Reactor For Water Treatment Research Articles

Improving membrane fouling via high phyllosilicate properties of ZnO-Kaolin in pilot-scale hybrid membrane photocatalytic reactor (MPR) for superior river water treatment

A study evaluated a pilot-scale hybrid membrane photocatalytic reactor (MPR) using ZnO-Kaolin to treat polluted river water. ZnO-Kaolin was successfully synthesised and characterised using various methods, such as X-ray diffraction (XRD), fourier-transform infrared (FTIR), and field emission scanning electron microscopy (FESEM). XRD and FTIR analyses verified the purity of ZnO-Kaolin, showing no impurities, while FESEM revealed ZnO nanoparticle growth on kaolin surfaces. Additionally, the ZnO-Kaolin band gap was shifted, demonstrating enhancement of photo-degradation efficiency. Optimisation identified pH 5 as the most effective condition for treating the polluted Sembrong River via pilot-scale hybrid MPR integrated with ZnO-Kaolin, achieving significant removal of ammoniacal nitrogen (85.71 %), chemical oxygen demand (91.53 %), biochemical oxygen demand (84.93 %), and suspended solids (99 %). This innovative system also regulated water quality parameters, enhancing pH to 6 and dissolved oxygen to 6.3 mg/L while minimising membrane fouling. This innovative approach has promising potential for commercial-scale water pollution control.

Multi-Scale Development and Integration of Granular Activated Carbon Electrodes in Multiphase Electrochemical Systems

Providing clean water remains a significant challenge in underserved areas that lack access to public water systems or are affected by extreme natural events like hurricanes. Electrochemical technologies show promise for developing affordable and effective water treatment systems due to their ability to efficiently oxidize contaminants. Particularly, the electrochemical synthesis of in-situ reagents, such as H2O2, systems can oxidize contaminants over the full range of pH with high oxidation potential, leaving only water and oxygen at the end of process, making it a safe and effective method for water treatment. This study is focused on integrating carbon-based electrodes into electrochemical water treatment systems emphasizing their scalability, cost effectiveness, and the efficient generation of reactive oxygen species (ROS). By employing multiscale computational approaches, we develop a comprehensive mechanistic understanding and optimization of ROS generation at the surface of granular activated carbon (GAC) electrodes. Using reactive molecular dynamics simulations, the thermodynamic and transport properties of water-based electrolyte (e.g., adsorption, viscosity, and diffusion) are investigated as a function of the GAC particle size and chemistry. The obtained results show that tuning the GAC particle structure at nanoscale can improve the local diffusion rates by three times. Subsequently, multiphase continuum simulations are used to integrate the GAC electrodes in full electrochemical systems through optimizing the dispersion and the solid-liquid-gas interactions in a reactive environment. The computational findings reveal that higher production of H2O2 and are observed at optimized electrode porosity values when the GAC electrodes are integrated at the system level. These observations are linked to the complex reactive solid-fluid interactions. Specifically, the electrochemical oxygen bubble splitting and coalescence are minimized by optimizing the electrode porosity, which improves the dispersion mass transfer processes by at least one order of magnitude. This leads to higher generation rates of ROS and enhanced degradation of water contaminants. These mechanistic observations will help in designing and scaling up carbon-based electrodes for developing efficient and cost-effective electrochemical water treatment reactors.

Laser Patterning of Porous Support Membranes to Enhance the Effective Surface Area of Thin-Film Composite-Facilitated Transport Membranes for CO2 Separation.

Although thin-film composite membranes have achieved great success in CO2 separation, further improvements in the CO2 permeance are required to reduce the size and cost of the CO2 separation process. Herein, we report the fabrication of composite membranes with high CO2 permeability using a laser-patterned porous membrane as the support membrane. High-aspect-ratio micropatterns with well-defined micropores on their surface were carved on microporous polymer supports by a direct laser writing process using a short-pulsed laser. By using a Galvano scanner and optimizing the laser conditions and target materials, in-plane micropatterns, such as microhole arrays, microline grating, microlattices, and out-of-plane hierarchical micropatterns, were created on porous membranes. An aqueous suspension of hydrogel microparticles doped with an amine-based mobile carrier was sprayed onto the patterned surface to form a defect-free thin separation layer. The surface area of the separation layer on the patterned support is up to 80% larger than that of flat pristine membranes, resulting in a 52% higher CO2 permeance (1106 GPU) with a CO2/N2 selectivity of 172. The laser-patterned porous membranes allow the development of inexpensive and high-performance functional membranes not only for CO2 separation but also for other applications, such as water treatment, cell culture, micro-TAS, and membrane reactors.

Design Rationale for CO2 Separation Membranes with Micropatterned Surface Structures.

Here, we report the design rationale of CO2 separation membranes with micropatterned surface structures. Thin film composite (TFC) membranes with micropatterned surface structures were fabricated by spray coating amine-containing hydrogel particles on the top of micropatterned porous support membranes, which were synthesized by a polymerization-induced phase separation process in a micromold (PIPsμM). The pore size of the support membranes was optimized by tuning the proportion of good and poor solvents for the polymerization process so that the microgels would be assembled as a defect-free separation layer. The relationship between the size of the micropatterned structures on the surface of the support membrane and the thickness of the separation layer was optimized to maximize the surface area of the separation layer. The rationally designed micropatterned TFC membrane showed a CO2 permeability (835.8 GPU) proportional to the increase in surface area relative to the flat membrane with a high CO2/N2 selectivity of 58.7. The rational design for micropatterned TFC membranes will enable the development of inexpensive and high-performance functional membranes not only for CO2 separation but also for other applications such as water treatment and membrane reactors.

PENGOLAHAN AIR TELAGA UNTUK MEMENUHI KEBUTUHAN AIR BERSIH DI DAERAH SETROHADI DUDUK SAMPEYAN GRESIK

There are several problems in Setrohadi Village, Duduk Sampeyan District, Gresik Regency, such as the lack of a clean water source from the lake which they use for their daily needs. To overcome this problem, lake water is processed into clean water by building a water treatment reactor and combining it with an upflow aeration and filtration system. Filtration is carried out using several filter materials including quick sand filter, manganese filter, zeolite filter, activated carbon filter, and paranet. Apart from that, two materials are also used which are key to water purification, namely silica sand and carbon. The aim of processing lake water into clean water is to meet the needs of the Setrohadi Village community for clean water, to improve the quality of lake water, and to provide feasibility for water consumption. The result of this water treatment is that the people of Setrohadi Village can enjoy clean, safe and quality water. From tests using variations in the use of activated carbon and silica sand, it was found that pH = 6.77, TDS = 249 ppm, %Cl = 0.02% and Cl = 524 mg/L. From the test data it can be concluded that the pH obtained is almost neutral which can be used for daily needs and consumption, so that the requirements for clean water have been met.

Recent advances in water falling film reactor designs for the removal of organic pollutants by advanced oxidation processes: A review

Chemical wastewater from industrial and urban activities is a major environmental concern. Advanced oxidation processes (AOPs) have emerged as efficient techniques for the removal of persistent organic pollutants from wastewater. AOPs generate highly reactive hydroxyl radicals (•OH) that effectively degrade and mineralize a wide range of organic contaminants in aqueous solutions. Research is ongoing to find simple and efficient reactor designs for AOPs. Water falling film (WFF) reactor designs have been effectively utilized for the removal of various organic pollutants from wastewater. This review provides an overview of the development and application of WFF reactor designs for organic pollutants degradation by various AOPs. This work summarizes recent studies on treating organic pollutants, highlights current challenges in applying WFF reactors for water treatment using AOPs, and proposes future research directions. The review aims to guide researchers and stimulate further investigations into practical applications of WFF reactors in wastewater treatment.

Thermal and multilayer analysis of magnetised dusty fluids under electroosmosis and pressure-driven effects in a microchannel

The study of an immiscible fluid flow models is complex in nature and it has crucial applications in engineering and industry, such as powder technology, dust assortment, dust in gas cooling systems, retrieval of crude oil, waste water treatment, sedimentation process and nuclear reactors. Therefore, the current study deals with the steady flow of two immiscible dusty Newtonian and Casson fluids in a horizontal porous microchannel. The effect of magnetic field, electroosmotic forces, thermal radiation, viscous dissipation, Joule heating and chemical reactions have been considered into account. Initially, the flow model is considered with the well-known set of partial differential equations. Under the assumptions and non-dimensional quantities, the coupled governing differential equations have been transmuted to the non-dimensional ordinary differential equations. The exact solutions for the velocity, temperature and concentration of the fluid and dusty phases have been obtained in both the regions. The behaviour of non-dimensional emerging constraints on the flow, thermal and mass characteristics have been expressed through graphical representations. It is noticed that the dust particles volume fraction enhances the dusty Newtonian fluid as well as the dusty Casson fluid temperature. Escalating the values of Schmidt number declines the concentration profile of Newtonian and non-Newtonian dusty fluids.

Reflector design for the optimization of photoactivated processes in tubular reactors for water treatment

Photoactivated advanced oxidation processes have excellent performance in removing recalcitrant pollutants from water. However, the high operating cost associated with the energy consumption of UV lamps is a big drawback. In this work, the design and optimization of the reflector in a tube-in-tube membrane photoreactor were carried out using a ray tracing methodology to maximize the light deployed to the reactor. Simulations were carried out using different lamps/reactor arrangements with 1, 2 and 3-sided flat reflectors and with circular and parabolic geometries. Results showed that direct radiation is maximized when the distance reactor-lamps is minimized, increasing optical efficiency. On the other hand, it was observed that for the flat reflectors, the closer the furthest point of the reflector to the center of the reactor, the higher optical efficiency is achieved due to the reduction in the number of bouncing rays in the reflector. In the case of parabolic geometries, some additional considerations are necessary, since not only the distance at which the reflector is placed matters, but also its geometrical focus. The best performance is achieved for those in which the distance from the furthest point of the reflector to the center of the reactor was lower and the lamps placed near the focus of the parabola. For the studied reflector geometries, the calculated optical efficiencies when using anodized aluminum were 46.1%, 56.5%, 60.0%, 41.8%, and 65.9% for reflectors of 1, 2, and 3 sides, cylinder, and parabola, respectively. Model predictions were successfully validated using experimental ferrioxalate actinometry data, confirming the huge potential of this simple simulation methodology for photoreactor design purposes.

Operation of a high-flow UV-LED water treatment reactor with secondary effluent for stress testing

For various applications, including water disinfection, the ultraviolet light emitting diode (UV-LED) has recently emerged as a sustainable alternative to the conventional mercury lamp. We performed an accelerated life and stress testing field study of a custom-designed high-flow UV-LED drinking water disinfection reactor operating 24/7 with 20 L per minute (LPM) of extreme quality secondary effluent. The low UV transmittance (55–64 %) and high turbidity (4–10 NTU) considerably affected the performance of the system. Organic and inorganic fouling were observed on the reactor walls and protective quartz windows. However, the surface areas that were exposed to higher irradiance were found to be less prone to an organic fouling formation. Despite the low operating temperature of the UV-LEDs, the chemical deposition, the extent of which correlated with the UV irradiance profile, was observed over the quartz windows. This indicates the effect of UVC in promoting quartz scaling formation when the water contains high levels of calcium and iron. Unexpected levels of zinc in the fouling, despite its low concentration in the water, showed the importance of this element in the formation of fouling in the UV-LED water disinfection systems. After 22 days of field testing, the UV transmittance of the protective windows dropped by 50–60 %, which, along with the radiant power reduction of the UV-LEDs, resulted in a 67 % overall reduction in an equivalent dose of the reactor. The study showed that optimally designed drinking water UV-LED reactors can maintain notable performance, even after exposure to accelerated life testing in extreme water conditions. Furthermore, the fouling was reversible, and the reactor was easily cleaned using household cleaning solutions in a two-step process with bleach and CLR®, where the cleaned quartz had a UV transmittance equal to an unused quartz window.

Study of water purification reactor operating modes

Wastewater treatment is one of the main problems of development and urbanization of the Arctic regions. This article is devoted to the development of a method for assessing the degree of water purification in order to determine the optimum operating parameters of treatment reactors for water treatment by ferrates from industrial and household waste resulting from the development of Arctic regions. Experiments reflecting the influence of the amount of air supplied to the purification plant on the processes of mixing and distribution of water were carried out and analyzed. Based on the experimental data, a method for determining the optimum operating parameters of a new mobile water purification plant has been developed and applied. The operation of the plant is based on the use of the ferrate method. equations and dependencies describing the relationship between the reactor volume, liquid flow rate and the degree of water purification are given. The degree of water pollution is estimated as its fraction which has left the reactor before the time required for complete treatment of the liquid from the moment it enters i the reactor. Optimal parameters of the ferrate reactor, such as volume and air supply, for a mobile water treatment plant were determined.

A novel vortex flocculation reactor for efficient water treatment: Kinetic modeling and experimental verification

We designed a novel vortex flocculation reactor with column-cone-column structure by adding vortex generators to form the micro-vortices to improve the flocculation efficiency. The vortex generators, actually wedge-shaped baffles, act as turbulence components to generate large flow resistance, thus reducing the size of the vortex to approach that of the floc. The inverted cone-cone-inverted cone structure in small-vortex flow flocculation zone prompts the fluid to form boundary layer dissociation phenomenon, thereby enhancing the relative motion of floc particles. The numerical simulation results of flow field structure indicated that the fluid presented a multiphase flow of “swirl flow-vortex flow-plug flow”; hence the fluid characteristic changed step by step. Moreover, the multistage velocity gradient of the fluid in different flow layers enhanced the probability of floc particles collision, thus strengthening the flocculation. Then the lab-scale vortex flocculation reactor was manufactured to conduct flocculation tests. The results revealed that the vortex flocculation reactor took the reaction time of only 10 s to achieve a superior chemical oxygen demand removal rate of 93.7%. The vortex flocculation reactor, based on the multiphase flow and multistage velocity gradient reinforcement flocculation strategy, can offer an effective way to improve the flocculation efficiency.

Radiation modeling and performance evaluation of a UV-LED photocatalytic reactor for water treatment

A photocatalytic reactor under UV-LED illumination is presented. It is an annular, packed-bed reactor filled with TiO2-coated glass rings. The reactor is irradiated both internally and externally in order to minimize the presence of dark zones. The knowledge of the radiation distribution inside the reactor is a key aspect to optimize its design and improve its efficiency. A three-dimensional model has been developed to describe the distribution of the local rate of photon absorption inside the reactor. The Monte Carlo method was applied to solve the radiation model. Simulation results were validated with experimental measurements. The model was able to predict the influence of the catalyst film thickness and the illumination conditions on the radiation distribution and on the total rate of photon absorption. Also, degradation assays of the pharmaceutical clofibric acid were carried out in the reactor and the performance of different illumination conditions was evaluated by means of the quantum efficiency parameter.

Flow and baffle configurations of settling pond and low-flow reactor for water treatment

Substrate reactors used to treat water have generally been vertical, and many settling ponds have zigzag baffles to increase the actual residence time. To improve the shape and flow configurations, baffle-type, weir-type, column-type, and SAPS-type reactors and settling ponds with zigzag and hanging baffles were studied by bench-scale and pilot-scale experiments and theoretical considerations. Tracer tests indicated that the extension of the flow line by zigzag baffles could prevent the short-circuiting of the SAPS-type reactor. The pilot-scale reactor with baffles in the longitudinal direction exhibited the highest treatment efficiencies among the baffle-type, weir-type, and column-type reactors. Nevertheless, the required hydraulic head is a critical constraint in the application of various types of reactors. The relationship between the maximum flow rate and the difference in hydraulic head or hydraulic conductivity indicated applicable flow rates for the baffle-type and weir-type reactors. If the hydraulic head difference is sufficiently high by pumping or the flow rate is sufficiently low, application of zigzag baffles in the longitudinal direction is highly encouraged in substrate reactors. Furthermore, pilot-scale experiments with a settling pond with zigzag baffles and hanging baffles indicated that the prevention of surface flow by using the hanging baffles reduced the required residence times to 51 %–69 % of those of zigzag baffles. The increased efficiency of the suggested reactors and settling ponds will decrease the required area and cost of construction.

A Comparative Study on Optofluidic Fenton Microreactors Integrated with Fe-Based Materials for Water Treatment.

The catalysts employed in catalytic reactors greatly affect the reaction efficiency of the reaction system and the reactor’s performance. This work presents a rapid comparative study on three kinds of Fe-based materials integrated into an optofluidic Fenton reactor for water treatment. The Fe-based sheets (FeSiB, FeNbCuSiB, and FeNi) were respectively implanted into the reaction chamber to degrade the organic dyes with the assistance of H2O2. In the experiment, by adjusting the hydrogen peroxide concentration, flow rate, and light irradiation, the applicable conditions of the Fe-based materials for the dye degradation could be evaluated quickly to explore the optimal design of the Fenton reaction system. The results indicated that FeNi (1j85) exhibits excellent degradability in the microreactor, the reaction rate can reach 23.4%/s at the flow rate of 330 μL/min, but its weak corrosion resistance was definitely demonstrated. Although the initial degradability of the microreactor by using FeNbCuSiB (1k107) was not as good as that of 1j85, it increased after being reused several times instead, and the degradation efficiency reached >98% after being reused five times. However, the FeSiB (1k101) material shows the worst degradability and recycling. Therefore, in contrast, 1k107 has the greatest potential to be used in Fenton reactors for practical water treatment.

Optimization of a gas–liquid plasma reactor for water treatment applications: Design guidelines and electrical circuit considerations

AbstractTo provide insights into the design, optimization, and scale up of plasma reactors for water treatment, the influences of discharge energy, grounded electrode size and position, and number of high voltage (HV) discharge points on the production of reactive species and the degradation of 1,4‐dioxane and perfluorooctanoic acid in a gas–liquid electrical discharge plasma reactor were assessed. Discharge energy and plasma area largely control the treatment effectiveness. Increasing the number of discharge points lowers the voltage in the reactor and consequently the production rates of reactive species. Bench‐scale findings apply directly to large volume systems, resulting in the highest contaminant removal rates using a single HV electrode and a grounded electrode spanning the entirety of the treatment zone.

Practical insights into ultrasound-assisted heterogeneous Fenton membrane reactors for water treatment

Cavitation damage to membranes is a major barrier for developing an ultrasound (US)-assisted membrane water treatment process. In this study, US was integrated to a heterogeneous Fenton membrane reactor for the treatment of pharmaceutical-containing water with the aims of i) fouling control, ii) enhancement of heterogeneous Fenton oxidation. In order to prevent membrane damages due to cavitation, the stable and violent cavitation regions were identified by quantification and analysis of the cavitation activity axial along the ultrasound transducer via hydrophone measurements. Results showed the cavitation activities occur in both regions with US on, while the cavitation damage to membrane materials was only observed when membranes were placed in the violent cavitation region. On one hand, cracking and physical erosion of the surface were observed on membrane samples when exposed to violent cavitation. On the other hand, no such erosion occurred in stable cavitation regions, and membranes kept their mechanical, chemical and morphological properties, confirming that cavitation damage was controlled by placing membranes in the identified stable cavitation region. Based on these results, a heterogeneous Sono-Fenton membrane reactor was designed by placing a scalable hollow-fibre membrane module in the stable cavitation region. Within this reactor, the experiments confirmed that the oxidation of organics was enhanced thanks to the US assistance in the novel designed heterogeneous Sono-Fenton membrane reactor. However, this study also showed that US accelerated membrane ageing and zeolite-catalysts erosion, leading to more severe fouling. Overall, this paper introduces a method to control the cavitation damage to membranes and discusses the issues in US-assisted membrane systems with practical insights.

Photocatalytic degradation of contaminants of emerging concern using a low-cost and efficient black bismuth titanate-based water treatment reactor

Photocatalysis is recognized as a sustainable technology for wastewater treatment, but it is limited by its scalability and efficiency. Here, we report the fabrication of a bespoke photocatalytic reactor, made from readily available consumer market components. The reactor was loaded with glass rods coated with a bismuth titanate photocatalyst deposited by reactive pulsed DC magnetron sputtering. Bismuth titanate is a remarkable material, which has shown the property of increasing its photocatalytic capabilities over repeated usage due to photoinduced oxygen vacancies, forming oxygen-vacancy rich “black” bismuth titanate. The reactor was tested with different rod configurations and photocatalytic material was cycled over 25 times, equivalent to 125 h of consecutive use, against methylene blue dye under UV light. Orange II dye degradation tests carried out in the presence of scavengers revealed that photocatalytic reactions were driven by superoxide (O2∙−) and holes (h+), when using pristine bismuth titanate and by superoxide (O2∙−), electrons (e−) and holes (h+), when using “black” bismuth titanate. Finally, the reactor was used to successfully degrade levofloxacin, a typical antibiotic, which was verified by UV–Vis (ultraviolet-visible) spectroscopy and inhibition zone tests in the presence of three different pathogens (E. coli, S. aureus and A. baumannii).

Influence of solution electrical conductivity and ionic composition on the performance of a gas–liquid pulsed spark discharge reactor for water treatment

The influence of solution electrical conductivity and ion composition on the performance of plasma reactors for water treatment applications is only partially understood. This study uses a point–point discharge over the surface of water in argon gas to determine the influence of solution conductivity, in the range of 0.3–45 mS/cm, on the physiochemical properties of spark discharges and the removal of two organic contaminants: perfluorooctanoic acid (PFOA) and Rhodamine B dye. The influence of various ions was also explored using chlorine and non-chlorine salts to adjust solution conductivity. The removal of PFOA increased with conductivity regardless of the salt type due to the salting out effect which increased PFOA's interfacial concentration. The removal of Rhodamine B dye depended on both salt type and solution electrical conductivity. In the presence of non-chorine salts, UV photolysis was the main mechanism for the dye degradation and its removal rate did not change with conductivity. The dye removal rate was the highest in the presence of chloride-based salts at the highest values of solution conductivities. In the presence of chorine salts, OH radicals are produced by the discharge generated hypochlorous acid, which is mixed into the bulk solution to react with the Rhodamine B dye. The generation rate of hydroxyl radicals appears to decrease with increasing solution conductivity, and these species are not directly involved in the degradation of the two compounds investigated in this study.

Development of a Separate Multiphase Dielectric Barrier Discharge Reactor and Study on the Treatment Effect of Methylene Blue

In order to improve the efficiency of dielectric barrier discharge (DBD) contaminants treatment and reduce the treatment cost, a multiphase DBD plasma water treatment reactor is used in this article. When processing methylene blue solution, the electrode distance is 3 mm, the input voltage is 85 V, and the input frequency is 7.8 kHz. The degradation rate can be maintained at about 90% when the experiment is carried out with different concentrations for 10 min. The energy efficiency value of the solution with different concentrations is continuously rising, and the energy efficiency of the solution with a concentration of 150 mg/L reaches 2091 mg/kW <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot \text{h}$ </tex-math></inline-formula> . In experiments under different water volume conditions, the degradation rate of the solution with 300 mL water volume was 74% after the same treatment time 30 min, compared with the degradation rate of 100 mL water volume of 89.3%, but the amount of methylene blue in the degraded solution increased. In the experiment of adjusting the gas volume to 100 ml/min, it is found that when the gas volume increases to 100 ml/min, the degradation rate is 86%, which is 20% higher than 67.3% when the gas input is 60 ml/min.

Performance analysis of a continuous-flow single-channel reactor for surface water treatment using electrocoagulation process

A Continuous-Flow Single-Channel (CFSC) reactor made of vertical flow channels was used for the treatment of surface water by Electrocoagulation (EC). The effects of different CFSC reactor configurations based on the number of Pair of Working Electrodes (PWE) were analysed by considering transport phenomena within the reactor, which including mixing time and theoretical minimal residence time of electro-dissolved electrodes inside the reactor (tmin). The main objective of this study is to prove that the widespread conclusion which stipulates that increasing the number of electrodes improves the performance of the EC process is not true for all reactor’s geometries. Since the pairs of electrodes are placed in the up-flow channel, the PWE’s number is interpreted as the number of Working Up-Flow Channel (WUFC) in the reactor. The results show that the increase in the WUFC’s number (m WUFC) in the CFSC reactor leads to a higher electrodes’ consumption and a lower tmin. The latter is due to the PWEs’ close location to the reactor’s outlet, resulting in a waste of electro-dissolved aluminium, as it does not fully contribute to destabilizing the suspended particles; rather, it promotes secondary pollution by increasing the residual aluminium concentration in treated water. The CFSC reactor configuration with m WUFC = 4 reduces the electrodes’ consumption and operating cost by approximately 28.1% and 14%, respectively. It also increases the mixing time (higher tmin value) and enhances turbidity removal by about 4% compared to the CFSC reactor configuration with m WUFC = 10 for the same energy consumption.