Pollutant Removal Rate Research Articles

The effect of oxygen vacancy in SnO2 based anodes on ozone generation and tetracycline removal

The electrochemical ozone production (EOP) during water oxidation represents a valuable method for producing pure ozone, which has attracted great attention. Oxygen vacancies on the surface of electrode materials can improve the electrocatalyst activity, but the mechanism remains unclear. Herein, the Ni-Sb-SnO2 (NSS) electrodes with different oxygen vacancies concentration were obtained by electrochemical activation, aiming to improve the ozone generation performance and the removal rate of pollutant. Moderate oxygen vacancies were conductive to generate a large number of new active sites or reactive surface oxygen species (O2-x) for promoting the oxygen molecules and oxygen intermediates to form ozone. The 1.1 %-Al-Ce-NSS electrocatalyst exhibited excellent EOP performance with a Faraday efficiency (FE) of 36.76 % at the current density of 40 mA·cm−2 and it achieved an optimal potential of 2.63 V (vs RHE) at 10 mA·cm−2, which was almost 1.5 times as much as that of 4.5 %-Al-Ce-NSS electrode. In addition, about 90.56 % of 10 mg·L−1 tetracycline (TC) could be removed through the 1.1 %-Al-Ce-NSS electrocatalyst in 40 min, and the ·OH was proved to be the main active species.

Investigation of nitrogen conversion in ditch-treated greywater: Contributions of biochar and aeration

This study aimed to assess the contribution of different combinations of uninterrupted aeration and tidal flow modes, as well as shallow and deep biochar landfill methods, to nitrogen removal pathways in ditches. Compared to natural ditches, the addition of biochar and aeration resulted in higher water pollution removal rates, lower Greenhouse Gas (GHG) emissions, and reduced sediment leaching. The nitrogen mass balance revealed that Total Nitrogen removal efficiency of each ditch group was 25.33% for CA-C, 43.75% for DBT-C, 49.08% for UBT-C, 30.75% for DBA-C, and 45.16% for UBA-C. Compared to the control group (CA-C), the tidal flow group with deep biochar landfill (DBT-C)demonstrated the highest efficiency in total nitrogen removal. To elucidate the fate of nitrogen elements, potential transformation processes of unexplained nitrogen were explored. The primary outflow pathway of nitrogen pollution in ditches is through liquids. The nitrogen composition in the liquid of each ditch indicated that for shallow biochar configurations (UBT-C/UBA-C), denitrification might be the main factor limiting TN removal efficiency. In contrast, for deep biochar configurations (DBT-C/DBA-C), hydrolysis and nitrification of organic nitrogen were identified as limiting factors, with tidal flow alleviating these limitations. Overall, the combination of shallow biochar and tidal flow aeration in a ditch is the most effective method for removing rural greywater, providing valuable insights for the development of design parameters in greywater removal systems.

Efficiency of the TEMJOUHERT date palm kernel as activated carbon in wastewater treatment for the Ghardaia region

This study aims to determine the potential for using activated carbon prepared by local agricultural waste for the treatment of wastewater loaded with organic pollutants. The activated carbon was prepared by chemical activation using phosphoric acid H3PO4 at an “85%” concentration, from local date kernels TEMJOUHERT (TMG) from the Ghardaïa region, Algeria. The activated carbon synthesis yield is equal to 28.56%. The adsorbent prepared was characterized by determining its physical and chemical characteristics, in particular the bulk density, the ash content, the iodine number, the surface functions by the Boehm method and the pH at the point of zero charge. Thus the textural properties are determined by scanning electron microscopy SEM and the Burnauer-emmett-Teller (BET). The surface area and micropore volumes of activated carbon TMG; were found to be 639.9190 m2/g and 0.420779 cm3/g respectively. All the results obtained from the treatment of wastewater from the Atteuf "kef doukhane area in the Ghardaia region. are clear that: the best pollutant removal rates are 84.75% for PO3-4; 85.21% for COD and 74.55% for NH4+ by activated carbons; using a mass of 1g of adsorbent per 100 ml of water, 90 min contact time and 250rpm stirring speed.

Performance of a pilot-scale microbial electrolysis cell coupled with biofilm-based reactor for household wastewater treatment: simultaneous pollutant removal and hydrogen production.

The septic tank is the most commonly used decentralized wastewater treatment systems for household wastewater treatment in on-site applications. The removal rate of various pollutants is lower in different septic tank configurations. The integration of a microbial electrolysis cells (MEC) into septic tank or biofilm-based reactors can be a green and sustainable technology for household wastewater treatment and energy production. In this study, a 50-L septic tank was converted into a 50-L MEC coupled with biofilm-based reactor for simultaneous household wastewater treatment and hydrogen production. The biofilm-based reactor was integrated by an anaerobic packed-bed biofilm reactor (APBBR) and an aerobic moving bed biofilm reactor (aeMBBR). The MEC/APBBR/aeMBBR was evaluated at different organic loading rates (OLRs) by applying voltage of 0.7 and 1.0V. Result showed that the increase of OLRs from 0.2 to 0.44kg COD/m3 d did not affect organic matter removals. Nutrient and solids removal decreased with increasing OLR up to 0.44kg COD/m3 d. Global removal of chemical oxygen demand (COD), biochemical oxygen demand (BOD), total nitrogen (TN), ammoniacal nitrogen (NH4+), total phosphorus (TP) and total suspended solids (TSS) removal ranged from 81 to 84%, 84 to 85%, 53 to 68%, 88 to 98%, 11 to 30% and 76 to 88% respectively, was obtained in this study. The current density generated in the MEC from 0 to 0.41 A/m2 contributed to an increase in hydrogen production and pollutants removal. The maximum volumetric hydrogen production rate obtained in the MEC was 0.007 L/L.d (0.072 L/d). The integration of the MEC into biofilm-based reactors applying a voltage of 1.0V generated different bioelectrochemical nitrogen and phosphorus transformations within the MEC, allowing a simultaneous denitrification-nitrification process with phosphorus removal.

Oxygen Reduction Reaction Coupled Electro‐Oxidation for Highly‐Efficient and Sustainable Water Treatment

AbstractElectro‐oxidation (EO) technology demonstrates significant potential in wastewater treatment. However, the high energy consumption has become a pivotal constraint hindering its large‐scale implementation. Herein, we design an EO and 4‐electron oxygen reduction reaction coupled system (EO‐4eORR) to replace the traditional EO and hydrogen evolution reaction (HER) coupled system (EO‐HER). The theoretical cathodic potential of the electrolytic reactor is tuned from 0 V (vs. RHE) in HER to 1.23 V (vs. RHE) in 4eORR, which greatly decreases the required operation voltage of the reactor. Moreover, we demonstrate that convection can improve the mass transfer of oxygen and organic pollutants in the reaction system, leading to low cathodic polarization and high pollutant removal rate. Compared with traditional EO‐HER system, the energy consumption of the EO‐4eORR system under air aeration for 95 % total organic carbon (TOC) removal is greatly decreased to 2.61 kWh/kgTOC (only consider the electrolyzer energy consumption), which is superior to previously reported EO‐based water treatment systems. The reported results in this study offer a new technical mode for development of highly efficient and sustainable EO‐based treatment systems to remove organic pollutants in waste water.

Oxygen Reduction Reaction Coupled Electro-Oxidation for Highly-Efficient and Sustainable Water Treatment.

Electro-oxidation (EO) technology demonstrates significant potential in wastewater treatment. However, the high energy consumption has become a pivotal constraint hindering its large-scale implementation. Herein, we design an EO and 4-electron oxygen reduction reaction coupled system (EO-4eORR) to replace the traditional EO and hydrogen evolution reaction (HER) coupled system (EO-HER). The theoretical cathodic potential of the electrolytic reactor is tuned from 0 V (vs. RHE) in HER to 1.23 V (vs. RHE) in 4eORR, which greatly decreases the required operation voltage of the reactor. Moreover, we demonstrate that convection can improve the mass transfer of oxygen and organic pollutants in the reaction system, leading to low cathodic polarization and high pollutant removal rate. Compared with traditional EO-HER system, the energy consumption of the EO-4eORR system under air aeration for 95 % total organic carbon (TOC) removal is greatly decreased to 2.61 kWh/kgTOC (only consider the electrolyzer energy consumption), which is superior to previously reported EO-based water treatment systems. The reported results in this study offer a new technical mode for development of highly efficient and sustainable EO-based treatment systems to remove organic pollutants in waste water.

In Situ Conductive Heating for Thermal Desorption of Volatile Organic-Contaminated Soil Based on Solar Energy

A novel conductive heating method using solar energy for soil remediation was introduced in this work. Contaminated industrial heritage sites will affect the sustainable development of the local ecological environment and the surrounding air environment, and frequent exposure will have a negative impact on human health. Soil thermal desorption is an effective means to repair contaminated soil, but thermal desorption is accompanied by a large amount of energy consumption and secondary pollution. Therefore, a trough solar heat collection desorption system (TSHCDS) is proposed, which is applied to soil thermal desorption technology. The effects of different water inlet temperature, water inlet velocity and soil porosity on the evolution of soil temperature field were discussed. The temperature field of contaminated soil can be numerically simulated, and a small experimental platform is built to verify the accuracy of the numerical model for simulation research. It is concluded that the heating effect is the best when the water entry temperature is the highest, at 70 °C, and the temperature of test point 4 is increased by 50.71% and 1.42%, respectively. When the inlet water flow rate is increased from 0.1 m/s to 0.2 m/s, the heating effect is significantly improved; when the inlet water flow rate is increased from 0.5 m/s to 1.5 m/s, the heating effect is not significantly improved. Therefore, when the flow rate is greater than a certain value, the heating effect is not significantly improved. The simulation analysis of soil with different porosity shows that larger porosity will affect the thermal diffusivity, which will make the heat transfer effect worse and reduce the heating effect. The effects of soil temperature distribution on the removal of petroleum hydrocarbon C6–C9 and trichloroethylene (TCE) were studied. The results showed that in the thermal desorption process of petroleum hydrocarbon C6–C9-contaminated soil, the removal rate of pollutants increased significantly when the average soil temperature reached 80 °C. In the thermal desorption of trichloroethylene-contaminated soil, when the thermal desorption begins, the soil temperature rises rapidly and reaches the target temperature, and a large number of pollutants are removed. At the end of thermal desorption, the removal of both types of pollutants reached the target repair value. This study provides a new feasible method for soil thermal desorption.

Enhanced Pollutant Removal and Antifouling in an Aerobic Ceramic Membrane Bioreactor with Bentonite for Pharmaceutical Wastewater Treatment.

This study examined the impact of adding bentonite clay (concentration of 1.5 to 10 g/L) to a pilot-scale aerobic ceramic membrane bioreactor (AeCMBR) for treating pharmaceutical wastewater (PhWW). The hydraulic retention time (HRT) was maintained at 24 h; the dissolved oxygen was between 2 mg/L (on) and 4 mg/L (off) throughout operation. Organic and nitrogen pollution removal rates and heavy metal (Cu, Ni, Pb, Zn) reduction rates were assessed. The chemical oxygen demand (COD) removal efficiency exceeded 82%. Adsorption improved ammonia (NH4+) removal to 78%; the addition of 5 g of bentonite resulted in a 38% improvement compared with the process without bentonite. The average nitrate concentration decreased from 169.69 mg/L to 43.72 mg/L. The average removal efficiencies for Cu, Ni, Pb and Zn were 86%, 68.52%, 46.90% and 56.76%, respectively. Bentonite at 5 g/L significantly reduced membrane fouling. The cost-benefit analysis enabled us to predict that the process will meet the multiple objectives of durability, treatment performance and economic viability. The combination of an AeCMBR and bentonite adsorption has proven to be a valuable solution for treating highly polluted wastewater.

Surface-coated PVDF@TAPEG selective ultrafiltration membranes: an investigation on membranes’ hydrophilicity, and antifouling characteristics for effective humic acid removal from wastewater

This research aimed to synthesize polyvinyl fluoride membranes and coat them with tannic acid (TA) nanoparticles and polyethylene glycol (PEG) additives so that the membrane’s removal efficacy for humic acid (HA) pollutant from agricultural wastewater was investigated. Thus, six membranes with PEG:TA ratios of 0:0, 1:0, 0:1, 1:1, 4:1, and 1:4 were synthesized. Then, the membranes’ characteristics were identified by FTIR-ATR, FESEM, and AFM analysis, and HA’s particle size and zeta potential were also investigated. Based on optimizing effective parameters, the operating pressure of 1.5 bar and HA concentration of 80 ppm were selected as optimal values. The membrane with PEG:TA = 4:1, as the optimally modified membrane, had a pure water flux of 446.03 L/m2.h, effluent flux of 72.43 L/m2.h, and pollutant removal rate of 86.62% at pH = 7 after 60 min had passed. These values for the pristine membrane (PEG:TA = 0:0) were 265.64 L/m2.h, 89.39 L/m2.h, and 75.59%, respectively. The results showed that although the effluent flux was lower in the optimized modified membrane than in the pristine membrane, HA removal percentage was increased.

Synthesis of high-value porous carbon from waste plastics and structure regulation promote solar interface water evaporation

Water scarcity and waste plastics elimination are long-term problems facing sustainable development, and solar interface evaporation to produce clean water is regarded as a promising water treatment technology. Herein, we report on low-cost waste plastic bottles synthetic carbon-based photothermal materials. By KOH activation and perforation, the surface crack structure of porous carbon is formed to facilitate multi-stage reflection of solar light, and significantly improve the solar light absorbance and photothermal conversion ability. Three-dimensional solar evaporators with low thermal conductivity and super hydrophilic wood sponge are fabricated, and the rectangular hole is designed to regulate water movement and prevent heat dissipation. When exposed to 1 sun illumination (1 kW/m2), an evaporation rate of 1.59 kg·m-2·h-1 is achieved, along with an energy conversion efficiency of 88.49 %. In addition, different micro-surface rough structures are constructed to boost the solar light absorption, thereby enhancing the photothermal conversion ability, among which the micro-cone structure increased the evaporation rate to 1.93 kg·m−2·h−1, demonstrating excellent stability over 15 cycles. In the simulated sewage purification process, the removal rate of pollutants is 99.9 %, and the evaporator without obvious salt accumulation in the seawater for 24 h, showing good salt resistance and self-cleaning ability. This research has important reference value for high-value preparation of carbon-based photothermal materials from waste plastics, extraction of clean water and environmental sustainable protection.

Exploration of radical chemistry, precursor sensitivity and O3 control strategies in a provincial capital city, northwestern China

As the core city in northwestern China, Xi'an has suffered from serious O3 pollution in recent years. An observational model, coupled with the Master Chemical Mechanism (V3.3.1) and comprehensive data, analyzed atmospheric oxidation capacity (AOC), O3 formation mechanism, precursor sensitivity and control strategies in Xi'an. The study examined two periods (period I and II), with notable temperature and humidity differences. Despite lower precursor levels in period I, an O3 episode (peak value: 102.68 ppb) occurred only in period I, highlighting the crucial influence of meteorological conditions. Higher removal rate of primary pollutants occurs in period I, but meteorological conditions may not alter the dominant factor of AOC. Period I exhibited markedly high OH reactivity, with aromatics, alkenes, and NOx being the main contributors. HONO photolysis (50.78%) in the morning and O3 photolysis (34.13%) in the afternoon were the main HOx sources in period I, while HONO photolysis (62.86–80.68%) was significant at daytime for period II. Higher temperatures in period I accelerated all reaction rates involved in radical cycling, especially emphasizing RO2 + NO → RO + NO2. The results of sensitivity analysis showed that O3 sensitivity regime is VOC-limited in Xi'an, but the specific reactive species target VOC reductions emissions exhibited discrepancies for two distinct periods. A 20% decrease in VOCs and a 50% decrease in NOx (VOCs/NOx = 0.4) was proposed to be the optimal solution to achieve the O3 control target in period I. This study enhances our understanding of O3 formation under different meteorological conditions and provides scientific evidence for O3 pollution abatement policies in northwestern China, with potential applicability to other cities in this region and similar countries.

Intensive coagulation of secondary effluent to mitigate reverse osmosis membrane fouling at low temperatures: Strategies of pre-oxidation and coagulant aids addition

Conventional coagulation-sedimentation, typically used as a pretreatment for ultrafiltration-reverse osmosis, is ineffective in solving the problem of reverse osmosis membrane fouling at low temperatures. In this study, the coagulation enhancement effect of pre-oxidation and the addition of coagulant aids on conventional coagulation with polyaluminum chloride as a coagulant was investigated. The results showed that the addition of fly ash, powdered activated carbon, or diatomite as coagulant aids improved the reduction of turbidity, dissolved organic carbon (DOC), and ultraviolet absorbance at 254 nm (UV254), and also reduced the residual content of dissolved aluminum ions. Among them, diatomite was superior. Pre-oxidation before conventional coagulation increased the reduction of turbidity and UV254 by about 50 % and doubled the removal of proteins, polysaccharides, and DOC compared to conventional coagulation. Ozone was superior to sodium hypochlorite. The combination of ozone pre-oxidation and diatomite addition with conventional coagulation further increased the pollutant removal rate, with the removal rates of turbidity, UV254, polysaccharides, proteins, and DOC reaching 82.20 %, 52.35 %, 26.34 %, 24.89 %, and 26.38 %, respectively. In addition, the residual content of dissolved aluminum ions decreased to 0.84 mg/L. The reverse osmosis filtration simulation test showed that pretreating the feed water with the enhanced coagulation by the combination of ozone pre-oxidation and diatomite addition resulted in a slower decrease in membrane flux, reduced foulant content on the membrane surface, and the smallest increase in contact angle. The results of this research may offer a viable pretreatment method to reduce fouling in reverse osmosis membranes operating at low temperatures.

Enhancing the production of reactive oxygen species in the rhizosphere to promote contaminants degradation in sediments by electrically strengthening microbial extracellular electron transfer

The production of reactive oxygen species (ROS) in the rhizosphere is limited by the low extracellular electron transfer capacity of indigenous microorganisms. In the present study, electrical stimulation was used to promote the generation of rhizospheric ROS by accelerating extracellular electron transfer. The result showed that •OH concentrations in the electrically stimulated group (ES group) exceeded the control group by 15.76 %. Accordingly, the removal rate of the target pollutant (i.e., 2,4-dichlorophenol, and sulfamethoxazole) was 20.01 %−24.80 % higher in the ES group than in the control group. The sediment of the ES group had a higher capacity (30.55 %) and a lower electrical resistance (29.15 %) compared to the control group, which subsequently promoted the dissimilatory iron reduction to produce Fe(II) for triggering a Fenton-like process. The increased extracellular respiratory capacity under electrical stimulation could be attributed to the polarization of C-N and CO bonds, which provided more electron storage sites and thus participated in proton-coupled electron transfer. In addition, the concentration of ATP and co-enzymes (NADH/NAD+ and Complex I/Complex III), reflecting electron exchange within respiratory chains, increased distinctly under electrical stimulation. Applying electrical stimulation seemed feasible to increase ROS production and contaminant degradation in the rhizosphere, deepening the understanding of electrical stimulation to promote the production of ROS in the natural system.

Amino polycarboxylic acid complex agent modified Fe0 enhanced activation of H2O2 double decomposition pathways for tetracycline removal under neutral condition

The summary of this study explores the modification of Fe0 with amino polycarboxylic acid complex agents (APCAs) to enhance H2O2 catalysis for tetracycline (TC) removal under neutral conditions. The ethylenediaminetetraacetic acid-modified Fe0/H2O2 system (EDTA-Fe0/H2O2) achieved a removal efficiency of 90.2 % for 50 mg/L TC, significantly higher than the 23.9 % efficiency of the traditional Fe0/H2O2 system. The removal rate of various pollutants by the EDTA- Fe0/H2O2 process is 2.9 to 8.4 times higher than that of the Fe0/H2O2 process. After four cycles of use, the removal rate of TC by the EDTA-Fe0/H2O2 system can still reach 76.3 %. Additionally, the effect of treating TC in natural freshwater can also achieve 80.1 %. Characterization revealed that EDTA-Fe0 had a larger Fe(II) proportion, better hydrophobicity, and lower corrosion potential than Fe0, indicating higher activity. Quenching experiments and electron paramagnetic resonance tests confirmed that •OH was the major reactive species. Shell-isolated nanoparticle-enhanced Raman spectroscopy indicated the presence of *OOH species, suggesting the involvement of a dioxygen coordination reaction. Density functional theory calculations showed that both dioxygen and single oxygen coordination H2O2 decomposition pathways played significant roles, and EDTA-Fe0 exhibited high catalysis ability for H2O2 in both pathways. Analysis of the relationship between APCAs’ group structure and APCAs-Fe0 properties indicated that the number of carboxyl groups was crucial for enhancing catalytic activity, while the number of amino groups also impacted antibiotic removal efficiency. Overall, this study provides a solid theoretical foundation for further Fe0 applications and suggests a new method to improve TC removal.

A novel piezoelectric fenton-like process mediated by FeOCl for efficient contaminant removal

Ferric oxychloride (FeOCl), an iron-based catalyst with a unique coordination structure, has demonstrated effective pollutant removal capabilities in various reaction systems such as photo-Fenton, Fenton-like, and electro-Fenton processes. However, in previous studies, little or no attention has been paid by researchers to the piezoelectric properties of FeOCl and the pollutant removal performance exhibited in the presence of piezoelectric fields. In this study, we observed that the piezoelectric effect significantly enhanced the Fenton-like reaction process of FeOCl. Whereas the piezoelectric properties of FeOCl have not been reported in the previous research. The process significantly enhances the kinetic removal rate of pollutant, which is 3.12 times higher than the Fenton process and 18 times higher than the Fenton-like process for FeOCl. Furthermore, we observed a significant increase in the kinetic removal rate of pollutant after lattice distortion of FeOCl under the piezoelectric field and revealed how this process mediates the ultrafast oxidative removal process. Notably, we also detect the formation of pollutant polymeric products during the piezoelectric enhancement process, confirming the existence of a pollutant polymerization pathway during piezoelectric catalysis. The piezoelectric-enhanced FeOCl Fenton-like process constructed in this study not only provides important theoretical support for the practical application of FeOCl but also opens new research perspectives for the application of FeOCl in the field of piezoelectric catalysis.

From Waste to Resource: Evaluating Biomass Residues as Ozone-Catalyst Precursors for the Removal of Recalcitrant Water Pollutants

Five different biomass wastes—orange peel, coffee grounds, cork, almond shell, and peanut shell—were transformed into biochars (BCs) or activated carbons (ACs) to serve as adsorbents and/or ozone catalysts for the removal of recalcitrant water treatment products. Oxalic acid (OXL) was used as a model pollutant due to its known refractory character towards ozone. The obtained materials were characterized by different techniques, namely thermogravimetric analysis, specific surface area measurement by nitrogen adsorption, and elemental analysis. In adsorption experiments, BCs generally outperformed ACs, except for cork-derived materials. Orange peel BC revealed the highest adsorption capacity (Qe = 40 mg g−1), while almond shell BC showed the best cost–benefit ratio at €0.0096 per mg of OXL adsorbed. In terms of catalytic ozonation, only ACs made from cork and coffee grounds presented significant catalytic activity, achieving pollutant removal rates of 72 and 64%, respectively. Among these materials, ACs made from coffee grounds reveal the best cost/benefit ratio with €0.02 per mg of OXL degraded. Despite the cost analysis showing that these materials are not the cheapest options, other aspects rather than the price alone must be considered in the decision-making process for implementation. This study highlights the promising role of biomass wastes as precursors for efficient and eco-friendly water treatment processes, whether as adsorbents following ozone water treatment or as catalysts in the ozonation reaction itself.

Separation and recovery of elements from drainage water arising in soilless tomato cultivation − Application of electrocoagulation

Soilless tomato cultivation requires significant water and nutrient inputs, resulting in the generation of drainage water (DW) with varying macro- and micronutrient compositions. This poses challenges for effective nutrient’s reuse due to technological and economic constraints. This study investigates the feasibility of using electrocoagulation, employing aluminum electrodes, to treat DW. The experiment involved three different current densities (2 A/m2, 4 A/m2, and 8 A/m2) and a 24-hour hydraulic retention time (comprising 4 h of electrocoagulation followed by 20 h of stirring). Treatment performance, kinetics, sludge characteristics, and energy consumption were evaluated. The elemental composition of the electrocoagulation-treated DW, including P, N, S, Cl, Ca, Mg, K, Na, Mo, Mn, Fe, Zn, Cu, B, organic compounds, and Al, was analyzed. The results showed that higher current densities resulted in increased pollutant removal rates and efficiencies. Importantly, the electrocoagulation process facilitated phosphorus recovery at pH < 7.0, ranging from 95.3 ± 0.6 % (at 2 A/m2) to 99.9 ± 0.1 % (at 8 A/m2), with corresponding energy consumption between 6.03 kWh/kgP and 29.98 kWh/kgP. Electrocoagulation as a drainage water treatment not only offers phosphorus recovery, but can also recovery B, and – to a certain extent – S, Mg, K, Mn, Zn and Cu. Other elements, such as Na and Cl, remained at stable levels. This allows for the separation of valuable elements (P) from those that interfere with cultivation (Na, Cl). This research could contribute to the development of a precise treatment process to address nutrient and pollutant management challenges in agricultural wastewater.

Recent progress and perspectives of typical renewable bio-based flocculants: characteristics and application in wastewater treatment.

The research on bio-based flocculants for waste resource utilization and environmental protection has garnered significant attention. Bio-based flocculants encompass plant-based, animal-based, and microbial variants that are prepared and modified through biological, chemical, and physical methods. These flocculants possess abundant functional groups, unique structures, and distinctive characteristics. This review comprehensively discussed the removal rates of conventional pollutants and emerging pollutants by bio-based flocculants, the interaction between these flocculants and pollutants, their impact on flocculation performance in wastewater treatment, as well as their application cost. Furthermore, it described the common challenges faced by bio-based flocculants in practical applications along with various improvement strategies to address them. With their safety profile, environmental friendliness, efficiency, renewability, and wide availability from diverse sources, bio-based flocculants hold great potential for widespread use in wastewater treatment.

Optimizing photocatalytic performance in an electrostatic-photocatalytic air purification system through integration of triboelectric nanogenerator and Tesla valve

Increasing the collision frequency between gas molecules and photocatalysts can enhance the removal efficiency of volatile organic compounds (VOCs) and particulate matter (PM) in air. In this study, we propose an Electrostatic-Photocatalytic air purification system, containing Tesla valve, triboelectric nanogenerator (TENG), and photocatalysis parts. The incorporation of Ag@ZnO nanorod array (Ag@ZnO-NR) photocatalysts into the internal baffles of the Tesla valve pipeline effectively enhances the collision probability between air pollutant molecules and photocatalysts, and thus facilitating the removal efficiency of pollutants. Additionally, the high-voltage electricity (∼9.0 kV) generated by the TENG facilitates the separation of electron-hole pairs in the photocatalyst, leading to increased production of superoxide radicals (O•−2), hydroxyl radicals (•OH), and holes (h+), thereby enhancing the photocatalytic efficiency. In a 1.8 L space system, we achieved an approximately 97 % removal efficiency for toluene within 130 minutes and a similar efficiency for formaldehyde (∼200 ppm) within 175 minutes. Additionally, the PM2.5 concentration rapidly decreased from 999 μg·m−3 to 42 μg·m−3 within 6 minutes, alongside with a significantly faster pollutant removal rate compared to conventional methods. By integrating Tesla valves, TENG, and photocatalysis, this combined system presents an efficient and promising approach for addressing indoor air pollution, with potential applications across various settings.

Ag-Incorporated Cr-Doped BaTiO3 Aerogel toward Enhanced Photocatalytic Degradation of Methyl Orange.

A novel Cr-doped BaTiO3 aerogel was successfully synthesized using a co-gelation technique that involves two metallic alkoxides and a supercritical drying method. This freshly prepared aerogel has a high specific surface area of over 100 m2/g and exhibits improved responsiveness to the simulated sunlight spectrum. Methyl orange (MO) was chosen as the simulated pollutant, and the results reveal that the Cr-doped BaTiO3 aerogel, when modified with the noble metal silver (Ag), achieves a pollutant removal rate approximately 3.2 times higher than that of the commercially available P25, reaching up to 92% within 60 min. The excellent photocatalytic performance of the Ag-modified Cr-doped BaTiO3 aerogel can be primarily attributed to its extensive specific surface area and three-dimensional porous architecture. Furthermore, the incorporation of Ag nanoparticles effectively suppresses the recombination of photo-generated electrons and holes. Stability and reusability tests have confirmed the reliability of the Ag-modified Cr-doped BaTiO3 aerogel. Therefore, this material emerges as a highly promising candidate for the treatment of textile wastewater.