Enhanced Removal Efficiency Research Articles

Promoting bioremediation of brewery wastewater, production of bioelectricity and microbial community shift by sludge microbial fuel cells using biochar as anode

Seeking low-cost and eco-friendly electrode catalyst of microbial fuel cell (MFC) reactor has received extensive attention in recent decades. In this study, a sludge MFC was coupled with biochar-modified-anode (BC-300, BC-400, and BC-500) for actual brewery wastewater treatment. The physicochemical properties of biochar largely depended on the pyrolysis temperature, further affecting the removal efficiency of wastewater indicators. BC-400 MFC proved to be efficient for TN and NH4+-N removal, while the maximum removal efficiencies of COD and TP were achieved by BC-500 MFC, reaching respectively 97.14 % and 89.67 %. Biochar could promote the degradation of dissolved organic matter (DOM) in wastewater by increasing the electrochemical performances of MFC. The maximum output voltage of BC-400 MFC reached 410.24 mV, and the maximum electricity generation of 108.05 mW/m2 was also obtained, surpassing the pristine MFC (BCC-MFC) by 4.67 times. High-throughput sequencing results illustrated that the enrichment of electrochemically active bacteria (EAB) and functional bacteria (Longilinea, Denitratisoma, and Pseudomonas) in BC-MFCs, contributed to pollutants degradation and electron transfer. Furthermore, biochar affected directly the electrical conductivity of wastewater, simultaneously changing microbial community composition of MFC anode. Considering both enhanced removal efficiency of pollutants and increased power generation, the results of this study would offer technical reference for the application of biochar as MFC catalyst for brewery wastewater treatment.

Enhanced size-dependent efficiency of removal of ultrafine particles: New solution of two-stage electrostatic precipitator with thermophoresis

Two-stage electrostatic precipitators (ESPs) are effective at removing ultrafine particles (UFPs) from gases; however, they fall short in capturing particles with diameters of less than 100 nm. In this study, an effective solution for removal of particles smaller than 300 nm was proposed. Our self-designed system combines a two-stage ESP with thermophoresis. We employed a combination of experimental and numerical simulation methods to examine the effects of temperature and thermophoresis on particle removal efficiency influenced by electrostatic forces. In our experiments, particle removal efficiency was positively correlated with gas temperature up to 75 °C, beyond which removal efficiency was no longer correlated with temperature. The findings also indicate that the introduction of thermophoresis improves particle removal efficiency, with the maximum increase approaching 8 %. However, this effect only occurs for particles smaller than 50 nm. The increase in the length of the thermophoresis segment and the decrease in inlet gas flow rate both enhance particle removal efficiency due to thermophoresis. Numerical simulations confirmed the experimental finding that nanoscale particles are more easily captured at higher temperatures. The simulations also revealed that the primary reasons for the enhanced removal efficiency are twofold: greater electric field strength and higher particle charge resulting from a higher temperature.

Degradation of chlorinated volatile organic compounds in waste gas by catalytic plasma system

Dichloromethane (DCM), one of the main components of chlorinated volatile organic compounds (Cl-VOCs), is recognized as extremely hazardous and severely affects human health and the environment. In this study, a self-designed Dielectric Barrier Discharge (DBD) reactor combined with different catalysts to treat the exhaust DCM gas containing ppm concentration levels. A plasma system can generate high-energy electrons and free radicals (such as hydroxyl radical (OH·), and superoxide radical (O2·)) to degrade DCM in the industrial exhaust gas into most HCl and CO2. The removal efficiency can achieve 98.7% under the conditions, a flow rate of 1042 mLmin−1, the residence time of 76.72 ms, concentration of DCM of about 1650 ppm, and specific input energy of 591 JL−1. Although the plasma was highly reactive, the selectivity of the desired products was low, and there were unwanted toxic byproducts such as CHCl3 (1.7%) and CCl4 (13.8%). Thus catalysts were loaded in the plasma discharging zone to enhance removal efficiency and change product distribution. The catalysts were conducive to producing water-soluble products such as HCl. At the same time, the formation of some unwanted byproducts, CHCl3 and CCl4, were also inhibited. We found that using 11.5 kVpp plasma operating voltage combined with 200 mg Co3O4/HZSM-5 can lower the DCM concentration of the outlet stream from 1650 ppm to 53 ppm. Under this condition, the removal efficiency was about 96.7%, attaining permitted emissions.

A novel ionic liquid-entrapped MIL-101(Cr) framework with enhanced removal efficiency towards phosphate from aqueous solution.

Developing adsorbent materials with high adsorptive dephosphorization (ADP) is significant for treating phosphate from aqueous solutions and eutrophic water. Herein, the MIL-101(Cr) framework was entrapped ionic liquid (IL) of 1-butyl-3-methylimidazoliumbromide ionic liquid ([C4mem]+[Br]-) using a ship-in-a-bottle approach to obtain novel adsorbents [C4mem]+[Br]-@MIL-101(Cr) contained varied IL contents, namely C4mem@MIL-101. The characterization results revealed that the formed [C4mem]+[Br]- molecules interacted with the MIL-101(Cr) frameworks, enhanced their stability, and offered additional adsorption sites. The batch adsorptions of phosphate showed that the optimized C4mem@MIL-101 adsorbent loaded with ~ 7% IL-based N content had the highest phosphate absorbing capacity of ~ 200mg/g, outperforming the pristine MIL-101(Cr) and other adsorbents. The ADP efficiency was facilitated in the acidic media, where the phosphate ions of H2PO4- and HPO42- captured onto the C4mem@MIL-101 via several interactions, including electrostatic attraction, H-bonds, and chemical interactions. In the meantime, the coexisting anions diminished the phosphate adsorption because they competed with the pollutants at adsorption sites. Furthermore, phosphate treatment under the continuous fixed-bed conditions showed that 1g of the polyvinyl alcohol (PVA)-mixed C4mem@MIL-101 pellets purified 25l of water containing phosphate with a 1mg/l concentration. The results suggest that the novel [C4mem]+[Br]-@MIL-101(Cr) structure had a high potential for treating phosphate in aqueous solutions.

Photocatalytic adsorption/degradation of tetracycline by S-scheme BiOI/BiOIO3 p-n heterojunction from dissociation of BiOIO3in-situ solvothermal process

The pollution of tetracycline (TC) had attracted more and more attention due to its unprecedented use and potential hazards. The S-scheme BiOI/BiOIO3 p-n heterojunction was successfully fabricated by in-situ solvothermal treatment of BiOIO3, and was used for the removal of TC from aqueous solutions. The results demonstrated that the construction of S-scheme p-n heterojunction could significantly improve the removal of TC by photocatalytic adsorption/degradation synergism. The removal rate of TC was significantly enhanced after solvothermal modification. The three main reasons for the enhanced removal efficiency were as follows: first, the light absorption range of the BiOIO3 was enhanced by solvothermal treatment; secondly, the construction of the heterojunction was beneficial to the valid separation and migration of the photo-generated carriers; finally, the adsorption of TC enhanced the speed of TC reaching the semiconductor interface and reacting with active species. Trapping tests were conducted to reveal that •O2− and 1O2 are the main reactive species for TC degradation. The nine degradation products were identified by the high performance liquid chromatography-mass spectrometry (HPLC-MS), and the three reaction pathways were deduced. A possible S-scheme p-n heterojunction photocatalytic mechanism was presented on the basis of band structures and active species capturing experiment.

Silver doped anatase nanocomposite: a novel photocatalyst with advanced activity under visible light for waste-water treatment

Anatase is a universal semiconductor photocatalyst; however, its wide band-gap energy limits its entire solar spectrum absorption to only 5%. Anatase could be activated in the visible region via nobel metal deposition. This study reports on the facile synthesis of colloidal mono-dispersed anatase nanoparticles of 5 nm particle size via hydrothermal synthesis. Nobel metals (Silver, Nickel) were deposited on colloidal anatase surface. The photocatalytic activities of Ag–TiO2, and Ni–TiO2 were investigated for the degradation of basic fuchsin dye. Ag–TiO2 nanocomposite demonstrated enhanced adsorption activity in dark, as well as superior photocatalytic. Ag–TiO2 nanocomposite demonstrated enhanced removal efficiency by 70.8% under visible irradiation to virgin anatase. Ag–TiO2 nanocomposite demonstrated enhanced oxygen-lattice with low binding energy using XPS analysis. Ag–TiO2 experienced band gap energy of 2.35 eV compared with 3.2 eV for virgin anatase; this feature could secure enhanced solar absorption. Ag–TiO2 demonstrated excellent photo-degradation efficiency of 88% with 0.3% H2O2 under visible light. Deposited silver could catalyze H2O2 decomposition and could promote free radical generation; Ag–TiO2 nanocomposite is a promising photocatalyst for wastewater treatment applications.

Preparation of novel CS/SiO2-EDTA nanocomposite from ash of rice straw pellets for enhanced removal efficiency of heavy metal ions in aqueous medium

The production valuable materials from waste for environmental treatment have attracted considerable attention worldwide. In this study, porous silica was produced from the ash of rice straw pellets. The porous silica was then modified with chitosan (CS) and ethylenediaminetetraacetic acid (EDTA) to produce novel CS/SiO2-EDTA nanocomposites for the removal of heavy metals in aqueous medium. The adsorption of Pb2+ was investigated to evaluate the effectiveness of the composite and the effects of reaction parameters on the adsorption process were extensively explored. The adsorption is fast in the initial 5 min, then almost reaches equilibrium in 10 min. The conditions for the highest adsorption capacity are an EDTA content of 1.0 M, a pH of 6, an adsorbent dosage of 0.1 g/L, and a Pb2+ concentration of 100 ppm. The removal efficiency, adsorption capacity, and rate constant are 70.39 %, 703.9 ± 21.1 mg/g, and 0.012 ± 0.003 g/mg·min, respectively. The conditions for the highest adsorption efficiency are an EDTA content of 1.0 M, a pH of 6, an adsorbent dosage of 0.5 g/L, and a Pb2+ concentration of 40 ppm, where the adsorption efficiency, adsorption capacity, and rate constant are 89.88 %, 71.91 ± 1.86 mg/g, and 0.013 ± 0.002 g/mg·min, respectively. The selectivity of the composite was investigated by using Ni2+, Cu2+ and Fe2+ ions under the same experimental conditions. In multi-metal solutions, the adsorbent showed the highest affinity for Pb2+. In addition, the adsorption isotherms and thermodynamics were investigated and an adsorption mechanism was proposed.

Enhanced uranium removal from aqueous solution by core–shell Fe0@Fe3O4: Insight into the synergistic effect of Fe0 and Fe3O4

In this study, Fe0@Fe3O4 was synthesized and used to remove U(VI) from groundwater. Different experimental conditions and cycling experiments were used to investigate the performance of Fe0@Fe3O4 in the U(VI) removal, and the XRD, TEM, XPS and XANES techniques were employed to characterize the Fe0@Fe3O4. The results showed that the U(VI) removal efficiency of Fe0@Fe3O4 was 48.5 mg/g that was higher than the sum of removal efficiency of Fe0 and Fe3O4. The uranium on the surface of Fe0@Fe3O4 mainly existed as U(IV), followed by U(VI) and U(V). The Fe0 content decreased after reaction, while the Fe3O4 content increased. Based on the results of experiments and characterization, the enhanced removal efficiency of Fe0@Fe3O4 was attributed to the synergistic effect of Fe0 and Fe3O4 in which Fe3O4 accelerated the Fe0 corrosion that promoted the progressively formation of Fe(II) that promoted the reduction of adsorbed U(VI) to U(IV) and incorporated U(VI) to U(V). The performance of Fe0@Fe3O4 at near-neutrality condition was better than at acidic and alkalic conditions. The chloride ions, sulfate ions and nitrate ions showed minor effect on the Fe0@Fe3O4 performance, while carbonate ions exhibited significant inhibition. The metal cations showed different effect on the Fe0@Fe3O4 performance. The removal efficiency of Fe0@Fe3O4 decreased with the number of cycling experiment. Ionizing radiation could regenerate the used Fe0@Fe3O4. This study provides insight into the U(VI) removal by Fe0@Fe3O4 in aqueous solution.

Simultaneous removal of As(V) and sulfamethazine from water in FeS2-H2O2 system

Sulfamethazine (SMT) and organic arsenic are usually used as feed additives in animal husbandry and aquaculture, which will produce severe compound pollution after metabolism and discharge. In this work, the FeS2-H2O2 system was used to simultaneously remove As(V) and SMT. Under 0.8 g/L of FeS2, 40 mM of H2O2, the simultaneous removal efficiency of SMT and As(V) was up to 97 %. The initial concentration of As(V) was unfavourable for SMT degradation, while the effect of initial concentration of SMT on As(V) removal could be ignored. Meanwhile, increasing FeS2 and H2O2 dosages enhanced removal efficiency of SMT and As(V). However, excessive FeS2 was detrimental to the removal of As, and the ·OH, ·O2−, and 1O2 were generated to degrade SMT. As was adsorbed on the surface of positively charged FeS2 firstly and then reacted with Fe(III) on the surface of FeS2 or released by Fenton reaction to form FeAsO4. No As(III) was detected during the simultaneous removal process in the FeS2-H2O2 system. This study revealed that SMT and As(V) could be removed simultaneously in the FeS2-H2O2 system, which produced new insight into animal husbandry and aquaculture wastewater treatments.

Trivalent lanthanum and ytterbium doped meso-silica/ceria abrasive systems toward chemical mechanical polishing (CMP) and ultraviolet irradiation-assisted photochemical mechanical polishing (PCMP)

Ceria (CeO2)-based abrasives are widely utilized in ultra-precision grinding and chemical mechanical polishing (CMP) applications over silica materials due to their unique physicochemical properties. Both mechanical and chemical contributions to polishing processes are highly affected by the size, shape, structure, component, defect of CeO2 abrasives. Herein, the composites involved mesoporous silica (mSiO2) cores and La- or Yb-doped CeO2 shells were synthesized and characterized in terms of X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, scanning transmission electron microscopy–energy dispersive X-ray mapping methods. The polishing effectiveness of the proposed composites toward quartz glass was experimentally evaluated under both CMP and ultraviolet irradiation-assisted photochemical mechanical polishing (PCMP) conditions. The polishing results indicated that the low-modulus mSiO2 cores strongly exerted the cushion effects for the friction and abrasion to substrates. Consequently, the heterostructured mSiO2/La-CeO2 and mSiO2/Yb-CeO2 abrasive systems offered nearly non-damage and ultra-smooth surfaces with angstrom-level roughness compared to conventional rigid abrasives. The enriched Ce3+ and oxygen vacancy defects at La- and Yb- doped CeO2 surfaces were responsible for the improvements of tribochemical and photochemical activities, thus allowing evidently enhanced removal efficiency with the assistance of ultraviolet irradiation. A possible polishing mechanism on the multi-component abrasive systems was also proposed.

Nucleophiles promotes the decomposition of electrophilic functional groups of tetracycline in ZVI/H2O2 system: Efficiency and mechanism

When zero-valent iron (ZVI) is prepared and applied under neutral conditions, it is easy to form oxides or hydroxides on its surface, which hinders the electron release of ZVI. To this end, a nucleophile was introduced into the ZVI system to inhibit the precipitation of iron ions, improve the conductivity of the solution, and promote the removal efficiency of electrophilic functional groups in organic compounds. In this study, the addition of nucleophiles such as ethylenediamine, methylamine and dimethylamine to the ZVI/H2O2 system resulted in an enhanced removal efficiency of tetracycline (TC) under neutral condition, while electrophiles such as EDTA-2Na and oxalic acid dihydrate impeded the removal of TC. Experimental results demonstrated that the presence of nucleophiles could effectively promote the release of iron ions and increase the proportion of ferrous in both aqueous solution and solid surface of ZVI. Experimental and theoretical calculation results revealed that the electrophilic functional group was eliminated in the TC molecule, and the toxicity of the treated solution was reduced significantly. Overall, this work provides a selection of the conditions and pollutants applicable to ZVI under neutral pH conditions.

Intermolecular interactions in mixed dye systems and the effects on dye wastewater treatment processes.

Dye wastewater discharge is a critical concern across textiles, paper, cosmetics, and other industries. This study explores the impact of dye-dye interactions on chemical coagulation and ultrafiltration process. Using basic and reactive dyes, representing cationic and anionic compounds, the intricate interplay between these dyes was examined through spectroscopic analysis. Remarkably, interactions between dyes of opposite charges exhibited significant effects on both techniques. Electrostatic attractions played a key role. Positive coagulant hydrolysates selectively attracted negative dyes, while negatively charged membranes effectively captured positive dyes. Combining dyes with opposite charges resulted in enhanced removal efficiency, addressing challenging dyes collectively. This discovery offers a novel approach to improving dye removal, utilizing opposite-charged dye mixtures can tackle stubborn dyes unmanageable by conventional methods.

Enhanced removal efficiency of Tetradesmus obliquus for nevirapine removal via co-substrate supplementation: removal mechanisms, relative gene expression and metabolomics

Enhanced removal efficiency of <i>Tetradesmus obliquus</i> for nevirapine removal <i>via</i> co-substrate supplementation: removal mechanisms, relative gene expression and metabolomics

Fabrication of Unique Mixed-Valent CoICoII and CuICuII Metal-Organic Frameworks (MOFs) for Desulfurization of Fuels: A Combined Experimental and Theoretical Approach toward Green Fuel.

Herein, metal-organic framework (MOF)-based adsorbents are designed with distinct hard and soft metal building units, namely, [Co2ICoII(PD)2(BP)] (Co_PD-BP) and [Cu2ICuII(PD)2(BP)] (Cu_PD-BP), where H2PD = pyrazine-1,4-diide-2,3-dicarboxylic acid and BP = 4,4'-bipyridine. The designed MOFs were characterized via spectral and SCXRD techniques, which confirm the mixed-valent states (+1 and +2) of the metal ions. Topological analysis revealed the rare ths and gwg topologies for Co MOF, while Cu-MOF exhibits a unique 8T21 topology in the 8-c net (point symbol for net: {424·64}). Moreover, severe environmental issues can be resolved by effectively removing heterocyclic organosulfur compounds from fuels via adsorptive desulfurization. Further, the developed MOFs were investigated for sulfur removal via adsorptive desulfurization from a model fuel consisting of dibenzothiophene (DBT), benzothiophene (BT), and thiophene (T) in the liquid phase using n-octane as a solvent. The findings revealed that Cu_PD-BP effectively removes the DBT with a removal efficiency of 86% at 300 ppm and an operating temperature of 25 °C, with a recyclability of up to four cycles. The adsorption kinetic analysis showed that the pseudo-first-order model could fit better with the experimental data indicating the physisorption process. Further, the studies revealed that adsorption capacity increased with the increasing initial DBT concentration with a remarkable capacity of 70.5 mg/g, and the adsorption process was well described by the Langmuir isotherm. The plausible reason behind the enhanced removal efficiency shown by Cu_PD-BP as compared to Co_PD-BP could be the soft-soft interactions between soft sulfur and soft Cu metal centers. Interestingly, density functional theory (DFT) studies were done in order to predict the mechanism of binding of thiophenic compounds with Cu_PD-BP, which further ascertained that along with other interactions, the S···π and S···Cu interactions predominate, resulting in a high uptake of DBT as compared to others. In essence, Cu_PD-BP turns out to be a promising adsorbent in the field of fuel desulfurization for the benefit of mankind.

Enhanced removal efficiency of nitrogen and phosphorus from swine wastewater using MgO modified pig manure biochar

Pig manure and swine wastewater from livestock and poultry contain high levels of nitrogen and phosphorus, which can seriously threaten ecosystems. In this study, biochar derived from pig manure (PMBC) was modified by various magnesium salts to obtain pig manure biochar modified with MgO (MgO-PMBC), Mg(OH)2 (Mg(OH)2-PMBC) and MgCl2 (MgCl2-PMBC), and their capacities of simultaneous adsorption of NH4+-N and PO43--P were investigated. Results showed that the adsorption quantities for NH4+-N and PO43--P decreased in the order: MgO-PMBC >Mg(OH)2-PMBC > MgCl2-PMBC > PMBC. When the optimal dosage for MgO-PMBC was determined to be 0.6 g/L and the initial solution pH was set to the ideal value of 7, the maximum adsorption quantities for NH4+-N and PO43--P by MgO-PMBC reached 122.01 mg/g and 206.85 mg/g, respectively, which were 49.8 and 85.5 times of those of the PMBC. The specific surface area and total pore volume of MgO-PMBC were 9.4 times and 4.1 times of the PMBC. Removal rate of PO43--P from swine wastewater was 97.57%, and the concentration of PO43--P from treated swine wastewater was lower than 0.5 mg/L, the primary discharge standard of China’s Comprehensive Wastewater Discharge Standard. The enhanced simultaneous adsorption of NH4+-N and PO43--P by modified PMBC (MgO-PMBC) was ascribed to its greater specific surface area and total pore volume, and the reaction of crystallisation of struvite. Our results demonstrated that pig manure biochar modified by MgO can be used to treat swine wastewater effectively.

Magnetic Fe3O4-grafted cellulose/graphene oxide nanocomposite for methylene blue removal from aqueous solutions: Synthesis and characterization

This research focuses on the development of efficient and cost-effective methods for the treatment of industrial wastewater. Magnetic Fe3O4 cellulose/graphene oxide nanocomposite was synthesized through free radical graft copolymerization of acrylic acid (AA) and acrylamide (AM) on the cellulose chains. The grafting copolymerization parameters, including molar ratio, temperature, and reaction time, were optimized. Structural characteristics of the prepared samples were analyzed using FT-IR, XRD, and VSM techniques, while morphological characteristics were examined using FE-SEM and HR-TEM. The prepared samples were evaluated for their adsorption capacity towards methylene blue (MB) dye under various conditions. The factors controlling the adsorption process, such as pH, contact time, adsorbent dose, and initial MB concentration, were studied. The experimental data were successfully described by the pseudo-second-order model, and the equilibrium adsorption results fitted the Freundlich and Dubinin-Radushkevich isotherms. Thermodynamic studies revealed that the adsorption process was endothermic and occurred spontaneously, leading to greater disorder. Optimal conditions for MB adsorption onto the magnetic cellulose/graphene oxide nanocomposite were determined to be pH 7, a contact time of 7 h, and an adsorbent dose of 0.0375 g in a 30 mg/L dye solution. The inclusion of magnetite and graphene oxide into cellulose resulted in enhanced removal efficiency of the dye, with the magnetic cellulose/graphene oxide nanocomposite exhibiting a removal percentage of 97%. These findings demonstrate the potential of the magnetic cellulose/graphene oxide nanocomposite as a powerful adsorbent for the removal of methylene blue dye from aqueous solutions, offering promising prospects for the treatment of industrial wastewater.

Two-step calcination synthesis of 1T/2H mixed-phase MoS2/g-C3N4 with sulfur defects for efficient removal of Cr(VI) from water

In this paper, 1T/2H mixed-phase MoS2/g-C3N4 composites (1T/2H-MG) were successfully synthesized by a simple two-step calcination method and used for Cr(VI) removal from aqueous environment. A series of characterization methods were used to characterize the microstructure and surface morphology of the prepared materials. The experiment results showed that 1T/2H-MG (1:12) composite with good pH and temperature adaptability could completely remove Cr(VI) (100 mg∙L–1) within 50 min and showed an excellent adsorption capacity of 342.06 mg∙g–1. The presence of abundant sulfur defects in 1T/2H-MG composite could provide more adsorption and reduction active sites, which was the main reason for the enhanced removal efficiency of 1T/2H-MG in comparison with pure MoS2 and g-C3N4. This work not only contributes an excellent adsorbent for the wastewater treatment, but also provides evidences for the defects engineering.

A review on the fate of micro and nano plastics (MNPs) and their implication in regulating nutrient cycling in constructed wetland systems

This review discusses the micro-nano plastics (MNPs) and their interaction with physical, chemical and biological processes in a constructed wetland (CW) system that is typically used as a nature-based tertiary wastewater treatment for municipal as well as industrial applications. Individual components of the CW system such as substrate, microorganisms and plants were considered to assess how MNPs influence the CW processes. One of the main functions of a CW system is removal of nutrients like nitrogen (N) and phosphorus (P) and here we highlight the pathways through which the MNPs influence CW's efficacy of nutrient removal. The presence of morphologically (size and shape) and chemically different MNPs influence the growth rate of microorganisms important in N and P cycling, invertebrates, decomposers, and the plants which affect the overall efficiency of a CW treatment system. Certain plant species take up the MNPs, and some toxicity has been observed. This review focuses on two significant aspects: (1) the presence of MNPs in a significant concentration affects the efficiency of N and P removal, and (2) the removal of MNPs. Because MNPs reduce the enzyme activities in abundance and overproduction of ROS oxidizes the enzyme active sites, resulting in the depletion of proteins, ultimately inhibiting nitrogen and phosphorus removal within the substrate layer. The review found that the majority of the studies used sand-activated carbon (SAC), granular-activated carbon (GAC), rice straw, granular limestone, and calcium carbonate, as a substrate for CW treatment systems. Common plant species used in the CW include Phragmites, Arabidopsis thaliana, Lepidium sativum, Thalia dealbata, and Canna indica, which were also found to be dominant in the uptake of the MNPs in the CWs. The MNPs were found to affect earthworms such as Eisenia fetida, Caenorhabditis elegans, and, Enchytraeus crypticus, whereas Metaphire vulgaris were found unaffected. Though various mechanisms take place during the removal process, adsorption and uptake mechanism effectively emphasize the removal of MNPs and nitrogen and phosphorus in CW. The MNPs characteristics (type, size, and concentration) play a crucial role in the removal efficiency of nano-plastics (NPs) and micro-plastics (MPs). The enhanced removal efficiency of NPs compared to MPs can be attributed to their smaller size, resulting in a faster reaction rate. However, NPs dose variation showed fluctuating removal efficiency, whereas MPs dose increment reduces removal efficiency. MP and NPs dose variation also affected toxicity to plants and earthworms as observed from data. Understanding the fate and removal of microplastics in wetland systems will help determine the reuse potential of wastewater and restrict the release of microplastics. This study provides information on various aspects and highlights future gaps and needs for MNP fate study in CW systems.

Enhancing biochar structure and removal efficiency of ammonium and microalgae in wastewater treatment through combined biological and thermal treatments

This study explored the efficiency of biological pre-treatment combined with thermal treatment to produce biochars, called E-biochars, for the removal of ammonium and microalgae without using chemical pre-treatment. The aim was to develop an environmentally sustainable approach for large-scale biochar production with high efficiency in wastewater treatment. The biological pre-treatment involved incubating the sawdust with Bacillus subtilis for 14 to 20 days and then subjected to pre-treatment at low temperatures (250-350 °C). This process broke down cellulose and altered its lignocellulosic structure, improving the biochar's morphology by leading to a more anisotropic pore structure. The thermal pre-treatment after that will help to open a broader range of pore sizes, spanning from macropores to micro-pores in the 1 μm to 5 μm dimension range. These alterations facilitated the efficient removal of ammonium and microalgae during adsorption experiments. The findings fit the Langmuir and the Freundlich models, according to the isotherm test of NH4+ and microalgae (R2 = 0.92÷0.99). The E-biochar termed EBH20, composted with Bacillus subtilis for 20 days at 350 °C, performed best, with Qmax equal to 40.2 mg/ g NH4+ under neutral conditions (pH = 7). Interestingly, the co-occurrence of ammonium and microalgae enhanced the removal of these contaminants. The interaction between microalgae cells and ammonium facilitated ammonium adsorption onto biochar and microalgae. The column breakthrough curves under NH4+ and NH4+ mixed microalgae adsorption were predicted using the Thomas model with the high agreement (R2 = 0.91÷0.99) for ammonium but for algae between prediction and running experimental column data.

Activate hydrogen peroxide for facile and efficient removal of aflatoxin B1 by magnetic Pd-chitosan/rice husk-hercynite biocomposite and its impact on the quality of edible oil

Due to the high heat and chemical stability of aflatoxin B1 (AFB1) with significant impacts on humans/animals and thus it needs to develop a practical and efficient approach for its removal. Herein, we fabricated a magnetic Pd-chitosan/glutaraldehyde/rice husk/hercynite (Pd@CRH-x) composite for efficient detoxification of AFB1. The Pd@CRH-x was obtained by a simple wet-impregnation procedure of CRH complexes followed by pyrolysis. The results confirmed that the unique structure of Pd@CRH-400 effectively improves dispersity, and mass transfer subsequently enhancing removal efficiency in batch conditions. Results indicate 94.30 % of AFB1 was efficiently degraded by 0.1 mg mL−1 Pd@CRH-400 with 4.0 mM H2O2 at wide pH ranges (3.0–10) at 60 min with a decomposition rate constant of 0.0467 min−1. Besides, by comparing the quality factors of edible oil (i.e., acid value, peroxide value, iodine value, moisture, volatile matters, anisidine value, and fatty acid composition), it was confirmed that there was no obvious influence on the physicochemical indicators of edible oil after removal/storage process. Subsequently, the systematic kinetic study and AFB1 degradation mechanism were presented. This study provides a new strategy for the efficient construction of controllable and dispersed Pd-based catalysts using CRH-x as a spatial support for alleviating the risk of toxic pollutants.