Emergence of microplastics in the aquatic ecosystem and their potential effects on health risks: The insights into Vietnam.

The increase of microplastic contamination in Vietnam is a growing concern due to various domestic, agricultural, and industrial activities. The use of plastic mulch and sludge application in agricultural farmland, textile production, daily consumer items, cleaning agents, and health/personal care products contribute significantly to the increasing microplastic pollution in the aquatic ecosystem. The concentration of microplastics reported in surface water ranged from 0.35 to 519,000 items m-3, with fibers and fragments being the most prevalent shapes. Notably, the high concentration of microplastics was observed in lakes, canals, and megacities such as Ha Noi and Ho Chi Minh City, which poses potential health risks to the local community via drinking-water supply and food chains. As an emerging pollutant, MPs are the transport vectors for contaminants in environmental matrices that act as a carrier of hazardous pollutants, release toxic compounds, and evenly aggregate/accumulate in biota. Recent studies have reported the presence of microplastics in various marine organisms, including fish and shellfish, highlighting the risk of ingestion of these particles by humans and wildlife. Thus, it is imperative to monitor microplastic contamination in the ecosystem to provide helpful information for the government and local communities. Efforts should be taken to reduce microplastic pollution at the source to minimize potential effects on ecological and health safety. This review paper emphasizes the urgent need for further research on microplastic pollution in Vietnam and highlights potential solutions to mitigate this emerging environmental threat. KEYWORKS: single-use plastics; microplastics; ecosystems; plastic waste; health risk; ecological and health safety; pollution mitigation.

Ecotoxicity of micro- and nanoplastics on aquatic algae: Facts, challenges, and future opportunities.

The production of plastic has exponentially increased in recent years, leading to the release of millions of tons of plastic waste into the environment annually. This waste can break down into smaller micro- and nanoplastics (MNPs) that are toxic and reactive to life forms, including humans. MNPs are particularly concerning for marine biologists and environmental scientists due to their toxic impacts on aquatic organisms, including algae, which are the foundation of the food chain. The review provides a comprehensive overview of the (eco)toxicity assessment of MNPs on aquatic algal communities, highlighting the novel insights gained into the ecotoxicity of various MNPs on algae and the associated health risks for aquatic ecosystems, food chains, and humans. This article also discusses current challenges and future research opportunities to address these challenges, making it a valuable contribution to the field of environmental science. Overall, this work is one of the first efforts to comprehensively assess the effects of MNPs on aquatic algae, emphasizing the significant risks that MNPs pose to essential ecosystems and human health.

A review on sterilization methods of environmental decontamination to prevent the coronavirus SARS-CoV-2 (COVID-19 virus): A new challenge towards eco-friendly solutions.

In recent years, the COVID-19 pandemic is currently wreaking havoc on the planet. SARS-CoV-2, the Severe Acute Respiratory Syndrome Coronavirus, is the current term for this outbreak. Reports about this novel coronavirus have been presented since the pandemic's breakout, and they have demonstrated that it transmits rapidly from person to person, primarily by droplets in the air. Findings have illustrated that SARS-CoV-2 can survive on surfaces from hours to days. Therefore, it is essential to find practical solutions to reduce the virus's impact on human health and the environment. This work evaluated common sterilization methods that can decontaminate the environment and items. The goal is that healthcare facilities, disease prevention organizations, and local communities can overcome the new challenge of finding eco-friendly solutions. Further, a foundation of information encompassing various sterilization procedures and highlighting their limits to choose the most appropriate method to stop disease-causing viruses in the new context has been presented. The findings of this crucial investigation contribute to gaining insight into the comprehensive sterilization approaches against the coronavirus for human health protection and sustainable environmental development.

Applying response surface methodology to optimize partial nitrification in sequence batch reactor treating salinity wastewater.

In this study, the operation parameters of a partial nitrification process (PN) treating saline wastewater were optimized using the Box-Behnken design via the response surface methodology (BBD-RSM). A novel strategy based on the control of the carbon/nitrogen ratio (C/N), alkalinity/ammonia ratio (K/A), and salinity in three stages was used to achieve PN in a sequence batch reactor. The results demonstrated that a high and stable PN was completed after 50 d with an ammonia removal efficiency (ARE) of 98.37 % and nitrite accumulation rate (NAR) of 85.93 %. Next, BBD-RSM was applied, where ARE and NAR were the responses. The highest responses from the confirmation experiment were 99.9 % ± 0.04 and 95.25 % ± 0.32 when the optimum C/N, K/A, and salinity were identified as 0.84, 2, and 5.5 (g/L), respectively. The results were higher than those for the nonoptimized reactor. The developed regression model adequately forecasts the PN performance under optimal conditions. Therefore, this study provides a promising strategy for controlling the PN process and shows how the BBD-RSM model can improve the PN performance.

Fabrication of Antibacterial Ag/Graphene-Integrated Non-woven Polypropylene Textile for Air Pollutant Filtering.

Air pollution and infectious diseases (such as the COVID-19 pandemic) have attracted considerable attention from governments and scientists worldwide to find the best solutions to address these issues. In this study, a new simultaneous antibacterial and particulate matter (PM) filtering Ag/graphene-integrated non-woven polypropylene textile was fabricated by simply immersing the textile into a Ag/graphene-containing solution. The Ag/graphene nanocomposite was prepared by reducing Ag ions on the surface of graphene nanoplatelets (GNPs) using the leaf extract. The prepared Ag/graphene textile was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Energy Dispersive X-ray (EDX), and contact angle measurements. The results showed excellent integration of the Ag/GNP nanocomposite into the non-woven polypropylene textile matrix. The prepared textile exhibited superhydrophobicity with a contact angle of 152°. The maximum PM removal percentage of the Ag/GNP-integrated textile was determined to be 98.5% at an Ag/GNP content of 1.5% w/w and a silicon adhesive of 1% w/w. The Ag/GNP textile exhibited high antibacterial activity toward Escherichia coli with no sign of bacteria on the surface. Remarkably, the as-prepared Ag/GNP textile was highly durable and stable and could be reused many times after washing.

Recent advances and applicable flexibility potential of electrochemical processes for wastewater treatment.

This study examined >140 relevant publications from the last few years (2018-2021). In this study, classification was reviewed depending on the operation's progress. Electrocoagulation (EC), electrooxidation (EO), electroflotation (EF), electrodialysis (ED), and electro-Fenton (EFN) processes have received considerable attention. The type of action (individual or hybrid) for each electrochemical procedure was evaluated, and statistical analysis was performed to compare them as a new manner of reviewing cited papers providing a massive amount of information efficiently to the readers. Individual or hybrid operation progress of the electrochemical techniques is critical issues. Their design, operation, and maintenance costs vary depending on the in-situ conditions, as evidenced by surveyed articles and statistical analyses. This work also examines the variables affecting the elimination efficacy, such as the applied current, reaction time, pH, type of electrolyte, initial pollutant concentration, and energy consumption. In addition, owing to its efficacy in removing toxins, the hybrid activity showed a good percentage among the studies reviewed. The promise of each wastewater treatment technology depends on the type of contamination. In some cases, EO requires additives to oxidise the pollutants. EF and EFN eliminated lightweight organic pollutants. ED has been used to treat saline water. Compared to other methods, EC has been extensively employed to remove a wide variety of contaminants.

Roles, mechanism of action, and potential applications of sulfur-oxidizing bacteria for environmental bioremediation.

Sulfur (S) is a crucial component in the environment and living organisms. This work is the first attempt to provide an overview and critical discussion on the roles, mechanisms, and environmental applications of sulfur-oxidizing bacteria (SOB). The findings reveal that key enzymes of SOB embarked on oxidation of sulfide, sulfite, thiosulfate, and elemental S. Conversion of reduced S compounds was oxidatively catalyzed by various enzymes (e.g. sulfide: quinone oxidoreductase, flavocytochrome c-sulfide dehydrogenase, dissimilatory sulfite reductase, heterodisulfide reductase-like proteins). Environmental applications of SOB discussed include detoxifying hydrogen sulfide, soil bioremediation, and wastewater treatment. SOB producing S0 engaged in biological S soil amendments (e.g. saline-alkali soil remediation, the oxidation of sulfide-bearing minerals). Biotreatment of H2S using SOB occurred under both aerobic and anaerobic conditions. Sulfide, nitrate, and sulfamethoxazole were removed through SOB suspension cultures and S0-based carriers. Finally, this work presented future perspectives on SOB development, including S0 recovery, SOB enrichment, field measurement and identification of sulfur compounds, and the development of mathematical simulation.

Adsorptive removal of phosphate from aqueous solutions using low-cost modified biochar-packed column: Effect of operational parameters and kinetic study.

Adsorption in the continuous mode plays a significant role in wastewater treatment. In this study, Mimosa pigra-derived biochar modified with 2 M AlCl3 salt was used to pack a lab-scale column to eliminate PO43- from aqueous solutions. The influence of the operational factors, such as inlet PO43- concentration (25-100 mg/L), flow rate (6-18 mL/min), and biochar bed height (1.5-4.5 cm), on the breakthrough curve was evaluated. The kinetic models of Adam-Bohart and Yoon-Nelson were utilized to analyze the experimental results. The best conditions were determined to be the influent PO43- strength of 50 mg/L, injection speed of 6 mL/min, and column height of 4.5 cm. These results can be applied in the design of large-scale columns for the sequestration of PO43- from wastewater.

Insights into the Pollutant Removal Performance of Stormwater Green Infrastructures: A Case Study of Detention Basins and Retention Ponds.

The quality of water has deteriorated due to urbanization and the occurrence of urban stormwater runoff. To solve this problem, this study investigated the pollutant reduction effects from the geometric and hydrological factors of green infrastructures (GIs) to more accurately design GI models, and evaluated the factors that are required for such a design. Among several GIs, detention basins and retention ponds were evaluated. This study chose the inflow, outflow, total suspended solids (TSS), total phosphorus (TP), watershed area, GI area (bottom area in detention basins and permanent pool surface area in retention ponds), and GI volume (in both detention basins and retention ponds) for analysis and applied both ordinary least squares (OLS) regression and multiple linear regression (MLR). The geometric factors do not vary within each GI, but there may be a bias due to the number of stormwater events. To solve this problem, three methods that involved randomly extracting data with a certain range and excluding outliers were applied to the models. The accuracies of these OLS and MLR models were analyzed through the percentage bias (PBIAS), Nash-Sutcliffe efficiency (NSE), and RMSE-observations standard deviation ratio (RSR). The results of this study suggest that models which consider the influent concentration combined with the hydrological and GI geometric parameters have better correlations than models that consider only a single parameter.

Impacts of potential evapotranspiration on drought phenomena in different regions and climate zones.

The present study is aimed at examining whether potential evapotranspiration (PET), which is important for drought assessment, influences a drought index (standardized precipitation evapotranspiration index; SPEI) for different regions and climate zones. The study regions were East Asia, Europe, the United States (US), and West Africa, and the climate zones considered were the arid, semiarid, subhumid, and humid zones. We examined the pattern of water deficits, spatial trend of the SPEI, area ratio of spatial extent, and temporal trend to provide an understanding of drought characteristics. Two datasets, Climate Research Unit (CRU) and National Centers for Environmental Prediction (NCEP), were used for assessing the drought phenomena. Two types of evapotranspiration obtained using Thornthwaite and Penman-Monteith equations were used to estimate the PET. Negative water deficit values were clearly observed in the arid and semiarid zones of the majority of regions, whereas positive water deficit values were observed in the subhumid and humid zones of the regions. The SPEI spatial trend largely presented a decreasing trend in East Asia and West Africa, a neutral or decreasing trend in Europe, and a neutral or increasing trend in the US. The area ratio of the spatial extent showed large values of a neutral or decreasing trend in East Asia and Europe, a neutral or increasing trend in the US, and a decreasing trend in West Africa. The temporal trend of the spatial extent primarily exhibited no trend or an increasing trend in the aforementioned regions, except in the case of the majority of West Africa. Although the results obtained from the two datasets appear to be slightly different, they show that the PET is predominant in regions, especially in the US. The PET trends are identified through comparisons and used to understand the drought phenomena while considering various geographic regions and climatic zones.

Assessment of regional threats to human water security adopting the global framework: A case study in South Korea.

Water resources have been threatened by climate change, increasing population, land cover changes in watersheds, urban expansion, and intensive use of freshwater resources. Thus, it is critical to understand the sustainability and security of water resources. This study aims to understand how we can adequately and efficiently quantify water use sustainability at both regional and global scales with an indicator-based approach. A case study of South Korea was examined with the framework widely used to quantify global human water threats. We estimated the human water threat with both global and local datasets, showing that the water security index using global data was adequately correlated with the index for regional data. However, particularly poor associations were found in the investment benefit factors. Furthermore, we examined several different aspects of the index with the local datasets as they have relatively high spatial and temporal resolution. For example, we used cropland percentage, population and moderate water use as surrogate indicators instead of employing the approximately 20 original indicators, and we presented a regression model that was able to capture the spatial variations from the original threat index to some extent. This finding implies that it would be possible to predict water security or sustainability using existing indicator datasets for future periods, although it would require regionally developed relationships between water security and such indicators.