Conventional Treatment Processes Research Articles

A review on triclosan in wastewater: Mechanism of action, resistance phenomenon, environmental risks, and sustainable removal techniques.

Triclosan, belonging to the bisphenols, is a known antiseptic broad-spectrum biocide. It has a very wide range of applications, both in health care and in the household. Triclosan enters the environment, both water bodies and soil, because of its high prevalence and the ability to accumulation. Excessive use of antimicrobial formulations may cause the generation of resistance among microorganisms. Reduced susceptibility to triclosan is observed more frequently and in an expanded group of microorganisms and is conditioned by a number of different mechanisms occurring on the molecular level. Conventional wastewater treatment processes are not always able to provide a reliable barrier to triclosan. Therefore, additional advanced treatment technologies are being considered in areas, where a triclosan contamination problem has been identified. Removal of triclosan from wastewater is carried out using different biological and chemical techniques; however, it should be pointed out that physico-chemical methods often generate toxic by-products. Toxicity of triclosan and its degradation products, bacterial resistance to this compound, and evident problems with triclosan elimination from wastewater are currently the main problems faced by companies creating products containing triclosan. PRACTITIONER POINTS: Triclosan is an emerging pollutant in the environment because of its ability to accumulation and high prevalence. Reduced susceptibility to triclosan is being observed more frequently. Conventional wastewater treatment processes are not always able to provide a reliable barrier to triclosan. Additional advanced treatment technologies should be implemented to remove triclosan from wastewater.

Twelve natural estrogens and ten bisphenol analogues in eight drinking water treatment plants: Analytical method, their occurrence and risk evaluation.

Bisphenol analogues (BPs) and natural estrogens (NEs) as two important groups of endocrine-disrupting compounds (EDCs) in drinking water treatment plants (DWTPs) have been hardly investigated except bisphenol A (BPA) and three major NEs including estrone (E1), 17β-estradiol (E2) and estriol (E3). In this study, a GC-MS analytical method was firstly established and validated for trace simultaneous determination of ten BPs and twelve NEs in drinking water, which included BPA, bisphenol B (BPB), bisphenol C (BPC), bisphenol E (BPE), bsiphenol F (BPF), bsiphenol P (BPP), bisphenol S (BPS), bisphenol Z (BPZ), bisphenol AF (BPAF), bisphenol AP (BPAP), E1, E2, E3, 17α-estradiol (17α-E2), 2-hydroestrone (2OHE1), 16hydroxyestrone (16α-OHE1), 4-hydroestrone (4OHE1), 2-hydroxyesstradiol (2OHE2), 4-hydroxyestradiol (4OHE2), 17-epiestriol (17epiE3), 16-epiestriol (16epiE3) and 16keto-estraiol (16ketoE2). This investigation showed that eighteen out of twenty-two targeted compounds were detected in drinking source waters of eight DWTPs with concentrations ranging from not detected to 142.8ng/L. Although the conventional treatment process of DWTP could efficiently remove both BPs and NEs with respective removal efficiencies of 74.1%-90.9% and 74.5%-100%, BPA, BPS, BPE, BPZ, E1, 2OHE1, and 2OHE2 were found in the finished drinking waters. Chlorination could remove part of BPs and NEs, but the efficiency varied greatly with DWTP and the reason was unknown. In the finished drinking waters of eight DWTPs, the highest chemically calculated estrogen equivalence (EEQ) derived from BPs and NEs was up to 6.11 ngE2/L, which was over 22 times that could do harm to zebrafish, indicating a potential risk to human health. Given the fact that many chlorination products of BPs and NEs likely have higher estrogenic activities, the estrogenic effect of BPs and NEs in finished drinking water should be accurately examined urgently with the inclusion of BPs, NEs as well as their main chlorinated by-products. This study shed new light on the occurrence, removal, and potential estrogenic effects of BPs and NEs in DWTPs.

Electrically conductive membrane distillation via an alternating current operation for zero liquid discharge

Membrane distillation (MD) shows promise for achieving high salinity treatment and zero liquid discharge (ZLD) compared to conventional water treatment processes due to its unique characteristics, including low energy consumption and high resulting water quality. However, performance degradation due to fouling and scaling under high recovery conditions remains a challenge, particularly considering the need to control both cations and anions for maximum scaling mitigation. Accordingly, in this study, alternating current (AC) operation for electrically conductive membrane distillation (ECMD) is newly proposed, based on its potential for controlling both cations and anions, in contrast to conventional direct current (DC) operation. Systematic experiments and theoretical analysis show that water recovery in ECMD can be increased by 27% through AC operation. The proposed modification and effective AC operation of ECMD increase the practicality of using MD in desalination for a high recovery rate, perhaps even for ZLD.

Impact of Drinking Water Treatment Process Using Life Cycle Assessment (LCA) to Minimize Environmental Impact Risk

The clean water treatment plant at DWTP is carried out with conventional treatment. The conventional water treatment process has an impact on the environment due to the clean water treatment process. Clean water treatment produces GWP and Eutrophication impacts derived from the use of chemicals and electricity. This study aims to analyze the factors causing environmental impacts arising from the clean water treatment process at the PDAM Water Treatment Plant (IPA) and determine policy priorities related to reducing environmental impacts and improving the quality of drinking water treatment at the Water Treatment Plant based on the results of LCA and AHP studies. The Life Cycle Assessment (LCA) method is a method of assessing the potential environmental impact and evaluating the environmental performance of a process on the product. Life Cycle Assessment (LCA) consists of four stages, namely determination of Goal and Scope, Life Cycle Inventory, Life Cycle Impact Assessment, and data interpretation. In research, the scope of LCA used is Gate to Gate, namely in the Coagulation, Flocculation, and Sedimentation process units. From the results of the LCA study, the potential impact of GWP of 12760.76 KgCO2-eq comes from flocculation which produces floc from the addition of chemicals. Meanwhile, the potential impact of eutrophication is 268.55 KgPO4-eq derived from mud generation. The results of the decision in reducing environmental impact at DWTP by optimizing chemicals as a top priority, then the second priority by recycling sludge, and finally making savings and energy alternatives are the last priority. Each respondent's score reached 55%, 23% and 22%. The results of the implementation of the program if implemented can reduce the impact of GWP 20079.17 kg CO2-eq and the impact of eutrophication can be reduced by 201.401 kg PO4-eq.mportant matters discussed in the paper that significantly contribute to the final result of the research may be noted here, but you have to consider, however, the limited space of the abstract.

Formation and transformation of pre-chlorination-formed disinfection byproducts in drinking water treatment process

As pre-chlorination is increasingly adopted in drinking water treatment plant (DWTP), an attractive question emerged: how the disinfection by-products that formed during pre-chlorination (preformed DBPs) would be transformed in the drinking water treatment process? This study investigated the DBP formation kinetics and molecular characteristics in chlorinated source water, DBP transformation and removal in practical DWTP. It was found that the formation of trihalomethanes (THMs) followed pseudo first-order kinetic model and the intensified Br− exposure facilitated the transformation of TCM into TBM. As Br− concentration shifted from 0.5 mg L−1 to 2.0 mg L−1, the predicted maximum yield of TBM was doubled to 53.7 μg L−1 with the increase of formation rate constant (k-value) from 0.249 h−1 to 0.336 h−1. Besides known DBPs, the molecular-scale investigation unveiled that the preformed unknown Cl-DBPs were a cluster of unsaturated aromatic DBPs ((DBE-O)/Cwa = 0.16, AImod, wa = 0.36) with high H/C (H/Cwa = 1.25). Pre-ozonation exhibited a preferential removal pattern towards condensed aromatic preformed Cl-DBPs with high H/C (AImod ≥ 0.67, H/C > 1.2 and O/C < 0.3). However, the removal of Cl-DBPs in coagulation-clarification process was limited with 56 more unknown Cl-DBP formulas identified. O3-biological activated carbon process exhibited effective removal of preformed DBPs featured with low MW (carbon number ≤ 13), high unsaturation (DBE ≥ 7), condensed aromaticity (AImod ≥ 0.67), and higher H/C (H/C > 1.6). When the pre-chlorination process is adopted, the removal of preformed DBPs during the conventional treatment process is limited, while advanced treatment process can effectively remove these preformed DBPs.

Enhancing the water quality of treated effluents from Wastewater Treatment Plants by mitigating emerging pollutants

With the increasing demand for water resources and growing environmental concerns, reclaimed water from wastewater treatment plants has gained prominence as an alternative water source for various non-potable applications. However, one of the major challenges in utilizing reclaimed water is the presence of emerging pollutants, which encompass a wide range of chemical and biological compounds not routinely monitored or regulated in conventional wastewater treatment processes.&#x0D; This study aims to address the pressing issue of emerging pollutants in reclaimed water by exploring and evaluating innovative strategies for their removal.&#x0D; Through a comprehensive literature review, cutting-edge technologies and advanced treatment methods will be assessed, focusing on their efficiency in eliminating a spectrum of emerging pollutants from treated effluents.&#x0D; Moreover, this research seeks to shed light on the potential risks associated with these emerging contaminants and their impact on human health and the environment.&#x0D; Ultimately, the finding from this study will contribute to the development of sustainable and effective approaches for enhancing the water quality of reclaimed water from wastewater treatment plants.by mitigating the presence of emerging pollutants, stakeholders can confidently promote the safe and reliable use of reclaimed water, thus fostering a more resilient and environmentally conscious water management paradigm.

Synthesis of solid NMC622 particles by spray drying, post-annealing and lithiation

Layered lithium-nickel-manganese-cobalt oxide (NMC) cathode materials are widely used in Li-ion batteries that require high energy densities, such as those used in plug-in hybrid electric vehicles (PHEVs) and electric vehicles (EVs). Here we studied the synthesis of NMC622 particles by spray pyrolysis, which is a simple one-step process for production of spherical particles. However, synthesising NMC powder using spray pyrolysis has a tendency to produce hollow NMC particles. To gain insight into the mechanism behind the formation of the hollow particles, one dimensional numerical simulation of the physical and chemical phenomena taking place during spray drying were carried out. The effects of several process parameters, including drying air temperature, drying air mass flow rate, and liquid feed mass flow rate, on the evaporation and particle formation process were studied. The increased evaporation rate at higher temperatures was found to result in crust formation on the droplet surface during the particle formation, and thus, in lower solid volume fractions in the dried particles. However, by optimizing the process parameters production of solid NMC622 sulphate particles by spray drying was achieved. The produced NMC622 sulphate particles were then oxidised and lithiated in air at 850 °C via the conventional thermal treatment process. Four lithium precursors, LiOH, Li2CO3, Li2SO4 and LiNO3, were tested for the lithiation of the oxidized NMC particles. The degree of lithiation and the crystalline phase of the powders were determined using ICP-OES and XRD, respectively.

Simultaneous degradation of microplastics and sludge during wet air oxidation

Microplastics (MPs) generated from daily life are commonly collected by urban sewage pipe networks and then transfer to sludge in wastewater treatment plants. Conventional biochemical treatment processes cannot degrade MPs effectively, causing an ecological risk via sludge land use. Wet air oxidation (WAO) is a promising sludge treatment technology with a strong ability to decompose complex organic matter, but its potential for the removal of MPs in sludge was unclear. In this study, three common MPs (polyethylene, polystyrene, and polyethylene terephthalate, which are called PEMPs, PSMPs, and PETMPs) were added into the sludge samples (1 g MP in 180 mL sludge), to test the effects of WAO on sludge and MPs. The results showed that WAO simultaneously degraded sludge and the PEMPs, and the two degradation processes were relatively independent when oxygen was supplied adequately. The dissolution of PSMPs and organic matter in sludge was not affected by each other, but the degradation rate was slowed down due to the interaction of ketones and benzene compounds. The hydrolysis of sludge and PETMPs was accelerated, while the hydrolyzed products such as terephthalic acid were oxidized without interfering with each other. No obvious MPs remained in the effluent, and volatile fatty acids (VFAs) were the main components, among which acetic acid accounted for 90%. When the sludge was treated with PEMPs, PSMPs, or PETMPs, the concentration of acetic acid finally accounted for 45%, 21%, and 18% of DOC. Overall, MPs can be degraded or even mineralized during sludge WAO, and humic acid derivatives, acetate, and other small molecules of alcohols, ketones, or aldehydes were the typical intermediates.

Efficient persulfate activation by photo-excited organic dyes: Mechanism and application for actual dyeing wastewater self-purification

Sulfate Radical-Advanced Oxidation Processes are considered an efficient way for purifying dyeing wastewater, which commonly resists conventional treatment processes owing to the complex components, low biodegradability and high toxicity. However, this emerging technique is associated with issues of secondary pollution and great energy consumption during peroxymonosulfate (PMS) or persulfate (PS) activation processes. Herein, a dye pollutant/PS/visible light self-catalytic system was constructed, based on the photosensitive property of organic dyes for PS activation without catalyst and energy input. In this system, the degradation ratio of 100 mL 10 mg L−1 basic fuchsin, rhodamine B and eosin Y significantly increased by 60%, 76% and 50%, compared with the process without light irradiation. Such improvements were attributable to an efficient photo-induced electron transfer from photo-excited dyes to PS, which has the precondition that the lowest unoccupied molecular orbital (LUMO) energy level of the dye is higher than that of PS, thereby generating oxidizing species like ·SO4−, ·OH and 1O2 for pollutants degradation. Due to the high performance of pollutants simultaneous removal, wide pH adaptability and anti-interference, the complex self-catalytic system consisted of nine dyes and bis-phenol A exhibited the possibility for practical application. Expectedly, the actual dyeing wastewater self-purification system featured a decolorization efficiency of 54% accompanied by the removal of co-existing aromatic proteins and tryptophan-like substances; moreover, the acute bio-toxicity of the raw wastewater greatly decreased by 61.6%. Owing to its high efficiency, eco-friendliness and low consumption, the constructed “using waste to treat waste” system provides a promising way for wastewater treatment.

Photocatalytic performance of buoyant TiO2-immobilized poly(ethylene terephthalate) beads for the removal of the anticonvulsant drug pregabalin from water and leachate

The application of TiO2 nanoparticles as photocatalyst for the removal of pharmaceutical compounds from water is extensively applied as an alternative to the conventional treatment processes. However, application of TiO2 as a powder requires energy costing separation stages to remove the catalyst at the end of the process. Thus, immobilization of the catalyst can be an attractive solution. Aiming to find a good support material for TiO2, in this study, the synthesis and characterization of three different PET/TiO2 photocatalytic beads are described along with their application in the photocatalytic degradation of the anticonvulsant drug pregabalin (PGB). The PET/TiO2 beads with different contents of TiO2 filler (10 wt%, 20 wt% and 30 wt%) were synthesized by using an anti-solvent precipitation method and were characterized by different techniques, such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Among the different composites, PET/TiO2 30 wt% beads proved to be the most efficient, achieving almost complete degradation of PGB within 6 h of treatment. The stability and reuse of the synthesized catalysts were also evaluated. Furthermore, the effect of matrix was examined, revealing slower kinetics in high loaded matrices like a leachate. Identification of the arising transformation products (TPs) was conducted using LC-HRMS analysis. Twenty-two TPs were identified, out of which fifteen were detected for the first time herein, stemming from hydroxylation, amidation, oxidation and oxidative deamination of PGB. Finally, the in silico prediction of their toxicity was conducted based on ECOSAR software revealing mainly the formation of non-toxic compounds. However, amidation can cause the formation of toxic/harmful by-products but they are susceptible to photocatalysis thus being eliminated until the end of treatment.

Predicting the removal efficiency of pharmaceutical and personal care products using heated metal oxides as adsorbents based on their physicochemical characteristics

Pharmaceutical and personal care products (PPCPs) are emerging pollutants that are commonly found in the environment and exist predominantly in nondegradable forms. Several attempts have been made to remove PPCPs via conventional wastewater treatment processes; however, these processes have limitations, such as high costs and insufficient removal efficiencies. Adsorption is a promising alternative for removing PPCPs because it is inexpensive, highly reusable, and easy to operate. Therefore, this study aims to determine the contributing characteristics that can be used to predict the adsorption behaviour of PPCPs based on their physicochemical properties, with heated metal oxide adsorbents (HMOAs). HAOP (heated aluminium oxide particles) and HIOP (heated iron oxide particles) with particle sizes below 38 μm were used. Results from the Brunauer-Emmett-Teller (BET) analysis show that HIOP has higher surface area and smaller pore size (113.7 ± 26.3 m2/g and 5.4 ± 1.8 nm) than HAOP (14.5 ± 0.6 m2/g and 18.6 ± 3.1 nm), which suggest that HIOP would show superior adsorption rates compared to HAOP. The adsorption mechanism is identified based on three major physicochemical properties of PPCPs: molecular weight (M.W.), octanol–water partition coefficient (log Kow), and acid dissociation constant (pKa). The results suggest that the most dominant factor that contributes to the adsorption of PPCPs on to HMOAs is the M.W., where the larger the molecular size, the better the adsorption efficiency. The tests conducted with varying log Kow values revealed that the hydrophilicity of the adsorbent influences the adsorption performance. It was found that HIOP exhibits better removal efficiencies with hydrophilic PPCPs (up to 83%) than with hydrophobic PPCPs (48%), while HAOP exhibits better removal efficiencies with hydrophobic PPCPs (86%) than with hydrophilic PPCPs, with less than 10% removal. Unlike the M.W. and pKa values, the log Kow does not exhibit any visible trend. Therefore, the adsorption behaviour can be predicted with the M.W. and pKa values of the PPCPs, when HAOP and HIOP are used as adsorbents.

Utilization of Activated Carbon Catalyzed Ozonation (ACCO) For Removal of Ciprofloxacin and Vancomycin from Hospital Wastewater.

Hospital wastewater is considered by health and environmental researchers due to the presence of various hazardous chemical contaminants such as residual of antibiotics and other drugs. The conventional treatment processes are not able to complete removal of them, and could lead to the entry of these compounds into the environment. Then, we aimed to analyze and evaluate the removal of ciprofloxacin and vancomycin antibiotics from hospital wastewater. The effect of antibiotic concentration and reaction time was investigated on the performance of single ozonation (SOZ) and activated carbon catalyzed ozonation (ACCO). In addition, COD and BOD of the effluent, antibiotics degradation kinetics and mathematical modeling were determined. Solid phase extraction columns (SPE) and high-performance liquid chromatography (HPLC) methods were used to extract and measure the intended antibiotics, respectively. The results of this study showed that degradation of both antibiotics follow pseudo-first order kinetic. SOZ was able to eliminate 6 mg/L of vancomycin and ciprofloxacin within 45 and 65 min, respectively. Due to the synergistic effect of activated carbon on ozonation, ACCO significantly reduced the degradation time to 20 and 25 minutes, respectively. BOD/COD ratio at the outlet of ACCO process increases from 0.2 in raw wastewater to 0.4 in treated wastewater, which could be appropriate for biological treatment. ACCO could be considered an efficient process for degradation of antibiotics in hospital wastewater.

A novel high nitrogen hot-work die steel 3Cr5Mo2SiVN achieving excellent hardness-strength-toughness balance

A novel high nitrogen hot-work die steel 3Cr5Mo2SiVN was manufactured by pressurized induction melting, possessing excellent hardness-strength-toughness balance under conventional heat treatment process. The results indicated that 3Cr5Mo2SiVN steel exhibited better hardness-toughness synergy compared with H13 steel. Meanwhile, its impact energy and elongation were improved by ca. 50% and 13% compared with H13 steel with similar hardness. The achievement of superior toughness of 3Cr5Mo2SiVN steel could be attributed to the following reasons: firstly, the higher fraction of operators 1 and 2, more uniform and refined close-packets and Bain groups as well as smaller effective grain size obtained a higher ratio of high angle grain boundaries, which resulted in the more changes of crack propagation direction and thus an increase of energy absorption. Secondly, the smaller size and number density of undissolved M(C, N) carbonitrides distributed along the prior austenite grain boundaries required greater tensile stress and then reduced grain boundary brittleness. For the strengthening mechanism, the precipitation strengthening increment was mainly provided by M(C, N) carbonitrides and M3C carbides for 3Cr5Mo2SiVN steel, and MC carbides for H13 steel, respectively. The smaller effective grain size and higher interstitial atom (C and N) content in the martensitic laths of 3Cr5Mo2SiVN steel were crucial factors in enhancing its strength.

Membrane modification in enhancement of virus removal: A critical review

Many waterborne diseases are related with viruses, and COVID-19 worldwide has raised the concern of virus security in water into the public horizon. Compared to other conventional water treatment processes, membrane technology can achieve satisfactory virus removal with fewer chemicals, and prevent the outbreaks of viruses to a maximal extent. Researchers developed new modification methods to improve membrane performance. This review focused on the membrane modifications that enhance the performance in virus removal. The characteristics of viruses and their removal by membrane filtration were briefly generalized, and membrane modifications were systematically discussed through different virus removal mechanisms, including size exclusion, hydrophilic and hydrophobic interactions, electronic interactions, and inactivation. Advanced functional materials for membrane modification were summarized based on their nature. Furthermore, it is suggested that membranes should be enhanced through different mechanisms mainly based on their ranks of pore size. The current review provided theoretical support regarding membrane modifications in the enhancement of virus removal and avenues for practical application.

Novel visible-light-active P-g-CN-based α-Bi2O3/WO3 ternary photocatalysts with a dual Z-scheme heterostructure for the efficient decomposition of refractory ultraviolet filters and environmental hormones: Benzophenones

The ubiquitous and refractory benzophenone (BP)-type ultraviolet filters, which are also endocrine disruptors, were commonly detected in the aquatic matrix and could not be efficiently removed by conventional wastewater treatment processes, thus causing extensive concern. Herein, a novel ternary nanocomposite, P-g-CN/α-Bi2O3/WO3 (P-gBW), was successfully fabricated by mixing cocalcinated components and applied to the decomposition of BP-type ultraviolet filters. The dual-Z-scheme heterostructure of P-gBW enhances visible-light absorption, efficiently facilitates separation and mobility, and prolongs the lifetime of photoinduced charge carriers via double charge transfer mechanisms. The optimum 95 wt% P-gBW exhibited excellent photocatalytic activity, degrading 96% 4-hydroxy benzophenone (4HBP) within 150 min and 93% 2,2′,4,4′-tetrahydroxybenzophenone (BP-2) within 100 min under visible-light illumination, respectively. The pseudo-first-order rate constant of 4HBP (1.15 h−1) was 6.8-, 3.1-, 3.3- and 2.2-fold higher than those of WO3, P-g-CN, α-Bi2O3, and P-g-CN/α-Bi2O3, respectively, while that of BP-2 (1.71 h−1) was 5.2-, 2.2-, 3.2- and 1.5-fold higher, respectively. The improved photocatalytic degradation was attributed to efficient photoinduced charge carrier separation and migration and prevented the recombination of electron holes, as verified by photoluminescence, transient photocurrent response, and electrochemical impedance spectroscopy. Trapping experiments, electron paramagnetic resonance, and band energy position indicated an efficient dual-Z-scheme heterostructure.

Fluorescence-based indicators predict the performance of conventional drinking water treatment processes: Evaluation based on the changes in the compositions of dissolved organic matter

This study investigated the treatability of dissolved organic matter (DOM) by the selected lab-scale drinking water treatment processes using fluorescence excitation-emission matrix (EEM) analysis. The fluorescence ratio Peak 3/Peak 2 was established from well-defined fluorescence peak intensity of humic-like components (Ex/Em: 225 nm/425 nm) and protein-like components (Ex/Em: 230 nm/345 nm). Peak 3/Peak 2 predicted the aromatic characteristics of DOM and their origins in the different natural surface water feeding the different drinking water treatment plants. The drinking water treatment processes confirmed the treatability of DOM using Peak 3/Peak 2 and was well-confirmed by specific UV260 absorbance relative to dissolved organic carbon (DOC) (SUVA) and fluorescence-based indices. Peak 3/Peak 2 was demonstrated to have a strong correlation with SUVA and DOC removal for the water after treatment by coagulation, adsorption, and chlorination. Compared to the humification index and fluorescence index, Peak 3/Peak 2 is better for indicating the DOM composition in terms of treatability. These findings can broaden the use of fluorescence spectroscopy in water treatment applications, by developing the fluorescence ratio to evaluate the performance of drinking water treatment plants.

Study of tramadol removal from water by the electro-Fenton process coupled with biological post-treatment: kinetics and energetic evaluation

ABSTRACT The pollution of the aquatic environment by the increasing presence of the non-biodegradable analgesic tramadol (TRA) is increasing due to its high consumption and incomplete elimination in conventional wastewater treatment processes. The aim of the present study is, firstly, to evaluate the oxidative degradation of TRA by the ‘electro-Fenton’ process, EF for short, at pH 3 (optimal operating pH) for 6 h at a constant current between 60 and 400 mA. Secondly, the possibility of coupling biological treatment with EF will be investigated in order to minimise energy input and increase the profitability of the treatment process. The experimental results showed a considerable mineralisation rate of TRA of over 94% after 6 h of electrolysis at an applied current of 300 mA and a Fe2+ catalyst concentration of 0.1 mM. The TRA degradation in this process followed pseudo-first order kinetics. Several TRA intermediates were identified by LC-MS/MS analysis. A likely reaction pathway for the process of mineralisation was suggested. Combining the EF process with biological post-treatment reduces the energy consumption by more than 66% and increases the economic viability of TRA mineralisation.

Greenwall Filtration System for Lakewater Treatment: A Case Study on Cocopeat/Perlite Filter Media

Anthropogenic activities often result in varying degrees of lakewater contamination. Conventional lakewater treatment processes require expansive space allocation which could be challenging under certain topographical situations. A greenwall filtration system is a vertical wall that consists of plants or greenery. In this system, greenery is planted in a growing medium made up of a combination of soil, stone, or water. A robust greenwall filtration system could serve as a potential solution for lakewater treatment. However, the efficacy of various filtering media in eliminating contaminants and various water quality indicators such as Chemical Oxygen Demand (COD) from lakewater remains unknown. Previous research has demonstrated that coir and perlite are suitable filter media for a greenwall system. In this study, the effects of various height ratios of the filter media and different lakewater flowrates were investigated. The treatment performance was assessed using various lakewater flowrates: low flowrate (13.10 L/h), medium flowrate (26.57 L/h) and high flowrate (45.18 L/h). The mixed media ratio of 3:1 cocopeat-to-perlite during low flowrate (13.10 L/h) attained the highest removal of COD with an overall removal of 71.00%. It was further discovered that the Langmuir isotherm model could better explain the adsorption process than the Freundlich isotherm model as it possesses an overall high coefficient of determination, R2 where the value of R2 for cocopeat to perlite ratio at 1:1, 1:3, and 3:1; are 0.9397, 0.9823, and 0.5348, respectively.

Synthesis and application of manganese-doped zinc oxide as a potential adsorbent for removal of Congo red dye from wastewater

Synthetic dyes are considered toxic compounds and as such are not easily removed by conventional water treatment processes. This study demonstrated the synthesis of pure and manganese- (Mn), silver- (Ag), and iron- (Fe) doped zinc oxide (ZnO) nanoparticles via the wet chemical route. In particular, it investigated the batch adsorption studies and physiochemical properties of synthesized pure and doped ZnO materials for removing toxic congo red (CR) dye. X-ray diffraction (XRD), Raman spectroscopy, and energy-dispersive X-ray spectroscopy (EDS) confirmed the synthesis of the pure and doped ZnO materials. The batch adsorption investigation revealed adsorption efficiencies of 99.4% for CR dye at an optimal dose of 0.03 g/30 ml for Mn-doped ZnO at a solution pH of 2. The adsorption capacity of each of the synthesized materials was found to be in order Mn-doped ZnO (232.5 mg/g) > Ag-doped ZnO (222.2 mg/g) > pure ZnO (212.7 mg/g) > Fe-doped ZnO (208.3 mg/g). Both pseudo-second-order kinetics model and the Langmuir isotherm model accurately explained the adsorption behaviors of CR dye. As such, Van der Waal interactions, H-bonding, and electrostatic interaction were found to be the adsorption mechanisms responsible for dye removal. In addition, the desorption–regeneration investigation indicated the successful reuse of the exhausted Mn-doped ZnO material for five cycles of CR dye adsorption with an efficiency of 83.1%. Overall, this study has demonstrated that Mn-doped ZnO could be considered a viable adsorbent for the cleanup of dye-contaminated water.

Investigation of high-turbidity tap water problem in Najaf governorate/middle of Iraq

Abstract Turbidity is a fundamental measure for assessing the quality of water supplied by water treatment plants (WTPs) employing a conventional treatment process. If it is present in amounts exceeding the permitted limit, disinfectants are less effective in killing microorganisms and the water becomes unsafe to drink. This article is a part of a comprehensive study that aims to investigate the high-turbidity problem of tap water in two cities of Najaf governorate and offer suitable measures to solve this problem. The purpose of this study was to determine how WTPs impact the turbidity of tap water. The work covered two main WTPs located in Najaf governorate: Unified Najaf and The Old Kufa. It included the collection of water samples from three locations in each plant: the influent of flash mix unit (raw water samples), the effluent of clariflocculation unit (settled water samples), and the effluent of filtration unit (filtered water samples). The samples were analyzed for turbidity using a turbidity meter. The efficacy of each plant's treatment units was revealed by monitoring the turbidity of the water inside each facility. For the Unified Najaf WTP, out of 99 TRE readings, there were 3, 92, and 60 positive values for TREc, TREf, and TREp, respectively. The maximum values of TREc, TREf, and TREp were 22.3, 86.5, and 61.5%, respectively. The performance of Old Kufa WTP was worse than that of Unified Najaf WT. Out of 99 TRE values, the number of positive values was 6, 76, and 31 for TREc, TREf, and TREp, respectively. They also showed that only 26 out of 99 and 9 out of 99 effluent turbidity readings in Unified Najaf and Old Kufa WTPs, respectively, satisfy Iraqi standards for tap water turbidity. The bad performance of the WTPs was the main reason behind the high-turbidity tap water in Najaf governorate. This study identified the causes of that performance and proposed solutions.