Conventional Treatment Processes Research Articles

Active pharmaceutical contaminants in drinking water: myth or fact?

Global water availability has been affected by a variety of factors, including climate change, water pollution, urbanization, and population growth. These issues have been particularly acute in many parts of the world, where access to clean water remains a significant challenge. In this context, preserving existing water bodies is a critical priority. Numerous studies have demonstrated the inadequacy of conventional water treatment processes in removing active pharmaceutical ingredients (APIs) from the water. These pharmaceutical active compounds have been detected in treated wastewater, groundwater, and even drinking water sources. The presence of APIs in water resources poses a significant threat not only to aquatic organisms but also to human health. These emerging contaminants have the potential to disrupt endocrine systems, promote the development of antibiotic-resistant bacteria, and bioaccumulate in the food chain, ultimately leading to unacceptable risks to public health. The inability of current conventional treatment methods to effectively remove APIs from water has raised serious concerns about the safety and reliability of water supplies. This issue requires immediate attention and the development of more effective treatment technologies to safeguard the quality of water resources and protect both aquatic ecosystems and human health. Other treatment methods, such as nanotechnology, microalgal treatment, and reverse osmosis, are promising in addressing the issue of API contamination in water resources. These innovative approaches have demonstrated higher removal efficiencies for a wide range of APIs compared to conventional methods, such as activated sludge and chlorination, which have been found to be inadequate in the removal of these emerging contaminants. The potential of these alternative treatment technologies to serve as effective tertiary treatment. To address this critical challenge, governments and policymakers should prioritize investment in research and development to establish effective and scalable solutions for eliminating APIs from various water sources. This should include comprehensive studies to assess the performance, cost-effectiveness, and environmental sustainability of emerging treatment technologies. The emerging contaminants should be included in robust water quality monitoring programs (Aus der Beek et al. in Environ Toxicol Chem 2016;35(4):823-835), with strict regulatory limits enforced to protect public health and the environment. By doing so, the scientific community and regulatory authorities can work together to develop a multi-barrier approach to safeguarding the water resources and ensuring access to safe, clean water for all. This review explores the potential of alternative treatment technologies to serve as viable solutions in the fight against API contamination. Innovative approaches, including nanotechnology, microalgal treatment, and reverse osmosis, have demonstrated remarkable success in addressing this challenge, exhibiting higher removal efficiencies compared to traditional methods.

Efficacy Assessment of Molecularly Imprinted Polymer Incorporated with Starch and Macadamia Capped Silver Nanoparticles for the Removal of Multi‐Class Pharmaceuticals in Wastewater

AbstractThe presence of pharmaceuticals in water bodies has been reported to be mainly due to their incomplete removal by the conventional wastewater treatment processes, resulting to their release into the aquatic environment where they thratens to human health and aquatic life. Therefore, it is important to remove these pollutants from the aquatic environment using affordable highly efficient materials. The goal of this study was to incorporate silver nanoparticles (AgNPs) into MIPs for selective removal of sulfamethoxazole, nevirapine, and ibuprofen in wastewater. The AgNPs were synthesized using starch (St) and macadamia (MCD) as both reducing and stabilizing agents. Thermogravimetric analysis showed high stability for the St/MCD‐nanoMIPs. The ANOVA analysis revealed that the parameters affecting adsorption of St/MCD‐nanoMIPs have a significant difference (p<0.05). The St/MCD‐AgNPs experimental data fitted to both Langmuir and Freundlich adsorption isotherms, however, the non‐linear Langmuir isotherm model yielded a better fit based on the higher R2 value (0.999). The non‐linear Freundlich model best fitted for the St/MCD‐nanoMIPs. The linear pseudo‐second order model shown best fit for St/MCD‐nanoMIPs, the thermodynamic results revealed that the adsorption process was spontaneous and endothermic. The St/MCD‐nanoMIPs showed improved qualities and were highly selective (>70 %) and effective in removing the selected pharmaceuticals from wastewater.

Research on a Novel Heat Treatment Process for Boron Steel Used for Soil-Engaging Components of Tillage Machinery

To address the issue of high fracture and wear failure rates caused by the lack of toughness and abrasion resistance in the steel used for soil-engaging components of tillage machinery, a novel composite heat treatment process, “normalizing and intercritical quenching and tempering (NIQT)”, is proposed. By regulating the austenitizing heating temperature in the intercritical area (ferrite/austenite two-phase area), the type, content, and distribution of phases in the 27MnCrB5 test sample could be precisely controlled, which further influenced the mechanical properties of the material. The results demonstrated that a multiphase composite microstructure, predominantly consisting of martensite and ferrite, could be obtained in the 27MnCrB5 steel treated by the NIQT process. The results of an EBSD test indicated that the predominant type of grain boundary following the NIQT heat treatment was a high-angle grain boundary (approximately 59.5%), which was favorable for hindering crack propagation and improving the impact toughness of the material. The results of the mechanical tests revealed that, when the quenching temperature was set to 790 °C, the 27MnCrB5 steel attained excellent comprehensive mechanical properties, with a tensile strength of 1654 MPa, elongation of 10.4%, impact energy of 77 J, and hardness of 530 HV30. Compared with conventional heat treatment processes for soil-engaging components, this novel process has the potential to enhance the performance of soil-engaging components and prolong their service life.

Insights into the role of electrochemical stimulation on sulfur-driven biodegradation of antibiotics in wastewater treatment

The presence of antibiotics in wastewater poses significant threat to our ecosystems and health. Traditional biological wastewater treatment technologies have several limitations in treating antibiotic-contaminated wastewaters, such as low removal efficiency and poor process resilience. Here, a novel electrochemical-coupled sulfur-mediated biological system was developed for treating wastewater co-contaminated with several antibiotics (e.g., ciprofloxacin (CIP), sulfamethoxazole (SMX), chloramphenicol (CAP)). Superior removal of CIP, SMX, and CAP with efficiencies ranging from 40.6 ± 2.6% to 98.4 ± 1.6% was achieved at high concentrations of 1000 μg/L in the electrochemical-coupled sulfur-mediated biological system, whereas the efficiencies ranged from 30.4 ± 2.3% to 98.2 ± 1.4% in the control system (without electrochemical stimulation). The biodegradation rates of CIP, SMX, and CAP increased by 1.5∼1.9-folds under electrochemical stimulation compared to the control. The insights into the role of electrochemical stimulation for multiple antibiotics biodegradation enhancement was elucidated through a combination of metagenomic and electrochemical analyses. Results showed that sustained electrochemical stimulation significantly enriched the sulfate-reducing and electroactive bacteria (e.g., Desulfobulbus, Longilinea, and Lentimicrobiumin on biocathode and Geobactor on bioanode), and boosted the secretion of electron transport mediators (e.g., cytochrome c and extracellular polymeric substances), which facilitated the microbial extracellular electron transfer processes and subsequent antibiotics removal in the sulfur-mediated biological system. Furthermore, under electrochemical stimulation, functional genes associated with sulfur and carbon metabolism and electron transfer were more abundant, and the microbial metabolic processes were enhanced, contributing to antibiotics biodegradation. Our study for the first time demonstrated that the synergistic effects of electrochemical-coupled sulfur-mediated biological system was capable of overcoming the limitations of conventional biological treatment processes. This study shed light on the mechanism of enhanced antibiotics biodegradation via electrochemical stimulation, which could be employed in sulfur-mediated bioprocess for treating antibiotic-contaminated wastewaters.

Synthesis of nano zero valent zinc-reduced graphene oxide nanocomposite using a novel electrochemical technique for the adsorptive degradation of methyl orange

Indiscriminate disposal of effluent contaminated with persistent azo dyes has become a significant environmental issue. Since the conventional wastewater treatment processes are ineffective in removing azo dyes completely, many studies are currently being focused on finding effective methods to degrade azo dyes. We herein report a novel in-situ synthesis of a nanocomposite with nano-zero valent zinc (nZVZ) and reduced graphene oxide (rGO) that can effectively remove methyl orange, an azo dye, from an aqueous solution via adsorptive degradation. nZVZ-rGO nanocomposite was synthesized by electrochemical reduction of Zn2+ ions on rGO. The presence of nZVZ particles on rGO with an average metal-loading of 4% was confirmed by SEM-EDS, TEM, XPS and XRD results. Batch experiments showed that a maximum removal efficiency of 99.6% of methyl orange can be achieved with 25mgL-1 initial dye concentration and by optimizing the pH, nanocomposite dosage and contact time. However, a noticeable reduction in removal efficiency was observed in the presence of anions such as Cl-, SO42- and CO32-. The degradation of methyl orange was monitored using UV-Visible spectroscopy, HPLC and FTIR spectroscopy. The peaks corresponding to -N=N- group, –C-N bond and –SO3Na group have completely disappeared in the product spectrum of FTIR analysis, indicating the degradation of methyl orange. The adsorptive degradation process of methyl orange obeys the Sips model (R2=0.9820) indicating a complex heterogenous adsorption mechanism while the kinetic model was shown to be pseudo-second-order model (R2=0.9999).

Photodegradation of tylosin tartrate by advanced oxidation processes.

Tylosin tartrate, a macrolide antibiotic, is one of a class of emerging contaminants that have been detected in natural bodies of water since they are not easily removed by conventional treatment processes. In this study, the direct and indirect photodegradation of tylosin tartrate was analyzed to understand the role of reactive oxygen species and organic matter that may be present in surface waters. While direct photolysis caused negligible degradation (k = (9.4 ± 1.8) × 10-5s-1), the addition of 0.4M hydrogen peroxide (k = (2.18 ± 0.01) × 10-4s-1) or usage of the photo-Fenton process (k = (2.96 ± 0.02) × 10-4s-1) resulted in greater degradation. The degradation was maximized by combining tylosin tartrate with an experimentally determined optimal concentration of humic acid (15mg/L), which readily produced singlet oxygen and increased the overall degradation (k = 1.31 ± 0.05) × 10-3s-1) by means of indirect photolysis. Absolute pseudo-first-order bimolecular reaction rate constants for tylosin tartrate were measured with singlet oxygen [(4.7936 ± 0.0001) × 105M-1s-1] and hydroxyl radical [(5.2693 ± 0.0002) × 109M-1s-1] using competition kinetics, and when combined with data on concentration of the reactive oxygen species, showed that the hydroxyl radical makes a contribution to the degradation that is approximately eleven orders of magnitude greater than singlet oxygen.

Enhanced sorption of hyper-cross-linked polymers for enrofloxacin via polystyrene adhesion: Exploring the feasibility of a collaborative treatment approach for emerging contaminants

The conventional treatment processes adopted by wastewater treatment plants (WWTPs) are unable to completely remove antibiotics and microplastics (MPs), resulting in the discharge of residual antibiotics and MPs into the environment, which poses threats to both ecological and human health. Therefore, targeted removal of residual antibiotics and MPs in effluent from WWTPs is crucial. Moreover, the presence of MPs in the wastewater system is likely to affect the removal of antibiotics. Here, the impact of polystyrene (PS) on the sorption characteristics and mechanisms of enrofloxacin (ENR) by hyper-cross-linked polymers (HCPs) was studied. The possibility of collaborative treatment of antibiotics and MPs was also discussed. The results showed that PS could affect the sorption of ENR by interacting with HCPs. The addition of PS increased dispersibility of HCPs and the number of sorption sites, thereby enhancing the sorption of ENR. However, as the concentration of PS increased, the repulsive energy between HCPs and PS decreased from 600 to 280 kT, leading to further heterogeneous aggregation between HCPs and PS. It prevented some of the sorption sites from being exposed to ENR, thereby reducing the promotion effect from 57% to 13%. Additionally, PS facilitated the sorption of ENR through promoting electrostatic attraction, π−π, and n−π interactions. The presence of PS also enhanced the removal of ENR in actual water samples with the efficiency of 98.2%. While removing antibiotics, MPs can also be separated from sewage by forming aggregates with HCPs. This study contributes to a deeper understanding of the role of MPs in the treatment of antibiotics within wastewater systems and offers new insights for the collaborative treatment of emerging contaminants in wastewater systems.

Abatement of algal extracellular organic matter by vacuum ultraviolet: Effect of dissolved oxygen and role of in-situ formed reactive oxygen species

Algal extracellular organic matter (EOM) in water produced during the outbreak of algal blooms is difficult to be effectively removed by conventional water treatment processes. Compared with ultraviolet (UV), vacuum ultraviolet (VUV) can additionally radiate 185 nm photons, and VUV can split water to produce reactive oxygen species (ROS) in-situ. Herein, abatement and characteristic variation of EOM under VUV irradiation and the mechanism were investigated. Results indicated that EOM abatement by VUV irradiation were significantly higher than that by UV irradiation. The mineralization rate constant of EOM under VUV was 2.25 times of that under UV. Besides, under VUV irradiation, the abatement efficiency of EOM was promoted with the increased dissolved oxygen (DO), and EOM with a lower initial concentration had a higher abatement efficiency. Intensities of characteristic fluorescence peaks of EOM decreased obviously after VUV irradiation, and removal rates of specific fluorescent organic components were ≥ 74.4%. Under VUV irradiation, organic matter in EOM with higher molecular weight was transformed into that with lower molecular weight. Moreover, hydroxyl radical (•OH) generated in-situ by VUV dissociating water with different DO was directly identified by fluorescence molecular probe technology, and the higher DO caused the higher production of •OH. Furthermore, the mechanism of EOM abatement by VUV was proposed. DO and the produced ROS enhanced the abatement efficiency of EOM, and they played important roles in EOM abatement. This study disclosed abatement characteristics of EOM under VUV irradiation and provided great value for expanding the utilization of VUV in water treatment.

Electropulsing rapidly refined the microstructure and enhanced the strength and plasticity of Cu-3.5Ti alloy

Recrystallization annealing is a necessary process for refining the grain of processed metallic materials and eliminating work hardening. However, it can cause a large amount of precipitation and coarsening of the second phase in supersaturated solid solution alloys, which is detrimental to the subsequent processing and aging processes aimed at controlling the precipitation phase. This article compared the effects of electropulsing (EPT) and conventional heat treatment (CHT) processes on the microstructure and mechanical properties of cold-rolled Cu-3.5Ti alloy. The results indicated that compared with CHT, EPT achieved full recrystallization of the alloy at a lower temperature (650 °C, 100 °C lower than CHT) and in a shorter time (10 s, 1/360 of CHT), and effectively inhibited the precipitation of β-Cu4Ti phase, resulting in a fine and uniform supersaturated solid solution. This process significantly improved both the strength and plasticity of the alloy. The yield strength, tensile strength and elongation to failure of the EPT-650 °C/10 s sample were 570 MPa, 598 MPa and 21.2 %, respectively, which were 27.8 %, 25.9 % and 19.1 % higher than those of the CHT-750 °C/1 h sample. EPT significantly increased the recrystallization nucleation rate of the alloy, while its rapid heating method inhibited the precipitation of β-Cu4Ti phase, ensuring the recrystallization process was not affected by the precipitated phase, which was the main reason for rapid recrystallization and grain refinement of Cu-3.5Ti alloy by EPT at lower temperatures and shorter time.

A novel and cost-effective biological denitrification associated with membrane process for treating pesticide wastewater: Excellent nitrogen removal effect and higher environment benefits

A two-phase anaerobic/aerobic/integrated deoxygenated and anoxic reactor associated with membrane process, namely biological denitrification associated with membrane process (BDMP), was designed to achieving effluent TN below 10 mg/L for pesticide wastewater. For 397 days, COD, TN, NH4+−N and alkali demand were investigated under different hydraulic retention times (HRTs) compared with conventional biological treatment process (CBTP), which was composed of anoxic-anaerobic-anoxic-aerobic process. The average COD effluent concentration of BDMP and CBTP was 36.41 mg/L and 984.42 mg/L. The average TN removal efficiency of BDMP (97.3 %) was significantly higher than that of CBTP (85.6 %), and the average NH4+−N removal efficiency of BDMP was 99.3 %. The alkali demand in BDMP decreased by 11.56 %. Through calculation, similar capital cost (776.132 and 753.812 US$ × 104) and operating cost (1.69 and 1.70 US$ × 104) and superior environmental benefits (746.71 and 695.72 US$/m3·d) were seen in BDMP and CBTP.

Enhancing adsorption capacity of carbon nanotubes through sand filters for the removal of organic pollutants: a column investigation

ABSTRACT Dissolved organic pollutants caused by paints, detergents, herbicides, and toxins cannot be removed by conventional water treatment processes such as filtration. Different figures of activated carbon such as carbon nanotubes (CNTs) are substances to obliterate these contaminants. Although these CNTs have higher ability to decompose organic contaminants, using the slurry form of CNTs is not suitable due to the removal requirement at the end of the treatment procedure. In this study, upgraded CNTs attached to particles of sand filters (CNTsand) were synthesised and applied to remove dissolved organic pollutants. The results revealed the high capacity of the CNTsand to extract organic contaminants. The column test with natural water compared to the distilled water had a more extended breakpoint, higher adsorption capacity, and consequently, further removal efficiency, such that for the surface area loading rate of 4.8 ml/min, the breakpoint increased from 739 minutes to 936 minutes as well as the volume of passed water grew from 3546 ml to 4493 ml; Therefore, the maximum adsorption capacity was enhanced from 67.3 mg/g to 89.5 mg/g. In conclusion, the adequacy and efficiency of the upgraded nanotube coating on sand grains to remove organic pollutants were confirmed.

New silica-based adsorbents for water purification: Removal of short- and long-chain perfluoroalkyl sulfonic acids (PFSA) at sub-nanomolar concentrations

Perfluoroalkyl acids (PFAAs) are widespread in the aquatic environment and also measurable in ground and drinking water. Because of the insufficient PFAA elimination in conventional water treatment processes, e. g. active carbon based methods, consumers in areas with contaminated water supplies are exposed to an elevated health hazard. For this purpose, the applicability of five differentially fluorinated silica-based adsorbents (HSU00107954-958) to remove the potentially human toxic perfluoroalkyl sulfonic acids(PFSAs) perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), and perfluorobutane sulfonic acid (PFBS) from water was investigated with regard to removal efficiencies (REs) and equilibrium loadings. During the adsorbent screening at nanomolar concentrations (20.0–33.4 nmol L−1) maximum REs of 46.9% for PFBS (HSU00107954), 79.4% for PFHxS (HSU00107954), and between 86.5 to 96.7% for PFOS (HSU00107956, and HSU00107954, respectively) have been achieved. Even at picomolar concentrations (< 400 pmol L−1) HSU00107954 was still able to eliminate PFBS and PFHxS with an efficiency of 46.3–51.2% and 79.1–88.2%, respectively. Analyses of the equilibrium loadings of the functionalized adsorbents in the concentration range 40.1 pmol to 3.34 nmol L−1 resulted in appropriate linearized Freundlich isotherms for all investigated PFSA. Compared to literature-based Freundlich adsorption coefficients (KF) for granular activated carbon (GAC), the determined KF values (nmol(1−n) Ln m−2) of the most efficient adsorbents HSU00107956 and HSU00107954 for each PFSA were significantly 8–10 and 50–60 times higher, respectively. These proven increased adsorption capacities relative to activated carbon possibly indicate specific PFSA selectivities of the functionalized macroporous silica adsorbents.

Theoretical studies into the degradation mechanisms and kinetics of gemfibrozil mediated by hydroxyl and sulfate radicals in the aqueous phase and ecotoxicity evaluation

Gemfibrozil (GEM), an acidic pharmaceutical used to reduce plasma triglycerides and total cholesterol levels, persists in conventional wastewater treatment processes. However, understanding its degradation mechanism and kinetics through advanced oxidation processes (AOPs) remains unexplored. Therefore, this study employed density functional theory (DFT) at the M06-2X/6-311++G(3df,2p) //M06-2X/6-311G(d,p) level to theoretically investigate the oxidation of GEM by hydroxyl and sulfate radicals in aqueous environments. Mechanistic pathways, reaction kinetics, and ecotoxicological assessments were conducted. Two distinct mechanisms involving addition and hydrogen abstraction were delineated. The overall rate constants, accounting for diffusion-limited effects, were determined as 1.84 × 109 M−1 s−1 and 7.73 × 109 M−1 s−1 at 298 K for •OH and SO4•−-initiated reactions, respectively. Analysis revealed that hydrogen abstraction at the carboxyl group predominated, while favorable addition occurred at the carbon atom positioned at the 3rd position of the benzene ring. The calculated half-life of GEM initiated by •OH and SO4•− was approximately 377 and 90 s with their concentration of 10−12 mol/L at 298 K. Ecotoxicity assessment via quantitative structure-activity relationship (QSAR) indicated a certain degree of danger posed by GEM and its degradation by-products to aquatic organisms, albeit exhibiting lower toxicity compared to GEM itself.

Monte Carlo Simulations of Water Pollutant Adsorption at Parts-per-Billion Concentration: A Study on 1,4-Dioxane.

1,4-dioxane, an emerging water pollutant with high production volumes, is a probable human carcinogen. The inadequacy of conventional treatment processes demonstrates the need for an effective remediation strategy. Crystalline nanoporous materials are cost-effective adsorbents due to their high capacity and selective separation in mixtures. This study explores the potential of all-silica zeolites for the separation of 1,4-dioxane from water. These zeolites are highly hydrophobic and can preferentially adsorb nonpolar molecules from mixtures. We investigated six zeolite frameworks (BEA, EUO, FER, IFR, MFI, and MOR) using Monte Carlo simulations in the Gibbs ensemble. The simulations indicate high selectivity by FER and EUO, especially at low pressures, which we attribute to pore sizes and shapes with a greater affinity to 1,4-dioxane. We also demonstrate a Monte Carlo simulation workflow using gauge cells to model the adsorption of an aqueous solution of 1,4-dioxane at a 0.35 ppb concentration. We quantify 1,4-dioxane and water coadsorption and observe selectivities ranging from 1.1 × 105 in MOR to 8.7 × 106 in FER. We also demonstrate that 1,4-dioxane is in the infinite dilution regime in the aqueous phase at this concentration. This simulation technique can be extended to model other emerging water contaminants such as perfluoroalkyl and polyfluoroalkyl substances (PFAS), chlorofluorocarbons, and others, which are also found in extremely low concentrations.

The efficacy of current treatment processes to remove, inactivate, or reduce environmental bloom-forming Escherichia coli.

Escherichia coli is excreted in high numbers from the intestinal tract of humans, other mammals, and birds. Traditionally, it had been thought that E. coli could grow only within human or animal hosts and would perish in the environment. Therefore, the presence of E. coli in water has become universally accepted as a key water quality indicator of fecal pollution. However, recent research challenges the assumption that the presence of E. coli in water is always an indicator of fecal contamination, with some types of E. coli having evolved to survive and grow in aquatic environments. These strains can form blooms in water storages, resulting in high E. coli counts even without fecal contamination. Although these bloom-forming strains lack virulence genes and pose little threat to public health, their presence in treated water triggers the same response as fecal-derived E. coli. Yet, little is known about the effectiveness of treatment processes in removing or inactivating them. This study evaluated the effectiveness of current treatment processes to remove bloom-forming strains, in comparison to fecal-derived strains, with conventional coagulation-flocculation-sedimentation and filtration investigated. Second, the effectiveness of current disinfection processes-chlorination, chloramination, and ultraviolet (UV) light to disinfect bloom-forming strains in comparison to fecal-derived strains-was assessed. These experiments showed that the responses of bloom isolates were not significantly different from those of fecal E. coli strains. Therefore, commonly used water treatment and disinfection processes are effective to remove bloom-forming E. coli strains from water.IMPORTANCEThe presence of Escherichia coli in water has long been used globally as a key indicator of fecal pollution and for quantifying water safety. Traditionally, it was believed that E. coli could only thrive within hosts and would perish outside, making its presence in water indicative of fecal contamination. However, recent research has unveiled strains of E. coli capable of surviving and proliferating in aquatic environments, forming blooms even in the absence of fecal contamination. While these bloom-forming strains lack the genes to be pathogenic, their detection in source or drinking water triggers the same response as fecal-derived E. coli. Yet, little is known about the efficacy of treatment processes in removing them. This study evaluated the effectiveness of conventional treatment and disinfection processes in removing bloom-forming strains compared to fecal-derived strains. Results indicate that these commonly used processes are equally effective against both types of E. coli, reassuring that bloom-forming E. coli strains can be eliminated from water.

Adsorptive and oxidative removal of phenolphthalein by sono-assisted synthesized FeAcC in advanced oxidation-integrated fluidized bed reactor

ABSTRACT Environmental water sources are under increasing threat due to the addition of harmful chemicals not addressed by conventional water treatment processes. To work on this concern, the current study aimed to synthesize sono-assisted Fe-modified activated carbon-chitosan (FeAcC) composite and construct a laboratory-scale ozone-integrated fluidized bed reactor (FBR) to eliminate phenolphthalein (php). Following 120 min of incubation, the adsorbent demonstrated a 27.28 mg g−1 of php adsorption capacity at pH 4 with 0.5 g L−1 of adsorbent dosage. The adsorption efficacy and mechanism were defined using isotherm and kinetic models. The study investigated the impact of different factors including, initial concentration, reuse of FeAcC, recirculation flow rate, and hydraulic retention time (HRT), on the efficiency of php removal. The optimum removal efficiency was observed at approximately 95% after 20 min of operation at 1.5 L min−1 recirculation flow rate (batch FBR) and 70 min of HRT (continuous FBR) under 400 mg h−1 ozonation rate. Experimental parameters were optimized using response surface methodology (RSM) with central composite design (CCD) to improve php removal. The large-scale implementation of the findings in the future can be a step for adding new technology for clean water treatment processes for emerging toxic pollutants.

The distribution and fate of pesticides in full-scale drinking water treatment plants

This study utilized HPLC-MS/MS combined with improved solid-phase extraction techniques to investigate the distribution and fate of 31 pesticides in three drinking water treatment plants (DWTPs), which source their water from the Yangtze River, the Yellow River, and Taihu Lake. The total concentration of pesticides in the raw water of the three water treatment plants ranged from 145.4 to 257.1 ng/L, while in the treated water it ranged from 22.8 to 59.0 ng/L, with an average removal efficiency of 78.3 %. Atrazine emerges as the predominant pesticide substance in the raw water of all three plants, indicating its continued widespread use. In the conventional treatment process, sand filtration and disinfection can remove a small amount of pesticides, while coagulation and sedimentation are ineffective. However, adding a pre-ozonation step before coagulation and sedimentation can enhance the removal efficiency of pesticides. Ozone and BAC are the most effective removal processes, with pesticide removal rates ranging from 31.8 % to 64.6 % for ozone and from 20.9 % to 47.7 % for BAC. The combination of ozone and H2O2 (64.6 %) has a higher pesticide removal efficiency compared to the ozone process alone (31.8 % and 50.7 %), especially for substances that are resistant to degradation by ozone. However, BAC's effectiveness in pesticide removal decreases significantly with increasing years of usage. After 2 years of use, the removal rate of BAC is 83.3 %, whereas after 4 years, it decreases to only 26.6 %. This study contributes to the understanding of the fate of pesticides in the drinking water treatment process.

Ultrafiltration and reverse osmosis integrated to conventional drinking water treatment to ensure human right to water in dam break scenarios: From bench- to pilot-scale

Previous events of tailing dam failures were associated with impacts in the water sources of drinking water treatment plants, which involves elevated concentrations of suspended solids and metal(oid)s. This study assesses the effectiveness of conventional treatment processes at a lab-scale, highlighting their limited robustness in treating water with different physicochemical qualities. Subsequently, it validates the integration of ultrafiltration (UF) and reverse osmosis (RO) into an existing water treatment plant to enhance its performance. The processes were conducted at a pilot scale, operating for 660 h under varied turbidity (<2 – 200 NTU) and contaminant (iron, manganese, and arsenic) concentrations. The membranes operated steadily with an average permeate flux of 38.6 ± 0.9 L/m2h and 19.6 ± 0.8 L/m2h for UF and RO, respectively. UF fouling was primarily related to internal pore blocking and attributed to organic matter and inorganic compounds, identified using excitation-emission matrix and energy-dispersive X-ray mapping across the cross-section of its fibers. Due to the limitations of UF in removing dissolved species, RO became necessary and ensured that all parameters analyzed met drinking water standards. The UF-RO contributes to higher robustness to conventional treatment processes and addresses operational challenges associated with a dam rupture event such as the unforeseen alteration in the quality of surface water that hinders the optimization of pre-oxidants and coagulants in conventional treatment process. To reduce costs, energy requirements, and the size of membrane-based systems, a blending strategy was proposed with a focus on achieving drinking water standards. The suggested blends include effluent from sand filters and RO permeate in a 1:1 ratio. That was only possible due to the high quality achieved for RO permeate. Apart from creating more compact systems, the blending strategy promotes the remineralization of RO permeate, mitigating undesirable characteristics such as corrosiveness, taste, and odor. For the concentrate, UF concentrate could be recycled back into the treatment process, improving water recovery in the drinking water facility, while the concentrate from RO adheres to discharge limits. Overall, the study advances investigations on integrating ultrafiltration and reverse osmosis with conventional drinking water treatment to address water quality issues from tailing dam ruptures.

Engineered lignocellulosic based biochar to remove endocrine-disrupting chemicals: Assessment of binding mechanism

The safety and health of aquatic organisms and humans are threatened by the increasing presence of pollutants in the environment. Endocrine disrupting chemicals are common pollutants which affect the function of endocrine and causes adverse effects on human health. These chemicals can disrupt metabolic processes by interacting with hormone receptors upon consumptions by humans or aquatic species. Several studies have reported the presence of endocrine disrupting chemicals in waterbodies, food, air and soil. These chemicals are associated with increasing occurrence of obesity, metabolic disorders, reproductive abnormalities, autism, cancer, epigenetic variation and cardiovascular risk. Conventional treatment processes are expensive, not environment friendly and unable to achieve complete removal of these harmful chemicals. In recent years, biochar from different sources has gained a considerable interest due to their adsorption efficiency with porous structure and large surface areas. biochar derived from lignocellulosic biomass are widely used as sustainable catalysts in soil remediation, carbon sequestration, removal of organic and inorganic pollutants and wastewater treatment. This review conceptualizes the production techniques of biochar from lignocellulosic biomass and explores the functionalization and interaction of biochar with endocrine-disrupting chemicals. This review also identifies the further needs of research. Overall, the environmental and health risks of endocrine-disrupting chemicals can be dealt with by biochar produced from lignocellulosic biomass as a sustainable and prominent approach.

An Extensive Analysis of Combined Processes for Landfill Leachate Treatment

Sanitary landfilling is the predominant process for solid urban waste disposal, but it generates leachate that poses environmental, economic, and social concerns. Landfill leachate (LL) contains complex and refractory pollutants and toxic compounds that can vary depending on landfill maturity, age, and biochemical reactions, making its treatment challenging. Due to its unique characteristics and occurrence in remote locations, LL requires separate treatment from wastewater. Various conventional treatment processes involving biological, chemical, and physical processes have been used for LL treatment, but a single treatment process is insufficient to meet environmental standards. This review demonstrates that combined treatment processes are more effective and efficient for LL treatment compared to single processes. Among the various combinations, chemical–chemical and chemical–biological treatments are the most commonly used. Specifically, the integration of Fenton with adsorption and a membrane bioreactor (MBR) with nanofiltration (NF) processes shows promising results. The combined processes of MBR with NF, Fenton with adsorption, and PF with biological treatment show maximum removal efficiencies for COD, reaching 99 ± 1%, 99%, 98%, and 97%, respectively. Additionally, the combined Fenton with adsorption process and EC with SPF process enhance biodegradability as indicated by increased BOD5/COD ratios, from 0.084 to 0.82 and 0.35 to 0.75, respectively. The findings emphasize the importance of developing and implementing enhanced combined treatment processes for LL, with the aim of achieving efficient and comprehensive pollutant mineralization. Such processes have the potential to address the environmental concerns associated with LL and contribute to sustainable waste management practices.