300 million metric tonnes of virgin plastics produced by 2017 (Geyer et al., 2017) and the subsequent amounts that have entered into our systems are exorbitantly voluminous and requires attention. Microplastics, plastic particles less than 5 mm, are now being recognised as an emerging contaminant and have been detected in the whole of water supply cycle, including raw water, treated potable water, as well as wastewater and biosolids (Senathirajah & Palanisami, 2023). The scale and gravity of the situation meets all criteria to be defined as a slow-onset disaster (Senathirajah, Bonner, et al., 2023). As an emerging field of science, knowledge gaps hinder the ability to fully understand the fate, transformation, behaviour and ramifications of microplastics in the water supply cycle. Although there has been some research into microplastics in potable water, treatment plants and wastewater, to date no research has holistically investigated the whole of water supply cycle nor studied the building of resilience to the ubiquitous, pervasive and persistent contaminant. This applied research tests the hypothesis that a holistic approach implemented concurrently will be able to reduce, remove and build resilience to microplastics in water supply systems. Utilising the disaster management framework (preparedness, response, recovery, mitigation) as the primary basis, underpinned with the Sendai Framework for Disaster Risk Reduction and the Australian National Disaster Risk Reduction Framework (2018) priorities (understand disaster risk, accountable decisions, enhanced investment, governance), this study journeys through the water cycle (source, treatment, conveyance, discharge) to contribute to knowledge to reduce the disaster risk (Figure GA.1). This is achieved by (i) shedding light on the hazards, exposure, vulnerability, capacity and compounding systemic risks and also (ii) proposing cross-cutting, multi-disciplinary strategies to not only reduce and remove microplastics and build resilience into water supply systems but generate multi-benefits by contributing to the achievement of targets of the Sendai Framework for Disaster Risk Reduction 2015–2030 and Sustainable Development Goals (SDGs), both of which possess fast-approaching targeted timeframes. The objectives of Chapter 2: Preparedness, Paper I, were to understand whether microplastics pose a disaster risk in the urban water supply system and, if so, how to build resilience. The paper deep dives into each parameter of the conceptual disaster risk equation, evaluating causal relationships and identifying strategies to intervene across the whole of water supply cycle, from source through to waste. This process strives to identify all stressors and outline the exposure pathway for receptors. Different types of capitals that can be utilised to build resilience were also unravelled. Given that many countries, including Australia, are signatories to the Sendai Framework and SDGs, rather than add to the burden, the synergies that can be leveraged to contribute towards the targets of multiple instruments were highlighted. Chapter 3: Response links with the accountable decisions priority and incorporates Papers II, III and IV. Paper II establishes that microplastics pollution meets the criteria of disaster, then examines science-based decision-making to ascertain sources of concern and develop targeted interventions. Abundant in highly populated areas, microplastics are shown to alter normal functioning and cause damage through creating vulnerable conditions; response is needed to satisfy critical human need, in this case the need for water. Through this paper, the synergies and benefits between the Sendai Framework and the SDGs are presented for consideration for incorporation into the new United Nations global legally binding agreement to end plastic pollution. Paper III is linked with the hazard parameter of the disaster risk equation and presents an accountable science-based decision-making process that addresses the fact that numerous polymers exist in various sectors and are all potential sources for the water supply cycle. Using Victoria as a case study, high-use polymers were established. Adopting a semi-quantitative to investigate 21 criteria derived using the DPSIR (Driving Forces–Pressures–State–ImpactsResponses) framework, and undertaking multiple analyses, risk factors were identified to determine that the polymers of concern for Victoria are polyvinyl chloride (PVC), polypropylene (PP) and polystyrene (PS), followed by polyamide (PA). The study also shed light on the dominant factors informing the different stages of the plastic lifecycle and the key sectors and corresponding stage of life cycle for the three polymers of concern. The hotspots for Victoria were identified and the outcomes fed into the newly rolled-out General Environmental Duty legislations in July 2021. The last component in Chapter 3, Paper IV, reinforces the urgent need for research on microplastics in the water supply cycle, looking at the exposure parameter of the disaster risk equation. Scanning, synthesising and analysing the available information showed that ingestion of microplastics from water is an issue that needs to be addressed. Data were extracted from various sources, uncertainties determined, assumptions made and a global average rate of microplastics ingested was derived. This was the work that I carried out for the World Wide Fund for Nature (WWF) global Your Plastic Diet campaign and was the first attempt to transform microplastic counts into a mass value relevant to human toxicology. This work changed the narrative globally and contributed to the call for a global treaty to end plastic pollution. The next parameter in the disaster risk equation, capacity, is addressed through Chapter 4: Recovery and linked with the enhanced investment priority, primarily examining ways of addressing microplastics in the water supply system through regular operations and established treatment processes. Two treatment methods are investigated: disinfection (Paper V), and electrocoagulation (Paper VI). Paper V examines disinfection, a well-established, standard practice to remove pathogens and organic matter. Investigation of the effects of chlorination and chloramination on seven polymer types showed that plastic polymers are degraded by both processes with polymers undergoing both physical and chemical changes. Of the seven polymers studied, PA, PP and expanded polystyrene (EPS) were the top three polymers of concern. This study helps policy makers, designers and water industry operators make informed decisions about water disinfection processes and contributes directly to public health protection. The other component of the capacity parameter involved examining an advance oxidation treatment process, which is an emerging technology that uses fewer chemicals and results in a lower volume of sludge needing disposal. Paper VI thus investigated the removal efficiency of a custom-built electrocoagulation chamber and its physical and chemical impacts on four plastic polymers of fibres and fragments. Although the removal efficiency is shown to be promising, the physicochemical changes induced by the electrocoagulation process indicated that the particles are susceptible to breakdown following treatment. To determine the feasibility of utilising this cost-effective technology for the removal of microplastics, it would be important to verify whether the particles were broken down to nanoplastics (below the limit of detection) or were fully degraded. The remaining parameter of the disaster risk equation, vulnerability, is the focus of Chapter 5: Mitigation and is linked with a governance responsibility priority to close the loop. Paper VII shifts from the treatment plant level to the local government scale to investigate the compounding disaster risks presented by microplastics in the water supply and climate change. Understanding the risks posed by microplastics, specifically their sources, transportation and fate within the water supply cycle, allows for the development and implementation of targeted interventions and fit-for-purpose and scale-relevant mitigation strategies and solutions. A study on the whole water supply cycle (from catchment to discharge from wastewater treatment plants) allows for the development of (i) more effective and efficient outcomes that could also generate multi-benefits, as well as (ii) enabling a more holistic and targeted approach to reduce, remove and build resilience to microplastics in the water supply cycle.
- Subject
- microplastics; water supply; resilience; polymers of concern; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1511378
- Identifier
- uon:56488
- Rights
- Copyright 2024 Kala Senathirajah
- Language
- eng
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