Continuous Water Research Articles

Mixed superoleophilic/superoleophobic hard granular media for coalescence of oil-in-water-emulsion

To enhance the coalescence separation efficiency of oil/water emulsions, the coalescence mechanism of oil droplets between two media of opposite wettability was investigated. A coalescent-bed comprising a mix of superhydrophobic and superoleophilic quartz sand, along with superhydrophilic and underwater superoleophobic quartz sand, was constructed in a coalescer. Single-factor and response surface experiments were used to study the effects of oleophilic/oleophobic sand mixing ratio, apparent velocity, initial oil concentration, bed thickness, sand particle size on coalescence-separation performance, and to determine the optimal experimental conditions. Employing the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, the agglomeration mechanism of oil droplets within the mixed particle bed was analyzed based on interfacial energy dynamics. Results indicate that the mixing ratio of the two sands significantly influences coalescence separation performance. An optimal oleophilic/oleophobic sand mixing ratio of 1:1 yielded a mass factor of 0.69 kPa−1, showcasing superior coalescence separation efficiency and an optimal balance of separation efficiency and pressure drop. Under the optimal conditions of apparent velocity of 2.7 m/h, initial oil concentration of 471.9 mg/L, bed thickness of 12.6 cm and mixed sand particle size of 0.5 mm, the oil/water separation efficiency reached 98.08 % ± 0.87 %, with effluent oil droplet size being 2.5 to 3 times larger than at the inlet. Analysis of the oil droplet coalescence mechanism revealed a synergistic effect between the two quartz sands, enhancing oil removal performance. The strong affinity of oil to the superhydrophobic and superoleophilic sand surface increases oil droplet wetting and coalescence efficiency, while the water attraction on the superhydrophilic and underwater superoleophobic sand surface forms a stable water film, improving the flux of the continuous water phase and reducing pressure drop across the bed. This study demonstrates that combining quartz sands of opposite wettability not only overcomes the limitations of single-wettability surfaces in coalescing oil removal but also achieves high efficiency and low energy consumption in oil removal.

Gravity‐driven packed bed filter, with copper‐impregnated activated carbon, for continuous water disinfection in absence of electricity

AbstractAvailability of safe drinking water is a major concern in many parts of the world. While many filtration units operating on various principles are available to combat this, most require electricity, which may not be consistently available in such areas. In the present study, we have designed and demonstrated a water disinfection system that can operate purely on gravity, without any electricity. For this, a potassium hydroxide modified copper‐impregnated activated carbon (KOH‐Cu‐AC) hybrid was used as a filter medium for disinfection, because it is less expensive, with performance comparable to previously reported hybrids containing silver. To maintain a constant water flow rate under gravity, during disinfection, a Mariotte bottle was used as the reservoir of the contaminated water. Using this and a constant head between the bottle and the treated water exit point, the required water‐filter contact time of 25 min (for decontamination) is maintained in the filter column, regardless of tank‐fill level. The demonstrated lab‐scale system can perform disinfection of simulated contaminated water (with an initial concentration of 104 CFU mL−1 Escherichia coli), for at least 6 h, with a flow rate of 150 mL h−1. The disinfection performance from the gravity‐based filter was further validated with the conventional pump‐driven filter, used for continuous disinfection of drinking water. Equivalence of results between pump‐ and gravity‐driven operations helps us to eliminate the need for power, without any compromise in disinfection efficacy. Finally, copper concentration from treated water (106 ppb at steady state) remains very well within the safe limit (1000 ppb as per USEPA guideline). Hence, the lab‐scale design of gravity‐based packed bed filter will be useful for domestic and community‐based supply of safe drinking water in resource‐constrained areas, because it eliminated electricity requirement of conventional power‐driven systems.Practitioner Points Cost‐effective KOH‐Cu‐AC hybrid is developed as a disinfection material. Mariotte bottle used for maintaining constant disinfected water flow rate works without any electrical power supply. This system can be used for getting on‐spot, continuous disinfected water supply. The concentration of copper in the treated water is well within the safety limit. It can be applicable in rural and remote areas (no electric power source) as well as natural calamity‐affected areas.

A superhydrophilic/air superoleophobic sponge based on layer by layer deposition for high-performance continuous adsorption water in oil

At present, there are few studies on the removal of water from oil, but water in fuel can cause machine malfunctions and even safety accidents, which cannot be ignored. In this study, an oil-resistant superhydrophilic/air superoleophobic sponge (SS-MS) was designed to selectively absorb water from oil. Through layer by layer deposition, polyphenols, particles, and fluorinated surfactants were assembled on the sponge, finally achieving the effect of super hydrophilic and super oil phobic in the air. The contact angle of the modified sponge SS-MS on diesel oil can reach 153°, and the absorption efficiency of water in diesel oil can reach more than 99 %. Moreover, a continuous selective absorption device for water in oil was constructed, the SS-MS sponge can still achieve a water absorption efficiency of 98 % after ten cycles. Importantly, the SS-MS has excellent mechanical and chemical stability under 80 % strain, different pH, UV irradiation times and temperatures. In addition, the materials used in this study are all green and low-pollution substances, and melamine sponge has the advantages of low price, light weight, good elasticity and high porosity. In summary, SS-MS offers a new approach to remove water from fuel and has the potential for large-scale applications.

Tracing fluorescent dissolved organic matter (fDOM) characteristics and water quality parameters: Insights from an urban industrial river to marine zone.

This study aims to identify continuous water quality changes and identify fluorescence properties from urban rivers to marine zones. Various types of natural and anthropogenic sources derived dissolved organic matter (DOM) have been identified in this study. These include soil-derived DOM, plant remnants, and soluble particles produced when organic material partially decomposes and is released by microorganisms, such as bacteria, algae, and plants. DOM was characterized using a three-dimensional excitation-emission matrix (3DEEM), parallel factor analysis (PARAFAC), and water quality parameters from the Buriganga River, Dhaka to Patenga Seaport, Chittagong, along with the Shitalakshya River, a small portion of the Padma River, and the Meghna River. To better understand the data analysis, the study area was divided into three central regions: urban industrial rivers, industrial estuarine rivers, and marine zones. In the urban industrial river, 3DEEM and PARAFAC identified five fluorophores (peaks: A, C, M, T, and Tuv) with five components: detergent-like, fulvic-like, tryptophan or protein-like, fulvic-like (C-type), and protein-like, which might originate from the industrial activities and sewage pollution. In the industrial estuarine river zone, three fluorophores have been identified (peaks: A, C, Tuv) with two known components, namely, fulvic acid (A-type) and fulvic acid (C-type), with an unknown photoproduct at Ex/Em = 295/368 (peak Tuv). Components in the industrial river zone may originate from terrestrial sources, indicating vegetation along the river. In the marine zone, four fluorophores have been identified (peaks: Tuv, A, T, C) with two components, that is, protein- or tryptophan-like and humic acid-like from coral origin. The intensities of both fulvic-like and protein-like substances were high in urban industrial river water owing to industrial activity and sewage pollution. SUVA254 suggests high aromaticity in all three regions, whereas the optical properties suggest that terrestrial and microbial components are present in the urban industrial and estuarine rivers. This further indicates that urban industrial river water quality is highly polluted. The lowest degradation potential index (DPI) in the marine zone might result from the presence of the highest number of dissolved solids in the water, and the highest DPI of industrial estuarine rivers explains the comparatively high presence of terrestrial-derived humic (A)- and humic (C)-like components in the ratio to the unknown photoproduct of mid-wavelength. PRACTITIONER POINTS: This study's uniqueness is a 220-km cruise from an urban river to a coastal seaport to analyze fluorescence properties. The study found that most water parameters were within the DoE standards, except for DO, which was consistently low. 3DEEM-PARAFAC identified five fluorophores linked to detergent, fulvic, and protein-like substances from sewage and industrial sources. Our study concludes that microbial and terrestrial sources dominate dissolved organic matter in urban, estuarine, and marine regions.

Carbon nanodots-based interfacial nanofluid for high-performance solar-driven water evaporation

Solar steam generation through volumetric heating using nanofluids is a promising approach for wastewater treatment and desalination. However, low evaporation rate and slow response time to the change in solar intensity seriously affect their cumulative evaporation performance in practice. Here, we propose an interfacial nanofluid structure for high-performance solar-driven water evaporation using carbon nanodot (CDs) nanofluid and airlaid paper. CDs nanofluid transferred down through the paper from a source water tank to form an interfacial evaporation structure and ensure continuous water supply for evaporation. The solar conversion heat was only localized on a small amount of nanofluid on the paper resulting in low heat loss to the bulk nanofluid and a fast response time of within 2 min to reach a steady evaporation rate. In addition, the flowing nanofluid on the paper can absorb environmental energy to achieve high-rate evaporation of 1.93 kg m−2 h−1 under one sun irradiation. This study provides an effective strategy to improve the performance of volumetric heating systems for solar wastewater treatment and desalination.

Internet of Things (IoT) Driven Water Management System for Efficient Level Control

Water is an essential and valuable resource in daily life, making its conservation crucial to prevent adverse effects. Storing water for domestic, industrial, agricultural, and other purposes is particularly important. Safe drinking water is increasingly becoming polluted due to the growing population and their demands for urbanization and industrialization. At the household level, some people leave electric water pumps running and either go to work or sleep, forgetting to turn off the pumps when the water container is full. This highlights the need for a reliable and continuous water supply. IoT plays a significant role in environmental monitoring, particularly in disaster management, early warning systems, and environmental data analytics. One major challenge in urban cities is water management, especially with the rapid growth of urbanization, necessitating sustainable urban development plans. To address these issues, we propose a "Water Level Monitoring System" solution. This paper presents an IoT-based water monitoring system for real-time applications. The system's sensors measure the water level in the tank, and the data is sent to a cloud server, allowing users to view it on a remote dashboard. This system can be used efficiently by both homeowners and industrial users, as well as other water utilities.

Water use efficiency and canopy temperature response of soybean subjected to deficit irrigation

Deficit irrigation is a key strategy for improving water use efficiency (WUE) under irrigated conditions. However, there is a lack of information regarding the optimal water replacement that have minimal negative effects on soybean productivity. The objective of this study was to determine the water replacement levels associated with insignificant grain yield (GY) losses in soybean crops. A rain shelter experiment was conducted using a randomized complete block design with six replicates. Eight irrigation replacement levels, L120, L100, L90, L80, L70, L60, L50, and L40, were applied, where L100 was the reference treatment that kept soil moisture content along the soil profile under field capacity conditions and all other replacement levels were a fraction of this reference level. Grain yield ranged from 2.2 Mg ha-1 in L40 to 4.4 Mg ha-1 in L100, with a significant GY reduction in irrigation levels below 70%. The average crop water stress index (CWSI) ranged between 0.26 at L120 and 0.66 at L40 irrigation levels. WUE varied significantly only for the extreme irrigation levels studied, with the greatest value at the L40 irrigation level (1.2 kg m-3) and the lowest value at the L120 irrigation level (0.65 kg m-3), whereas for the intermediate irrigation levels from 50 to 100%, the WUE was equal to approximately 1.1 kg m-3. The relationship between CWSI and GY (R2 = 0.85) suggested that the maximum GY occurred at a CWSI of 0.34. In addition, the relationship between CWSI and WUE (R2 = 0.73) showed that as evapotranspiration decreased, crop temperature increased. In conclusion, the implementation of a continuous water deficit in soybeans is feasible for farmers in water-scarce areas, but the minimum value of area productivity must be considered, even though WUE increases under more intensive values of water deficit.

Interfacial Polymerization Fabricated Polydopamine Capsules as a Step Toward a Photothermal Protocell Model

AbstractPhotothermal is a significant solar energy conversion process on Earth, and photothermal‐responsive protocells are a potential model for prebiotic chemistry. Here, polydopamine microcapsules are fabricated via emulsion droplets‐templated interfacial polymerization and investigated their potential as synthetic protocell models for photothermal conversion and utilization. DNAzyme‐mediated dopamine peroxidation and polymerization occur at the water/oil interface of the emulsion droplets, facilitated by a biphasic microfluidic technique, leading to the formation of uniform polydopamine microcapsules, which retain structural integrity upon transfer into a continuous water phase. These microcapsules exhibit size‐dependent semi‐permeability and high photothermal capability due to their broad spectral absorbance. The photothermal‐mediated temperature rise within the microcapsules triggers DNA denaturation and rearrangement, and intermittent photothermal irradiation modulates reversible phase separation of DNA condensates, mimicking membrane‐less organelles. This work suggests that interfacial polymerization fabricated polydopamine capsules are a plausible photothermal protocell model that can demonstrate aspects of primitive abiotic cellularity.

Assessment of the health risks associated with heavy metal contamination in the groundwaters of the Leh district, Ladakh.

There has been a significant rise in cancer-related mortality in the Ladakh region during the past 10years. The most common type of case is gastrointestinal cancer, which has been linked in theory by medical research to lifestyle factors, high altitude conditions, and the prevalence of Helicobacter pylori bacteria brought on by poor hygiene. Nevertheless, the precise cause of the rise in cancer cases is still unknown. Concurrently, there has been a significant change in Ladakh's water use practices due to development, improved basic utilities, and related vocational shifts. The local population has become increasingly reliant on groundwater since it provides a year-round, continuous water supply for home and agricultural uses. In this study, we assessed heavy metal contamination in groundwaters and associated human health risks. The results indicate that 46-96% of the groundwater samples have heavy metal pollution with a health hazard index > 1, which means using these groundwaters for drinking, food preparation, and agriculture is likely to result in carcinogenic and non-carcinogenic health hazards. The main heavy metal contaminants found in the groundwater of the Leh district include Cr, As, Hg, and U. According to the health risk assessment, 46-76% of the groundwater samples contain unsafe levels of Cr and As. Prolonged exposure to these levels is likely to cause gastrointestinal cancer in the local population. Acute to chronic exposure to U and Hg concentrations present in some groundwater samples is likely to result in various non-carcinogenic health risks.

Internally-cooled atmospheric water harvesting enabling improved productivity

Sorption-based atmospheric water harvesting holds promise for alleviating water scarcity, but current prototypes have not shown significant increases in practical yields despite efforts in the enlarged engineering scale. This is due to weakened heat and mass transfer with a packed sorbent bed. In this work, the desiccant-coated adsorbers were employed to fabricate the water harvesting device that incorporates internal fluid for cooling and heating during sorption and desorption. Featured with an internal cooling effect, practical water productivity could be improved by 1.75–9.96 times with a low desorption temperature (45–62 °C). The continuous water harvesting system could produce 0.77–3.98 Lwater/kgsorbent/day with a thermal energy consumption of 7.7–30.4 MJ/kg in wide climates from 20 % to 80 % RH, providing a reference for device design in the engineering view. The demonstration revealed that using natural cooling in the sorption stage has great benefits in improving water harvesting performance, which can be integrated into the building sectors or a wider range of scenarios.

Prediction of Physico-Chemical Parameters of Surface Waters Using Autoregressive Moving Average Models: A Case Study of Kis-Balaton Water Protection System, Hungary

In this work, the authors provide a case study of time series regression techniques for water quality forecasting. With the constant striving to achieve the Sustainable Development Goals (SDG), the need for sensitive and reliable water management tools has become critical. Continuous online surface water quality monitoring systems that record time series data about surface water parameters are essential for the supervision of water conditions and proper water management practices. The time series data obtained from these systems can be used to develop mathematical models for the prediction of the temporal evolution of water quality parameters. Using these mathematical models, predictions can be made about future trends in water quality to pinpoint irregular behaviours in measured data and identify the presence of anomalous events. We compared the performance of regression models with different structures for the forecasting of water parameters by utilizing a data set collected from the Kis-Balaton Water Protection System (KBWPS) wetland region of Hungary over an observation period of eleven months as a case study. In our study, autoregressive integrated moving average (ARIMA) regression models with different structures have been compared based on forecasting performance. Using the resulting models, trends of the oxygen saturation, pH level, electrical conductivity, and redox potential of the water could be accurately forecast (validation data residual standard deviation between 0.09 and 20.8) while in the case of turbidity, only averages of future values could be predicted (validation data residual standard deviation of 56.3).

Water Lily-Inspired CNT@cotton towel solar evaporator with Marangoni effect and optimal water supply for achieving zero liquid discharge desalination and irrigation

Solar-driven interfacial evaporation is an environmentally friendly technology to address the global water scarcity crisis by efficiently purifying unavailable water resources (seawater, brackish water, high salinity wastewater and various water resources). However, the inevitable contradiction between salt deposition and highly efficient water evaporation during long-term desalination remains a major challenge. In this work, we report a self-floating bionic water lily evaporator with zero liquid discharge, consisting of CNT@cotton towel with the uneven-gap structure as the photothermal material and the square groove insulation foam with controllable water supply as edge-preferred crystallization support. The formed four-building-in ramp structure generates different surface tensions along the whole ramp and brings Marangoni flow. With the combination of Marangoni flow and optimal water supply volume, salt is spatially isolated from the CNT@CT surface, the biomimetic design can achieve continuous water evaporation and salt collection (79 g m-2h−1) for 84 h in 10 wt% NaCl under edge-preferred crystallization. The purified water meets drinking water standards and is applied to growing crops. This distinctive solar evaporator provides new insights for designing a low-cost and zero-liquid-discharge evaporator, advancing its application in high-saline brines, various water resources, and irrigation.

Feasibility of continuous water and carbon dioxide splitting via a pressure-swing, isothermal redox cycle using iron aluminates

Efficient solar thermochemical fuel production has been hindered by either solid–solid heat recuperation and material stability challenges associated with conventional temperature swing operation or low reactant conversion associated with isothermal operation. Increasing the oxidation pressure has emerged as a method for achieving efficient and practical solar-to-fuel conversion with certain redox mediators. When coupled with isothermal operation, pressure-swing redox cycling with iron aluminates eliminates irreversible heating penalties associated with large temperature swings while simultaneously enabling greater reactant conversion. However, remaining questions persist regarding 1) kinetics, 2) co-splitting capabilities, and 3) continuous processing prior to implementation beyond the lab scale. Here, we provide mechanistic insight on how pressure impacts the oxidation kinetics of iron aluminates, demonstrate syngas production with H2:CO ratios ranging from 1.3 ± 0.05 to 3.2 ± 0.25, and produce fuel continuously over an eight-hour period using dual fluidized bed reactors to evaluate the key considerations for large scale implementation. This work demonstrates the feasibility of a continuous solar thermochemical fuel production process via pressure-swing, isothermal redox cycling.

Experimental study of the strategy of C6F12O and water mist intermittent spray to suppress lithium-ion batteries thermal runaway propagation

Extinguished lithium-ion battery fires can experience temperature rebound and re-ignition, necessitating proper fire extinguishing and cooling measures for battery safety. This study introduces a novel approach that integrates C6F12O and water mist as a strategy to prevent the spread of thermal runaway in lithium-ion batteries, evaluating the fire-suppression and cooling ability under various intermittent spray modes. The findings demonstrate that the strategy has a stronger suppression effect compared to continuous water spray and could prevent the spread of thermal runaway. C6F12O can extinguish fires in just 1 s. During the cooling phase, the cooling capacity generally decreases with increasing cycle period and duty cycle. Among different cycle periods, C6F12O combined with intermittent water mist spray (DC = 0.5, Pt = 2 s) exhibited the most effective cooling, significantly reducing peak temperature and providing the highest heat suppression. In terms of duty cycles, C6F12O combined with intermittent water mist spray (DC = 0.1, Pt = 20 s) achieved the longest cooling duration, lowering the temperature of Cell #3 to below 50 °C. The combination of C6F12O and intermittent water mist spray rapidly extinguishes flames, maximizes the cooling impact of water mist, and ultimately hinders the propagation of thermal runaway.

Active flow control on unsteady cloud cavitation: Insights into jet dynamics

Unsteady cloud cavitation significantly impairs the performance of marine systems. Active flow control method has shown promise in effectively reducing cavitation, yet its specific mechanisms of action require elucidation. This study investigates continuous water injection on a NACA66 (MOD) hydrofoil as an active control against unsteady cloud cavitation. Results show notable reductions in cavitation volume: 52.57 % at a cavitation number of 0.83 and 86.24 % at 1.29. Employing the Lagrangian approach, the study tracks ideal particles to explore the jet's behavior and its interaction with cavitation. The interaction between the jet and cavitation is reciprocal: cavitation draws the jet, which in turn alters the cavitation's structure. The jet's movement is synchronized with the evolution process of cavitating flow, effectively limiting the spread of attached cavitation, disrupting cloud integrity, and encircling scattered clouds to prevent their growth. The analysis identifies the jet's streamwise direction as critical in suppressing cavitation, with the normal direction providing supplementary support, and the spanwise direction having minimal impact. Furthermore, the jet promotes a condensation-dominant state in local flow regions, hindering cavitation growth by altering the water-vapor mass transport process.

Continuous low water pressure dissection technique minimizing air bubbles during underwater endoscopic submucosal dissection.

Continuous low water pressure dissection technique minimizing air bubbles during underwater endoscopic submucosal dissection.

Preliminary Validation of Persulfate Delivery Through Porous Pipe in the Vadose Zone: A Two-Dimensional Sandbox Experiment

ABSTRACT When remediating contamination in the vadose zone, which is a potential source of continuous groundwater and surface water pollution, technical challenges are often encountered. In this study, the feasibility of delivering sodium persulfate (SPS) oxidant to unsaturated soils was explored by integrating porous pipes, commonly used in agriculture, with in-situ chemical oxidation (ISCO). An evaluation of the operating characteristics of the pipe determined a recommended influent rate of < 0.1 L min−1 and an initial influent water pressure < 20 kPa to prevent percolation pore enlargement. Two-dimensional sandbox experiments revealed that pulse infiltration at an influent rate of 0.05 L min−1 was effective in creating matrix flow and lateral movement, minimizing preferential flow induced by continuous infiltration. Application of SPS (10% by wt.) under these conditions resulted in approximately 90% wetting of the sandbox area SPS flow at the experimental time that infiltrated from the pipe. After a 14-d post infiltration resting state, residual SPS concentrations ranged from 6,000 -12,000 mg/kg in soil, with soil pH levels of 3–4, ORP around 600 mV, and 40–60% decreases in soil organic carbon. This developed method helps retain the oxidant and promote chemical reactions, making ISCO a viable option for remediating unsaturated soil contamination.

Solar Water Heating System with Absorption Heat Transformer for Annual Continuous Water Heating

We show the performance of solar heating by coupling a Solar Water Heating System (SWHS) with an Absorption Heat Transformer (AHT) for annual continuous water heating. Solar Fraction (SF), Solar Heat Gain (SHG), and Auxiliary Heat (Qaux) were meticulously assessed for three Mexican cities located in the most characteristic climates (Saltillo, Toluca, and Tapachula). This rigorous assessment process ensures the reliability and accuracy of our findings. The potential reduction in net solar collector area (Ac) and storage tank volume (Vt) can be seen by comparing its annual performance to that of a conventional SWHS. Both configurations were designed to deliver the same hot water amount (0.019 kg/s, 1693.4 L/day, heating from 15.8 to 94.4 °C) and simulated using TRNSYS software version 16.01 concerning combinational systems. The results showed that SWHS-AHT achieved superior performance in solar water heating, achieving a higher SF (up to 99.6%) and SHG (up to 1352 kWh/m2-year) compared to the conventional SWHS. On the other hand, the SWHS-AHT achieved similar performance to a conventional SWHS with up to 60% less Ac. For instance, in Tapachula, a SWHS-AHT with an Ac of 150 m2 and a Vt of 18 m3 matched the performance of a SWHS with an Ac of 375 m2 and a Vt of 15 m3. Notably, both systems required the same Qaux. Thus, the Qaux requirement shows that SWHS-AHT is promising for industrial applications in Mexico, offering improved performance and a reduced footprint.

Sorption-based atmospheric water harvesting for continuous water production in the built environment: Assessment of water yield and quality

Sorption-based atmospheric water harvesting (SAWH) is a promising solution for localized high-quality water production. Application of SAWH indoors offers dual benefits of on-site water generation and humidity control. This study evaluated the use of SAWH for water production in residential or office buildings, employing a portable zeolite-based SAWH device. Over the twelve-month testing period in the arid southwestern USA, the device achieved a median water yield of 3.6 L/day at a cost 30 % less than bottled water sold in the U.S. A mathematical model was developed for predicting water yield under different temperature and relative humidity (RH) conditions. Daily water yields were well fitted with the modified Langmuir model, with absolute humidity serving as the only prediction variable. Water extracted from a well-ventilated office building generally met the drinking water standards set by USEPA. However, elevated levels of dissolved organic carbon (DOC) were detected in the samples collected from the residential house (median = 32.6 mg/L), emphasizing the influence of human activities (e.g., cooking) on the emission of volatile and semi-volatile organic compounds in the air, which consequently reside in harvested water. Aldehydes and volatile fatty acids (formate, acetate) comprised roughly 50 % of the DOC found in the AWE water. A carbon fiber filter was not effective at removing these substances, highlighting the need for further research into effective treatment methods for DOC management before the safe use of AWE water. Overall, this study provides critical insights for the practical application of indoor SAWH as a decentralized source of high-quality water and emphasizes the need to identify and manage DOC for its safe use.

Tidal Freshwater Forested Wetlands in the Mobile-Tensaw River Delta along the Northern Gulf of Mexico

Tidal freshwater forested wetlands (TFFWs) typically occur at the interface between upriver non-tidal forests and downstream tidal marshes. Due to their location, these forests are susceptible to estuarine and riverine influences, notably periodic saltwater intrusion events. The Mobile-Tensaw (MT) River Delta, one of the largest river deltas in the United States, features TFFWs that are understudied but threatened by sea level rise and human impacts. We surveyed 47 TFFW stands across a tidal gradient previously determined using nine stations to collect continuous water level and salinity data. Forest data were collected from 400 m2 circular plots of canopy and midstory species composition, canopy tree diameter and basal area, stem density, and tree condition. Multivariate hierarchical clustering identified five distinct canopy communities (p = 0.001): Mixed Forest, Swamp Tupelo, Water Tupelo, Bald Cypress, and Bald Cypress and Mixed Tupelo. Environmental factors, such as river distance (p = 0.001) and plot elevation (p = 0.06), were related to community composition. Similar to other TFFWs along the northern Gulf of Mexico, forests closest to Mobile Bay exhibited lower basal areas, species density, diversity, and a higher proportion of visually stressed individual canopy trees compared to those in the upper tidal reach. Results indicate a strong tidal influence on forest composition, structure, and community-level responses.