Mixing Of Effluent Research Articles

Occurrence, transformation, and transport of PFAS entering, leaving, and flowing past wastewater treatment plants with diverse land uses

Per- and polyfluoroalkyl substances (PFAS) have been detected ubiquitously throughout the environment. Wastewater treatment plants (WWTPs) have been identified as potential hotspots for the introduction of PFAS into the environment. Therefore, the occurrence, transformation, and transport of 18 PFAS in two WWTPs with varying treatment processes, prevailing land uses, and during two distinct time periods were investigated. Polar Organic Chemical Integrative Samplers (POCIS) were installed at two WWTPs in Central Kentucky during April and July of 2022. PFAS concentrations typically increased from influent to effluent at both WWTPs, regardless of wastewater treatment processes, but changes in surface water concentrations from upstream to downstream of the effluent mixing zones varied. Both WWTPs discharged the 18 PFAS at higher loads than received, indicating prevalent transformation of PFAS precursors and non-measured PFAS analytes into measurable PFAS. Nearly all measured PFAS persisted in aqueous (86–98%) compartments rather than sediment or biosolids (2–14%). All biosolids had low content of PFAS with the dominant compound being PFOS (1.59–2.60 ng/g). Based on recent US EPA proposed maximum contaminant levels, hazard indexes for drinking water were exceeded in effluent and downstream surface waters at both WWTPs. The WWTP located in a heavily developed area and downstream from a firefighting training facility, had significantly higher concentrations of most PFAS species at most monitoring sites and was less impacted by sampling period compared to the WWTP located in a moderately developed, pastured area. Findings support the importance of WWTPs and land use practices as contributing to PFAS impact to downstream ecosystems along with potentially increasing strains on downstream drinking water source waters in regions that are surface water dependent.

Modeling the geochemical evolution of mine waters during mixing

This study focuses on assessing the hydrogeochemical processes influencing the mobility of dissolved metal and metalloid species during mine effluent mixing. Field samples were collected to characterize effluents at an active gold mine located in the Abitibi Greenstone belt in western Québec, Canada. Controlled laboratory mixing experiments were further performed with real effluents. In situ physicochemical parameters, concentrations of major dissolved ions and trace elements were analyzed. Mineralogical analyses were also performed on precipitates from the laboratory mixtures. The data were used for statistical analyses and for modeling the geochemical evolution of effluents using PHREEQC with the wateq4f.dat database (with modifications). The results suggest that the formation of secondary minerals such as schwertmannite, Fe(OH)3, and jarosite could significantly affect the concentrations of trace elements in effluents. The precipitation of secondary minerals immobilized trace elements through coprecipitation and sorption processes. The main limitations of the modeling approach used here include the evaluation of the ion balance for low pH samples with high Fe and Al concentrations and the omission of biological processes. The approach provides insights into the geochemical evolution of mine effluents and could be adapted to several mining sites as a tool for improving water management.

Liquid treatment with a plasma jet surrounded by a gas shield: effect of the treated substrate and gas shield geometry on the plasma effluent conditions

The treatment of a well plate by an atmospheric pressure plasma jet is common for in vitro plasma medicine research. Here, reactive species are largely produced through the mixing of the jet effluent with the surrounding atmosphere. This mixing can be influenced not only by the ambient conditions, but also by the geometry of the treated well. To limit this influence and control the atmosphere, a shielding gas is sometimes applied. However, the interplay between the gas shield and the well geometry has not been investigated. In this work, we developed a 2D-axisymmetric computational fluid dynamics model of the kINPen plasma jet, to study the mixing of the jet effluent with the surrounding atmosphere, with and without gas shield. Our computational and experimental results show that the choice of well type can have a significant influence on the effluent conditions, as well as on the effectiveness of the gas shield. Furthermore, the geometry of the shielding gas device can substantially influence the mixing as well. Our results provide a deeper understanding of how the choice of setup geometry can influence the plasma treatment, even when all other operating parameters are unchanged.

Scale avoidance during waterflooding by optimized effluent mixing

Scale avoidance during waterflooding by optimized effluent mixing

Concentration Field Estimation on Effluent Mixing and Transport With a Parameter‐Based Field Reconstruction Convolutional Neural Network and Random Forests

AbstractEstimating the concentration field of effluent mixing and transport is a challenging task because of the complex mechanisms and three‐dimensional (3D) variability, but it is of great importance for water quality assessment and water resources management. Sophisticated numerical models based on the 3D computational fluid dynamics (CFD) technique can provide accurate predictions, but they are computationally expensive and require high‐level 3D CFD expertise, impeding their widespread usage. This work primarily develops a Parameter‐based Field Reconstruction convolutional neural network (PFR‐CNN) that can predict the complete concentration field of a target variable using the main influencing parameters, and explores the possibility of employing the proposed network to model the process of effluent mixing and transport. A validated numerical solver, TwoLiquidMixingFoam, was utilized to provide extensive data for multiple vertical buoyant effluents. A PFR‐CNN was developed to estimate the concentration fields based on the densimetric Froude number (F) and normalized port spacing (S/D). The network was developed using the training‐validating dataset from the numerical dataset, and further assessed using additional testing data. A random forest model was also developed, and the results showed that both methods can provide good performance, but the PFR‐CNN method was more robust and required less disk storage space. The results of our study demonstrated that the proposed PFR‐CNN approach is a promising tool for estimating effluent mixing and transport, and can be potentially leveraged to estimate other variables in the field of water resources with the governing parameters.

Influence of ozone microbubble enhanced oxidation on mine effluent mixes and Daphnia magna toxicity

The mining industry often must mix different kinds of water on the mine site during pre-treatment or post-treatment before the final discharge of the treated water to the environment. Microbubble ozonation has proven to be efficient in the removal of contaminants of concern from mine water, such as metals, metalloids, and nitrogen compounds, which can persist in the environment and entail toxicity issues. This study evaluated the efficiency of ozone microbubbles combined with lime precipitation on contaminant removal and its impact on toxicity for Daphnia magna with five different mine effluent mixes from an active mine site located in Abitibi-Témiscamingue, QC, Canada. For the non-acidic mixes, two scenarios were tested: first, pre-treatment of metals using lime precipitation and a flocculant was conducted prior to ozonation; and second, ozonation was conducted prior to metals post-treatment using the same precipitation and flocculation technique. Results showed that the NH3–N removal efficiency ranged from 90% for the lower initial concentrations (1.1 mg/L) to more than 99% for the higher initial concentrations (58.4 mg/L). Moreover, ozonation without metals pre-treatment improved NH3–N treatment efficiency in terms of kinetics but entailed abnormal toxicity issues. Results of bioassays conducted on water with metals pre-treatment did not show any toxicity events but showed abnormal toxicity patterns on the mixes treated without metals pre-treatment (diluted effluents were toxic, while undiluted were not). At 50% dilution, the water was toxic, probably due to the potential presence of metal oxide nanoparticles. The confirmation of the source of toxicity requires further investigation.

Extraction, analysis, and occurrence of per- and polyfluoroalkyl substances (PFAS) in wastewater and after municipal biosolids land application to determine agricultural loading

Given the ubiquitous detection of per- and polyfluoroalkyl substances (PFAS) within numerous soil and water environmental compartments, there is a need for global understanding of current methodologies for extracting water, solids, polar organic chemical integrative samplers (POCIS), and plant tissue for these substances. This study provides details of several current extraction methods, demonstrates the use of POCIS in monitoring these compounds in a wastewater environment, and provides evidence of detectable levels of certain PFAS compounds within Midwestern municipalities and agroecosystems. Validated extraction procedures help characterize occurrence and release of 18 PFAS in a midwestern wastewater treatment plant (WWTP), surface water, runoff after land application of biosolids to agricultural test plots, infiltration into topsoil, and uptake by grain sorghum. Of the compounds measured, 14 PFAS were detected at least at one sampling site or type. The average total (Σ PFAS) dissolved phase time-weighted average (TWA) concentration in wastewater influent, effluent and in the upstream and downstream effluent mixing zone (EMZ) sites in the receiving stream, respectively, were 27.9, 132, 37.7, and 71.4 ng L−1. Long-chain PFAS dominated most of the aqueous compartments, and perfluoroalkyl acids (PFAAs) occurred in the WWTP and receiving surface waters. Total Σ14 PFAS measured in municipal biosolids applied to soils were 22.9 ng g−1 dw with long-chain PFAS comprising 77.5% of the cumulative PFAS mass. Perfluorooctanesulfonic acid (PFOS) was the most abundant compound detected in biosolids at the highest concentration (9.40 ng g−1 dw). Accumulation in WWTP biosolids was estimated to occur at a rate of 72.8 g day−1 dw based on the difference between influent and effluent time weighted average concentrations. PFAS were detected in both surface soil and runoff after land application of biosolids, but also in control plots consistent with background PFAS contamination. PFAS concentrations in surface runoff decreased over time from plots treated with biosolids. These results provide evidence of the introduction of PFAS to agroecosystems from wastewater effluent and land application of biosolids in the Midwest.

A novel pre-dilution, swirling jet diffuser to enhance effluent mixing: Hydrodynamics and dilution performance

Diffusers are widely-used to quickly dilute effluents in receiving water bodies. This study proposed a novel diffuser that pre-mixes effluent with ambient water before discharging and that uses the swirling jet to further enhance near-field dilution. The nozzle of the diffuser was examined in two ambient flow conditions: co-flow and counter-flow that are commonly-met in the environment such as oceans due to tidal effect. Physical experiments were first conducted in co-flow on its dilution performance and hydrodynamics, using heated water as the effluent. A 3-D CFD model was developed and calibrated the co-flow scenarios, and then used to investigate the diffuser in counter-flow. The results showed that the nozzle can effectively reduce the maximum temperature rise of the effluent by about 50 % before discharging. The swirling jet from the outlet has a larger shear area, half-width and entrainment rate, enabling the effluent to be rapidly diluted to a minimum of around 10 times at x/D = 6 in co-flow, whereas the dilution for conventional nozzles is about 1 because of the potential core. The flow amplification ratio (α) decreases gradually with increasing velocity ratio in co-flow but increases with increasing velocity ratio in counter-flow. The counter-flow reduces the water drawn into the device; however, the pre-dilution effect at the outlet remains stable. The near-field dilution in counter-flow was significantly enhanced than that in co-flow. Environmental regulations at outfalls and mixing zones can be more easily met using this novel diffuser.

Impact of Textile Effluents on Soil in and Around Pali, Western Rajasthan, India

The study was carried out to investigate the spatial effects of industrial effluents on physicochemicalproperties of soil around the textile industrial area of Pali. The analysis of soil becamean apparent need for best agriculture practices. Textile industries discharge plenty of pollutantsthat get mixed up with water bodies. These effluents contain largely alkalis, residual dyes,soluble salts, organic carbons, oils and heavy metals etc. These water bodies are basicallythe parts of Bandi River. The soil sites near to the end points or nearby points of this riverbecame polluted due to mixing of industrial effluents coming from textile industries locatednearby this river. When same wastewater is used for irrigation it adversely affects the soilproperties. Disposal of industrial waste is the major problem responsible for soil pollution. Thephysicochemical analysis of soil was done for one year and present reveals that pH was foundmore than standard levels and other parameters was found in higher concentration. Thus thereis need for treatment of textile effluent before they are discharged into the environment.

Using an Adaptive Neuro-Fuzzy Inference System to Predict Dilution Characteristics of Vertical Buoyant Jets Subjected to Lateral Confinement

In order to predict the dilution characteristics of vertical buoyant jets constrained by lateral obstructions, we propose a new method based on a commonly used machine learning algorithm: the adaptive neuro-fuzzy inference system (ANFIS). By using experimental data to train and test the ANFIS model, this study shows that it had better performance than commonly used empirical equations for laterally confined jets and another artificial intelligence technique—genetic programming. The RMSE values of the ANFIS-based model were lower, and the R2 values were higher, compared with those of the empirical equation and genetic programming models. The reduction in RMSE achieved by using ANFIS to replace the empirical equations or genetic programming algorithm exceeded 20%. This research confirms that the ANFIS technique has real potential in the development of effective and accurate models that can be used to estimate the dilution characteristics of a vertical buoyant jet subjected to lateral confinement, providing a new avenue for the prediction of dilution characteristics using artificial intelligence techniques, which can also be utilized for other effluent mixing problems in marine systems.

Modelling mixing and transport of radioactive effluents in water reservoirs: an application to the operation of a fusion facility

The aim of the present study is to model mixing and transport of radioactive effluents in the course of time between two water reservoirs. To test the model, a hypothetical case study is presented of liquid effluents potentially released during normal operation of a fusion neutron source devoted to radioisotopes production. A suitable example is an accelerator-driven intense D-T 14 MeV neutron source relying on T and D ion beams, with the potential to provide a neutron yield in the range \( 5{-}7 \cdot 10^{13}\) s-1. It is expected that during normal operation a number of radionuclides will be produced and managed. The present report discusses the mechanisms and parameters which affect and control the fate of radionuclides potentially released into two connected water reservoirs during normal operation of the plant. A mathematical mixing model is developed that describes groundwater flow and radioactive transport between the two basins. The aim of this study is to estimate the amount of radioactivity concentration in both water reservoirs at any time, an information that can be used for radiation protection purposes.

High-Resolution Nonhydrostatic Outfall Plume Modeling: Cross-Flow Validation

AbstractMarine outfalls discharge wastewater on the inner shelf and are designed to encourage rapid effluent mixing sufficient to maintain a submerged wastefield. A high-resolution nonhydrostatic R...

The Effect of Irrigation with Magnetically Treated Effluent on Chemical Properties and Soil Heavy Metals

Due to increasing population and limited food resources, the share of access to agricultural water and soil resources is declining and has faced human beings with the great challenge of food security and regional and international crises. Heavy metal toxicity in plants causes disorders in the plant that may eventually reduce plant growth. One of the methods that can be used to remediate the soil is the use of magnetic water. In this study, the effect of using magnetically treated effluent on the chemical properties and traceability of soil heavy metals was investigated. For this purpose, a factorial experiment was conducted in a randomized complete block design with three replications in 2020 at Babolsar city. Treatments include irrigation with well water (W1), irrigation with mixing 25% of effluent and 75% of well water (W2), irrigation with the mixing of 50% of effluent and 50% of well water (W3), irrigation with mixing of 75% of effluent and 25% of water Well (W4), irrigation with 100% effluent (W5) under magnetic field (I1) and without magnetic field (I2) was. The results showed that the effect of irrigation type and water and effluent mixing on electrical conductivity, solutes, and heavy metals in the soil at different depths was significant at 1% probability level. On average, irrigation with magnetic water reduced electrical conductivity by 30.43%, lead by 35.25%, and cadmium by 56.11% in the soil profile. In treatments with higher effluent mixing percentages, the number of solutes increased in different soil depths, which was due to higher amounts of elements, especially heavy metals in the effluent. Therefore, by using magnetic technology to reduce the solutes and heavy metals in the soil, the conditions for better cultivation in terms of reducing the toxicity of plants to absorb heavy metals can be provided.

Investigation on fog formation of LNG ambient air vaporisers

Fog formation and mitigation have attracted increasing attention when vaporising cold liquids, such as LNG. The fog formation process during AAV (Ambient Air Vaporiser) operations for LNG regasification is discussed in this study to obtain an in-depth understanding of the effect of both ambient conditions and AAV operating conditions. A multiphase CFD model is applied to simulate fog formation during the mixing of cold AAV effluents and warm & humid ambient air. An operational AAV site is taken as an example to establish the base case of fog formation. Two key parameters, fog bypassing rate and air intake temperature, are monitored to understand the entrainment of cold effluents at AAV air inlet. Parametric studies are conducted to investigate the effect of various air conditions on fog formation comprehensively such as wind direction, wind speed, relative humidity, and AAV operating conditions such as exit velocity, effluent temperature, and air upflow. It is found that the model can help understand the fog formation process and the phenomenon of fog bypassing, which can be used to optimise the AAV operating conditions and investigate the potentials for fog mitigation.

Mixing characteristics of 45° inclined duckbill dense jets in co-flowing currents

The use of duckbill valves in submerged outfalls for dense effluents is now prevalent to prevent the intrusion of ambient water into the outfall pipe during periods of low production of the facility. In the present study, an experimental investigation was conducted using the technique of Planar Laser Induced Fluorescence (PLIF) to examine the mixing characteristics of 45° inclined dense jets from a duckbill shape nozzle in co-flowing currents. The measured characteristics included the jet trajectory, concentration decay, centreline peak dilution and cross-sectional concentration distribution. The Froude number ranged from 10 to 25, and the nominal Froude number from 0.2 to 3.0. Two mounting orientations of the duckbill nozzle, namely vertical and horizontal, were also investigated. The experimental results showed that two regimes, namely dense-jet- and co-flow-dominated, can be clearly observed. When the co-flow velocity increases, the centreline peak height and dilution of the inclined dense jet decrease. Comparing to the available results in the literature for inclined circular dense jets, the centreline peak dilution for inclined duckbill dense jets is generally higher. In other words, the installation of the duckbill valve also contributes to the mixing of the dense effluent with surrounding ambient waters, in addition to preventing the ambient intrusion. With respect to the mounting orientation, the horizontal induces a relatively higher dilution but also a larger centreline peak height. Thus, the horizontal orientation would be preferable when the cover water depth is sufficient, while the vertical orientation can be considered in shallow waters for full submergence.

Physical and Chemical Technologies of Metal Mining and Water Resources

The article is devoted to minimizing the negative impact of mining on the water resources of the mining regions. An assessment is made of leaching technologies with the involvement of non-conventional reserves for traditional methods of mining, reducing costs and lowering the level of environmental impact, including water resources. A reference is given on the use of leaching technologies for the development of natural and technogenic deposits in Russia. The mechanism of contamination of water resources with reagents and products of ore mining and processing is described. The typification of the processes of water migration of substances and components of underground leaching solutions is proposed. The zones of interaction between mineral deposits and water resources are differentiated. Fundamental differences of technology are formulated by the criterion of impact on water resources. An example of preventing the mixing of clean water and industrial effluents by creating a barrier in practice of a mining enterprise is given. It is concluded that the use of technologies with leaching of metals from ores at the place of their localization is promising

Microbial contamination and its associations with major ions in shallow groundwater along coastal Tamil Nadu.

Microbes in groundwater play a key role in determining the drinking water quality of the water. The study aims to interpret the sources of microbes in groundwater and its relationship to geochemistry. The study was carried out by collecting groundwater samples and analyzed to obtain various cations and anions, where HCO3-, Cl- and NO3- found to be higher than permissible limits in few samples. Microbial analysis, like total coliform (TC), total viable counts (TVC), fecal coliforms (FC), Vibrio cholera (V. cholerae) and total Streptococci (T. streptococci) were analyzed, and the observations reveal that most of the samples were found to be above the permissible limits adopted by EU, BIS, WHO and USEPA standards. Correlation analysis shows good correlation between Mg2+-HCO3-, K+-NO3-, TVC- V. cholerae and T. streptococci-FC. Major ions like Mg+, K+, NO3, Ca2+ and PO4 along with TS and FC were identified to control the geochemical and microbial activities in the region. The magnesium hardness in the groundwater is inferred to influence the TVC and V. cholerae. The mixing of effluents from different sources reflected the association of Cl with TC. Population of microbes T. streptococci and FC was mainly associated with Ca and Cl content in groundwater, depicting the role of electron acceptors and donors. The sources of the microbial population were observed with respect to the land use pattern and the spatial distribution of hydrogeochemical factors in the region. The study inferred that highest microbial activity in the observed in the residential areas, cultivated regions and around the landfill sites due to the leaching of sewage water and fertilizers runoff into groundwater. The concentrations of ions and microbes were found to be above the permissible limits of drinking water quality standards. This may lead to the deterioration in the health of particular coastal region.

Surface Water Pollution by Untreated Municipal Wastewater Discharge Due to a Sewer Failure

The study is an attempt to assess the pollution impact on the aquatic ecosystem related with an emergency discharge of untreated municipal wastewater from the “Czajka” wastewater treatment plant (WWTP) in Warsaw. The present case study is based on the analysis of available monitoring data for chemical oxygen demand (COD), total nitrogen (TN), ammonia nitrogen (N-NH4), and total phosphorus (TP) in the effluent mixing zone (MZ), the stretch of the river and before the discharge point. Data analysis was supported by a basic statistical analysis based on Pearson’s correlation coefficient. The results proved the importance of efficient and reliable nutrient removal technologies used in modern WWTPs. A statistically significant correlation was achieved between the COD (r = 0.567) and TP (r = 0.714) discharged loads and their concentration in the MZ. However, no significant correlation has been identified with TN and N-NH4. Furthermore, the dissolved oxygen (DO) deficits in the MZ were observed within 7 days of the discharge period resulting in an average DO concentration decrease from 8.4 to 7.1 mgO2/L. The river stretch has not been affected by DO deficits while the average observed DO concentration 30 km behind the discharge point was 9.1 mgO2/L. The analysis results present the pollutants assimilation capacity of a river ecosystem and its real reaction to sudden excessive nutrient loads discharge.

Evaluation of Point Source Pollutants impact on Water Quality and Self-purification Capacity of Abay River in Ethiopia

This study was conducted to evaluate influence of point source pollutants on self-purification capacity of Abay River within 8 kms from Lake Tana to Sebatamit. For assessment of the overall water quality level, the water quality index was used. The river's self-cleaning potential was assessed based on physicochemical parameters as indicators and using the modified Streteer-Phelps model after selecting the best reaeration coefficient through velocity and depth measurements. The outcome of the study showed that TDS, EC, BOD5, Ammonia, temperature, pH, and salinity were found within the permissible limits of EPA. The turbidity was higher than the WHO limit at sampling point two and DO value was below the WHO and EPA limit at sampling points two, three, four, five and six. The result shows that the critical distance and time in which the river attains its self-purification capacity is at 1.3, 2.8 and 0.3 kms from Bahirdar Textile, Bahir Dar municipal and Habesha Tannery Effluent mixing points for 1.68, 0.82 and 0.48 hour, respectively. This showed that the river have good purification capacity at a moment even though the point sources are discharging an effluent which is not properly treated. Keywords: Physicochemical parameters, Reaeration coefficient, Water Quality Index DOI: 10.7176/CER/12-3-01 Publication date: March 31 st 2020

Benthic Foraminifera Response to Ecosystem Pollution in the Uppanar Estuary, Tamil Nadu Coast, India

A total of 14 surface (0-1cm) sediment grab samples and bottom water samples were collected at water depths varying from 0.8 to 2.5m in the Uppanar estuary. All the samples were analyzed to recognize the spatial distribution of benthic foraminifer assemblages and their relationship with environmental variables. The values of physicochemical parameters of bottom waters revealed that normal marine to hyposaline, low DO and high pH conditions were prevailing at the water-substrate interface at the time of sampling. The pH varies from 8.3 to 7.8, salinity from 32.46 PSU to 20.24 PSU, the DO from 5.4ml/L to 2ml/L from estuarine mouth to upstream direction. A total of 54 benthic foraminifer species belonging to 18 genera are identified and the faunal assemblages are dominated by Ammonia parkinsoniana, A. beccarii, A. tepida and Quinqueloculina spp. The dominance of Ammonia at all stations infer that it has a high tolerance to environmental variables and also reproduces more periodically than other taxa. The abundance and diversity (species richness) of living and total benthic foraminifera roughly corroborate the trends of salinity, pH and DO, indicating that these ecological variables largely affect the distribution of foraminiferal assemblages. The relative richness of species is high in lower estuary (stns.1–3), moderate in the middle estuary (stns. 4–7) and low in upper estuary (stns.8–14). The species richness in comparable samples is an indicator of environmental health, thus low values signifying deteriorated environmental conditions in the middle and upper estuarine zones. These estuarine zones are proximal to outfall of industrial effluents, resulting in low species richness and frequency. Four biotopes are recognized by cluster analysis of the total (live+dead) foraminiferal abundance data and their distribution are closely related to variations in salinity, DO and other parameters related to the hydrodynamics of the region. The unsystematic grouping of stations as disclosed by cluster analysis for total foraminifera suggests that the middle and upper estuarine zones are severely stressed due to industrial pollution. The FORAM index (FI) ranging from 1 to 1.45 indicates that estuary is environmentally stressed and inhospitable for symbiotic foraminifera. The Foram Stress Index (FSI) ranges from 0 to 4.23 and the decreasing trend of values indicate that severity of pollution increases in the upstream direction. Stations 1,2 and 4 are moderately polluted and the remaining are highly polluted. Ammonia-Elphidium index (AEI) with >90 at stns. 3–13 indicates increased hypoxic conditions, probably prevailed due to the mixing of industrial effluents. The species diversity indices (H’, M, D and J) show a positive correlation with each other and low values of these indices clearly denote serious environmental degradation of the ecosystem. The foraminifer distribution data of this study will form the baseline against which future environmental monitoring of the Uppanar estuary will be compared.