The 10th International Conference on Water Resource and Environment (WRE 2024)

Abstract: Legacy persistent organic pollutants (POPs) and emerging chemicals of concern pose grave threats to ecological systems and human health. These chemicals are highly persistent, extremely toxic, and can travel long distances. This presentation unveils comprehensive findings and robust recommendations derived from three UNEP/GEF projects, aiming to tackle managing these chemicals. The 1st project "Regionally Based Assessment of Persistent Toxic Substances (PTS)" (2000-2003) [1a, b] meticulously examined the sources, concentrations, and impacts of PTS (e.g., DDT), and some highly persistent heavy metals, i.e., Hg, and Pb. Moreover, it identified transboundary transport routes and root causes of the problems, evaluated regional capacity to manage these substances, and offered prioritized intervention strategies. This project complemented the Stockholm Convention on POPs (2003). The 2nd project "Emerging Chemicals Management Issues in Developing Countries and Countries with Economies in Transition" (2010-2012) [2] concentrated on identifying and assessing emerging chemicals of concern (e.g., PBDE), evaluating potential risks to ecosystems and human health, and providing recommendations to enhance monitoring, assessment, and management strategies. The 3rd project "Plastics and the Circular Economy" (2017-2018) [3] highlighted the critical issues related to the global overuse and misuse of plastics and their associated toxic chemicals, i.e., bisphenol A and phthalates. In addition, the Household Dirty Dozen (e.g., coal tar dyes, triclosan) commonly used as ingredients in a wide range of pharmaceutical and personal care products (PPCPs) and cosmetics also raised public health concerns [4]. These projects emphasized the paramount significance of sustainable management practices in safeguarding the environment and human well-being. The experiences gained from these projects underscore the urgent need for collaborative efforts, knowledge sharing, and capacity building among stakeholders.

Keywords: Persistent toxic substances, transboundary movement, ecological and human health, microplastics, emerging chemicals of concern, sustainable management

References
[1a] Wong MH, et al (2002). Regionally Based Assessment (RBA) of Persistent Toxic Substances (PTS). Regional Report of Central and North-East Asia. UNEP/GEF.
[1b] Whylie P, et al, Wong MH (2003). RBA of PTS. Global Report. UNEP/GEF.
[2] Bouwman H, Wong MH, Barra R (2012). GEF Guidance on Emerging Chemicals Management Issues in Developing Countries and Countries with Economy in Transition. UNEP/GEF.
[3] Barra OR, et al (2018). Plastics and the Circular Economy – A STAP Document. UNEP/GEF.
[4] Rajput VD, et al, Wong MH (2024). The Household Dirty Dozen. CleanUp 2024, 15-19 Sept 2024, Adelaide,

Biography: Professor Wong is an advisor at the Education University of Hong Kong, Chang Jiang Chair Professor of the Ministry of Education, China, and a member of the European Academy of Sciences and Arts. He served as the Editor-in-Chief of ‘Environmental Geochemistry and Health’ (Springer Nature) from 2002 to 2023. In addition to his PhD (Durham), he was awarded two higher Doctoral Degrees: DSc (Durham) and DSc (Strathclyde) in 1992 and 2004 based on publication. Under Environmental Science, he is ranked (career-long ranking) 6^th for 3 years and 8^th for 1 year globally (World’s Top 2% Scientists, Stanford University, 2020-2023), and 1^st in China (Research.com's Best Researchers in Various Disciplines, 2023).

He was awarded the Croucher Senior Fellow (Croucher Foundation of Hong Kong) in 1997; the Royal Society Visiting Fellow (Royal Society, UK) in 2000; the Milton Gordon Award for Excellence in Phytoremediation (International Phytotechnology Society) in 2016; Fellow of the Society of Environmental Geochemistry and Health (SEGH) in 2018; Silver Medal (Food Waste for Safe and Quality Fish Production) of the International Inventions (Geneva) in 2019.

Abstract: Traditional wastewater treatment plants (WWTPs), relying on the activated sludge process and disinfection process to remove contaminants and inactivate bacteria, have been widely used around the globe to secure water safety and protect natural resources. However, these processes suffer from a plethora of limitations, such as intensive carbon emissions, excessive power consumption, and chemical intensity induced by chemical addition. Aiming to address the limitations of conventional wastewater treatment processes, our research team conducted a series of research to develop a novel chemical-free photoelectrochemical (PEC) system in both batch and large-size reactors for saline sewage treatment to remove multiple contaminants (including organic pollutants, ammonia, and pathogenic microorganisms) coupled with hydrogen generation, reduce energy consumption, and achieve low carbon emissions for wastewater treatment.

The PEC experiments were first conducted in the batch reactor for proving the concept of multifunctional PEC system and revealing the mechanisms. activity of the material for PEC reactions by redistributing electrons and activating oxygenated species in aqueous solutions (Wu et al., 2018; Xiao et al., 2021; Zheng et al., 2022). In our batch PEC reactor, two ports for water sampling and gas collection were also established in the system. In the PEC tests conducted in the batch reactor, 100 mL of simulated sewage or real sewage collected from the local WWTPs was treated at an applied voltage of 2.0 V vs. Ag/AgCl, under solar light illumination with the intensity of 1041 ± 34 W/m2. Outstanding performance was achieved by the developed batch PEC system in terms of simulated sewage treatment. Full degradation of NH3-N and inactivation of E. coli is achieved by the PEC/r-BiVO4 system, while 93.2 % of COD is degraded within 40 minutes. It is notable that, after the PEC treatment of the simulated sewage, the effluent meets the local discharge standards for COD, ammonia-N, and E. coli under 2.0 V vs. Ag/AgCl. To highlight the ability of the PEC system to generate hydrogen gas as potential green energy, it is found that 633.1 μmol of H2 evolved (6.33 mol/m3, equals 0.29 kWh/m3 of electricity) in 40 minutes of PEC reaction.

Our research team is then committed to advancing the multifunctional PEC system for low-carbon-emissions saline sewage treatment from the laboratory-scale study and development phase to industrialization ultimately. After a verification of the feasibility of applying the batch PEC system to real sewage treatment, we fabricated the large-size continuous-flow PEC reactor stepping forward the industrial application of the developed technique. The long-term performance of the PEC system using the large-scale reactor in treating real sewage from the Stonecutters Island WWTP under natural sunlight was evaluated. In order to fully manipulate natural sunlight as the light source for the PEC system, the reactor is equipped with a sun-tracking system.

In comparison to the conventional biological treatment process, the large-scale PEC system achieved significant reductions in greenhouse gas emissions. Specifically, it accomplished a 99.3% reduction in CH4 emissions, and a substantial 93.8% reduction in N2O emissions. Furthermore, the PEC system delivered outstanding environmental benefits, achieving 95.8% reduction in scope 1 emissions, offsetting scope 2 emissions through H2 evolution, and an 95.5% reduction in total carbon emissions.

Biography: Ir Prof Irene Lo, JP is currently a Chair Professor in the Department of Civil and Environmental Engineering at The Hong Kong University of Science and Technology. She is an elected Academician of the European Academy of Sciences and Arts, as well as Elected Fellow of the Hong Kong Academy of Engineering Sciences, Hong Kong Institution of Engineers, and American Society of Civil Engineers. She was appointed by HKSAR Government as Justices of the Peace (JP) in 2017. She was also Adjunct Professor of Tongji University, Tianjin University, Jilin University and Harbin Institute of Technology. She had been Visiting Professor of Technical University of Denmark and the University of Wisconsin at Madison.

She was the recipient of numerous prestigious international research awards, such as 2007 ASCE Samuel Arnold Greeley Award, 2009 ASCE Wesley W Horner Award, and the 2012 ASCE EWRI Best Practice-Oriented Paper Award. In addition, she received the 2019 Higher Education Outstanding Scientific Research Output Awards in the Natural Science/Technology Advancement by Ministry of Education, China. She has been invited to give over 50 plenary/keynote/invited speeches at many international conferences in Asia, Europe, Africa, and North America.

Her research interests include advanced oxidation processes and nanoparticles/nanotechnology for environmental applications. Her citation is 20900+ with H-index 78, as reported by Google Scholar. She was recognized as "Top 2% Scientists in the World” by Stanford university in 2020, 2021 and 2022.

Abstract: Large-scale industrial activities have the potential to generate significant pollution causing harm to the surrounding ecosystem and human health. Here, we provided three examples for assessing potential risks from large-scale extractive and recycling industries. In project one, the study evaluated the extent of metal contaminations across two gold mine sites post-mining operation. Lead (Pb), arsenic (As), cadmium (Cd), and zinc (Zn) were found at levels exceeding the Health Investigation Levels (HIL), particularly in soil. Cattle production areas are often overlapping mined land in Australia. For environmentally sustainable development post-mining, key areas of the mine site were rehabilitated with pasture that would suit cattle grazing. Laboratory and field feeding trials using cattle were conducted to measure the bioavailability of targeted elements in soil and pasture. Biopsies of the muscle and liver were sampled at intervals to measure the elemental concentrations by ICP-MS and to compare with the national food standards. A predictive model and management framework were established for cattle grazing ensuring animal and human health protection. In the second project, we conducted mapping and characterisation of all potential exposure pathways of Pb in Mount Isa town adjacent to the Mount Isa Mine and Smelter. Synchrotron X-Ray spectroscopy and Pb isotopic ratios were utilised to identify chemical forms and sources of Pb. In-vitro bioaccessibility and in-vivo bioavailability data obtained were used to feed into the IEUBK model to predict blood Pb levels in children. The predicted blood Pb exceedances from significant exposure pathways agreed with the blood Pb survey in children. This is a useful tool for predicting potential risks to each household so that preventive and remedial actions can be implemented. In a third project, we assessed the risks of mixed metal/loid(s) to the local population living at and near the world's largest open beaching ship-wrecking yards in Bangladesh. Sixteen metal/loids in sediment, soil, groundwater, rice, vegetables, seafood, and human urine were measured. Higher urinary metal/loids, including As, Cd, and Mo, in the occupational and environmental exposure groups compared to the control site and international reference values, suggest a health threat. Quantile regression analysis suggests the impacted locations with shipwrecking activities are significant predictors of exposure and are probably due to the uncontrolled release of metal/loids during shipwrecking and recycling activities. In addition, the combined risk from all exposure pathways is also higher in shipwrecking areas. It is prudent that regular environmental monitoring and stricter regulatory control are needed to protect the environment and the public better. The above examples provide key steps and tools for a more refined risk assessment approach to better inform environmental and public health protection for sustainable development.

Keywords: Metals, mining, bioavailability, predictive tool, sustainable development

Biography: Professor Jack Ng has a PhD in Environmental Toxicology and Chemistry from The University of Queensland. He is an internationally recognised certified toxicologist (Diplomate of the American Board of Toxicology). His major research themes include mixture toxicity of both organic and inorganic pollutants; chemical speciation in environmental and biological media; bioavailability in relation to toxicities and risk assessment; carcinogenicity and mechanistic studies using various in vitro and in vivo models. He was the first in the world to establish a mouse model demonstrating inorganic arsenic at environmental levels in drinking water induced multiple tumours.

At the international level, Professor Ng’s expertise has been recognised by the World Health Organisation (WHO), the International Agency for Research on Cancer (IARC), and WHO/FAO Joint Expert Committee on Food Additives (JECFA) as demonstrated by his contribution to several monographs and technical reports produced by these agencies including the recent “Monograph 135 on PFOA and PFOS”. At the national level, Jack served as a member of the National Health and Medical Research Council Health Investigation Levels (HIL) Working Committee which oversaw the setting of the current National Environmental Protection Measures (NEPM) Health Investigation Levels (HILs).

Abstract: Effluent from the textile industry is generally associated with toxic and nonbiodegradable synthetic azo dyes. Conventional biological activated sludge treatment process followed by perchlorate oxidation may not be a proper process to treat such effluent because of its low treatment efficiency and concerns about chlorination in the water environments. Advanced oxidation processes using HO• and SO4•– radicals are an effective way to degrade the complex structures of synthetic azo dyes. Researchers have gained more interest in studying the activated persulfate (PS) decontamination process mainly because the process can generate high reactive SO4•– radicals and work on a wide pH range. Nevertheless, selecting a suitable oxidation process remains challenging because an activation process's degradation efficacy and operating cost depend not only on the operating parameters but also on the activation material itself. Consequently, searching for an activation process for the effective degradation of complex dye structures with ease of operation while keeping the cost down is essential. Due to its non-toxic nature and low cost, iron is the most favorable activator among the transition metals. However, the selection of a suitable Fe activator is crucial. This presentation outlines the performance of using Fe-based materials, such as Fe2+ ion, nano-Fe0, Fe0 aggregates, magnetite, and magnetic Fe-nanocomposites. The prospect of natural iron-rich minerals (Schorl, biotite, Mackinawite, and pyrite) as highly efficient catalysts in activating persulfate to treat textile wastewater will be addressed in depth. In particular, using ultrasound and heat to examine the robustness of the Fe-mineral-activated PS process further underscores its potential for optimism about the future of wastewater treatment.

Biography: Distinguished Professor Chih-Huang Weng is the Chairman of the Department of Civil Engineering at I-Shou University, Taiwan. He also served as Vice-President of North Kaohsiung Community University, Taiwan. Prof. Weng received his MS and Ph.D. degrees in 1990 and 1994, respectively, from the Department of Civil Engineering of The University of Delaware, USA. He is serving as the Editor of Water (MDPI) and Editor of Environmental Geochemistry and Health (Springer), and on the Editorial Board Panel Member of Coloration Technology (Wiley). He has also served as a Guest Editor of SCI journals, such as Agricultural Water Management (Elsevier) and Environmental ScPrience and Pollution Research (Springer). He has also organized and chaired several international conferences. Professor Weng was listed in the World’s Top 2% of Scientists (Stanford University, 2021 and 2022). His main research interests focus on using advanced oxidation processes and adsorption to treat wastewater and bacteria inactivation, groundwater modeling, and application of electrokinetic technologies to soil remediation/sludge treatment/activated carbon regeneration.