Abstract: Dumping dredged sediment into the ocean has become controversial due to its potential environmental implications and threats to human health. Dredged sediment often contains various contaminants which significantly impact marine ecosystems. This presentation highlights the need for more stringent regulations and innovative sediment management strategies to mitigate these impacts by citing two case studies the author involved: (1) Mass fish-kill at fish culture zones due to dumping dredged sediment without safeguarding the environment, and (2) Stringent environmental regulations were enforced for dumping sediment at the ocean. Before the construction of the contained aquatic disposal (CAD) facility to the South of The Brothers Contaminated Mud Pits (SB CMPs) (near the Hong Kong Airport), the Civil Engineering and Development Department (CEDD) conducted a detailed review and update of EIA findings for the facility in 2009/2010. An Environmental Monitoring and Audit (EM&A) program was subsequently implemented, covering the dredging, disposal, and capping operations of the CMPs. Stringent procedures were followed concerning the construction of disposal pits, disposal of contaminated mud, capping pits, and an extensive environmental monitoring program. The EM&A procedures (from July 2013 to June 2017) included the baseline surveys, monitoring of water and sediment quality, bioassays of sediment toxicity, recolonization of benthic organisms, and loading of major contaminants: heavy metals (Cr, Cd, Cu, Hg, Ni, Zn, Pb, Ag), metalloid (As), organic pollutants (PAH, DDT, PCB, TBT), and total organic carbon. The overall results indicated no drastic water and sediment quality changes due to the operations. The potential impacts were monitored on the Ma Wan mariculture site (the most sensitive receiver) and other mariculture sites. The EM&A data obtained under the Project for these four years were compared against the corresponding key Water Quality Objectives. No unusual changes in water quality (especially DO and E. coli), which may threaten fish health, were noted. Based on the results, it can be concluded that there is no need to conduct additional monitoring/mitigation measures or studies to examine the Project’s impact on mariculture zones.

Biography: Professor Wong is a Member of the European Academy of Sciences and Arts, and Chang Jiang Chair Professor of the Ministry of Education, China. He served as the Editor-in-Chief of ‘Environmental Geochemistry and Health’ (Springer Nature) for 20 years (2002-2023). Professor Wong was the Coordinator of Central and North-East Asia of ‘Regionally Based Assessment of Persistent Toxic Substances’ and a Panel Member (of 3 experts) of ‘Chemicals Management Issues of Developing Countries and Countries with Economies in Transition’, sponsored by UNEP/GEF, during 2001-2003 and 2010-2012, respectively. His research areas included ‘Environmental toxicology’; ‘Ecological restoration’; and ‘Resource reuse’. He has published over 840 SCI papers. In addition to his PhD (Durham), he was awarded two higher Doctoral Degrees: DSc (Durham) and DSc (Strathclyde) based on published papers in 1992 and 2004. Professor Wong is ranked 6th for 3 years and 8th for 1 year (career-long ranking) and is listed as the top Chinese scientist in Environmental Science according to the World’s Top 2% Scientists (Stanford University, 2020-2023). According to Research.com's Best Researchers in Various Disciplines (2nd Ed, 2023), he ranked No. 1 in China under Environmental Science.

Abstract: With the escalating yield, oyster shell waste has become a greater environmental problem impacting shorelines and fisheries worldwide. The oyster shell is a residue composed of more than 95% calcium carbonate, which can be reused as a raw material for creating multiple values, such as blended cement, concrete ingredients, anti-mold paint, soil conditioner, functional fabrics, and pharmaceutical excipients. Turning the oyster shells into a valuable biomass disinfectant material would be a win-win strategy, providing a cost-effective material source and alleviating the environmental issue. Bacterial infection and subsequent disinfection of microorganisms are ongoing issues around the world. Bio-calcium oxide derived from heated oyster shell (HOS) waste products has been shown to be an effective disinfectant. It has the advantage of marketing waste materials that would otherwise contribute to environmental problems. This speech will briefly review the circular use of oyster shells and then concentrate more on the mode of inactivation of bacteria by HOS. Specifically, the use of fluorescence microscopy (FM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and electron spin resonance (ESR) spectrometer techniques in characterizing the mode of inactivation of bacteria via HOS, exemplified by S. aureus (gram-positive) and E. coli (gram-negative), one of the primary pathogens involved in nosocomial infections in medical institutions worldwide. This is the first work to provide insight into the three-dimensional morphology and biophysical properties of the inactivated S. aureus and E. coli cells via HOS. Therefore, this study provides a template for the early assessment of altered bacterial cell structure and cell membrane permeability using FM, TEM, and quantification of K⁺ that leaks from bacterial cells. The biophysical properties showing the damage to bacterial height, surface roughness, Derjaguin-Muller-Toporov (DMT) elastic modulus, and adhesion following HOS treatment are also elaborate. Noteworthy, the presence of singlet oxygen in HOS suspension altered bacterial cell permeability, leading to sustained inactivation. The HOS exhibited excellent disinfection capacity and achieved a 5-log-inactivation E. coli within 60 min with a dose of 0.2 g/L, superior to other shell-derived disinfectants. Overall, the cost-effective HOS disinfectant, derived from natural resources, has a high potential to be applied as a universal disinfectant and alleviate an aquaculture waste pollution problem.

Biography: Distinguished Professor Chih-Huang Weng is currently 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. He is serving as the Editor of Water (MDPI), 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), Environmental Science and Pollution Research (Springer), and Lecture Notes in Civil Engineering. He has also organized and chaired several international conferences. Professor Weng was listed in the World’s Top 2% of Scientists (Stanford University, 2021-2023). 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.