•A novel image processing was conducted to determine oil separation levels.•Predictive models for bilgewater emulsion stability were first developed.•Coalescence and kinetic emulsion stabilities were ...separately determined.
Bilgewater is a shipboard multi-component oily wastewater, combining numerous wastewater sources. A better understanding of bilgewater emulsions is required for proper wastewater management to meet discharge regulations. In this study, we developed 360 emulsion samples based on commonly used Navy cleaner data and previous bilgewater composition studies. Oil value (OV) was obtained from image analysis of oil/creaming layer and validated by oil separation (OS) which was experimentally determined using a gravimetric method. OV (%) showed good agreement with OS (%), indicating that a simple image-based parameter can be used for emulsion stability prediction model development. An ANOVA analysis was conducted of the five variables (Cleaner, Salinity, Suspended Solids SS, pH, and Temperature) that significantly impacted estimates of OV, finding that the Cleaner, Salinity, and SS variables were statistically significant (p < 0.05), while pH and Temperature were not. In general, most cleaners showed improved oil separation with salt additions. Novel machine learning (ML)-based predictive models of both classification and regression for bilgewater emulsion stability were then developed using OV. For classification, the random forest (RF) classifiers achieved the most accurate prediction with F1-score of 0.8224, while in regression-based models the decision tree (DT) regressor showed the highest prediction of emulsion stability with the average mean absolute error (MAE) of 0.1611. Turbidity also showed a good emulsion prediction with RF regressor (MAE of 0.0559) and RF classifier (F1-score of 0.9338). One predictor variable removal test showed that Salinity, SS, and Temperature are the most impactful variables in the developed models. This is the first study to use image processing and machine learning for the prediction of oil separation for the application of bilgewater assessment within the marine sector.
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This study presents a systematic investigation of bilgewater emulsion characteristics using various in situ analytical methods, while assessing the effect of environmental parameters e.g., ionic ...strength, suspended solids (SS), and temperature on emulsion destabilization. The stabilizing properties of three emulsifiers Triton X-100, B&B 3100, and sodium dodecyl sulfate (SDS) were evaluated under various conditions over 5 days. Time-course visual observation, relative oil separation, droplet size distribution, and grayscale intensity profiles were used for the physical characterization of the emulsion samples. In particular, the grayscale intensity was found to be a useful technique for the rapid detection of emulsion separation using simple image analysis. Major findings on bilgewater emulsion stability in this study are as follows: (1) emulsion stability decreased with NaCl (ionic strength) addition and temperature increase, resulting in higher oil separation, (2) emulsions stabilized with B&B 3100 (commercial cleaner) were more stable than Triton X-100 and SDS (neat surfactants) at the equivalent critical micelle concentration, and (3) SSs particle size larger than the initial droplet size could promote the formation of larger emulsion droplets, thus increasing oil coalescence as corroborated by visual observation. Overall, this study highlighted a defined set of easy and rapid emulsion analytical methods, which provided significant information regarding bilgewater emulsion stability. These techniques demonstrated to be a rapid solution for the in situ characterization of bilgewater emulsions primarily in offshore locations lacking sophisticated equipment. These methods can be used for further investigation of other cleaning products found on ships and actual bilgewater samples to assist in the appropriate bilgewater treatment and management.
Intensification of pollution loading worldwide has promoted an escalation of different types of disease-causing microorganisms, such as harmful algal blooms (HABs), instigating detrimental impacts on ...the quality of receiving surface waters. Formation of unwanted disinfection by-products (DBPs) resulting from conventional disinfection technologies reveals the need for the development of new sustainable alternatives. Quaternary Ammonium Compounds (QACs) are cationic surfactants widely known for their effective biocidal properties at the ppm level. In this study, a novel silica-based antimicrobial nanofilm was developed using a composite of silica-modified QAC (Fixed-Quat) and applied to a fiberglass mesh as an active surface via sol–gel technique. The synthesized Fixed-Quat nanocoating was found to be effective against E. coli with an inactivation rate of 1.3 × 10−3 log reduction/cm min. The Fixed-Quat coated fiberglass mesh also demonstrated successful control of Microcystis aeruginosa with more than 99% inactivation after 10 hr of exposure. The developed antimicrobial mesh was also evaluated with wild-type microalgal species collected in a water body experiencing HABs, obtaining a 97% removal efficiency. Overall, the silica-functionalized Fixed-Quat nanocoating showed promising antimicrobial properties for water disinfection and HABs control, while decreasing concerns related to DBPs formation and the possible release of toxic nanomaterials into the environment.
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•MAIFAS displayed better N and P removal compared to suspended control.•MAIFAS process removed >99% ammonia and 51% P without mechanical aeration.•Localized photo-oxygenation at the ...biofilm surface was observed using microelectrodes.•Biofilm microprofiles showed no ammonia uptake by algal portion of biofilms.•Candidatus Accumulibacter contributed to 55% of the rRNA in the MAIFAS biofilm.
The Integrated Fixed-Film Activated Sludge (IFAS) process is an advanced biological wastewater treatment process that integrates biofilm carriers within conventional activated sludge to uncouple the sludge retention time for nitrifiers and heterotrophic bacteria. In this study, we incorporated microalgae into the IFAS configuration for photo-oxygenation and evaluated the symbiotic reaction between microalgae and bacteria for both suspended solids and IFAS biofilm media. In a sequencing batch mode, the microalgae-IFAS system removed more than 99% ammonia and 51% phosphorous without the need for mechanical aeration. Biofilm microprofiles revealed localized photo-oxygenation by the algal biofilm and nitrification by nitrifiers on the IFAS media. Genetic sequencing showed that the addition of microalgae to the IFAS system promoted significant changes in the bacterial community structure and altered metabolic activity of several bacterial groups. Overall, this research represents a novel strategy for reducing energy consumption while meeting stringent effluent standards using a hybrid symbiotic microalgae-IFAS technology.
The Integrated Fixed-Film Activated Sludge (IFAS) process is an advanced biological wastewater treatment process that integrates biofilm carriers within conventional activated sludge to uncouple the ...sludge retention time for nitrifiers and heterotrophic bacteria. In this study, we incorporated microalgae into the IFAS configuration for photo-oxygenation and evaluated the symbiotic reaction between microalgae and bacteria for both suspended solids and IFAS biofilm media. In a sequencing batch mode, the microalgae-IFAS system removed more than 99% ammonia and 51% phosphorous without the need for mechanical aeration. Biofilm microprofiles revealed localized photo-oxygenation by the algal biofilm and nitrification by nitrifiers on the IFAS media. Genetic sequencing showed that the addition of microalgae to the IFAS system promoted significant changes in the bacterial community structure and altered metabolic activity of several bacterial groups. Overall, this research represents a novel strategy for reducing energy consumption while meeting stringent effluent standards using a hybrid symbiotic microalgae-IFAS technology.
Abstract
For over a decade, the incidence of Huanglongbing (HLB) has grown at an alarming rate, affecting citrus crops worldwide. Current methods of nutrient therapy have little to no effect in ...alleviating symptoms of HLB, and scarce research has been put forth towards non‐destructive tools for monitoring zinc transport in citrus plants. Here, we have developed and characterized a solid contact micro‐ion‐selective electrode (SC‐μ‐ISE) for the determination of zinc transport in sour orange seedlings using a non‐invasive microelectrode ion flux estimation (MIFE) technique. The SC‐μ‐ISE displayed a 26.05±0.13 mV decade
−1
Nernstian response and a LOD of (3.96±2.09)×10
−7
M. Results showed a significant Zn
2+
uptake in the leaves and roots of sour orange seedlings when bulk concentrations were higher than 5.99 mM. Above this concentration, a linear relationship between flux and bulk Zn
2+
concentration was observed. This relationship suggests passive diffusion may be a key mechanism for Zn transport into plants. Overall, this study is the first to use a Zn
2+
SC‐μ‐ISE for the determination of ion transport processes in plants. This novel tool can be used to further knowledge the effect of nutrient therapy and disease progression on HLB infected citrus plants.
•Reported surfactant properties of common shipboard detergents•Evaluated the impacts of experimental properties of cleaners on emulsion stability•Demonstrated that CMC of a cleaner can change in the ...presence of oil•CMC indicates the likelihood of a cleaners to stabilize bilgewater emulsions
Oil-in-water emulsions created in shipboard bilgewater can be challenging to treat to hydrocarbon-limiting environmental discharge regulations. While emulsion behavior has been widely studied in other disciplines, research on bilgewater emulsions has been limited due to the variability of bilgewater composition. In this context, surfactant types and concentrations are generally unknown. Therefore, experimental properties of neat surfactants and commercial cleaners were evaluated for predicting bilgewater emulsion stability. Critical micelle concentration (CMC), CMC in the presence of oil (CMCIFT), and equilibrium interfacial tension (IFT) were investigated for emulsion stability using different surfactant types, oil concentrations, and homogenization energies. It was found that CMC was significantly larger in the presence of mineral oil. Γ∞ values of all three surfactants were similar for the oil-water and air-water cases; however, the κ values were larger for the oil-water interface suggesting that, for a given surfactant, the adsorption of the surfactant molecules to the oil-water interface was more active than to the air-water interface. It was also determined that emulsion stability was most closely related to CMCIFT. Coalescence into a separated oil layer was only observed in emulsion samples with surfactant concentrations below CMCIFT. This relationship was observed for different homogenization intensities and oil concentrations. Experiments also validated the relationship between CMCIFT and oil separation in more complex formulations of commercial cleaners commonly found aboard ships. Four different cleaners with unique compositions all demonstrated separated oil at concentrations below CMCIFT. Overall, CMCIFT represents a practical way to evaluate a cleaner's likelihood of developing stable (> 72 h with no observable oil separation) emulsions in bilgewater.
This study presents in situ detection of Zn2+ using a novel two-step square-wave anodic stripping voltammetry (SWASV)-based needle-type microsensor for citrus plant applications. A double-barrel ...bismuth/platinum (Bi/Pt) microelectrode was fabricated with a solid metal tip (~110 µm), which was durable enough to penetrate the thick skin of the citrus leaves and sensitive enough to detect ppb changes in Zn2+ concentration using SWASV. The microelectrode tip size was also determined to reduce mass transport limitation and improve limit of detection. Overall, the developed Bi/Pt microelectrode successfully measured Zn2+ concentrations within the vascular bundle of citrus plants.
For over a decade, the incidence of Huanglongbing (HLB) has grown at an alarming rate, affecting citrus crops worldwide. Current methods of nutrient therapy have little to no effect in alleviating ...symptoms of HLB, and scarce research has been put forth towards non‐destructive tools for monitoring zinc transport in citrus plants. Here, we have developed and characterized a solid contact micro‐ion‐selective electrode (SC‐μ‐ISE) for the determination of zinc transport in sour orange seedlings using a non‐invasive microelectrode ion flux estimation (MIFE) technique. The SC‐μ‐ISE displayed a 26.05±0.13 mV decade−1 Nernstian response and a LOD of (3.96±2.09)×10−7 M. Results showed a significant Zn2+ uptake in the leaves and roots of sour orange seedlings when bulk concentrations were higher than 5.99 mM. Above this concentration, a linear relationship between flux and bulk Zn2+ concentration was observed. This relationship suggests passive diffusion may be a key mechanism for Zn transport into plants. Overall, this study is the first to use a Zn2+ SC‐μ‐ISE for the determination of ion transport processes in plants. This novel tool can be used to further knowledge the effect of nutrient therapy and disease progression on HLB infected citrus plants.
As the demand for reliable and safe water supplies increases, both water quality and available quantity are being challenged by population growth and climate change. Greywater reuse is becoming a ...common practice worldwide; however, in remote locations of limited water supply, such as those encountered in military installations, it is desirable to expand its classification to include dishwashing water to maximize the conservation of fresh water. Given that no standards for dishwashing greywater reuse by the military are currently available, the current study determined a specific set of water quality standards for dishwater recycling systems for U.S. military field operations. A tentative water reuse standard for dishwashing water was developed based on federal and state regulations and guidelines for non-potable water, and the developed standard was cross-evaluated by monitoring water quality data from a full-scale dishwashing water recycling system using an innovative electrocoagulation and ultrafiltration process. Quantitative microbial risk assessment (QMRA) was also performed based on exposure scenarios derived from literature data. As a result, a specific set of dishwashing water reuse standards for field analysis (simple, but accurate) was finalized as follows: turbidity (<1NTU), Escherichia coli (<50cfumL−1), and pH (6–9). UV254 was recommended as a surrogate for organic contaminants (e.g., BOD5), but requires further calibration steps for validation. The developed specific water standard is the first for dishwashing water reuse and will be expected to ensure that water quality is safe for field operations, but not so stringent that design complexity, cost, and operational and maintenance requirements will not be feasible for field use. In addition the parameters can be monitored using simple equipment in a field setting with only modest training requirements and real-time or rapid sample turn-around. This standard may prove useful in future development of civilian guidelines.
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•A compact ultrafiltration system was developed for field dishwashing water reuse.•A review was conducted to recommend standards for dishwashing water reuse.•A specific dishwashing water reuse standard was developed for military use.•The water standard was cross-evaluated by monitoring reclaimed dishwashing water.
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