North America

Trent University

One of Canada's top universities, Trent University was founded on the ideal of interactive learning that's personal, purposeful and transformative. Consistently recognized nationally for leadership in teaching, research and student satisfaction, Trent attracts excellent students from across the country and around the world. Across all disciplines, Trent brings critical, integrative thinking to life every day. Trent's unique approach to personal development through supportive, collaborative community engagement is in more demand than ever. Students lead the way by co-creating experiences rooted in dialogue, diverse perspectives and collaboration.

The environmental and sustainability science literature had increasingly called for a “transformation to sustainability” to address overlapping and converging social and ecological crises (Future Earth 2014). These calls have been put forth with increasing urgency as we face a cascade of challenges that seem to grow in magnitude and complexity on a daily basis, including but not limited to hunger, the climate crisis, the Sixth Extinction, escalating social inequality and soil depletion. Many voices within academic communities are trying to respond to these pressing and complex issues face the challenge of responding thoughtfully and practically in the face of such great urgency. This raises a fundamental question: How, as scholars/advocates/activists can we be reflective within and activated by this urgency? How can our work meet the urgent challenges of our times while at the same time further longer-term radical and systemic societal shifts in mindsets and actions, including our understanding, experience, relationship with and treatment of natural systems? This panel offers a cross-disciplinary conversation about our respective efforts to negotiate and respond to this call for urgent action through understanding, managing and guiding society towards the needed transformation.


Tempering the Urgency of Extinction
Professor Stephanie Rutherford (School of the Environment)

This talk explores the tensions that emerge in conservation practice when the extinction crisis drives urgent—but short-term—solutions. Drawing on two brief vignettes from my research on wolves in Canada, I assert that this urgency, while justified, can work privilege some animals over other in ways that do little to change the narratives and practices which drive widespread species decline.

Teaching Hope in the Anthropocene
Professor Stephen Hill (School of the Environment)

In my talk, I consider the responsibility that environmental educators have in teaching about global environmental crises such as climate change. I argue that our conventional methods of environmental teaching increase the potential for students to be susceptible to eco-anxiety, grief, outrage and even hopelessness. As a response to these risks, I argue that educators should teach solutions whenever they can, to localize solutions and give opportunity for real-world learning, and to partner with community “doers.” I highlight some models and research at Trent of how community-based education can facilitate more hopeful student learning.

A hunger for urgency: from food charity to food solidarity
Professor Michael Classens (School of the Environment)

In this presentation I attend to the urgency of food insecurity and hunger - rates of which have risen dramatically since the beginning of the global pandemic. I outline how in Canada, the Federal Government has approached this crisis by doubling down on neoliberal and corporatized charity. Finally, I discuss the promise of several paradigms that can help re-frame how we think about food and inform more effective ways of eliminating food insecurity and hunger.

Pathways to a Transformation to Sustainability
Professor Asaf Zohar (Director, Sustainability Studies)

In my talk I explore how I respond to the call for a "transformation to sustainability" to address our urgent and threatening social and ecological crises. I argue for the need to create learning contexts that inspire hope for learners and communities by offering multiple paths for engaging in sustainability. In classroom settings, this requires helping learners find their own voice and spheres of personal influence in meeting the urgent challenges of our times, while at the same time promoting longer-term radical and systemic societal shifts in mindsets and actions. In addition, it requires moving beyond traditional discipline-based competencies and nurturing a wider range of knowledge, skills, and attitudes that enable successful task performance and problem solving for real-world sustainability challenges and opportunities.

UK / Europe



A Circular Economy: UCL's research, the case of metals, collaborations
Professor Raimund Bleischwitz (Bartlett School of Environment, Energy and Resources)

This IIES session deals with the exciting perspective of a circular economy, one that is restorative by design, keeps materials and products in closed loops, and creates public values while staying within planetary boundaries. A first part of my lecture will welcome you to what I call a ‘super year 2021’ for a green recovery. I’m then introducing the shape of a future circular economy contrasting from the lack of circularity today. To address interlinkages across resources, the lecture gives merit to the nexus concept. Inviting collaborations, the slides share information about five large CE Centres starting in January 2021 in the UK. We make a case for circular steel and macro-economic repercussions estimated via a CGE model. The lecture ends with proposed topic areas for further research. The session is hosting more contributions: Julia Stegemann will talk through construction materials; Teresa Domenech navigates through Industrial Symbiosis in Europe; Beijia Huang introduces an assessment framework for construction materials and demolition waste with evidence from Shanghai & China.

Looking forward to feedback and discussions!

UKRI Interdisciplinary Circular Economy Centre for Mineral-based Construction Materials
Professor Julia Stegemann (Department of Civil, Environmental & Geomatic Engineering)

177 million tonnes of virgin aggregates, 15 million tonnes of cement and 2 billion bricks were used to build houses, civic and commercial buildings, roads and railways, etc, in the UK in 2016. Meanwhile, 64 million tonnes of waste arose from construction and demolition. Materials from construction and demolition are mainly managed by down-cycling with loss of the value imparted to them by energy-intensive and polluting extraction and manufacturing processes. The UKRI Interdisciplinary Circular Economy Research Centre for Mineral-based Construction Materials therefore aims to do more with less mineral-based construction materials, to reduce costs to industry, reduce waste and pollution, and benefit the natural environment that we depend on. Firstly, our research will try to better understand how mineral-based construction materials flow through the economy, over all the stages of their life cycle, including extraction, processing, manufacture, and end-of-life. Secondly, we will work on technical improvements that we can make in design of mineral-based products and structures, and in all the life-cycle stages of mineral-based construction materials. Thirdly, we will look at how changes in current business models and practices, government policy and education could support use of less mineral-based construction materials. In the first 4 years of our Centre, a budget of ~£8M provided by UKRI, industry and the host universities will fund more than 25 academic investigators representing different disciplines, who will guide the activities of 15 postdoctoral researchers, in collaboration with more than 40 industrial partners. More than 20 PhD and 30 MSc students will also be trained in the Centre.

Potential of Industrial Symbiosis in Europe: Towards a Circular Manufacturing Sector
Dr. Teresa Domenech

Manufacturing sector in Europe is the second largest of the NACE sections within the EU-27 non-financial business economy, employs around 28.5 million persons (22.8%) and in 2017 generated EUR 1 820 billion of value added (29.3%) (EUROSTAT, 2020). The manufacturing sector is also an important generator of waste, which amounts to 21.3% of all waste generated in Europe (excluding major mineral waste), although variations across MSs are very significant. A key component of the Europe 2020 strategy and Green Deal, the Circular Economy (CE) stresses the connections between increased material efficiency and climate change pointing to the need of ensuring decoupling of economic growth from consumption of resources and environmental impacts as an essential element of the sustainability agenda, as recognised by SDGs (SGD12 and ). The manufacturing sector plays a key role in the transition towards new sustainable patterns of production and consumption and recovery of products, components and materials at the end of life and is pivotal to the transition towards the CE. One practical strategy for CE implementation is related to Industrial Symbiosis. Industrial Symbiosis can be defined a system approach to a more sustainable and integrated industrial system, which identifies business opportunities that leverage underutilised resources (such as materials, energy, water, capacity, expertise, assets etc.) (Lombardi and Laybourn, 2012). IS involves organisations operating in different sectors of activity that engage in mutually beneficial transactions to reuse waste and by-products, finding innovative ways to source inputs and optimising the value of the residues of their processes. IS has also been seen as a practical approach to “enhance resource efficiency, reduce waste generation and GHG emissions via material, energy, by-products exchange between different processes and industries” (Sun et al., 2017). European MSs have seen a surge of Industrial Symbiosis (IS), driven both by public and private initiative. In this talk I present an updated overview of IS activity in Europe, with a mapping of key networks, and a study of prevailing typologies of networks, size, geographical distribution and main streams/ resources traded. The analysis is based on a combination of desk research, gathering of primary data from case studies, a survey to IS network facilitators (n = 22) and in-depth interviews and focus groups (3) with IS practitioners, policy officers and industry representatives (n = 25). The analysis identified pockets of IS activity across all Europe, although varying in nature, resources exchanged and scale and scope of the initiatives. The average size of the mapped networks is approx. 473 members, but the median is approx. 100 members, which indicates high variability of sizes. The geographical scope of the synergies also seems to be dependent upon the following factors: 1) the type of waste stream/by-product; 2) transport costs and 3) market value of secondary materials. Types of waste streams exchanged common to most networks, are chemicals (e.g. chemical base products), biomass and agriculture by-products, wood and wood pellets, plastics, reusable construction materials, equipment, inert waste and water (different qualities including industrial water), residual heat and steam. Secondly, the assessment of performance of IS network is briefly discussed, providing evidence of contribution of IS to sustainability targets and its performance, measured as value of IS investment. The talk concludes with a brief identification of key obstacles facing IS development in Europe highlighting: 1) weakness of economic incentives given the low margin of IS projects associated to undeveloped secondary markets; 2) geographical variation of incentives and drivers, given differences in policy frameworks and support mechanisms (e.g. landfill tax levels) and 3) legislative issues that make transport over geographic boundaries extremely complex and administratively burdensome.

A Life Cycle Thinking Framework to Mitigate the Environmental Impact of Building Materials
Professor Beijia Huang (University of Shanghai for Science and Technology)

Urbanization and population growth have contributed to a tripling of building material consumption from 2000 to 2017. Building materials have a range of environmental impacts throughout their life cycle, from extraction, processing, and transport of raw materials to building construction, use, and eventual demolition and waste. Mitigation measures that target specific materials or value chain stages may therefore have incremental or even adverse net environmental effects. In this perspective, we develop a framework for applying life cycle thinking to identify key impacts and corresponding mitigation approaches, inform building design and material selection, and ensure effective treatment and recycling of construction and demolition wastes. Life cycle evaluation can also be used to assess and avoid environmental trade-offs among life cycle stages. Challenges for implementing these life cycle principles include collecting and integrating inventory data for products, managing multiple stakeholders within the construction industry, and monitoring end-of-life impacts; measures for overcoming such challenges are discussed.

University of Edinburgh

As a world-leading research-intensive University, we are here to address tomorrow’s greatest challenges. We celebrate and strengthen our deep-rooted and distinctive internationalism, attracting the world’s best minds and building innovative global partnerships for research, teaching and impact. Edinburgh is a truly global university and we have always had a commitment to diversity and a community in which students and staff feel valued and welcome. Our international students now represent 44% of our total community, coming from 180 nations, including more than 4,800 students from the EU. While 29% of our staff come from outside the UK. We are currently the top UK University for incoming Erasmus+ exchanges and have agreements with over 250 universities across Europe. We are an active member of international organisations including Universitas 21, the League of European Research Universities, the Coimbra Group, Eurolife, UNICA, UNA Europa, and the U7 Alliance of over 30 universities from G7 countries. The University of Edinburgh has stood proudly for 436 years and it will continue to be a beacon of excellence, with a determinedly international outlook, for generations to come.


Feed Temperature Effects on Organic Fouling of Reverse Osmosis Membranes: Competition of Interfacial and Transport Properties
Dr. Santiago Romero-Vargas Castrillon

We investigated the effect of feed temperature on organic fouling of reverse osmosis (RO) membranes. Experiments were conducted over the range 27 < T < 40 °C, relevant to feed temperatures in arid, near-equatorial latitudes. Fouling by alginate, a major component of extracellular polymeric substances, was investigated at the nanoscale by means of AFM-based temperature-controlled colloidal-probe force spectroscopy (CPFS). The CPFS results, complemented by interfacial property characterisation (contact angle, surface roughness and charge) conducted under temperature-controlled conditions, enabled us to rationalize the observed fouling kinetics in cross-flow fouling experiments. We observed less severe flux loss at 35 °C (J/Jo = 75%, t = 24 hr) compared to 27 °C (J/Jo = 65%), which is due to weaker adhesion forces with rising temperature. The observed variation in the magnitude of adhesion forces is consistent with the temperature dependence of hydrophobic interactions. At 40 °C, the observed flux loss (J/Jo = 68%) was similar to that at 27 °C, despite the fact that adhesion forces are relatively weak (and similar to those at 35 °C). Analysis using a series-resistance model shows that the foulant layer hydraulic resistance is equal at 35 and 40 °C, consistent with the CPFS results. More severe fouling was observed at 40 °C compared to 35 °C, however, due to the higher water permeability coefficient at 40°C, which resulted in a greater flux of foulant to the membrane. Our experiments further show that the fouling layer develops within ~2 hours, during which the flux sharply decreases by 26% at 27 °C, 19% at 35 °C, and 22% at 40 °C; thereafter, flux losses are small and temperature independent. CPFS experiments show that this behaviour is due to the foulant layer, which results in weak, often repulsive, and *T</em|-independent foulant-foulant interactions, which hinder further foulant deposition.

Designer Microbes for Sustainable Synthesis
Dr. Stephen Wallace (Biology)

The use of genetically modified microorganisms is transforming the modern chemical industry. Using modern synthetic biology techniques, multi-step biosynthetic pathways can be genetically encoded into a living cell and used to produce small molecules of industrial value directly from sustainable feedstocks. This stands in stark contrast to traditional chemical synthesis methods that utilize non-renewable petrochemical feedstocks, generate unacceptable quantities of greenhouse gas and contribute significantly to global climate change.

In my talk I will outline our efforts to design a strain of E. coli to synthesise adipic acid, one of the most prolific small molecules used in the modern chemical industry for the synthesis of nylon-6,6. The biotransformation combines newly-discovered enzymes in a single biosynthetic pathway to generate adipic acid from lignin-derived guaiacol, a natural waste material that is widely considered to be one of the most untapped sources of carbon on Earth.

Vanadium: a Sustainable Energy- and Space-Critical Element and an Emerging Contaminant
Dr. James Watt (Chemistry/Physics)

Vanadium (V) is a potentially toxic trace element that is seeing a resurgence in the environment. In the past, V was released into the environment primarily through the combustion of fossil fuels. However, in the last 10 years there has been a considerable increase in the extraction of V driven by a combination of novel technological applications and demand for metallurgical products such as steel and aluminium. This increase poses a potential issue as V rich industrial wastes will start to become more common and our understanding of V mobility and cycling in natural systems is still limited. This presentation will serve as a call to increase the focus on V geochemistry by outlining the various vanadium related research activities undertaken at Edinburgh. We present evidence of V cycling and chemical associations from a Red mud polluted sediment 40 years after a major pollution event. This research has allowed use to understand how V is distributed and re cycled in sediments over long time periods. The research has allowed us to understand the potential risk that V poses to freshwater systems as well as informing remediation strategies. We used a combination of sequential extractions, ICP-OES, ICP-MS and XANES to identify the major operational pools of V. From our sequential extractions, we found the three largest pools of V were related to calcareous minerals, organic matter and Fe / Mn bearing phases respectively. Our XANES spectroscopy also showed that there were different V oxidation states found in the fractions. Based on these results we then suggest recommendations on future avenues of V related research to help understand the biogeochemistry of an element that is set to become a critical element in the development of a de carbonised future.

Linking Chemical Characterisation of NPs With Their Human Health Impacts: Emerging Research Needs in a Post-COVID World
Dr. Craig Poland (Medicine)

Engineered nanomaterials (ENM) are a class of manufactured particulates that are playing an increasing role in technological developments with societal benefit. However, with increased use comes increased potential for exposure and there is a need to understand possible health ramifications of such exposure to prevent possible harm. Whilst ENM are relatively new, particulates ranging from the micron to nanometre scale are endemic in the environment and as such, our exposure to them via a variety of routes from inhalation to ingestion occurs throughout our lives, beginning before birth. Whilst exposure to most particles occurs without incident, some exposures such as air pollution affect all biological systems and are associated with millions of excess deaths each year and considerable disease burden on health services worldwide. Understanding the potential health effects of particulates, irrespective of if they are naturally occurring (e.g., volcanic dust), anthropogenic in nature (e.g., fossil fuel emissions) or emerging risks (e.g., nanotechnology) requires knowledge of the particle properties and the exposure scenario as well as the toxicological response. The physicochemical properties of a particulate such as composition, size, surface area, reactivity, shape and solubility all dictate its interaction with a biological system and the molecular initiation of adverse outcomes, and as such, influence the hazard status of a particle. The exposure scenario including route of exposure, concentration, duration as well as particle properties such shape, size, density profoundly influence dose, distribution and target tissues within the body. As such, to fully understand the drivers of (nano)particle mediated toxicity and disease, we must first understand the properties of the particles including the characteristics and processes that result in exposure. This undertaking by its very nature, is multi-disciplinary and places particle toxicology at the intersect between biomedical sciences, chemistry, exposure science and physics. Furthermore, given the complex and multifaceted nature of particle interactions and resultant disease pathways, there is an increasing need for data science driven approaches to exploring potential associations, drivers of toxicity and interventional approaches. It is both the use of such a multi-disciplinary route to understand and predict possible ENM risks as well as the use of a collaborative approach to design ENM to explore and identify physicochemical drivers of particle toxicity that is explored in this talk.

Developing and Improving Statistical Models to Predict Numbers of Homes in Scotland With Internal Pb Piping
Dr. Gail Robertson (Mathematics)/Professor Margaret Graham (GeoSciences)

Lead has been used in plumbing systems since ancient times due to its malleability, low melting point, corrosion resistance and versatility, and remains ubiquitous in UK household plumbing systems. Exposure to lead can have serious effects on human health and lead in drinking water is known to cause neurodevelopmental problems in children with prolonged exposure. The Scottish Government, working via the Drinking Water Quality Regulator (DWQR) and Scottish Water, has reduced the number of lead pipes in the publicly owned water distribution network, but a large number of houses within Scotland are thought to have internal lead piping which could contribute significantly to lead contamination in tap water. We worked with the DWQR to build a statistical model to estimate the total number of houses in Scotland with internal lead piping and identify postcodes with greater proportions of houses with lead piping. We sourced appropriate datasets from Scottish Water and the Scottish Government and used a Poisson distributed hurdle model to identify important risk factors for houses with lead piping and to predict the number of houses in each postcode with lead pipes. We used these predictions to develop a stratified sampling regime to validate our model. We found that our model fitted the available data reasonably well, although estimates in some areas showed lower accuracy when comparing model predictions with tap water sampling data. We suggest improvements that may be made to the model to account for spatial autocorrelation in the data including new data from further sampling. Our study will allow the Scottish Government to estimate the scale of work involved with removing lead piping from residential properties and the effect this will have on improving health in Scotland.


Nanjing University (NJU)

The School of the Environment at Nanjing University is the top institute in China; it is also the headquarters of IIES. In recent years, many faculties have focused their research on the transformation and toxicity effect of emerging contaminants, particularly microplastics. In this session, several professors from NJU will introduce their recent studies, including the ageing process of microplastics, the degradation behaviour of C14 labelled microplastics and cytotoxicity of microplastics.


14C-Radiotracer-Based Study on Degradation of Polystyrene Micro/Nanoplastics
Professor Rong Ji, School of the Environment, State Key Laboratory of Pollution Control and Resource Reuse (SKLPCRR)

Ubiquitous occurrence of fine plastic particles including microplastics (MPs) and nanoplastics (NPs) in the environment has been causing increasing concerns, however, their degradation in nature has not been well evaluated yet. One of the reasons is that the difficulty in their detection and quantification. Here, we used 14C-radioisotope tracer technology to overcome this limit. We chemically synthesized 14C-labelled polystyrene (14C-PS) in both nanometer and micrometer sizes and studied photo-degradation and fungal degradation of PS. The results showed that UV-irradiation could transform PS and mineralized nanoplastics both in air and water, but the presence of water significantly increased the mineralization and generated by-products with small molecular weight, while irradiation in air increased the molecular weight of the PS nanoplastics, suggesting that water molecules were involved in photo-transformation of plastics in the environment. Additionally, in the presence of water, more soluble transformation products were produced, which were mineralizable in natural water. In the case of fungal degradation of PS, high density of Penicillium variabile biomass in liquid medium without additional carbon substrate could mineralize PS, and the PS particles with a lower molecular weight had a higher mineralization rate. Chemical pretreatment of PS particles with ozone O 3 strongly enhanced the mineralization of PS. Ozonation generated carbonyl groups on PS surface and the amount of the carbonyl groups decreased after incubation of the PS with the fungus. The data suggest that ozonation pretreatment could be a potential approach for degradation of PS waste and remediation of PS-contaminated sites. Our studies provided direct evidence of abiotic degradation of PS nanoplastics in aqueous environment and of biotic degradation of PS with chemical pretreatment.

Single-cell RNA Sequencing Reveals Size-Dependent Effects of Polystyrene Microplastics on Zebrafish Intestines
Professor Bing Wu, School of the Environment, SKLPCRR

Microplastics (MPs) as widespread contamination pose a high risk for aquatic organisms. Due to hard-to-degrade components and properties, e.g., size, MPs can accumulate in the intestines of aquatic organisms and cause physical damage and inflammatory responses. However, current approaches for understanding the adverse effects of MPs are based on cell population-averaged measurements, which might obscure the critical contributions of individual cell populations. Our aim was to gain a comprehensive understanding of the size-dependent effects of polystyrene MPs (PS-MPs) on intestinal cell populations in zebrafish and characterize the interplay of MPs, intestinal cells and intestinal microbiota. Here, we used single-cell RNA sequencing to determine the transcriptome heterogeneity of 12000 intestinal cells obtained from zebrafish exposed to 100-nm, 5-μm and 200-μm PS-MPs for 21 days. Eight intestinal cell populations were identified, including enterocytes, secretory cells (enteroendocrine and goblet cells), lymphocytes (T cells and B cells) and phagocytes (M1 macrophages, M2 macrophages and neutrophils). Combined with changes in intestinal microbiota, our findings highlight a previously unrecognized endpoint that all three sizes of PS-MPs induced dysfunction of intestinal immune cells (including effects on phagosomes and regulation of immune system processes) and increased the abundance of pathogenic bacteria. However, only 100-nm PS-MPs altered expression of genes related to phagocyte-produced ROS generation and increased mucus secretion by secretory cells. Microsize PS-MPs specifically changed the lysosome (5 μm) and cell surface receptor signaling (200 μm) processes of macrophages. This study for the first time shows the feasibility of using scRNA-seq to investigate the heterogeneity of zebrafish intestinal cells in response to MPs, and our findings pinpoint to cell-specific and size-dependent responses to PS-MPs in fish intestine, which can provide a reference for future study directions.

Sunlight Leads to the Release of Hazardous Cadmium Ion from Coloured Microplastics Containing Cadmium Pigment
Professor Xiaolei Qu, School of the Environment, SKLPCRR

Cadmium pigments are widely used in the polymer industry. Their potential environmental risk is under debate, being the major barrier for appropriate regulation. Little is known about the leaching of hazardous cadmium ion (Cd2+) from coloured microplastics containing cadmium pigment in aquatic systems. Here, we reported the release of Cd2+ from different sized microplastics containing cadmium pigment under sunlight exposure. The release of Cd2+ was caused by the photo-dissolution of cadmium pigment induced by the reactions between photogenerated holes and the pigment lattices. The photo-dissolution process can be activated by both ultraviolet and visible light in the solar spectrum. The release kinetics is highly size-dependent. It was relatively low for microplastics with size larger than 0.85 mm but increased significantly with decreasing size for microplastics smaller than 0.85 mm. The polymer matrix was oxidized during light exposure, leading to lower average molecular weight and the formation of oxygen-containing groups. Part of the polymer matrix was degraded into soluble organic carbon under simulated sunlight, resulting in continuous Cd2+ release from the pigment particles embedded in the polymer. The polymer degradation rate is also highly size-dependent. The degradation of the polymer matrix and the release of Cd2+ were intertwined. Cadmium leaching from microplastics from a commercial product containing cadmium pigment was confirmed in water under simulated sunlight. Our results suggest that the photochemical processes of inorganic pigments will lead to the release of heavy metals from coloured plastic debris.

Microplastics: A Small but Not Negligible for Health of the Ecosystem
Professor Mei Li, School of the Environment, SKLPCRR

Plastics products are becoming widely used in agriculture, animal husbandry, industry and daily life. They have replaced glass, wood and other materials with its advantages of lightness, convenience and low cost. However, plastics can fragment leading to the formation of small plastics particles, known as microplastics (MPs), which has become a serious threat to the environment and ecosystem health. Therefore, to explore the potential toxicity of microplastics on model organisms, our research interests center around the behavior, transformation, and effects of microplastics in the ecosystem, with a view to improve ecological risk assessment of microplastics.

Firstly, we focused on the effects of polystyrene microplastics (PS-MPs) on E. gracilis, a freshwater microalgae. Our findings showed that PS-MPs do have adverse effects on microalgae, inhibiting growth, reducing pigment contents and increasing activities of antioxidant enzymes, inducing vacuoles increasing, chloroplast deformation and algae homo-aggregation. Secondly, laser confocal scanning microscopy observations confirmed that nano- PS-MPs entered V. faba roots and probably blocked cell connections or cell wall pores and disrupted the nutrients transport causing the observed toxic effects. These findings indicated that PS-MPs can be toxic to V. faba, what should be considered in future ecological risk assessment of interaction between microplastics and higher plants. Finally, to bridge the knowledge gaps between MPs and soil organisms, studies focusing on the effect of MPs on terrestrial ecosystems and on soil organisms, especially in earthworms, are important. Data on uptake or accumulation of PS-MPs in earthworm intestines, histopathological changes, oxidative stress, and DNA damage demonstrated that the toxicological effects of low concentrations of PS-MPs (≤ 1 mg/kg of soil) on earthworms (Eisenia fetida) were also occurred. These findings provide new insights regarding the toxicological effects of low concentrations of microplastics on earthworms and on the ecological risks of microplastics to soil animals.

Photo-Aging of Microplastics and the Effects on the Environmental Behaviors of Organic Contaminants in Aquatic Environments
Professor Cheng Gu, School of the Environment, SKLPCRR

Multiple aging pathways in the aquatic environments and the underlying transformation mechanism were described for microplastics (MPs). The polystyrene and high-density polyethylene microplastics could be altered by heat-activated K2S2O8 and Fenton treatments, thus further improving the understanding of their long-term natural aging in aquatic environments. The active oxidizing species generated in advanced oxidation processes are generally free radicals, e.g., hydroxyl radical (OH•) for Fenton and OH•/SO4• − (sulfate radical anion) for persulfate, and their high redox potentials are likely to enhance the oxidation of microplastics. In our recent study, the photo-alteration was investigated for polyvinyl chloride microplastics (PVC-MPs), and the aging reaction could be facilitated in the presence of low-molecular-weight organic acid (LMWOA) and LMWOA-Fe (III) complex under simulated and natural sunlight irradiation and ambient conditions. The OH• generated from the photolysis of LMWOA or its ferric complexes played a dominant role in enhancing PVC-MP degradation. PVC-MP surface oxidation led to the increase of the specific surface area and affinity towards water, which would further enhance the adsorption of polar contaminants on PVC-MPs and thus increase the health risk of PVC-MPs on aquatic organisms. In addition to enhancing the sorption capacity for hydrophilic antibiotics, aged PVC-MPs exhibited great potential to accelerate the hydrolysis of cephalosporin pharmaceuticals, which could be ascribed to the interfacial hydrogen-bonding interactions between β-lactam antibiotics and oxygenated PVC-MPs. The intermolecular hydrogen-bonding force was able to lower the energy gap for the hydrolytic reaction of cephalosporin antibiotics. These researches shed light on the aging reaction of microplastics and the effects on the environmental behaviors of organic contaminants in aquatic environments.

National Taiwan University

To pursue sustainability requires knowledge of interaction between the components of the environment and between the environment and the anthroposphere. Building upon strong scientific foundation, the Graduate Institute of Environmental Engineering (GIEE) continues to develop innovative technologies to address issues ranging from global scale like climate change to local scale like air, water and soil contamination. In addition to scientific and engineering endeavors, economic and social perspectives are also incorporated to identify driving forces of environmental problems and facilitate designing of governance and management strategies. With two programs – science and engineering division and planning and management division, the students are equipped with thinking and analytical skills with both depth and breadth. With emphasis on cultivating abilities of multidiscipline integration, students are able to meet the need of the ever-changing times and tackle realistic challenges, while the research results have contributed to the strengthening of the governments and the industries. Sustainability involves intertwining environment, economy and energy and demands integration of science, engineering, and management approaches.


Temporal and Spatial Variation of Physical and Chemical Properties in PM2.5 and PM1.0 and Their Influence on Atmospheric Visibility
Professor Ta-Chih Hsiao, Graduate Institute of Environmental Engineering (GIEE)

The atmospheric visibility is directly related to the light absorbing and scattering by aerosol particles, which is depending on PM’s physical and chemical properties and vary significantly in space and time. It is thus of great importance to explore the relationship between these physiochemical parameters and their influences on the light extinction. Urban development would reshape the terrain features and landscapes in Taichung, and it could intensify urban heat island effect and further result in changes of the chemical composition of air pollutants. All the above would enable us to understand aerosol’s impact on atmospheric visibility and to mitigate the impairment.

In this project, field observations and various measurements will be performed at two different locations in Taichung metropolitan and suburban areas. The Metropolitan station is selected to investigate the contributions of traffic emissions, and the suburban station in Taichung is selected to study the pollution transport. The first phase of the project has been completed, and the two identical experimental setups were installed in the two stations. The on-site calibrations were conducted for the instruments, including TEOM, nephelometer, aethalometer, SMPS etc. The hourly data sets of the two identical instruments in the same station are well correlated with each other and demonstrated the comparability and reliability of the data. In addition to continuous monitoring of aerosol physical properties, the seasonal intensive observations on aerosol chemical properties are conducted.

Capacitive Deionization for Electrochemical Desalination, Water Reclamation and Ion Separation
Professor Chia-Hung Hou, GIEE

Water-energy nexus, or referred to as the interdependence between water and energy, is increasingly highlighted as as an important global issue for environmental sustainability. Energy-efficient separation technologies that can remove ions from aqueous solutions have attracted great attention for desalination and water treatment. Recently, capacitive deionization (CDI) is a promising electrochemical technology to separate salt ions or charged contaminants from water. In CDI, ions can be temporarily held within the charged nanopores of carbon electrodes by electrical double-layer formation. CDI has several operational advantages including low-energy consumption, low fouling potential, high water recovery, and environmental friendliness. To further improve the performance of CDI, ion-exchange membranes can be positioned in front of each carbon electrode to avoid co-ion effects: a configuration called membrane capacitive deionization (MCDI). As demonstrated, MCDI is more competitive in treating brackish water (total dissolved salt < 4000 ppm) to deliver fresh water due to the relatively low energy input. Most recently, a scaled-up MCDI stack was developed to desalinate the bio-treated effluent of municipal wastewater treatment plant. The MCDI can continuously produce remarkably high-quality reclaimed water that meet the water quality standard for industrial reuse. In addition, CDI shows great potentials for remediation of arsenic-contaminated groundwater, selective removal of nitrate and recovery of rare metal ions (e.g., indium) from wastewaters. Therefore, the electrochemical processes with nanoporous carbon electrodes enable a wealth of environmental applications, ranging from desalination, industrial water remediation to recovery of elements.

Plant Microbial Fuel Cells for Soil Remediation, Urban Greening and Waste Valorization
Professor Chang-Ping Yu, GIEE

The plant microbial fuel cell (PMFC) is a novel technology that integrates plants, microbes and electrochemical elements together to create renewable energy. However, research is still limited regarding the application of PMFCs. Here we will provide examples of their application conducted in our research group in the past several years.

In the first example, PMFCs were installed as green roofs in a subtropical metropolis (Taipei city). Urban greening, such as green roofs, is considered as one of the measures to resolve the urban heat island effect caused by the increasing urbanization. The PMFCs based green roofs could mostly achieve electricity production; however, little output voltage of Dwarf rotala PMFCs indicated different plant species in PMFC systems would result in varied efficiencies of electricity generation. The PMFCs based green roofs could also largely lower the temperature of underneath floor slabs compared with bare slabs at noon. Our roof-top research demonstrated that using PMFCs based green roofs for urban greening is promising and warrants the potential for future application.

In the second example, we intended to evaluate the use of PMFCs for bioremediation of Cr(VI)-contaminated soils and also produce energy at the same time, and explore the chemical and microbial characteristics under long-term operation. PMFCs with Chinese pennisetum and common reeds were employed to treat different levels of Cr(VI)- contaminated soil for evaluating the treatment performance. We have also demonstrated that PMFCs could be applied in treating real field contaminated soil containing Cr(VI). Our results suggest that using PMFCs to remediate metal contaminated soils is promising, and the effects of decontamination are mostly contributed by bioelectrochemical processes and plant uptake.

In the end, since in the second example of PMFCs, Chinese pennisetum could absorb heavy metals during soil remediation similar to phytoremediation. After plants are harvested, the system will generate biomass waste. After drying and crushing of plant waste, the biomass waste can be collected and valorized for biorefinery. This example presents the catalytic valorization of PMFC waste into levulinic acid (LA). Under microwave heating, increasing temperature to 180oC increased the yield of LA in water with sulfuric acid. Furthermore, gamma-Valerolactone (GVL)/H2O ratios could affect LA yields. These findings help to better understand the acid catalytic conversion of biomass under microwave heating for future application of valorization of plant waste.

Advanced Oxidation Processes for Water Treatment
Professor Yi-Pin Lin, GIEE

Advanced oxidation processes (AOPs) have been used to remove recalcitrant organic pollutants in water and wastewater. AOPs rely on the formation of reactive radicals, such as hydroxyl radical, sulfate radical and superoxide radical, for the superior degradation efficiency of target pollutants. In this presentation, recent works on ozonation, catalytic ozonation, Fenton-like process and persulfate technology conducted in our research group will be summarized. The focus will be on fundamental chemistry and reaction mechanisms. Specifically, the roles of natural organic matter (NOM) and effluent organic matter (EfOM) in terms of direct ozone reaction, initiation, promotion and inhibition in the OH radical chain reactions during ozonation were explored. The use of multiwall carbon nanotube (MWCNT) in transforming molecular ozone to hydroxyl radical for the removal of emerging contaminants was investigated. The integration of MnO2 with H2O2 in a Fenton-like process was examined for the degradation of perfluorooctanesulfonic acid (PFOS) in neutral pH, in which the roles of formed superoxide radical and hydroxyl radical were investigated. Finally, CuO was used to activate peroxydisulfate (PDS) for the removal of chlorophenol. Surface- bound sulfate radical and hydroxyl radical were found to be responsible for the chlorophenol degradation and the kinetics was successfully modeled.