•There is a lack of information on the use of ultrasonication at large scales/the field.•The efficiency of ultrasonication for algal removal in field is still debatable.•Attenuation of ultrasonic ...intensity needs to be considered in field applications.•Further field data is required for the upscaling of ultrasonication devices.
Algal blooms are a naturally occurring phenomenon which can occur in both freshwater and saltwater. However, due to excess nutrient loading in water bodies (e.g. agricultural runoff and industrial activities), harmful algal blooms (HABs) have become an increasing issue globally, and can even cause health effects in humans due to the release of cyanotoxins. Among currently available treatment methods, sonication has received increasing attention for algal control because of its low impact on ecosystems and the environment. The effects of ultrasound on algal cells are well understood and operating parameter such as frequency, intensity, and duration of exposure has been well studied. However, most studies have been limited to laboratory data interpretation due to complicated environmental conditions in the field. Only a few field and pilot tests in small reservoirs were reported and the applicability of ultrasound for HABs prevention and control is still under question. There is a lack of information on the upscaling of ultrasonication devices for HAB control on larger water bodies, considering field influencing factors such as rainfall, light intensity/duration, temperature, water flow, nutrients loading, and turbidity. In this review article, we address the challenges and field considerations of ultrasonic applications for controlling algal blooms. An extensive literature survey, from the fundamentals of ultrasound techniques to recent ultrasound laboratory and field studies, has been thoroughly conducted and summarized to identify future technical expectations for field applications. Case studies investigating spatial distribution of frequency and pressure during sonication are highlighted with future implications.
Water quality control and management in water resources are important for providing clean and safe water to the public. Due to their large area, collection, analysis, and management of a large amount ...of water quality data are essential. Water quality data are collected mainly by manual field sampling, and recently real-time sensor monitoring has been increasingly applied for efficient data collection. However, real-time sensor monitoring still relies on only a few parameters, such as water level, velocity, temperature, conductivity, dissolved oxygen (DO), and pH. Although advanced sensing technologies, such as hyperspectral images (HSI), have been used for the areal monitoring of algal bloom, other water quality sensors for organic compounds, phosphorus (P), and nitrogen (N) still need to be further developed and improved for field applications. The utilization of information and communications technology (ICT) with sensor technology shows great potential for the monitoring, transmission, and management of field water-quality data and thus for developing effective water quality management. This paper presents a review of the recent advances in ICT and field applicable sensor technology for monitoring water quality, mainly focusing on water resources, such as rivers and lakes, and discusses the challenges and future directions.
•Salt concentration had more of an effect than salt type on algal metabolisms.•Salinity stress reduced the growth of Chlorella vulgaris.•Salinity stress increased total lipid content and saturated ...portions of fatty acids.•Algae settling was improved by 33–83% with increased NaCl concentrations.
Microalgae can offer several benefits for wastewater treatment with their ability to produce large amounts of lipids for biofuel production and the high economic value of harvested biomass for biogas and fertilizer. This study found that salt concentration (∼45gL−1) had more of an effect than salt type on metabolisms of Chlorella vulgaris for wastewater treatment and biofuel production. Salinity stress decreased the algal growth rate in wastewater by 0.003day−1permScm−1 and slightly reduced nutrient removal rates. However, salinity stress was shown to increase total lipid content from 11.5% to 16.1% while also increasing the saturated portions of fatty acids in C. vulgaris. In addition, salinity increased the algal settling rate from 0.06 to 0.11mday−1 which could potentially reduce the cost of harvesting for algal biofuel production. Overall, C. vulgaris makes a suitable candidate for high salinity wastewater cultivation and biofuel production.
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•Emulsion liquid membranes (ELMs) were applied to remove various metallic ions from phosphoric acid solutions.•Three carrier agents of ELMs were evaluated for their suitability in ...extracting metallic ions in a Taylor-vortex column.•Cyanex 301 was proved to be the most suitable carrier agent for metal extraction from 40wt% of phosphoric acid.
Separating the impurities (such as metallic ions) from phosphoric acid solutions has been a major challenge in phosphoric acid purification as current technologies (such as solvent extraction) are costly. Therefore, emulsion liquid membranes (ELMs) were employed in this study as an alternative technology for the purification of phosphoric acid solutions due to their outstanding selectivity, high extraction efficiency, and relatively low energy consumption compared to other separation methods. Three carrier agents (Cyanex 301, Cyanex 302, and Alamine 336) were evaluated for their suitability in extracting various metallic ions, for the development and optimization of a Type II ELM system in a Taylor-vortex column. At moderate pH (>2), ELMs with Alamine 336 were most efficient (metal removal efficiency of almost 100%); however, their removal efficiency significantly decreased for the simulated phosphoric acid solution. Only ELMs with Cyanex 301 showed the potential to separate some of the tested metals, such as cadmium, lead, and zinc from the synthesized phosphoric acid. The observed failure of the ELM process for the extraction of multiple metals might have resulted from either the lack of proper bonding between the carrier agents and metals or the instability of emulsion membranes under extreme pH conditions.
Due to climate change, population growth, industrialization, urbanization, and water contamination, it is becoming more difficult to secure and supply clean and safe drinking water. One of the ...challenges many water utilities often face is the taste and odor (T&O) problem in drinking water treatment plants, mostly associated with geosmin and 2-MIB. These representative T&O compounds are mainly produced by the metabolism of blue-green algae (cyanobacteria), especially in summer. In this study, the correlation between algae blooms and T&O compounds was identified in the intake and raw water of a large-scale water treatment plant in the Republic of Korea. The removal efficiency of geosmin and 2-MIB by each treatment process was intensively evaluated. According to the obtained results, ozonation and granular activated carbon (GAC) adsorption were more effective for removing the troublesome compounds compared to other water treatment processes, such as coagulation/flocculation, filtration, and chlorination. Because of their seasonal concentration variation and different removal rates, optimal operation methods need to be developed and implemented for drinking water treatment plants to solve the T&O problems.
Direct interspecies electron transfer (DIET) between electroactive microorganisms (EAMs) offers significant potential to enhance methane production, necessitating research for its practical ...implementation. This study investigated enhanced methane production through DIET in an anaerobic digester bio-augmented with EAMs. A horizontal anaerobic digester (HAD) operated for 430 days as a testbed to validate the benefits of bioaugmentation with EAMs. Anaerobic digestate slurry, discharged from the HAD, was enriched with EAMs in a bioelectrochemical auxiliary reactor (BEAR) under an electric field. This slurry enriched with EAMs was then recirculated into the HAD. Results showed bio-augmentation with EAMs led to an increase in volatile solids removal from 56.2% to 77.5%, methane production rate from 0.59 to 1.00 L/L.d, methane yield from 0.26 to 0.34 L/g CODr, and biogas methane content from 59.9% to 71.6%. It suggests that bio-augmentation enhances DIET, promoting the conversion of volatile fatty acids to methane and enhancing resilience against kinetic imbalances. The enrichment of EAMs reached optimal efficacy under an electric field intensity of 2.07 V/cm with a mean exposure time of 2.53 days to the electric field in the BEAR. Bio-augmentation with externally enriched EAMs is a feasible and effective strategy to optimize anaerobic digestion processes.
Factors that increase protein thermostability are of considerable interest in both scientific and industrial fields. Disulfide bonds are one of such factors that increase thermostability, but are ...rarely found in intracellular proteins because of the reducing environment of the cytosol. Here, we report the first example of an intermolecular disulfide bond between heteromeric subunits of a novel-type phosphoserine phosphatase from a thermophilic bacterium Hydrogenobacter thermophilus, which contributes to the protein thermostability at the physiological temperature. Comparison of remaining soluble proteins between wild-type and cysteine-deleted mutant using SDS-PAGE revealed that the disulfide bond increases the thermostability of the whole protein by tightly connecting a subunit with low solubility to the partner with higher solubility. Furthermore, it was strongly suggested that the disulfide bond is formed and contributes to the stability in vivo. This finding will open new avenues for the design of proteins with increased thermostability.
Intermolecular disulfide bond was found in a heterodimeric protein from a thermophilic bacterium. It is essential for the protein thermostability.
Objectives : This study compared the CODMn and TOC concentrations of the influent and effluent from six industrial wastewater treatment plants (WWTPs) and the wastewater from manufacturing facilities ...in the industrial complexes, and to understand the correlation between the two indicators.Methods : The sampling campaigns were performed four times at each WWTP for both influent and effluent. Water quality surveys were also conducted to assess the characteristics of organic matter in the wastewater from the manufacturing facilities. A total of 272 facilities including manufacturing, non-manufacturing, and miscellaneous manufacturing units were surveyed. Results and Discussion : The CODMn/TOC ratios of the influent and the effluent of the WWTPs ranged from 0.78 to 1.79 (average 1.19) and 0.94 to 1.58 (average 1.20), respectively. The ratio of CODMn/TOC ratio in the wastewater from the manufacturing facilities was 1.06~1.22 (average 1.12). Industries with high R2 values for the CODMn/TOC ratios included rubber and plastics manufacturing (CODMn/TOC = 1.17), nonferrous metals manufacturing (CODMn/TOC = 0.94), medical materials and pharmaceutical manufacturing (CODMn/TOC = 0.98), and chemicals manufacturing (CODMn/TOC = 1.27).Conclusion : CODMn/TOC ratios of the influent and effluent of the six plants and the wastewater from manufacturing facilities varied in different ranges for each WWTP, with an average value of 1.12. The results of this study can be used as basic information to manage the effluent water quality of the WWTPs.
Discharge from sewage treatment plants (STPs) is a significant pathway of entry for microplastics (MPs) to the environment. Therefore, STPs should be considered as an important barrier to the ...distribution and circulation of MPs in the aquatic environment. In this study, the fate and material-specific properties of MPs were investigated in an STP-equipped and granule-activated carbon (GAC) tower with a thermal regeneration system. This system functioned with a tertiary treatment unit. The GAC with thermal regeneration removed 92.8% of MPs and was useful for removing MPs with a specific gravity less than that of water and with a size of 20–50 µm, which had negligible removal in the conventional STP process. In addition, a lab-scale electric-coagulation experiment was conducted to examine its potential utility as a pretreatment process for further enhancing the removal efficiency of MPs by GAC. After 30 min of electro-coagulation using aluminum electrodes, 90% of MPs were converted into separable flocs by centrifugation. These flocs may be effectively removed by GAC or other tertiary treatment steps. This study demonstrates that GAC with thermal regeneration is a tertiary process that can efficiently prohibit the release of MPs from STPs and circulation of MPs in the natural environment.
Algal bloom is a significant issue when managing water quality in freshwater; specifically, predicting the concentration of algae is essential to maintaining the safety of the drinking water supply ...system. The chlorophyll-a (Chl-a) concentration is a commonly used indicator to obtain an estimation of algal concentration. In this study, an XGBoost ensemble machine learning (ML) model was developed from eighteen input variables to predict Chl-a concentration. The composition and pretreatment of input variables to the model are important factors for improving model performance. Explainable artificial intelligence (XAI) is an emerging area of ML modeling that provides a reasonable interpretation of model performance. The effect of input variable selection on model performance was estimated, where the priority of input variable selection was determined using three indices: Shapley value (SHAP), feature importance (FI), and variance inflation factor (VIF). SHAP analysis is an XAI algorithm designed to compute the relative importance of input variables with consistency, providing an interpretable analysis for model prediction. The XGB models simulated with independent variables selected using three indices were evaluated with root mean square error (RMSE), RMSE-observation standard deviation ratio, and Nash-Sutcliffe efficiency. This study shows that the model exhibited the most stable performance when the priority of input variables was determined by SHAP. This implies that on-site monitoring can be designed to collect the selected input variables from the SHAP analysis to reduce the cost of overall water quality analysis. The independent variables were further analyzed using SHAP summary plot, force plot, target plot, and partial dependency plot to provide understandable interpretation on the performance of the XGB model. While XAI is still in the early stages of development, this study successfully demonstrated a good example of XAI application to improve the interpretation of machine learning model performance in predicting water quality.
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•XGBoost ensemble learning model predicts chlorophyll-a concentration in stream.•XAI algorithm used to interpret ensemble learning model•Effect of input variable selection on model performance analyzed using three indices•Input variable selection using Shapley value provided most stable model performance.
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