Additional Water Treatment Research Articles

Additive-Free, In Situ Rapid Repair of Vacancies in Fe[Fe(CN)6] Electrodes for Efficient Capacitive Deionization.

Fe[Fe(CN)6] (FeHCF) is considered a promising material for capacitive deionization-desalination of saline wastewater due to its excellent structure. However, additives are usually introduced during the synthesis of FeHCF in order to avoid [Fe(CN)6]3- vacancy defects filled by ligand water, which can result in the appearance of harmful byproducts and additional water treatment costs. In this study, an additive-free in situ vacancy repair strategy is proposed for the rapid synthesis of high-quality FeHCF in a saturated K3Fe(CN)6 solution. During the process of synthesizing FeHCF in solution, a high concentration of [Fe(CN)6]3- is found to facilitate the binding of Fe3+ to [Fe(CN)6]3- and hinder the hydrolysis and coordination reaction of Fe3+. After undergoing repair, FeHCF4 demonstrates an increased capacity and highly reversible electrochemical performance due to the robust structure. When utilized as Faraday cathodes in hybrid capacitive deionization (HCDI) systems, FeHCF4 exhibits a higher salt removal capacity (65.67 mg g-1) and lower energy consumption (0.68 kWh kg-1-NaCl) compared to unrepaired FeHCF1, while still maintaining excellent cycling performance. This environmentally friendly approach of repairing vacancies serves as a source of inspiration for the advancement of high-performance Prussian Blue analogues as capacitive sodium-removing materials.

TRACE ELEMENTS IN THE GROUNDWATER OF THE NEMYRIV DEPOSIT (UKRAINE)

The data obtained and published to date by experts in various fields indicate that there are no absolutely harmful or absolutely beneficial trace elements, the only question is their concentration and form in natural waters (including groundwater). The forms of occurrence in natural waters are particularly important for elements that may have different degrees of oxidation (e.g., arsenic, manganese) or a high ability to form complexes with water anions (e.g., nickel). In addition, the possible positive and negative effects of biological exposure to drinking water that meets the quality criteria but has slightly elevated levels of trace elements (the so-called “chronic” effect) are currently being actively discussed. The aim of this study is to determine the speciation of biologically active trace elements in the waters of the Nemyriv drinking water deposit in the Southern Bug River basin by geochemical modelling. The modelling was performed using the PHREEQC software. Trace elements found in water in concentrations measured by analytical methods are considered in this paper. The data on the content of 7 elements (As, Mn, Sr, Ni, P, Si and F) in the water of 6 wells in the Skifska area (3 wells in the ravine and 3 wells along the Ustia River) were analysed. The concentrations of Sr, Ni, P and F in the water of the wells considered in the Nemyriv drinking water deposit do not exceed the MPC. The concentration of As exceeds the MPC. Mn concentrations in the wells located in the ravine do not exceed the MPC, but significant excesses are observed in the wells located along the Ustia River. Based on the mineral composition of the rocks, the results of geochemical modelling, and the different supply mechanisms of the wells located in the ravine and along the river, it can be concluded that the manganese is of anthropogenic origin. None of the water in the Skifska area under consideration meet the water quality requirements in terms of the total specific content of pollutants of the first and second hazard classes. The main reason for this discrepancy is the increased concentration of arsenic in the water. However, this is in the relatively safe form of As(V). Phosphorus and arsenic concentrations are largely determined by co-precipitation with iron minerals. Fluorine behaves like a classical halogen in the well water of the Skifska area and is in oxidation state-1, and the main source of fluorine is biotite and fluorite. Strontium and manganese in the well waters of the Skifska area of the Nemyriv deposit are in oxidation degree +2, mainly in the form of Me2+ cations. The manganese occurrence in such a oxidation degree indicates its potential bioavailability, so it is necessary to carry out additional analytical studies to determine the concentrations of Mn and organic compounds, perform repeated geochemical modelling, assess the hazard of these waters to humans and develop additional water treatment measures.

Assessment of the Possibility of Using Treated Wastewater for Irrigation in the Republic of Crimea

The possibility of using wastewater in the Republic of Crimea for irrigation of agricultural crops was considered, the volume of which in 2021 amounted to over 50 % of the total water intake for national economic needs from all sources. It is shown that a significant part of the wastewater after its additional purification and water treatment can be used in irrigated agriculture in the Azov Sea basin, where there are agricultural lands prepared with irrigation. It is concluded that the use of other wastewater will require reconstruction and modernization of treatment facilities, drainage systems and the creation of utilities for the accumulation of wastewater, its post-treatment for irrigation purposes and transportation to irrigation systems.

The use of precipitation from water treatment plants

Urban water purification by sedimentation treatment is one of the important steps widely used in a large cities’ infrastructure. The waste of technology mentioned is a high-humidity sludge with a different mineral and biological composition and various particle size. Due to the presence of significant amounts of active fractions, these sediments can be secondary used as an additional water treatment agent. To explore this statement in a more detail, the study presented deals with the natural-derived waste obtained through Rostov-on-Don urban water sedimentation treatment with aluminum sulfate Al2(SO4)3 and polycationite VPK-402. The following parameters were analyzed: humidity, density, mass and volume fractions of solid phases coupled with its chemical and physical characteristics. It is shown that the secondary utilization of the sediment produced will lead to treatment agents’ economy up to 30%.

Failure analysis of corroded heat exchanger CuNi tubes from a geothermal plant

This study examined the premature failure of cupronickel (CuNi10Fe) tubes in a shell-and-tube heat exchanger after five months of service. An investigation to identify the root cause of the tube burst was carried out using macroscopic and microscopic inspection, chemical analysis, and mechanical analysis. The optical microscopy (OM) and scanning electron microscopy (SEM) evaluation revealed crack propagation characterized by pits and inclusions at the tube surface. This was due to the diffusion of hydrogen ions into the material from the hydrogen sulfide (H2S) rich geothermal environment. Furthermore, high tensile residual stresses of 172 MPa were recorded in the failed tube, leading to stress cracking in hydrogen-containing material. Additionally, the high sulfide content in corroded water and condensate samples suggests that the leading cause of tube rupture was through hydrogen embrittlement and sulfide stress cracking mechanism in the presence of hydrogen sulfide. Therefore, the use of laser cladding to protect tubes using functionally graded materials is recommended to mitigate degradation in aggressive environments, through careful material selection and additional water treatment to eliminate the contaminants.

METHODS OF ENERGY SAVING IN DEVICES FOR HYDRO-CRACKING OF SCALE

The cause of scale formation on the cast blanks and in the process of ivy is considered, the difference between the physical properties of the scale and base metal is shown, which reduces the quality and stability of the metal, and also complicates the processing of the product. The proposed effective way to remove the scale, which is environmentally friendly, does not require additional water treatment and does not deform the metal surface. The analysis of devices for removal of scale from the metal surface showed that the first collectors with nozzles had problems with operation: high water and energy consumption and poor cleaning of the metal surface. They are proposed to replace them with a hydraulic device with a rotary principle with rotary heads that use very low cost at high impact pressure, which also reduces electricity consumption. A comparative table of ordinary collectors and collectors with a different principle is provided by improving the design of devices for supplying fluid to the metal surface with the quality of cleaning of the metal from scale. Electricity is proposed. It is revealed that you can reduce the eager expenses by optimizing the operation of the pumping station. The optimization result is given in the form of an energy saving schedule in the period of hydraulic pauses by means of an adjustable electric drive with frequency control and hydraulic rods. It is proposed on the basis of the analysis of devices for removal of scale another way to reduce electro -energy by improving the design of water supply devices to the metal surface by improving their properties. It is revealed that not only the features of the design of the nozzles, but their optimal location, plays an important role in removing the scale. The hydraulic scale system is fully controlled by the machine, which allows to regulate the parameters of removal of the scale and to provide the required working pressure in the system, to compensate for the wear of the nozzles.

Environmental footprint of organic and conventional grapefruit production irrigated with desalinated seawater in Spain

Citrus fruit production is a major food business with global relevance in the agricultural sector. The surface area of citrus irrigated with desalinated seawater in Spain, the leading citrus producer of Europe, has increased dramatically in the last decade. Desalinated seawater has alleviated water scarcity, but is facing environmental and agronomical challenges due to its high energy consumption and high boron content. The latter particularly affects citrus production due to its sensitivity to boron, since additional water treatment may be required to prevent phytotoxicity damage. The objective of this work was twofold: to quantify and compare, for the first time, the life cycle environmental footprint of (i) organic and conventional grapefruit systems irrigated with desalinated seawater, and (ii) two on-farm boron reduction technologies, namely reverse osmosis and ion exchange resins. Life Cycle Assessment has been used to evaluate the grapefruit production systems and the two technologies. The systems compared had similar characteristics (cultivar and planting density), to enable a fair comparative assessment between organic and conventional woody crops. The results show that the organic grapefruit production had better environmental performance than the conventional system in all selected impact categories and both, land and mass, functional units. The comparison of deboronation technologies showed that ion exchange resins caused a much (one order of magnitude) lower environmental footprint than reverse osmosis. Overall, this study shows that the most environmentally friendly grapefruit system irrigated with desalinated seawater was organic production combined with the use of ion exchange resins for deboronation.

Nanoconfined MXene-MOF Nanolaminate Film for Molecular Removal/Collection and Multiple Sieving.

Balancing the trade-off between permeability and selectivity while realizing multiple sieving from complex matrices remains as bottlenecks for membrane-based separation. Here, a unique nanolaminate film of transition metal carbide (MXene) nanosheets intercalated by metal-organic framework (MOF) nanoparticles was developed. The intercalation of MOFs modulated the interlayer spacing and created nanochannels between MXene nanosheets, promoting a fast water permeance of 231 L m-2 h-1 bar-1. The nanochannel endowed a 10-fold lengthened diffusion path and the nanoconfinement effect to enhance the collision probability, establishing an adsorption model with a separation performance above 99% to chemicals and nanoparticles. In addition to the remained rejection function of nanosheets, the film integrated dual separation mechanisms of both size exclusion and selective adsorption, enabling a rapid and selective liquid phase separation paradigm that performs simultaneous multiple chemicals and nanoparticles sieving. The unique MXenes-MOF nanolaminate film and multiple sieving concepts are expected to pave a promising way toward highly efficient membranes and additional water treatment applications.

Analysis of wastewater reuse options using a multicriteria decision tool for Phuket, Thailand

The act of balancing between water demand and water supply in Phuket Island is facing challenges, suggesting water reuse options in various activities on the island should be properly promoted considering the potential benefits in a variety of dimensions. This research presented options to reuse effluent water from wastewater treatment plants for Phuket Municipality in 3 main activity groups, namely, domestic reuse, agricultural reuse, and raw water for water treatment plants (WTP). Water demand, additional water treatment trains, and the length of the major water distribution pipeline for each water reuse option were designed, and its cost and expenses were calculated. Multi-criteria decision analysis (MCDA) was used by 1000Minds internet-based software to prioritize the suitability of each water reuse option based on a four-dimensional scorecard, including economic, social, health, and environmental aspects. The decision algorithm for the trade-off scenario based on the government's budget allocation was proposed to obtain weighing without subjective expert opinions. The results revealed that recycling effluent water as raw water for the existing WTP was the first priority, followed by agriculture reuse for planting coconut, Phuket's economic crops, and domestic reuse. There was a significant difference in the total scores of economic and health indicators between the first- and second-priority options because of the difference in the additional treatment system in which the first-priority option applied the microfiltration and reverse osmosis system, which could effectively eliminate viruses and chemical micropollutants. In addition, the first priority option required a much smaller piping system than other water reuse options because it relied on the existing plumbing system of WTP, lowering the investment cost, which was a very important indicator for decision-making.

Study on Retrofitting of Small-scale Water Supply Facility using aeration and Closed-circuit Reverse Osmosis

Objectives : A water treatment system, combining aeration and reverse osmosis (RO) processes, was introduced to improve water supply facilities in a small village where additional water treatment was required due to high concentrations of natural radioactive substances, nitrate nitrogen, and fluoride. In this study, CCRO(Closed-circuit reverse osmosis) was first introduced for commercial use in Korea. With this system, we evaluated its water treatment efficiency and effectiveness of blending the aerated water and RO permeate for improved waterworks in rural areas.Methods : The removal rate of major pollutants and other ionic substances was evaluated by analyzing the water quality of raw water and unit processes. In addition, the operational efficiency of a small-scale water supply facility was verified and optimized by evaluating a change in operational characteristics depending on the blending ratio of the treated waters by aeration and CCRO processes.Results and Discussion : Up to 86% of the radon contained in raw water was removed by the aeration process within 2 hours, and 98.9% of uranium, 85.5% of nitrate nitrogen, and 82.8% of fluoride were removed by the RO process. In the case of other ionic substances, more than 80% was removed on average by the RO process. The higher blending ratio of RO permeate up to 75% resulted in the better quality of the final treated water. However, since requiring the high flux and pressure (at 1.8 m<sup>3</sup>/hr and 7.6 bar, respectively), CCRO operation resulted in a relatively high specific power consumption at 0.27 kWh/m<sup>3</sup>.Conclusion : In this study, we found that the major contaminants (natural radioactive substances, nitrate nitrogen, and fluoride) were effectively removed by the water treatment system wherein the aeration and CCRO processes were combined. In particular, it was confirmed for the first time in Korea that the stable operation and water treatment efficiency of the CCRO process was satisfactory for commercial purposes. It could produce high-quality tap water through the blending of waters treated by aeration and CCRO, expecting that meeting drinking-water quality standards would be attainable even when raw water contains high-concentration pollutants.

Use of Water from Petroleum Production in Colombia for Soil Irrigation as a Sustainable Strategy Adapted from the Oman Desert

Production water represents a major sustainability challenge for oil and gas industries, which is why various strategies have emerged globally to encourage its reuse in proactive projects. One of the most recognized strategies has been developed in the Omani desert where artificial wetlands were designed to physically and biologically treat production water. The present study proposes to adapt this strategy to a Colombian context to further study the sustainability of production water reuse. The methodology of this study consists of three phases: evaluate in-field production water through the characterization of irrigation water, identify and prioritize the variables of said strategy, and propose an adequate soil irrigation strategy for a Colombian field. An expert matrix and multicriteria analysis are used to identify the level of interaction among the variables presented, according to the criteria of experts in the field of sustainable production water management. Water quality was ranked by the experts as the most important single variable. On a scale of 1–5, the variables with the highest level of interaction (2.8) are water quality and the type of treatment seedlings, and the variables with the lowest level of interaction (1.3) are additional water treatment systems and final water use. These results have led to the formation of a hierarchy of variables according to impact, which has been used to create a triple bottom line diagram and demonstrate the feasibility of implementing the Omani strategy in Colombia.

Transmission of stony coral tissue loss disease (SCTLD) in simulated ballast water confirms the potential for ship-born spread

Stony coral tissue loss disease (SCTLD) remains an unprecedented epizootic disease, representing a substantial threat to the persistence and health of coral reef ecosystems in the Tropical Western Atlantic since its first observation near Miami, Florida in 2014. In addition to transport between adjacent reefs indicative of waterborne pathogen(s) dispersing on ocean currents, it has spread throughout the Caribbean to geographically- and oceanographically-isolated reefs, in a manner suggestive of ship and ballast water transmission. Here we evaluate the potential for waterborne transmission of SCTLD including via simulated ballast water, and test the efficacy of commonly-used UV radiation treatment of ballast water. Two species of reef-building corals (Orbicella faveolata and Pseudodiploria strigosa) were subjected to (1) disease-exposed or UV-treated disease-exposed water, and (2) a ballast hold time series of disease-exposed water in two carefully-controlled experiments to evaluate transmission. Our experiments demonstrated transmission of SCTLD through water, rather than direct contact between diseased and healthy corals. While UV treatment of disease-exposed water led to a 50% reduction in the number of corals exhibiting disease signs in both species, the statistical risk of transmission and volume of water needed to elicit SCTLD lesions remained similar to untreated disease-exposed water. The ballast hold time (24 h vs. 120 h) did not have a significant effect on the onset of visible disease signs for either species, though there appeared to be some evidence of a concentration effect for P. strigosa as lesions were only observed after the 120 h ballast hold time. Results from both experiments suggest that the SCTLD pathogens can persist in both untreated and UV-treated ballast water and remain pathogenic. Ballast water may indeed pose a threat to the continued spread and persistence of SCTLD, warranting further investigation of additional ballast water treatments and pathogen detection methods.

Influence of chemical structure of organic micropollutants on the degradability with ozonation

The increasing environmental problems due to various organic micropollutants in water cause the search of suitable additional water treatment methods. Gaining experimental data for the large amount and variety of pollutants would consume a lot of time as well as economic and ecologic resources. An alternative approach is predictive quantitative structure-property relationship (QSPR) modeling, which establishes a correlation between the structural properties of a molecules with a biological, physical, or chemical property. Therefore, in this study, QSPR modeling has been conducted using extensive validation techniques and statistical test to investigate the structural influence on the degradability of organic micropollutants with ozonation. In contrast to most of the other studies, the underlying dataset - rate constants for 92 organic molecules - were obtained under standardized conditions with defined experimental parameters. QSPR modeling was executed using a combination of the software PaDEL for descriptor calculation and QSARINS for the modeling process respecting all five OECD-requirements for applicable QSAR/QSPR-models. The final model was selected using a multi-criteria decision-making tool to evaluate the model quality based on all calculated statistical quality parameters. The model included 10 selected descriptors and fingerprints and showed good regression abilities, predictive power, and stability (R² = 0.8221, CCCtr = 0.9024, Q²loo = 0.7436, R²ext = 0.8420, Q²F1 = 0.8104). The applicability domain of the QSPR model was defined and an interpretation of selected model descriptors has been connected to previous experimental studies. A significant influence of the interpretable descriptors was put into experimental context and compared with previous studies and models. For example, the molar refractivity as a measure of size and polarizability of a molecule and the occurrence of important substructures such as a formamide group seem to decrease the removal rate constant. The contribution of lone electrons entering into resonance as well as the occurrence of fused rings were identified as influences for the increase of the degradability of micropollutants by ozonation.

EXPERIMENTAL SCALING POTENTIAL OF HEATED WATER

The previously proposed mechanism of bicarbonate ions decomposition by the H-mechanism (with the formation of H+ and CO32-) or OH-mechanism (with the formation of OH- and CO2) is confirmed experimentally without and with heating water up to 190oC. The change decomposition mechanism depends on hardness, alkalinity and pH. The H-mechanism is observed at higher pH values (pH decreases) and the OH-mechanism is observed at lower values (pH increases) in particular solutions.
 The developed technique is based on the measurement of changing the pH (ΔрНt) of the solution (at a fixed temperature of 15 to 25oC) after heating it to a given temperature (ranging from 40 to 190oC) and maintaining this temperature for at least 30 minutes. A decrease in the pH of the water after heating (ΔрНt>0) indicates the formation of carbonate ions and the need for additional water treatment to reduce the hardness, alkalinity or pH. The greater the ΔрНt, the greater the concentration of carbonate ions formed in water. If ΔрНt is zero then this temperature can be used as a water quality index. This temperature is 86.4oC for tap water in Kyiv (pH 7.4). Measurement of ΔрН in water meeting standards for water in German heating supply systems (pH 9.06, Hardness 45 μmol/dm3 - 5 times less than in Ukraine) shows that such water is not scale-safe (ΔрН150=0.15).
 The proposed technique will be able to replace the Langelier index (up to 90oC) and the carbonate index (up to 190oC) under the condition of systematic processing of experimental data obtained for the water of different compositions on its basis. This method can be used in addition to the expensive experimental method of dynamic tube blocking.

Relative contributions of different local sources to riverborne microplastic in a mixed landuse area within a tropical catchment

Information on the relative contributions of microplastics coming from different sources is important to help prioritise measures to reduce river contamination levels and limit human and ecological health risks. This paper reports on work which aimed to quantitatively assess the relative concentrations and types of microplastic delivered from differed sources to a second order river. The study was undertaken in a mixed landuse area within a rapidly urbanising catchment in Malaysia. Over a six-week period, water samples were collected from road culverts and drains in residential and industrial areas across the area to assess microplastic concentrations, while inputs from atmospheric deposition and wastewater treatment plants (WWTPs) were also quantified. Microplastic fibres and fragments were the dominant material in all sources, with the majority consisting of styrene-butadiene rubber and nylon. Culverts draining main roads were the main contributor to riverborne microplastic, delivering 42.20 ± 35.29 particles/L directly to the river channel. Road inputs were up to seven times greater than those from residential (8.53 ± 9.91 particles/L) and industrial (5.67 ± 4.88 particles/L) areas. The five WWTPs had removal efficiencies of between 30.95 ± 5.51% and 69.94 ± 22.17%, with their outflows delivering microplastics to the river in concentrations similar to those in uncontrolled residential and industrial drains. Atmospheric deposition across the study area was estimated to be 76.07 ± 32.85 particles/m2/day (=8.35 ± 5.11 particles/L). Mitigation strategies in the study area should focus on improving management of water draining roads, and re-routing discharges from domestic and industrial areas to WWTPs rather than allowing them to flow directly to the river. The low efficiencies of some of the WWTPs are not unusual, and indicate the need for additional water treatment to deal with microplastic present in wastewater.

MAIN FACTORS WHICH LEAD TO REDUCING THE RELIABILITY OF REVERSE COOLING SYSTEMS

Problem statement. The main issues that arise during the operation of circulating cooling systems are the deterioration of thermal and hydraulic characteristics, as well as corrosion processes that lead to increased operating costs for the replacement of equipment and pipelines. This is due to both the input parameters related to water quality and the operating parameters of the system related to the evaporation coefficients and the temperature difference in the circuit. Methods. The research was performed on the basis of the analysis of Ukrainian and foreign scientific sources and reporting data on the specifics of the operation of circulating water supply systems. The influence of various factors on the mode of operation of the system has been studied as a result of our own research. Scientific novelty. The analysis of influence of determining factors on work of system of circulating water supply is carried out. The controlling factor in ensuring the reliability of the circulating water supply system is determined. Practical significance. Теоретичні викладки є важливими з огляду на те, що компанії, які займаються процесами охолодження, як правило, не мають у своєму штаті інженера, який би розбирався в процесах очищення води. Інженери проектувальники теплотехнічної частини проектів не навчаються за даною тематикою і також не розуміють проблему, пов’язану з відсутністю належної підготовки води. Conclusion. A large number of factors that determine the reliability of evaporative cooling systems, shows the complexity of forecasting and calculating its trouble-free operation. The main factors that determine the reliability of evaporative cooling systems include the chemical composition of water, temperature and purge. Blowing can be taken as a control factor in the operation of the reversible system, but the purge itself usually can not prevent the formation of scale, as some compounds exceed the saturation level and settle on heat exchange surfaces and other internal devices of the system. To ensure the reliability of the systems in most cases requires additional water treatment by chemical or physical methods.

Reductions of human enteric viruses in 10 commonly used activated carbon, polypropylene and polyester household drinking-water filters

Drinking-water treatment in non-networked rural communities relies on the use of point-of-use (PoU) household filters. Source waters treated by PoU filters are often microbially contaminated, but information about human enteric virus reductions in these filters is limited. This study evaluated human rotavirus, adenovirus and norovirus reductions in 10 commonly used, new PoU carbon, polypropylene and polyester microfilters. The viruses were spiked into chlorine-free tap water (pH 8.0, ionic strength 1.22 mM), and 3 sequential challenge tests were conducted in each filter under a constant flow rate of 1 L/min. In most of the filters investigated, the norovirus and adenovirus reductions were similar (P > 0.49). Compared with the norovirus and adenovirus reductions, the rotavirus reductions were significantly lower in the carbon filters (P ≤ 0.009), which may relate to rotavirus's higher zeta potential and lower hydrophobicity. Virus reductions appeared to be dictated by the filter media type through electrostatic and hydrophobic interactions; the effects of filter media pore sizes on virus reductions via physical size-exclusion were very limited. The virus reductions in the carbon filters were significantly greater than those in the polypropylene and polyester filters (P ≤ 0.0001), and they did not differ significantly between the polypropylene and polyester filters (P > 0.24). None of the filters met the “protective” rotavirus reduction level (≥3 log10) required for household drinking-water treatment. Our study's findings highlight a critical need for additional water treatment when using PoU microfilters, for example, water boiling or ultraviolet radiation, or the use of effective surface-modified filter media to prevent drinking-waterborne infections from enteric viruses.

Robust ultrathin nanoporous MOF membrane with intra-crystalline defects for fast water transport

Rational design of high-performance stable metal–organic framework (MOF) membranes is challenging, especially for the sustainable treatment of hypersaline waters to address critical global environmental issues. Herein, a molecular-level intra-crystalline defect strategy combined with a selective layer thinning protocol is proposed to fabricate robust ultrathin missing-linker UiO-66 (ML-UiO-66) membrane to enable fast water permeation. Besides almost complete salt rejection, high and stable water flux is achieved even under long-term pervaporation operation in hash environments, which effectively addresses challenging stability issues. Then, detailed structural characterizations are employed to identify the type, chemical functionality, and density of intra-crystalline missing-linker defects. Moreover, molecular dynamics simulations shed light on the positive atomistic role of these defects, which are responsible for substantially enhancing structural hydrophilicity and enlarging pore window, consequently allowing ultra-fast water transport via a lower-energy-barrier pathway across three-dimensional sub-nanochannels during pervaporation. Unlike common unfavorable defect effects, the present positive intra-crystalline defect engineering concept at the molecular level is expected to pave a promising way toward not only rational design of next-generation MOF membranes with enhanced permeation performance, but additional water treatment applications.

Fluid dynamics analysis and performance of polymer flow regulators for polymer flooding in multilayered reservoirs

Polymer flooding, a high viscosity solution of water and polymer, is introduced as an enhancement of oil recovery methods which is pumped through injector wells to push the liquid hydrocarbon towards production wells. Nowadays, the polymer injections method through layers for different flow admissions has allowed the improvement of heterogeneous flow distribution and the oil recovery factor itself. However, choke valves are needed to get the flow control in admission layers. Nevertheless, any flow obstruction affects the polymer viscosity via mechanical degradation. The shear stress in a standard orifice waterflood regulator breaks down the polymer molecule, causing viscosity loss, and hence reducing the recovery factor properties. In order to avoid shear degradation, several proposal nonstandard regulators of flow/pressure control options have been selected. In this work, experimental and computational studies were made to evaluate the design performance of pressure regulators to inject a polymer solution. The intermittent flow patterns concept has gotten a superior performance. The experimental data from this shock absorber has shown the average viscosity loss being less than 10% and pressure drop up to 34.5 bar with a polymer concentration of up to 700 mg/L, high flowrate around 89 m 3 /d and average salinity water was used to prepare the polymer solution. It was confirmed that the computational results have achieved a good match with experimental data. These results will validate regulator design, and improve cost estimation, saving materials and additional water treatment facilities. • Polymer flood regulator must be a static choke to guarantee the shear control. • There should be a specific choke for each flow-rate. • The shear rate is the main issue of polymer mechanical degradation. • High pressure drop does not induce directly the polymer degradation. • The fluid path longitude is an important issue to design a polymer flood regulator.

Prediction of degradability of micropollutants by sonolysis in water with QSPR - a case study on phenol derivates

The increasing quantity and variety of organic contaminants discharged into surface and groundwater increase the necessity of additional and suitable water treatment methods, which can be incorporated into existing wastewater treatment plants. The huge variety of micropollutants and local variability of the composition of the organic load or matrix effects paired with multiple possible degradation processes lead to the requirement of a recommendation tool for the best possible water treatment method under given local conditions. Due to the diversity of physicochemical properties of micropollutants, such predictions are challenging. In this study, a quantitative correlation between the structural properties of certain micropollutants and their degradability using high-frequency sonolysis has been investigated. Therefore, Quantitative Structure-Property Relationship (QSPR) has been applied on a set of phenol derivates. To obtain the kinetic data, all experiments have been conducted in standardized, constant conditions for all 32 investigated phenol derivates. QSPR modelling was then executed using the software PaDEL for descriptor calculation and the software QSARINS for the overall modelling process including genetic algorithm (GA) and multiple linear regression (MLR). The final model consisting of 5 molecular descriptors was selected using a multi-criteria decision-making method based on extensive statistical parameters. The predictive power and robustness of the model was evaluated by means of internal cross validation and external validation using an independent validation set. The final selected model showed very good values for regression abilities, predictive power as well as stability (R2adj = 0.9455, CCCtr = 0.9777, Q2loo = 0.9285, CCCext = 0.9797 and Q2ext-F1 = 0.9711). The applicability domain of the QSPR model was defined based on the Williams plot and Insubria plot. The five OECD principles for the application of QSPR/QSAR modelling in industry and regulation were fulfilled in the whole process to the best of our knowledge, including the collection of the underlying experimental data as well as the entire modelling process. The final QSPR model included the molecular polarity and occurrence of hydrogen bonds as major influences on the reaction rate constants in accordance with previous studies. Nevertheless, potential biases in the selection of these descriptors due to the small size of the dataset were highlighted.