Conventional Treatment Processes Research Articles

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 that are 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). After 120 min of incubation, the adsorbent demonstrated a 27.28 mg g−1 of php adsorption capacity at a pH of 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 a 400 mg h−1 ozonation rate. Experimental parameters were optimized using response surface methodology with central composite design 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 organic pollutants.

Solar photocatalytic degradation of ciprofloxacin using biochar supported zinc oxide- tungsten oxide photocatalyst.

Ciprofloxacin (CIP) is an antibiotic used to treat bacterial infections. It is not completely broken down during conventional wastewater treatment processes and can persist in the environment, leading to the development of antibiotic-resistant bacteria. This study focuses on the solar photocatalytic degradation CIP using biochar-supported photocatalysts. The photocatalysts developed by combining ZnO and WO3 in different ratios (1:2, 1:1, 2:1) were supported on hemp herd biochar. The photocatalyst made with a ratio of 2:1:1 of ZnO:WO3:biochar (Z2W1H) reported the highest CIP degradation efficiency of 87.3% and TOC removal efficiency of 43.1% at a catalyst dosage of 2g/L, initial CIP concentration of 3mg/L, and treatment time of 150min. Subsequently, the effects of operating parameters on CIP degradation were investigated using central composite design (CCD). About 85.4% degradation efficiency of CIP was obtained at optimum conditions (pH ∼8.4, initial CIP concentration ∼4.4mg/L, catalytic dosage ∼3.4g/L) within 90min. A quadradic model was developed to interpret the linear and interactive effect of operating parameters on the CIP degradation efficiency with 2.24-4.59% error. The adsorption-desorption study showed around 42.21% of adsorbed CIP was desorbed from Z2W1H. Scavenger studies demonstrated that the CIP breakdown was notably done by the superoxide radical (O2•-). The mechanism of CIP degradation was adsorption on biochar and subsequent degradation by photocatalyst. The prevalent degradation reactions such as C-N bond cleavage, decarboxylation, decarbonylation, defluorination, and ring opening lead to formation of various intermediates. The Z2W1H reusability test showed ~ 4.2% decrease in CIP removal efficiency after three cycles.

Occurrence, efficiency of treatment processes, source apportionment and human health risk assessment of pharmaceuticals and xenoestrogen compounds in tap water from some Ghanaian communities

The occurrence of pharmaceuticals and xenoestrogen compounds (PXCs) in drinking water presents a dire human health risk challenge. The problem stems from the high anthropogenic pollution load on source water and the inefficiencies of the conventional water treatment plants in treating PXCs. This study assessed the PXCs levels and the consequential health risks of exposure to tap water from selected Ghanaian communities as well as that of raw water samples from the respective treatment plants. Thus the PXCs treatment efficiency of two drinking water treatment plants in the metropolises studied was also assessed. The study also conducted source apportionment of the PXCs in the tap water. Twenty six (26) tap and raw water samples from communities in the Cape Coast and Sekondi-Takoradi metropolises were extracted using SPE cartridges and analysed for PXCs using Ultra-fast-HPLC-UV instrument. Elevated levels of PXCs up to 24.79 and 22.02 μg/L were respectively recorded in raw and tap water samples from the metropolises. Consequently, elevated non-cancer health risk (HI > 1) to residential adults were found for tap water samples from Cape Coast metropolis and also for some samples from Sekondi-Takoradi metropolis. Again, elevated cumulative oral cancer risks >10−5 and dermal cancer risk up to 4 × 10−5 were recorded. The source apportionment revealed three significant sources of PXCs in tap water samples studied. The results revealed the inefficiency of the treatment plants in removing PXCs from the raw water during treatments. The situation thus requires urgent attention to ameliorate it, safeguarding public health. It is recommended that the conventional water treatment process employed be augmented with advanced treatment technologies to improve their efficacy in PXCs treatment.

Molecular Simulation Studies of Pharmaceutical Pollutant Removal (Rosuvastatin and Simvastatin) Using Novel Modified-MOF Nanostructures (UIO-66, UIO-66/Chitosan, and UIO-66/Oxidized Chitosan).

The ubiquitous presence of pharmaceutical pollutants in the environment significantly threatens human health and aquatic ecosystems. Conventional wastewater treatment processes often fall short of effectively removing these emerging contaminants. Therefore, the development of high-performance adsorbents is crucial for environmental remediation. This research utilizes molecular simulation to explore the potential of novel modified metal-organic frameworks (MOFs) in pharmaceutical pollutant removal, paving the way for the design of efficient wastewater treatment strategies. Utilizing UIO-66, a robust MOF, as the base material, we developed UIO-66 functionalized with chitosan (CHI) and oxidized chitosan (OCHI). These modified MOFs' physical and chemical properties were first investigated through various characterization techniques. Subsequently, molecular dynamics simulation (MDS) and Monte Carlo simulation (MCS) were employed to elucidate the adsorption mechanisms of rosuvastatin (ROSU) and simvastatin (SIMV), two prevalent pharmaceutical pollutants, onto these nanostructures. MCS calculations demonstrated a significant enhancement in the adsorption energy by incorporating CHI and OCHI into UIO-66. This increased ROSU from -14,522 to -16,459 kcal/mol and SIMV from -17,652 to -21,207 kcal/mol. Moreover, MDS reveals ROSU rejection rates in neat UIO-66 to be at 40%, rising to 60 and 70% with CHI and OCHI. Accumulation rates increase from 4 Å in UIO-66 to 6 and 9 Å in UIO-CHI and UIO-OCHI. Concentration analysis shows SIMV rejection surges from 50 to 90%, with accumulation rates increasing from 6 to 11 Å with CHI and OCHI in UIO-66. Functionalizing UIO-66 with CHI and OCHI significantly enhanced the adsorption capacity and selectivity for ROSU and SIMV. Abundant hydroxyl and amino groups facilitated strong interactions, improving performance over that of unmodified UIO-66. Surface functionalization plays a vital role in customizing the MOFs for pharmaceutical pollutant removal. These insights guide next-gen adsorbent development, offering high efficiency and selectivity for wastewater treatment.

Novel nanostructure approach for antibiotic decomposition in a spinning disc photocatalytic reactor

Conventional wastewater treatment processes are often unable to remove antibiotics with resistant compounds and low biological degradation. The need for advanced and sustainable technologies to remove antibiotics from water sources seems essential. In this regard, the effectiveness of a spinning disc photocatalytic reactor (SDPR) equipped with a visible light-activated Fe3O4@SiO2-NH2@CuO/ZnO core–shell (FSNCZ CS) thin film photocatalyst was investigated for the decomposition of amoxicillin (AMX), a representative antibiotic. Various characterization techniques, such as TEM, FESEM, EDX, AFM, XRD, and UV–Vis-DRS, were employed to study the surface morphology, optoelectronic properties, and nanostructure of the FSNCZ CS. Key operating parameters such as irradiation time, pH, initial AMX concentration, rotational speed, and solution flow rate were fine-tuned for optimization. The results indicated that the highest AMX decomposition (98.7%) was attained under optimal conditions of 60 min of irradiation time, a rotational speed of 350 rpm, a solution flow rate of 0.9 L/min, pH of 5, and an initial AMX concentration of 20 mg/L. Moreover, during the 60 min irradiation time, more than 69.95% of chemical oxygen demand and 61.2% of total organic carbon were removed. After the photocatalytic decomposition of AMX, there is a substantial increase in the average oxidation state and carbon oxidation state in SDPR from 1.33 to 1.94 and 3.2, respectively. Active species tests confirmed that ·OH and ·O2− played a dominant role in AMX decomposition. The developed SDPR, which incorporates a reusable and robust FSNCZ CS photocatalyst, demonstrates promising potential for the decomposition of organic compounds.

The effectiveness and feasibility of ball-milled powdered activated carbon (BPAC) for removal of organic pesticides in conventional drinking water treatment process

In the conventional drinking water treatment process (CDWTP), powdered activated carbon (PAC) is commonly used for removing organic pesticides, or other organic contaminants. However, the hydraulic retention time (HRT) in CDWTP is insufficient for fulfilling PAC adsorption equilibrium to realize its full capacity. This study examined the adsorption kinetics, adsorption thermal dynamics, and removal efficiency for six organic pesticides using the ball-milled PAC (BPAC) with varying particle sizes in CDWTP. Based on the experiments with the pesticides of atrazine, diazinon, dimethoate, fenitrothion, isoproturon and thiometon, the results indicated that as the particle size reduced from around 38 μm for the commercial PAC to 1 μm for the BPAC, the adsorption rates for hydrophobic pesticides increased up to twentyfold. Diffusional adsorption from the bulk solution to the external PAC surface is the most likely predominant mechanism. This could allow a sufficient pesticides’ adsorption within the limited HRT and to achieve a great depth removal of these toxic compounds. However, the addition of BPAC with a diameter of 1 μm was observed to significantly increase residual particles in treated water after the conventional treatment process. With a further systematic evaluation of both adsorption rate and particle penetration, a particle size of around 6 μm BPAC was considered a practical compromise between the adsorption rate and particle penetration for real application. Results from five surface waters of different water quality indicated that, compared to commercial PAC, application of 6 μm BPAC could achieve up to a 75% reduction in adsorbent dosage while maintaining around the same pesticide removal efficiencies. Additionally, thermodynamic analyses suggest that adsorption of these pesticides could be enthalpically or entropically driven depending on the degree of pesticide hydrophobicity.

The removal of microplastics from reverse osmosis wastewater by coagulation

Wastewater treatment plants (WWTPs) are major sources of microplastic (MP) discharge into water bodies, leading to plastic pollution in the environment and negative effects on aquatic ecosystems. Research is increasingly being focused on MP removal from wastewater, as their presence in freshwater environments, and associated risks, are matters of growing concern. Eliminating MPs from wastewater is a significant challenge for WWTPs, and mitigation actions are required to develop and improve removal treatments. Coagulation has been shown to have high removal efficiency for suspended particles, including MPs. This process involves the addition of coagulants, such as aluminum or iron salts that together with the MPs form larger flocs, facilitating their removal by settling or flotation. Our study evaluated the coagulation process, aiming to improve MP removal from wastewater generated from reverse osmosis (RO) concentrate, backwash microfiltration (MF), and cleaning chemicals for membranes operated by MF and RO processes in industrial water supply facilities. More than 1000 MP particles, predominantly polymers with polyethylene (PE), polypropylene (PP), and polystyrene (PS) were identified as being influenced by the current process. We used polyaluminum chloride (PAC) as chemical coagulant to evaluate MP removal during batch experiments (jar test). Our coagulation process achieved higher efficiencies for microplastic removal than conventional biological treatment processes at an optimal PAC dose and pH. Remarkable results were obtained, with more than 90% of MPs being removed. Our findings indicate that chemical coagulation is effective for removing MPs, and that the process could be optimized by selecting an appropriate coagulant and pH.

BIO-MITIGATION STUDIES OF ARTIFICIAL SWEETENER IN WASTE WATER: A REVIEW

Artificial sweeteners, which are widely used in modern diets and are persistent and may have negative effects on aquatic ecosystems, such as saccharin (SAC), cyclamate (CYC), aspartame (ASP), acesulfame (ACE), sucralose (SUC), alitame (ALT), neotame (NEO), and neohesperidin dihydrochalcone (NSDH), are being found in wastewater effluents at an increasing rate. In order to address this problem, bio-mitigation studies have shown promise as a method of reducing the harm that wastewater-borne artificial sweeteners do to the environment. This review provides a comprehensive overview of recent advancements in bio-mitigation approaches for artificial sweeteners in wastewater treatment systems. Firstly, the prevalence and persistence of artificial sweeteners in wastewater are discussed, highlighting their widespread occurrence and challenges associated with their removal during conventional wastewater treatment processes. Subsequently, various bio-mitigation strategies are examined, including microbial degradation, phytoremediation, and advanced oxidation processes. Microbial degradation, facilitated by diverse microbial communities, has shown potential for degrading artificial sweeteners into less harmful byproducts. several other techniques like Photocatalytic Degradation, Bank filtration, Granular activated carbon (GAC), advanced oxidation processes, such as ozonation and UV/H2O2 treatment, are explored for their ability to degrade artificial sweeteners into non-toxic compounds.

Four-in-one multifunctional self-driven photoelectrocatalytic system for water purification: Organics degradation, U(VI) reduction, electricity generation and disinfection against bacteria

This study addresses the energy-intensive nature of conventional wastewater treatment processes and proposes a solution through the development of a green, low-energy, and multifunctional wastewater treatment technology. The research focuses on a multifunctional self-driven photoelectrocatalytic (PEC) system, exploring its four-in-one applications in eliminating organic pollutants, reducing U(VI), generating electrical energy, and disinfecting pathogenic microorganisms. A TiO2-decorated carbon felt (CF@TiO2) cathode is synthesized to enhance interfacial charge transfer, with TiO2 coating improving surface binding sites (edge TiO and adsorbed -OH) for UO22+ adsorption and reduction. The self-driven PEC system, illuminated solely with simulated sunlight, exhibits remarkable efficiency in removing nearly 100 % of uranium within 0.5 h and simultaneously degrading 99.9 % of sulfamethoxazole (SMX) within 1.5 h, all while generating a maximum power output density (Pmax) of approximately 1065 μW·cm−2. The system demonstrates significant anti-interference properties across a wide pH range and coexisting ions. Moreover, 49.4 % of the fixed uranium on the cathode is reduced into U(IV) species, limiting its migration. The self-driven PEC system also excels in detoxifying various toxic organic compounds, including tetracycline, chlortetracycline, and oxytetracycline, and exhibits exceptional sterilization ability by disinfecting nearly 100 % of Escherichia coli within 0.5 h. This work presents an energy-saving, sustainable, and easily recyclable wastewater purification system with four-in-one capabilities, relying solely on sunlight for operation.

The fate and transport of neonicotinoid insecticides and their metabolites through municipal wastewater treatment plants in South China

Neonicotinoid insecticides (NEOs) have gained widespread usage as the most prevalent class of insecticides globally and are frequently detected in the environment, posing potential risks to biodiversity and human health. Wastewater discharged from wastewater treatment plants (WWTPs) is a substantial source of environmental NEOs. However, research tracking NEO variations in different treatment units at the WWTPs after being treated by the treatment processes remains limited. Therefore, this study aimed to comprehensively investigate the fate of nine parent NEOs (p-NEOs) and five metabolites in two municipal WWTPs using distinct treatment processes. The mean concentrations of ∑NEOs in influent (effluent) for the UNITANK, anaerobic–anoxic–oxic (A2/O), and cyclic activated sludge system (CASS) processes were 189 ng/L (195 ng/L), 173 ng/L (177 ng/L), and 123 ng/L (138 ng/L), respectively. Dinotefuran, imidacloprid, thiamethoxam, acetamiprid, and clothianidin were the most abundant p-NEOs in the WWTPs. Conventional wastewater treatment processes were ineffective in removing NEOs from wastewater (−4.91% to −12.1%), particularly major p-NEOs. Moreover, the behavior of the NEOs in various treatment units was investigated. The results showed that biodegradation and sludge adsorption were the primary mechanisms responsible for eliminating NEO. An anoxic or anaerobic treatment unit can improve the removal efficiency of NEOs during biological treatment. However, the terminal treatment unit (chlorination disinfection tank) did not facilitate the removal of most of the NEOs. The estimated total amount of NEOs released from WWTPs to receiving waters in the Pearl River of South China totaled approximately 6.90–42.6 g/d. These findings provide new insights into the efficiency of different treatment processes for removing NEOs in current wastewater treatment systems.

Applying Recurrent Neural Networks and Blocked Cross-Validation to Model Conventional Drinking Water Treatment Processes

The jar test is the current standard method for predicting the performance of a conventional drinking water treatment (DWT) process and optimizing the coagulant dose. This test is time-consuming and requires human intervention, meaning it is infeasible for making continuous process predictions. As a potential alternative, we developed a machine learning (ML) model from historical DWT plant data that can operate continuously using real-time sensor data without human intervention for predicting clarified water turbidity 15 min in advance. We evaluated three types of models: multilayer perceptron (MLP), the long short-term memory (LSTM) recurrent neural network (RNN), and the gated recurrent unit (GRU) RNN. We also employed two training methodologies: the commonly used holdout method and the theoretically correct blocked cross-validation (BCV) method. We found that the RNN with GRU was the best model type overall and achieved a mean absolute error on an independent production set of as low as 0.044 NTU. We further found that models trained using BCV typically achieve errors equal to or lower than their counterparts trained using holdout. These results suggest that RNNs trained using BCV are superior for the development of ML models for DWT processes compared to those reported in earlier literature.

Perencanaan Sistem Penyediaan Air Bersih di Desa Teluk Melano Kecamatan Simpang Hilir Kabupaten Kayong Utara

The lack of access to clean water services had led a significant portion of the community in Teluk Melano Village to rely on river water and rainwater as their primary sources to meet their needs. Teluk Melano Village has the highest population in the Simpang Hilir District, Kayong Utara Regency. As of now, Teluk Melano Village does not have a Clean Water Supply System (BPAM). Therefore, a study was needed to meet the demand for clean water by conducting a Clean WaterTreatment Plant (IPA Bersih) Planning for Teluk Melano Village. This study aimed to design a clean water supply system with a planning period of the next 15 years (2023-2037). The method used involved primary data collection based on SNI 6989.57.2008 and SNI 8066:2015, and secondary data collection sourced from the Teluk Melano Village Monograph for the years 2020 and 2022. The total demand for clean water in Teluk Melano Village in 2037 would be 3.39 liters/second with a population of 1930 people. The results of the water quality test of the Melani River in this study showed that the parameters of E-coli, color, and pH, based on Government Regulation No. 22 of 2021, Class1, on the Implementation and Management of the Environment, did not meet the standard quality requirements for clean water. The planned Water Treatment Plant (WTP) included a complete conventional treatment process, including coagulation using hydraulic type rapid mixing utilizing gravity on the waterfall, flocculation using vertical baffled channels, sedimentation using plate settlers to reduce turbidity, filtration using rapid sand filters with filter media consisting of quartz sand and support media consisting of gravel, disinfection using chemical disinfectant in the form of chlorine solution, neutralization using a dosing pump for the addition of lime, and the type of reservoir used is a ground reservoir.Keywords: clean water, Water Treatment Plant, Teluk Melano Village

Insights into feasibility and microbial characterizations on simultaneous elimination of dissolved methane from anaerobic effluents and nitrate/nitrite reduction in a conventional anoxic reactor with magnetite

Discovery of nitrate/nitrite-dependent anaerobic methane oxidation (DAMO) challenges the conventional biological treatment processes, since it provides a possibility of simultaneously mitigating dissolved methane emissions from anaerobic effluents and reducing additional carbon sources for denitrification. Due to the slow growth of specialized DAMO microbes, this possibility has been just practiced with biofilms in membrane biofilm reactors or granular sludge in membrane bioreactors. In this study, simultaneous elimination of dissolved methane from anaerobic effluents and nitrate/nitrite reduction was achieved in a conventional anoxic reactor with magnetite. Calculations of electron flow balance showed that, with magnetite the eliminated dissolved methane was almost entirely used for nitrate/nitrite reduction, while without magnetite approximately 52 % of eliminated dissolved methane was converted to unknown organics. Metagenomic sequencing showed that, when dissolved methane served as an electron donor, the abundance of genes for reverse methanogenesis and denitrification dramatically increased, indicating that anaerobic oxidation of methane (AOM) coupled to nitrate/nitrite reduction occurred. Magnetite increased the abundance of genes encoding the key enzymes involved in whole reverse methanogenesis and Nir and Nor involved in denitrification, compared to that without magnetite. Analysis of microbial communities showed that, AOM coupled to nitrate/nitrite reduction was proceeded by syntrophic consortia comprised of methane oxidizers, Methanolinea and Methanobacterium, and nitrate/nitrite reducers, Armatimonadetes_gp5 and Thauera. With magnetite syntrophic consortia exchanged electrons more effectively than that without magnetite, further supporting the microbial growth.

Treatment of hospital wastewater using aerobic granular sludge technology: Removal performance and microbial dynamics

Hospital wastewater contains several contaminants of emerging concern that cannot be removed by conventional treatment processes. Many of these emerging contaminants are pharmaceutical compounds, which are found in hospital wastewater at high loads. The presence of these toxics affects to the performance of biological processes in receiving wastewater treatment plants. This research evaluated the capability of the aerobic granular sludge technology to remove pharmaceutical compounds from hospital wastewater in a single chamber, which to date has not been investigated with real hospital wastewater. Despite the high non-biodegradable organic matter content, COD and BOD5 removal reached 75 % and 100 %, respectively. Nitrogen removal ranged from 70 %–90 %, and phosphate removal was maximum 50 %. The technology was able to efficiently remove antibiotics, antiepileptic and antidepressant drugs, whereas non-steroidal anti-inflammatory drugs were removed and released under oscillating patterns. The granular biomass increased in size, but it reduced the settling velocity. Bacterial and fungal communities were acclimated to pharmaceutical inlet, whereas the archaeal population had a progressive adaptation over time. The aerobic granular sludge technology is therefore a viable approach to enhance the disposal of real hospital wastewater prior to discharge into the urban wastewater network.

Magnetic γ-Fe2O3/ZnO@CNTs synthesized by a green precipitation method for the degradation of aniline through photocatalysis coupling catalytic ozonation

Aniline is highly toxic and difficult to degrade by conventional biological treatment processes. Thus, more efficient processing technology needs to be developed. Photocatalysis coupling catalytic ozonation (PCO) could be a solution. In this study, a green precipitation method was used to synthesize a γ-Fe2O3/ZnO@CNT catalyst, which exhibits high activity for aniline PCO degradation and strong magnetic properties for rapid separation. Under the optimal conditions, the aniline removal rate reached 93.5%. After 5 reaction cycles, the γ-Fe2O3/ZnO@CNT catalysts can be separated easily with a magnet, and a 91% aniline removal rate can be maintained. Furthermore, there are at least 4 kinds of advanced oxidation processes (AOPs) in this system, i.e., (1) photocatalytic oxidation; (2) catalytic ozonation; (3) photocatalytic ozone; and (4) Fenton oxidation. Thus, a novel stable and magnetically separable catalyst was developed, and new insight were provided for the role of PCO processes in the treatment of aniline.

Microstructure effects on improving rolling contact fatigue by a double-quenching heat treatment process for GCr15 steel

The heat treatment process is important in improving the rolling contact fatigue (RCF) life of GCr15 bearing steel by changing the microstructure. The conventional heat treatment process of GCr15 bearing only has one quenching (CQ) process, and the corresponding RCF life cannot satisfy the requirements of many applications. A double-quenching (DQ) heat treatment with two quenching processes was proposed, and it can improve the RCF life. However, the improving mechanisms are not clarified. Therefore, the authors applied the CQ and the DQ heat treatment processes on GCr15 bearing steel and performed the ball-on-disk RCF tests for the specimens heat treated by the different processes. Moreover, comparisons of the microstructure and mechanical behavior between specimens were made. The results show that the DQ heat treatment decreases the average grain size, enhances the retained austenite content, and has no special effect on the carbide distribution. It also increases the homogeneity of grains, hardness, and retained austenite distribution. Moreover, the combined effect of grain size and retained austenite evolutions is the main mechanism that decides the RCF life improvement.

A comparative study on the degradation of carbamazepine by UV laser/chlorine and UV laser/PS processes: Performance and mechanisms

Residual carbamazepine (CBZ) in water is difficult to remove through conventional treatment processes, threatening the safety of drinking water. Ultraviolet-based advanced oxidation processes (UV-AOPs) have shown promise in removing refractory organic pollutants, while the low energy and efficiency of traditional mercury lamps hinder their practical applications. In this study, the performance and mechanism of an intensive-energy light source, UV laser, were systematically explored in UV-AOPs (laser/chlorine, laser/persulfate (PS)). It was found that UV laser exhibited a significantly activating ability for chlorine and PS due to its precise wavelength and high pulse energy. When exposed to UV laser (266 nm, 4.2 mW/cm2) combined with 200 μM chlorine and PS, the kinetic rate constants for the degradation of 10 μM CBZ were determined to be 3.160 × 10-3 and 1.227 × 10-3 s−1, respectively. The degradation of CBZ was dominated by hydroxyl radicals (60.98 %) and sulfate radicals (23.15 %) in laser/PS system, while in laser/chlorine system, hydroxyl radicals (54.90 %), chlorine radicals (27.43 %), and chlorine oxide radicals (13.81 %) were primary reactive species. Furthermore, both the laser/chlorine and laser/PS systems demonstrated compatibility with a wide pH range of 5.0–9.0 and high resistance to anionic interference. Moreover, the electrophilic and nucleophilic sites of CBZ and energy barrier of the initial reaction were calculated based on the density functional theory (DFT). Additionally, the degradation pathways of CBZ and the toxicity of transformation products in laser/chlorine and laser/PS processes were proposed and evaluated. These results demonstrated that the UV laser-based processes exhibited promising prospects in eliminating refractory organic pollutants in water treatment.

The role of algae-based wastewater treatment systems: A comprehensive review

Algae-based wastewater treatment systems have gained significant attention as sustainable and efficient solutions for nutrient removal, organic pollutant degradation, and biomass production. This comprehensive review explores the role of algae-based systems in wastewater treatment, covering key aspects such as nutrient uptake mechanisms, cultivation techniques, system design considerations, and environmental sustainability implications. Algae offer unique advantages for wastewater treatment, including high nutrient removal rates, CO2 sequestration, and the production of valuable biomass for biofuel production and nutrient recycling. Various cultivation methods, including open ponds, raceways, photobioreactors, and wastewater treatment wetlands, are evaluated for their suitability in different wastewater treatment scenarios. The integration of algae-based systems with conventional wastewater treatment processes, such as activated sludge and membrane bioreactors, is discussed to enhance treatment efficiency and resource recovery. Furthermore, the environmental sustainability of algae-based systems, including carbon footprint, water footprint, and ecosystem impacts, is assessed to identify opportunities for mitigating environmental impacts and promoting ecosystem resilience. Future research directions in algae-based wastewater treatment systems, such as optimization of cultivation conditions, development of novel algal strains, and techno-economic analysis of large-scale implementation, are proposed to address remaining challenges and accelerate the adoption of algae-based technologies in wastewater treatment practices. Overall, this review provides valuable insights into the role of algae-based systems as sustainable and versatile tools for wastewater treatment, highlighting their potential to address the growing challenges of nutrient pollution and water scarcity in the 21st century.