Achieved Removal Rates Research Articles

Design, construction and evaluation of collaborative bio-system of Vibrio fluvialis with Chlorella sorokiniana for treating actual printing and dyeing wastewater

Treating actual printing and dyeing wastewater (APDW) using bacteria/algae collaborative is considered an eco-friendly and cost-effective strategy. In this study, Vibrio fluvialis (V. fluvialis) and Chlorella sorokiniana (C. sorokiniana) were isolated from APDW and used to construct the bacteria/algae collaborative treatment system (BACTS) for treating APDW. The results showed that the V. fluvialis / C. sorokiniana collaborative treatment could achieve removal rates of 87.31 % for TP, 73.23 % for COD, and 35 % for dyes under the optimized conditions (V. fluvialis first added, C. sorokiniana followed, V. fluvialis / C. sorokiniana inoculation ratio of 1:2, pH 6.5 and light intensity 8,000 Lux). The APDW water quality improved 55.6 % after the V. fluvialis / C. sorokiniana collaborative treatment. Additionally, the collaborative system generated a significant amount of high-value products (27.63 % lipid yield, 81.1 mg/g polysaccharide and 16.62 mg/g protein). The transcriptome analysis demonstrated that the expression of various enzymes such as laccases, peroxidases and azoreductases, etc. related pathways in V. fluvialis / C. sorokiniana involved in textile dyes degradation and biotransformation. This study provides an efficient and low-cost treatment method for APDW through a novel synergistic biological system of bacteria and algae.

Novel magnetic adsorbents based on oyster and clam shells for the removal of cadmium in soil

Magnetic adsorbents can effectively remove heavy metals from soil. However, the magnetization process may reduce availability of adsorption sites, making it challenging to balance magnetic and adsorption properties. In this study, oyster shell (OS) and clam shell (CS) material was magnetized by an improved chemical co-precipitation method. The organic matter in the shells was destroyed by calcination modification to expose new active sites, and calcinated ferro-magnetic adsorbent was produced with either ferrosodium EDTA (giving CEOS and CECS) or with iron citrate (for CCOS and CCCS). All four modified adsorbents reached adsorption equilibrium for Cd2+ in solution within 120 min, with maximum adsorption capacities ranging from 115.5 to 266.5 mg/g, giving high removal efficiencies for Cd2+. Adsorption by precipitation and cation exchange mechanisms was dominant, together contributing >60 % of all adsorption capacity, followed by complexation. When used for remediation of Cd-contaminated soil, CEOS demonstrated the best Cd removal efficiency, achieving removal rates of 46 % and 58 % for total and available Cd, respectively. This was mainly because CEOS had the highest magnetic recovery rate, of 98 %. CEOS maintained removal rates of 34 % for total Cd after regeneration and reuse three cycles, with recovery rates remaining above 90 %. Contaminated soil was treated with the novel adsorbents and in pot experiments with water spinach cultivation it was shown that both CEOS and CECS treatment significantly reduced Cd content (by up to 56 %). The magnetic adsorbents presented here demonstrate excellent performance to remove Cd from water and soil, and have promising application prospects.

Applications of coagulation-sedimentation and ultrafiltration for the removal of nanoparticles from water

The removal of engineered nanoparticles (NPs) in drinking water treatment has posed a longstanding challenge due to their small sizes and widespread presence. This study aimed to assess the effectiveness of different methods, namely natural sedimentation, coagulation-sedimentation, and polyvinyl chloride (PVC) membrane ultrafiltration (UF), in removing silver NPs coated with carboxyl-terminated polymer with a primary diameter of 4.7 nm, hematite NPs of three diameters (53, 98, and 205 nm), and SiO2 NPs (740 nm). The results revealed that after 24 h of natural sedimentation, only approximately 28 %, 10 %, and 3 % of SiO2, hematite, and silver NPs, respectively, were removed. However, when coagulation with aluminum sulphate at an Al3+ dosage of 60 mg/L was implemented, followed by 4 h of sedimentation, the removal efficiencies of the three types of NPs increased to 90–95 %. Furthermore, membrane ultrafiltration achieved removal rates of 99.95 % for hematite, 99.6 % for silver, and 99.70 % for SiO2, unaffected by variations in solution pH (ranging from 5.0 to 10.0) and the initial concentrations (approximately 10 and 100 mg/L). Analyses based on the blocking filtration model indicated that the primary removal mechanism involved straining for 53 nm-hematite NPs, and a combination of straining and inside pore attachment for silver NPs.

One stone two birds: Simultaneous control of eutrophication and microplastic pollution via surface functionalized nano-Fe3O4

Microplastics (MPs) aggregate with phytoplankton to form aggregates that impede light and oxygen penetration, and the adsorbed nitrogen and phosphorus are either taken up by algae or released into the water column, thereby exacerbating water eutrophication. Therefore, it is imperative to simultaneously control nutrients (N and P) and MPs pollution in water. To address this, nano-Fe3O4 with different surface modifications (–COOH, –NH2, and –OH) was developed to control these mixed pollutants. The results showed that the surface modification can enhance the affinity for NH4+, PO43- and polyethylene microplastic (PE-MP), which can achieve exceptional adsorption capacities for NH4+-N (18.45 mg/g), PO43--P (30.04 mg/g), and PE-MP (1611 mg/g). OH-Fe3O4 efficiently removed NH4+-N (2 mg/L), PO43--P (5 mg/L), and PE-MP (1 g/L, 13 μm) from two types of water, achieving removal rates of 80 %, 95 %, and 62 % in freshwater, and 78 %, 94 %, and 70 % in seawater, respectively. FTIR, XPS, kinetic analysis, and density functional theory (DFT) calculations revealed that nano-Fe3O4 provides abundant active sites for MPs and PO43- through electrostatic adsorption and hydrogen bonding, while there is a Fe-O-P bond with PO43-. The NH4+ can be adsorbed on MPs via ion exchange. In addition, –COOH enhances affinity for NH4+, –NH2 increases the holding capacity for PO43-, and –OH strengthens PE-MP adsorption. The environmental impact of the production of nano-Fe3O4 demonstrates the economic feasibility and environmental friendliness of this process. The findings of this study offer promising data that can inform the future development of sustainable and cost-effective materials to combat eutrophication and MPs pollution.

Exploring electrochemical mechanisms for clindamycin degradation targeted at the efficient treatment of contaminated water

Numerous studies reveal pollutants like clindamycin (CLD) in the environment, posing environmental and health risks. Conventional water treatment methods are ineffective at removing these contaminants, typically found in low concentrations. An innovative treatment approach is introduced through pre-concentration via adsorption, which is highly efficient, energy-saving, and reusable. The innovation uses solvents like methanol or ethanol to desorb pollutants, creating concentrated CLD solutions for more effective electrochemical degradation than conventional methods. Thus, this study explores, for the first time, the behavior of CLD electro-oxidation in different media—water, methanol, and ethanol—using a Dimensionally Stable Anode (DSA®-Cl₂). The study reveals distinct degradation mechanisms and offers new insights into solvent-assisted electrochemical treatments. After 30 min of electrolysis, all the current densities evaluated promoted significant degradation, ranging from 90 to 92%. The energy consumption was 2.9 Wh m⁻³ per percentage point at current densities of 2 and 3.5 mA cm⁻2. This demonstrates that using higher current densities over shorter electrolysis times is feasible, achieving removal rates of approximately 90%.The performance of chloride-based electrolytes was superior to that of sulfate-based electrolytes due to the ability of DSA®-Cl2 electrodes to generate reactive chlorine species more efficiently. A higher concentration of supporting electrolytes initially improved CLD removal, but no significant changes were observed after 1 h. Neutral pH conditions optimized CLD degradation, achieving up to 91% removal. Higher pollutant concentrations were associated with lower kinetic constants and decreased removal percentages. Methanol and ethanol enhanced removal rates to 98.3% and 92.3%, respectively, by generating oxidizing species such as methoxy, hydroxymethyl, and ethoxy radicals. The degradation by-products differed across the three media, with each solvent exhibiting distinct oxidation mechanisms. These findings highlight the potential of using methanol or ethanol as an electrolytic medium with efficiency comparable to water.

Development of Z-scheme BiVO4/g-C3N4/rGO heterojunction nanocomposite for enhanced photocatalytic degradation and antibacterial activity

In this study, we synthesized a novel BiVO4/g-C3N4/rGO (BGR) heterojunction photocatalyst using the hydrothermal method. The synthesized catalysts were characterized through X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDX), Transmission Electron Microscopy (TEM), and Ultraviolet-Visible Diffuse Reflectance Spectroscopy (UV-DRS) to analyze their structural, morphological, and optical properties. The hybrid BGR nanocomposite displayed remarkable absorption characteristics, photocatalytic activity, and notable stability. Photocatalytic degradation performance was evaluated against methylene blue (MB) and indigo carmine (IC) dyes. The BGR ternary hybrid nanocomposites demonstrated significant photocatalytic degradation efficiency, achieving removal rates of 95.6 % for MB and 97.5 % for IC dyes within 120 min. The improved photocatalytic efficiency of the ternary photocatalyst is attributed to superior electron-hole pair separation and the formation of the heterojunction structure. The BGR nanocomposite exhibited excellent recyclability, maintaining its activity and crystalline characteristics over five photodegradation cycles. Additionally, the antibacterial activity of the BGR nanocomposites against Staphylococcus aureus,Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa was evaluated under UV–visible light exposure. This study provides insights for designing efficient visible-light-driven photocatalysts for environmental remediation purposes.

Defect engineering on metal-organic frameworks for enhanced photocatalytic reduction of Cr(VI)

Cr(VI) stands as a profoundly toxic chemical and photocatalysis technology has shown promising potential in photocatalytic reduction of Cr(VI) to Cr(III), where the reduced Cr(III) is less toxic and can be further precipitated in a wide pH range. Metal-organic frameworks (MOFs), as emerging class of porous coordination polymers, is expected to be ideal platform for photocatalysis. In this study, defect engineering on MOFs was applied to promote photoreduction of Cr(VI). The obtained oxygen vacancy-containing MIL-125-NH2 samples showed modified electron structure, adjusted surface and porous properties, and enriched active sites. Among these oxygen vacancy-containing MIL-125-NH2 samples, the 300-M (MIL-125-NH2 heated at 300 °C for 2 h under N2 atmosphere) displayed the most remarkable performance in terms of photocatalytic Cr(VI) reduction. The pronounced efficacy of 300-M is evident from the achieved removal rate of Cr (VI), reaching an impressive 98 % in just 20 mins (19.6 mgCr(VI) g−1cata min−1), in stark contrast to MIL-125-NH2, which exhibited a modest removal rate of 53 %. Remarkably, the k-value for 300-M is 5.1 times that of MIL-125-NH2, further underscoring the superior efficiency of 300-M. The photoreduction mechanism of 300-M was further substantiated through a battery of advanced characterization techniques including transient photocurrent, electrochemical impedance spectroscopy, fluorescence spectroscopy, the Mott-Schottky analysis, and electron spin resonance. Those results disclosed that oxygen vacancies and mesopores introduced via controlled heat treatment play a pivotal role in facilitating the photoreduction of Cr(VI) within the MIL-125-NH2 structure. More advanced characterizations for the structures of photocatalysts and the photocatalytic mechanisms including charge transfer path need further studied. The systematic exploration of temperature-dependent effects on material properties opens avenues for future research in designing efficient and versatile MOF-based photocatalysts for environmental remediation applications.

Highly efficient degradation of ethanol, acetaldehyde, and ethyl acetate removal by bio-trickling filter reactors with various fillers

This study investigates the purification performance of bio-trickling filters (BTFs) using different media to treat ethanol, acetaldehyde, and ethyl acetate in kitchen waste malodorous gases. The media compared included a custom composite medium, pine bark, hollow polyhedral spheres, and ceramic particles. Over 25 days, the composite medium outperformed the traditional media, achieving removal rates of 90.13 % for ethanol, 63.89 % for acetaldehyde, and 82.56 % for ethyl acetate during the biofilm initiation phase, with the others below 60 %. Even under low empty bed residence time and high inlet concentrations, the maximum elimination capacity for ethanol, acetaldehyde, and ethyl acetate was 8.34–14.70 g/m3·h, 9.55–15.06 g/m3·h, and 6.18–10.45 g/m3·h. Kinetic analysis showed the Michaelis-Menten model fit well, indicating enhanced removal potential. High-throughput of 16S rDNA sequencing identified dominant microorganisms like Enterobacteriaceae (13.89 %), Stenotrophomonas (29.23 %), and Acinetobacter (4.09 %) in the composite medium, which thrived even at high pollutant concentrations. Principal component analysis (PCA) demonstrated differences in the microbial composition of the custom composite medium compared to traditional media under varying inlet concentrations and loads. This study provides technical support for the treatment of complex malodorous gas mixtures.

Hydrothermal carbonization of coking sludge: Migration behavior of heavy metals and magnetic separation performance of hydrochar

This study comprehensively investigated the migration behavior and environmental risk of heavy metals (HMs) during the hydrothermal carbonization (HTC) of coking sludge (CS). The results indicated that over 90 % of HMs accumulated in the coking sludge hydrochar (CHC). The decomposition and loss of organic matter led to an increased concentration of HMs with rising temperatures. However, HTC also facilitated the transformation of HMs from bioavailable fractions to more stable fractions. Higher hydrothermal temperatures positively influenced the control of HMs' environmental risks. Ecological risk assessments revealed that the Potential Ecological Risk Index (RI) values of HMs in CHC decreased from 631.15 to 134.23, reaching considerate risk levels. Risk assessment codes indicated that, except for Mn, other HMs were reduced to no risk or low risk after hydrothermal treatment. Furthermore, the magnetic separation performance of CHC was explored, and its practical value was validated using a semi-continuous adsorption-separation device. The results showed that CHC achieved removal rates of 80.41–87.15 % for Congo red (CR) and tetracycline (TC), maintaining stability in various complex water environments. The CHC was rapidly separated after adsorption with a simple magnetic field, achieving a separation and recovery rate of over 80 %. These findings provided theoretical support for the stabilization of HMs in CS and the resource utilization of hydrochar in water treatment applications.

Reusable pyrene-based fluorescent organogels for polychlorinated biphenyl detection and removal

Highly toxic hydrophobic polychlorinated biphenyls (PCBs) pollutants are resistant to degradation, and limited methods are available for their elimination, leading to their long-term persistence in ecosystems, which can harm humans and the environment. Therefore, early detection, removal, and continuous monitoring of PCBs are crucial. In this study, a novel fluorescent polymeric probe (P1) to detect PCB congeners (77, 118, and 126) in water was developed. P1 was synthesized by incorporating N,N’-dimethylacrylamide (DMAA) and pyren-1-ylmethyl methacrylate (PyMMA) to form p(DMAA-co-PyMMA). P1 demonstrated high sensitivity toward the most toxic coplanar PCB congeners, 77 and 126, via a fluorescence turn-on mechanism. This sensitivity was attributed to hydrophobic and π–π interactions between the PCBs and PyMMA units of P1. The detection limits for PCB congeners 77 and 126 were determined to be 0.028 and 0.039 mM, respectively. However, PCB 118, a mixed planar congener, exhibited less detection sensitivity than PCB 77 and 126. A porous three-dimensional polymeric organogel (OG) comprising butyl acrylate, PyMMA, and a cross-linker ethylene glycol dimethacrylate was synthesized for practical application. The OG selectively removed PCBs compared to other competing pollutants due to the high hydrophobicity of the PCBs, achieving removal rates of 63 % for PCB 77 and 55 % for PCB 126. The large surface area of the OG facilitated enhanced hydrophobic and π-π interactions between the PCBs and pyrene units. This work emphasizes the efficacy of P1 in detecting PCBs and the potential of using OG in eliminating PCBs, offering a viable method for monitoring and remedying PCB-contaminated environments.

Study on the treatment of black and odorous water bodies by aeration combined with sulfur-iron autotrophic denitrification MBBR

ABSTRACT As China's economy grows rapidly, there is a growing problem of rural water pollution, particularly regarding black and odorous water bodies. However, the current treatment technologies have proven inadequate in both nitrogen and phosphorus removal, primarily due to the insufficient carbon-to-nitrogen ratio in these black and odorous water bodies, resulting in low nitrogen removal efficiency. To address this challenge, the study proposes a novel treatment process, namely ‘aeration + sulfur-iron autotrophic denitrification MBBR’. This innovative approach was compared with the traditional ‘aeration + MBBR’ treatment process and blank control group over an 18-day experimental period. Ten water quality indicators were monitored and compared, including odor, turbidity, DO, pH, COD, BOD5, NH3-N, NO3-N, TN, and TP. The results revealed satisfactory performance of both treatment processes in terms of odor, turbidity, DO, COD, BOD5, and NH3-N indicators. However, significant disparities were observed in denitrification and phosphorus removal, with the new process achieving removal rates of 85.65 and 78.02%, respectively, compared to −2.30 and −4.05% for the existing process. Furthermore, the new process met the surface water class IV quality standard for all 10 monitored indicators, indicating its potential for effectively addressing the issue of black and odorous water in rural China.

Efficient removal of high concentration organic pollutants by ZnIn2S4 with highly active sulfur vacancy

Metal sulfides have attracted much attention because of their wide light response range and negative conduction band (CB) position, which can generate abundant charges to participate reduction and oxidation reactions. In recent years, efforts are devoted to enhance the charge separation and transfer to improve its overall performance in photocatalytic applications. Herein, we synthesized zinc indium sulfide (ZnIn2S4, named as ZIS) with S vacancy (VS) defects via a hydrothermal method with assist of excess sulfur sources. All the as-prepared samples exhibited significant photocatalytic degradation performance on organic pollutants with high concentration. Among them, the VS-ZIS (TAA) demonstrated exceptionally high photodegradation activity under visible light (λ＞420 nm) irradiation, achieving removal rates up to 96 % and 90 % over TC (80 mg/L) and RhB (40 mg/L), respectively. Moreover, VS-ZIS (TAA) also displayed an excellent cycling stability. Combining experimental and theoretical studies, we unveil that the introduction of VS defects broadens the light absorption range, accelerates carrier separation and transfer, and provides additional surface active sites, thus improving the photocatalytic degradation efficiency. This study suggests that creating VS can induce effective charge separation, thus enhancing the photocatalytic activity and providing a viable pathway for treating high concentration organic pollutants.

Novel avenues for achieving simultaneous high-efficiency oil removal and sterilization: Designing a quaternary ammonium-hydrophobic ternary template copolymer

In treating complex sewage containing microorganisms, flocculation and disinfection typically occur as distinct stages, involving the addition of flocculants and disinfectants separately. To integrate oil removal and disinfection, a novel quaternary ammonium-hydrophobic ternary template polymer, TPAMA-DA, was engineered with capabilities for both flocculation and sterilization functions. Optimal copolymer characteristics were determined through Response Surface Methodology of the preparation parameters for TPAMA-DA. The copolymer prepared was applied to model wastewater, and the results indicate that, in emulsified oil and E. coli single systems, TPAMA-DA achieved removal rates of 95.71 % and 97.19 % for emulsified oil and OD600 (residual OD600 = 0.0239), respectively, showcasing superior oil removal and antibacterial capabilities compared to TPAMA and PAMA. Meanwhile, TPAMA-DA exhibited excellent oil removal efficiency across a broad range of pH environments, contrasting sharply with its pH-sensitive antibacterial properties. Surprisingly, applying TPAMA-DA to the oil-E. coli binary systems, it not only maintained high efficiency in oil removal but also showed certain pH adaptability in antibacterial activity, suggesting TPAMA-DA’s outstanding ability for simultaneous oil removal and antibacterial action in oil-E. coli binary systems. Impressively, SEM and 3D-EEM analyses confirm that TPAMA-DA disrupts the bacterial cell, resulting in the death of E. coli. These findings may pave the way for new avenues in the development of multi-functional, efficient, low-consumption, and environmentally friendly high-performance copolymers with dual capabilities for oil removal and sterilization.

Enhancing visible-light-driven photocatalysis: unveiling the remarkable potential of H2O2-assisted MOF/COF hybrid material for organic pollutant degradation.

In this study, we synthesized MOF/COF hybrid material (NH2-MOF-5/MCOF) by integrating NH2-MOF-5 (Zn) with a melamine-based COF (MCOF) to target the photocatalytic degradation of methylene blue (MB) dye. Characterization using SEM, XRD, XPS, FT-IR, and UV-DRS confirmed the synthesized MOF/COF hybrid's exceptional photocatalytic performance under visible light. The addition of H2O2 significantly enhanced the photocatalytic degradation, achieving removal rates of 90%, 92%, and 57% for 11.75mg L-1, 30mg L-1, and 83mg L-1 of MB, respectively. Kinetic studies revealed first-order kinetics, with a rate constant nearly 3.5 times higher with added H2O2. We proposed a comprehensive photocatalytic mechanism elucidated through energy band structure analysis and scavenger tests. Our findings revealed the formation of a heterojunction between NH2-MOF-5 and MCOF, which mitigates electron-hole recombination, with ∙OH identified as the principal species governing methylene blue degradation. Moreover, the NH2-MOF-5/MCOF hybrid displayed excellent reusability and chemical stability over six cycles. Notably, this H2O2-assisted hybrid material demonstrated the removal of 99% of ibuprofen, a pharmaceutical drug, showcasing its broad applicability in removing organic contaminants in aqueous solutions, thereby holding great promise for wastewater treatment.

Study on membrane fouling mechanisms and mitigation strategies in a pilot-scale anaerobic membrane bioreactor (P-AnMBR) treating digestate

Anaerobic Membrane Bioreactor (AnMBR) are employed for solid-liquid separation in wastewater treatment, enhancing process efficiency of digestion systems treating digestate. However, membrane fouling remains a primary challenge. This study operated a pilot-scale AnMBR (P-AnMBR) to treat high-concentration organic digestate, investigating system performance and fouling mechanisms. P-AnMBR operation reduced acid-producing bacteria and increased methane-producing bacteria on the membrane, preventing acid accumulation and ensuring stable operation. The P-AnMBR effectively removed COD and VFA, achieving removal rates of 82.3 % and 92.0 %, respectively. Higher retention of organic nitrogen and lower retention of ammonia nitrogen were observed. The membrane fouling consisted of organic substances (20.3 %), predominantly polysaccharides, and inorganic substances (79.7 %), primarily Mg ions (10.1 %) and Ca ions (4.5 %). To reduce the increased transmembrane pressure (TMP) caused by fouling (a 10.6-fold increase in filtration resistance), backwash frequency experiment was conducted. It revealed a 30-min backwash frequency minimized membrane flux decline, facilitating recovery to higher flux levels. The water produced amounted to 70.3 m³ over 52 days. The research provided theoretical guidance and practical support for engineering applications, offering practical insights for scaling up P-AnMBR.

Enhancing Emerging Pollutant Removal in Industrial Wastewater: Validation of a Photocatalysis Technology in Agri-Food Industry Effluents

Emerging pollutants in wastewater pose significant risks to human health and wildlife, particularly due to their persistence in treated effluents from WWTPs. Very recent research has focused on developing new techniques based on advanced oxidation processes using inorganic and organic photocatalysts for treating polluted effluents under visible light. This study investigates a pesticide-removal system utilizing heterogeneous photoactive polymeric materials P2, P3, and P4. These materials, engineered as hydrophilic polymeric microparticles and functionalized with Rose Bengal, have demonstrated efficient singlet oxygen generation and first-order kinetics in the degradation of AHMPD, a pyrimidine fungicide. Given that most studies in the literature have concentrated on urban WWTPs, with less emphasis on industrial wastewater treatment, this research focused on real water samples from the effluent of an industrial WWTP in the agri-food sector, which processes large volumes of citrus and where high concentrations of AHMPD and other pesticides were detected at certain times of the year. The degradation potential of photoactive materials P3 and P4 was evaluated, achieving removal rates of AHMPD up to 85% under conditions of pH = 11 with 48 h of exposure to visible light.

Evaluation of the potential ultrafiltration to improve the quality of secondary effluents in tertiary treatment and reuse

Unsatisfactory effluent purification, limited to secondary treatment, considerably restricts the reuse of treated water. In this study, the performance of three ceramic ultrafiltration (UF) membranes UF1 (0.02 μm), UF2 (0.05 μm), and UF3 (0.1 μm) was evaluated for the recovery of secondary effluent (SE) from a wastewater treatment plant (WWTP) in Kenitra. The effects of different parameters on treated water quality were assessed, including transmembrane pressure (TMP), circulation velocity (CV), and membrane pore size. The results indicated that the UF1 membrane was more effective than UF2 and UF3, achieving maximum removal rates for chemical oxygen demand (COD), biochemical oxygen demand at 5 days (DBO5), and total suspended solids (TSS) of 75%, 72%, and 96%, respectively, under optimal operating conditions of TMP at 1 bar and CV at 1 m/s. UF2 achieved removal rates of 70%, 71%, and 94% for COD, BOD5, and TSS, respectively, under the same conditions. For UF3, the highest removal rates were 64%, 62%, and 92% for COD, BOD5, and TSS, respectively, at 2 bar and 1 m/s. Moreover, the experiments also demonstrated that an increase in TMP results in increased permeate flux and fouling resistance, while CV has also an impact on the permeate flux. Additionally, a very satisfactory retention rate for microorganisms was observed, exceeding 90%, with no presence of helminth eggs (100% removal) detected in the treated water. Nutrient elimination was also notable, with reductions of 14% for total Kjeldahl nitrogen (TKN) and 50% for total phosphorus (TP) using the UF1 membrane, which was selected based on its optimal performance.

Enhanced removal of antibiotics and heavy metals in aquatic systems using spent mushroom substrate-derived biochar integrated with Herbaspirillum huttiense.

A novel integrated removal strategy was developed to enhance the concurrent elimination of copper (Cu), zinc (Zn), oxytetracycline (OTC), and enrofloxacin (ENR) from the aqueous environments. The underlying adsorption mechanisms of spent mushroom substrate (SMSB) and the Herbaspirillum huttiense strain (HHS1), and their efficacy in removing Cu, Zn, OTC, and ENR was also examined. Results showed that the SMSB-HHS1 composite stabilized 29.86% of Cu and 49.75% of Zn and achieved removal rates of 97.95% for OTC and 59.35% for ENR through a combination of chemisorption and biodegradation. Zinc did not affect Cu adsorption, and ENR did not impact the adsorption of OTC on SMSB. However, the co-presence of OTC and ENR modified the adsorption behaviors of both Cu and Zn. Copper and Zn enhanced the adsorption of OTC and ENR by serving as bridging agents, facilitating the interaction between the contaminants and SMSB. Conversely, OTC and ENR inhibited the adsorption process of Cu by obstructing its interaction with the SMSB and occupying the oxygen-containing functional groups. The ‒OH (3415 cm-1) and C-O-C (1059 cm-1) functional groups were identified as the principal active sites to form hydrogen bonds and interact with Cu and Zn, leading to the formation of CuP4O11 and Zn4CO3(OH)6H2O. HHS1 also enhanced antibiotic removal through biodegradation, as evidenced by the decrease of ‒C‒O and increase of ‒C = O groups. This study underscores the innovative potential of the SMSB-HHS1 composite, offering a sustainable approach to addressing multifaceted pollution challenges in the aquatic environments.

A fully degradable flexible membrane via green synthesis for highly effective separation of oil-water emulsions

Flexible membranes have attracted extensive attention in water treatment due to their outstanding plasticity, portability, and toughness. However, conventional flexible membranes are usually made from non-degradable polymers or hazardous reagents, posing threats to the environment. In this work, a flexible silica nanofiber-regenerated cellulose composite membrane was fabricated by “no polymer solvents electrospinning” with cellulose regeneration. The membrane was fully degradable and eco-friendly, and it exhibited low oil adhesion force and recyclable oil emulsion separation performance. It achieved removal rates of almost 100 % and up to 0.1 % residual oil rate for six different types of oil emulsions with the addition of surfactant, which represents the optimal level reported in the literature to date. The presence of these extremely water-attracting functional groups on the surface of the membrane allows them to bond with water molecules, creating a stable water layer held together by hydrogen bonds. This layer can reject oil compounds during the separation process due to the inherent immiscibility between water and oil. Importantly, this membrane has excellent degradability. The regenerated cellulose layer on its surface can undergo complete microbial degradation (activated sludge) within 7 days, while the remaining substrate can be degraded continuously in concentrated hydrochloric acid, thereby facilitating complete environmentally benign disposal and providing a new strategy for developing green flexible membranes, which holds promise for addressing water scarcity and water pollution issues.

Diclofenac sodium and paracetamol removal with ZnCl2 activated carbon produced from rice straw

This study explored the efficacy of activated carbon derived from rice straw and treated with ZnCl2 (ZnCl2-RS) for the removal of diclofenac sodium (DCF) and paracetamol (PCM) through an adsorption process. The investigation included examining the variations in removal efficiency at different pH levels and ZnCl2-RS doses. The characteristics of the ZnCl2-RS, prepared for the study, were determined through SEM and FTIR analyses, revealing a composition of 49.4% carbon and 8.3% zinc. At pH 5, the adsorption efficiency for DCF and PCM was enhanced, achieving removal rates of 92.2% for DCF and 89.1% for PCM with 0.2 g of ZnCl2-RS. The adsorption of DCF and PCM by ZnCl2-RS followed pseudo-second-order kinetic and adhered to the Langmuir isotherm model. The maximum adsorption capacities were calculated as 26.04 mg/g for DCF and 19.05 mg/g for PCM. In conclusion, the cost-effective production of activated carbon from agricultural waste like rice straw yielded a promising adsorbent material for efficiently removing pharmaceuticals such as diclofenac sodium and paracetamol. This approach not only contributes to waste reduction but also promotes the repurposing of agricultural waste materials.