Removal Efficiency Of Organic Pollutants Research Articles

Predicting removal efficiency of organic pollutants by soil vapor extraction based on an optimized machine learning method

Soil vapor extraction (SVE) was a cost-effective technology for remediating volatile and semi-volatile organic contaminated soils. Many factors, including SVE parameters, soil properties, and contaminant characteristics, significantly influenced the remediation efficiency of SVE. The optimal conditions for organic contaminant removal efficiency were site-specific and varied among studies. Therefore, a generalized model was needed to predict the remediation efficiency in organic contaminated soils. This study employed machine learning to predict the removal efficiency of organic pollutants by SVE. The model's development was based on a trainset, and its predictive capabilities were evaluated using a testset. An XGBoost (XGB) model was derived from literature data (R2 = 0.9775). Time, pollutant type, and temperature were identified as the three most important features affecting SVE remediation efficiency. The accuracy (R2 = 0.9799) and universality of the model were enhanced through an optimization scheme. The developed XGB model demonstrated the ability to predict the removal efficiency of organic pollutants by considering all collected influential factors. The mechanism of multi-factor interaction on remediation efficiency was clarified. Overall, this study would contribute to evaluating the remediation potential of SVE for specific organic contaminated soils, aiding in maximizing the removal efficiency of organic pollutants under optimal conditions.

Deep purification of pesticide waste salt containing high-concentration organic pollutants by ethanol solvents washing and heating treatment

The increasing production of industrial waste salt has become a growing concern. These waste salts are usually filled or deposited without treatment, causing serious environmental pollution and a waste of salt resources. The ideal solution to this problem is to recycle the waste salts after the removal of organic pollutants. In this study, organic solvent washing and heating are chosen to deeply remove the organic pollutants from actual pesticide waste salts. The experimental results showed that the optimum removal efficiency of organic pollutants in waste salts achieves as high as 99.82% under the conditions of 3:5 mass-to-volume ratio of waste salts-to-ethanol (EA), heating temperature of 400 °C (60 min). In addition, the removal mechanism and migration pathways of organic pollutants in the washing and heating were proposed. Salts washing with EA could remove most of the organic pollutants and subsequent heating treatment could completely purify the waste salts without the emission of the harmful gaseous compounds. As the best eluent, EA can not only effectively remove organic pollutants, but also be readily recycled. At the same time, the EA washing and heating process could avoid the pollution of organic waste liquid and noxious tail gas. Therefore, the EA washing process has the advantages of green, high efficiency, safety and energy saving. The EA washing and heating effectively avoids the problem of environmental pollution caused by harmful gases generated by heating and promotes the purification process and reuse of industrial waste salts.

Unraveling the mechanisms behind sodium persulphate-induced changes in petroleum-contaminated aquifers’ biogeochemical parameters and microbial communities

Sodium persulphate (PS) is a highly effective oxidising agent widely used in groundwater remediation and wastewater treatment. Although numerous studies have examined the impact of PS with respect to the removal efficiency of organic pollutants, the residual effects of PS exposure on the biogeochemical parameters and microbial ecosystems of contaminated aquifers are not well understood. This study investigates the effects of exposure to different concentrations of PS on the biogeochemical parameters of petroleum-contaminated aquifers using microcosm batch experiments. The results demonstrate that PS exposure increases the oxidation-reduction potential (ORP) and electrical conductivity (EC), while decreasing total organic carbon (TOC), dehydrogenase (DE), and polyphenol oxidase (PO) in the aquifer. Three-dimensional excitation-emission matrix (3D-EEM) analysis indicates PS is effective at reducing fulvic acid-like and humic acid-like substances and promoting microbial metabolic activity. In addition, PS exposure reduces the abundance of bacterial community species and the diversity index of evolutionary distance, with a more pronounced effect at high PS concentrations (31.25 mmol/L). Long-term (90 d) PS exposure results in an increase in the abundance of microorganisms with environmental resistance, organic matter degradation, and the ability to promote functional genes related to biological processes such as basal metabolism, transmission of genetic information, and cell motility of microorganisms. Structural equation modeling (SEM) further confirms that ORP and TOC are important drivers of change in the abundance of dominant phyla and functional genes. These results suggest exposure to different concentrations of PS has both direct and indirect effects on the dominant phyla and functional genes by influencing the geochemical parameters and enzymatic activity of the aquifer. This study provides a valuable reference for the application of PS in ecological engineering.

The various effects of hydrogen phosphate and bicarbonate in the degradation of some pollutants in the UV/chlorine and the UV/H2O2 processes

In this study, the degradation kinetics of three target pollutants (i.e., levofloxacin (LEV), P-nitrosodimethylaniline (RNO), and basic fuchsin (BF) in four UV-based Advanced Oxidation Processes (UV/AOPs) (i.e., UV/NaOCl/HPO42−, UV/NaOCl/HCO3−, UV/H2O2/HPO42−, and UV/H2O2/HCO3−) were comprehensively investigated. The results showed that LEV and RNO were resistant to UV irradiation, chlorination, and H2O2 when applied separately, but significantly degraded in UV/AOPs. The chlorination process and alkaline conditions were beneficial to the degradation of BF. In UV/AOPs, the degradation rates of the pollutants were enhanced remarkably with different rate constants which were dependent on the dosage of oxidants, and the presence of HPO42− and HCO3−. This enhancement is due to the generation of reactive species (i.e., •OH, RCS, and secondary reactive radicals like PO42•-, and CO3•-). The study also investigated the role and contribution of the reactive species to the degradation of the pollutants in UV/AOPs. The study demonstrated the difference in the degradation kinetics of the pollutants in UV/H2O2/(HPO42− or HCO3−) and UV/NaOCl/(HPO42− or HCO3−) in which the contribution of each oxidizing factor was determined. Acidic conditions were beneficial to the degradation rate of the pollutants in all UV/AOPs, except BF in UV/NaOCl. Seawater and river water were demonstrated to significantly promote the degradation rate of pollutants in UV/NaOCl/(HPO42− or HCO3−) but depressed it in UV/H2O2/(HPO42− or HCO3−). In addition, a typical PPCP (pharmaceutical and personal care product) (here LEV) was selected for further LC-MS analysis to determine its degradation pathway. The results provide a novel alternative strategy in the use of HPO42− and HCO3− in UV/NaOCl and UV/H2O2 to increase the removal efficiency of organic pollutants.

A coupling mechanism of anodic oxygen evolution reaction during organic pollutants oxidation

In this work, β-PbO2/Ti and RuO2-IrO2/Ti anodes and Ti cathodes were employed to conduct electrocatalytic phenol degradation experiments at various current densities. The difference in degradation rates between the two anodes indicated that the oxygen evolution reaction (OER) is related to the organic matter concentration. Consequently, a coupling mechanism “active-site competition mechanism (ACM) + adsorbate evolution mechanism (AEM)” for anodic oxygen evolution was described. Based on this mechanism and experimental results, it can be concluded that the ACM influences the initial degradation rate, and the AEM affects final organic matter concentrations. DFT calculations showed that RuO2-IrO2 exhibits excellent AEM activity attributed to the lower OER overpotential (0.7 V) and stronger adsorption energies of *O oxygenated intermediate (-1.52 eV). At the same time, RuO2-IrO2 possesses slight thermodynamic reaction energy of ACM, which are 103.3, 31.6 and 89.5 kJ/mol. Therefore, the slower degradation rates and lower removal efficiency on RuO2-IrO2/Ti are owing to the better ACM and AEM activity. Then, electrocatalytic experiments at various pH were conducted to verify the conclusion that AEM affects final organic matter concentrations. Finally, this work has implications for a better understanding of the OER mechanism and provides theoretical guidance for improving the removal efficiency of organic pollutants.

Activated carbon modified titanium dioxide/bismuth trioxide adsorbent: One-pot synthesis, high removal efficiency of organic pollutants, and good recyclability

Considerable endeavors have focused on tightly combining adsorption with photocatalysis in designing composite materials for environmental pollution treatment. Recent advances in coupling titanium dioxide/bismuth trioxide (TiO2/Bi2O3) with activated carbon (AC) show significantly enhanced photocatalytic performance but face critical limitations including low adsorption capacity and multi-step synthesis. In this work, we introduce a one-pot synthesis of activated carbon modified TiO2/Bi2O3 composite materials (TiO2/Bi2O3/AC). Thanks to the integrated adsorbent/photocatalyst system, TiO2/Bi2O3/AC shows a drastically enhanced removal efficiency for sulfamethazine (>81%), far beyond the corresponding value of the reported AC/TiO2/Bi2O3 adsorbent (<40%). Notably, the removal rates of other typical pollutants including tetracyclines, methyl orange, and rhodamine B are as high as >98%. Furthermore, TiO2/Bi2O3/AC obtains >80% of its adsorption rate for the fifth cycle after simple photo-regeneration without any other post-treatments. Kinetic analysis and photoelectric characterization are carried out to provide insight into adsorption mechanism. Therefore, this work demonstrates a considerable potential to design and construct other multifunctional adsorbents with advanced performance.

Ball-milled PET plastic char as an electron shuttle accelerated anaerobic degradation of 2,4,6-trichlorophenol in water environment

11The number behind BMPC denotes the pyrolysis temperature.The combination of carbonaceous materials and microbial degradation is an attractive measure in improving the removal efficiency of organic pollutants in water environment. In this study, the anaerobic dechlorination in a coupled system of ball-milled plastic chars (BMPCs) and the microbial consortium were investigated. The anaerobic microorganism cultured from raw sludge (CAM) contributed to the dechlorination of the 2,4,6-trichlorophenol (2,4,6-TCP) into 4-chlorophenol (4-CP) as the final product via ortho-dechlorination in all testing groups. The dechlorination rate was accelerated in different BMBC plus CAM groups than that in only CAM group (0.048 d−1), of which, it was greater in BMPC-500 plus CAM group (0.375 d−1) than that in BMPC-700 plus CAM group (0.171 d−1). The electron exchange capacity (EEC) of BMPCs decreased with the increase of pyrolysis temperature (0.053 mmol e−/g for BMPC-500 and 0.037 mmol e−/g for BMPC-700), which directly affected anaerobic dechlorination. Direct interspecies electron transfer (DIET) of BMPCs also boosted the biogas yield by 1.5 times compared to that without BMPCs. Microbial community analysis illustrated that BMPCs helped to enrich the putative dechlorinating bacteria. The abundance of Clostridium_aenus_stricto_12, as a dominant dechlorinator, significantly increased from 0.02 % to 11.3 % (without BMPCs), 39.76 % (BMPC-500) and 9.3 % (BMPC-700), and followed by， Prevotella and Megaspheara, which was reported to take part in anaerobic dechlorination and digestion as H2 producers, also increased in the presence of BMPC. This study contributes to the realization of 2,4,6-TCP in-situ reduction technology and provides a scientific reference for anaerobic dechlorination by cultured anaerobes combined with BMPCs.

Efficiency and mechanism of ozonated microbubbles for enhancing the removal of algae and algae-derived organic matter

The effective control of eutrophication caused by algae blooms is still the focus of global attention. The traditional dissolved air floatation process for algae removal has a low adhesion efficiency between bubbles and algal cells and a low removal efficiency of organic pollutants. Aiming to address these defects, this study set up an ozone microbubble-enhanced air flotation experiment to explore the removal trends of algal cells and algal organic matter (AOM) pollution. In contrast to traditional air flotation, this approach targets the removal of various forms of AOM after algal cell damage. The highest removal rates of algal cells, extracellular microcystin (Mc), intracellular Mc-lr and total Mc-lr were 96.6%, 60.1%, 95.2% and 93.7%, respectively. Compared with the traditional process, the absorption rate and utilization rate of ozone were increased by 41.9% and 46.2%, respectively. The removal effect of AOM was also greatly improved, and ozone microbubbles enhanced the removal of aromatic protein-like substances and high-molecular-weight fulvic acid, humic acid and humic substances. The advantageous synergistic effect of ozone and microbubbles on algae removal was analyzed by exploring the enhanced air flotation removal mechanism of ozone microbubbles' enhanced air floatation removal. Good vacuole adhesion and strong oxidation caused by ozone microbubbles jointly guaranteed a good removal rate of AOM. The enhanced air flotation process with ozone microbubbles has high feasibility and a good effect, can effectively remove algal cells and algal pollutants, and has great potential in algal removal and control of water eutrophication.

Axially wrinkled tubular SnO2/TiO2 heterostructures for effective degradation of organic pollutants

Axially wrinkled SnO2/TiO2 heteronanotubes have been successfully prepared by sacrificial template method combined with hydrothermal synthesis. The special folded morphology of SnO2/TiO2 nanostructures may provide more active sites, and the S-scheme heterojunction between SnO2 and TiO2 enhances the separation of photogenerated electron-hole pairs, which are conducive to the improvement of photocatalytic degradation for organic pollutants. Using SnO2/TiO2 nanotubes as catalyst, the removal rate of Rhodamine B (RhB), methyl orange (MO) and tetracycline hydrochloride (TCH) under the irradiation of a xenon lamp is 93%, 91% and 85%, respectively. After five cycles, the removal efficiency of organic pollutants maintains almost unchanged, indicating that the synthesized SnO2/TiO2 nanotubes has good stability and reusability. In addition, trapping experiments have been carried out to investigate the major reactive oxidative species for organic pollutants photodegradation. This study provides a facile avenue to design nanotublar photocatalysts with enhanced degradation performance for organic pollutants.

Insight into the dual-cathode peroxi-coagulation process for cost-effective treatment of organic wastewater: Increase pH application range and reduce iron sludge

An improved dual-cathode peroxi-coagulation (PC) process using natural air diffusion electrode (NADE) and HNO3 modified carbon felt (MCF) was first proposed to improve the removal efficiency of organic pollutants in neutral and alkaline wastewater and reduce the formation of iron sludge. The improved PC process does not require any additional oxidants or catalysts, nor does it need to adjust the pH of the wastewater in advance but can directly treat actual wastewater, achieving a target pollutant (C12H14N4O2S, sulfamethazine) removal of 87%-100% within 60 min and TOC removal of 46–76% within 240 min with the corresponding energy consumption below 0.02 kWh gTOC-1. Compared with the conventional PC process, this improved process could produce hydroxyl radical (•OH) and superoxide radical (O2•-) more efficiently, which greatly increased the SMT removal rate constant by 3–4 times and oxidative removal proportion of organic pollutants from 42 ∼ 47% to 85 ∼ 90%. Thanks to the Fe(II) regeneration capacity of MCF to promote iron circulation, the yield of •OH was 4.1 times higher while the iron sludge production was less than a quarter when compared with that of conventional PC. The improved PC process illustrated better purification performance and lower energy consumption for actual wastewaters such as pharmaceutical wastewater, surface water and rural decentralized domestic sewage than the conventional PC process. Our work elucidated the mechanism of promoting Fe(II) regeneration through MCF cathode under alkaline conditions to enhance •OH production and O2•- oxidation, showing a good environmental application prospect.

G-C3N4/ZnO heterojunction as Fenton-like catalyst for degradation of organic pollution

g-C3N4/ZnO Fenton-like catalysts were prepared by impregnation of g-C3N4 with a solution of zinc nitrate hexahydrate followed by calcination. XRD, FT-IR, XPS, HRTEM, SEM, and other characterization techniques were used to assess the chemical composition, morphology, and structure. The Fenton-like catalytic activity of g-C3N4/ZnO composites was measured in the removal of organic pollutants. The results showed that the g-C3N4/ZnO Fenton-like catalyst can efficiently remove the organic pollutants than pure g-C3N4. The removal efficiency of organic pollutants by g-C3N4/ZnO composite was of 89%, which is 4 times higher than that of pure g-C3N4. This clearly shows a significant improvement in the Fenton-like catalytic activity of g-C3N4/ZnO. This improved result was explained by the production of hydroxyl radicals in the g-C3N4/ZnO-H2O2 catalytic system, in a similar way as in the mechanism involved in the Fenton-like degradation. The formation of coordinate covalent bonds between N and Zn in g-C3N4/ZnO catalyst played an important role in the removal of organic dye, and thus considered another key factor of the excellent activity.

Comparative study on COD removal from reverse osmosis concentrate using two physicochemical combined processes

Reverse osmosis concentrate (ROC) produced from landfill leachate contains a substantial fraction of refractory organics with low biodegradability that is challenging for conventional wastewater treatment methods. To achieve high-efficiency ROC degradation, two physicochemical combined processes, i.e. ceramic membrane/ozone-nanofiltration (CM/O3+NF) and Ca(OH)2 coagulation-ceramic membrane/ozone-nanofiltration (Ca(OH)2+CM/O3+NF) were proposed. In this study, the removal efficiency of organic pollutants in process 1 (CM/O3+NF) and process 2 (Ca(OH)2+CM/O3+NF) was investigated, respectively. The results showed that process 1 and process 2 were both sufficient to eliminate the refractory COD, the permeates have a COD lower than the requirements for discharge. But the process 2 had a better performance than that of process 1. The COD and TOC of ROC decreased from 2500 mg/L and 1050 mg/L to 20.23 mg/L and 8.26 mg/L after process 2 treatment, and the removal efficiency was 1.9% and 4.04% higher than those of process 1, respectively. In process 2, Ca(OH)2 flocculation significantly improves the oxidation effect of CM/O3, effectively shortens the oxidation time by 25%, improves the membrane flux of the ceramic membrane, and reduces the treatment cost of the ROC. Furthermore, the change of the composition of the macromolecular organics in the ROC during the treatment of process 1 and process 2 was compared and explored through analysis by UV254, 3D-EEM, GC-MS. The results indicated that the types of organic matter in the ROC treated by Process 2 decreased from 27 to 8, which was 5 less than that of Process 1. Ca(OH)2 flocculation in process 2 significantly reduces the content of macromolecular humic acid in ROC, especially has a good flocculation effect on lipids, aldehydes, carboxylic acids, ketones and other substances containing carbon-oxygen double bonds. At the same time, Ca(OH)2 provides an alkaline environment and strengthens the decomposition ability of alkanes, alkenes, and aromatics in ROC into more soluble by-products by CM/O3. The remaining pollutants that are difficult to be oxidized are effectively filtered by NF. Overall, the Ca(OH)2+CM/O3+NF process with complementary functions has great potential in realizing effective ROC treatment.

A review on future wastewater treatment technologies: micro-nanobubbles, hybrid electro-Fenton processes, photocatalytic fuel cells, and microbial fuel cells.

The future prospect in wastewater treatment technologies mostly emphasizes processing efficiency and the economic benefits. Undeniably, the use of advanced oxidation processes in physical and chemical treatments has played a vital role in helping the technologies to remove the organic pollutants efficiently and reduce the energy consumption or even harvesting the electrons movements in the oxidation process to produce electrical energy. In the present paper, we review several types of wastewater treatment technologies, namely micro-nanobubbles, hybrid electro-Fenton processes, photocatalytic fuel cells, and microbial fuel cells. The aims are to explore the interaction of hydroxyl radicals with pollutants using these wastewater technologies, including their removal efficiencies, optimal conditions, reactor setup, and energy generation. Despite these technologies recording high removal efficiency of organic pollutants, the selection of the technologies is dependent on the characteristics of the wastewater and the daily production volume. Hence the review paper also provides comparisons between technologies as the guidance in technology selection.

Improving Degradation Efficiency of Organic Pollutants through a Self-Powered Alternating Current Electrocoagulation System.

Although electrocoagulation technology has been widely researched in wastewater treatment, high energy consumption and electrode passivation are still the main challenges for its widespread applications. Here, we propose a self-powered electrocoagulation system based on a triboelectric nanogenerator (TENG) with alternating current (AC) outputs to solve these two issues, and thus enhance the removal efficiency of organic pollutants. Compared with the direct current source, the AC power source can reduce the electrode passivation, produce more aluminum hydroxide compounds after consuming an equal amount of charges, and thus improve the degradation efficiency. Moreover, the removal efficiency can be further enhanced by decreasing the frequency AC, in which a 5.7-fold improvement was achieved at 0.2 Hz compared to DC at 1.8 Hz. Inspired by the low frequency of ocean wave water, we developed a self-powered AC-electrocoagulation system to directly drive the electrocoagulation reaction by harvesting water wave energy, which can effectively remove 94.8% of xylenol orange and 98.8% of water-oil emulsion, and thus completely address the problem of energy consumption. This study further promotes the application of self-powered electrochemical systems in treating environmental pollution.

Aqueous phase reforming of distiller's grain derived biogas Plant wastewater over α-MoO3 nanosheets

A novel method which combines aqueous phase reforming (APR) and activated carbon adsorption (ACA) was proposed to treat the distiller's grain derived biogas plant wastewater (DGBW). APR was performed over α-MoO3 nanosheets with oxygen vacancies (α-MNOV), Pt/C and Ni/α-MNOV catalysts under temperature of 225 °C and residence time of 30 min. An optimal yield of 4.91 mLhydrogen/mLDGBW was obtained over α-MNOV, which also exhibited the highest organic pollutants removal efficiency. After APR over α-MNOV and following ACA, the removal efficiencies of non-purgeable organic carbon (NPOC), chemical oxygen demand (COD) and total nitrogen (TN) reached 79.45%, 87.82% and 44.78%, respectively. The significant performance of α-MNOV could be attributed to two aspects: shorter van der Waals (vdW) heterostructures presented α-MNOV which enhanced the hydrogen generation process, and the abundant oxygen vacancies (OVs) in α-MNOV which increased its stability and lattice oxygen generation capability, facilitating the decomposition of the organics during APR.

Water Purification of Classical and Emerging Organic Pollutants: An Extensive Review

The main techniques used for organic pollutant removal from water are adsorption, reductive and oxidative processes, phytoremediation, bioremediation, separation by membranes and liquid–liquid extraction. In this review, strengths and weaknesses of the different purification techniques are discussed, with particular attention to the newest results published in the scientific literature. This study highlighted that adsorption is the most frequently used method for water purification, since it can balance high organic pollutants removal efficiency, it has the possibility to treat a large quantity of water in semi-continuous way and has acceptable costs.

Preparation and properties of Al3+-doped BiVO4 semiconductor photocatalyst

The xAl3+/BiVO4 (x = 0, 1%, 2%, 5%, 10%) photocatalysts were successfully prepared by hydrothermal method, and the removal efficiency of organic pollutants was improved in different degrees under the conditions of visible light irradiation. The results showed that proper Al3+-doping could improve the morphology of BiVO4, narrow the band gap and expand the absorption range of visible light. Meanwhile, Al3+ acted as a capture center for photogenerated electrons, reducing the recombination rate of the photogenerated electron-hole pair. When the doping amount of Al3+ was 1%, the photocatalytic activity was maximized, and the removal rate of RhB within 90 min was as high as 96%, this was an improvement of about 43% compared to pure BiVO4. In the whole reaction system, O2−, h+ and OH were the main active species, contributing 72.4%, 18.4% and 5.9% to the degradation of RhB, respectively.

Treatment of Combined Dairy and Domestic Wastewater with Constructed Wetland System in Sicily (Italy). Pollutant Removal Efficiency and Effect of Vegetation

Dairy wastewater (DWW) contains large amounts of mineral and organic compounds, which can accumulate in soil and water causing serious environmental pollution. A constructed wetland (CW) is a sustainable technology for the treatment of DWW in small-medium sized farms. This paper reports a two-year study on the performance of a pilot-scale horizontal subsurface flow system for DWW treatment in Sicily (Italy). The CW system covered a total surface area of 100 m2 and treated approximately 6 m3 per day of wastewater produced by a small dairy farm, subsequent to biological treatment. Removal efficiency (RE) of the system was calculated. The biomass production of two emergent macrophytes was determined and the effect of plant growth on organic pollutant RE was recorded. All DWW parameters showed significant differences between inlet and outlet. For BOD5 and COD, RE values were 76.00% and 62.00%, respectively. RE for total nitrogen (50.70%) was lower than that of organic compounds. RE levels of microbiological parameters were found to be higher than 80.00%. Giant reed produced greater biomass than umbrella sedge. A seasonal variation in RE of organic pollutants was recorded due to plant growth rate Our findings highlight the efficient use of a CW system for DWW treatment in dairy-cattle farms.

Reshaped structure of microbial community within a subsurface flow constructed wetland response to the increased water temperature: Improving low-temperature performance by coupling of water-source heat pump

To evaluate the pollutant removal mechanisms and pathways in traditional constructed wetlands (CWs), and remove its operation bottleneck under low temperature, a co-system was established by coupling a subsurface flow constructed wetland (SFCW) and the water-source heat pump (WSHP) units. Experimental consequence demonstrated that the water temperature had increased significantly, and the mean temperature of influent was 8 ± 3 °C while that of effluent was 15 ± 5 °C. High average removal efficiencies of COD (64.5%), NH3-N (89.5%), NO3-N (90.2%), TN (58%), and TP (93.5%) were achieved in the experimental co-system. Optimal removal efficiency was achieved when pH was 6–7.5 and hydraulic retention time (HRT) was 4 days. Nitrification led to the higher organic pollutants removal efficiency. Meanwhile, it was considered to be due to the significant variation of the microbial community structure after the application of the WSHP units, in which the species richness and community equitability significantly improved. The thermophilic communities grew and reproduced in large numbers. The results also showed the application of co-system was an effective and sustainable strategy for removing diverse pollutants in cold climate.

A mechanistic study on removal efficiency of four antibiotics by animal and plant origin precursors-derived biochars

Extensive research has been performed on the utilization of biochar for pollutant removal via sorption. Additionally, the relationship between sorption strength of organic pollutants by organic matter and nanomaterials and their sorption site energy distribution has been studied. However, the linkage between removal efficiency of organic pollutants and the sorption site energy distribution on biochars is unknown. As a first attempt to address this knowledge gap, three biochars were derived from two plant-origin precursors (corn straw-CS; birch sawdust-BS) and one animal-origin precursor (meat and bone meal-MBM) at 500 °C (CS-500, BS-500, and MBM-500). In addition, two biochars were prepared with CS at 300 and 800 °C (CS-300 and CS-800) to examine the relationship between their site energy distribution and removal efficiency of antibiotics including sulfadiazine (SDZ), sulfamethoxazole (SMX), tetracycline (TC) and ciprofloxacin (CFX) by these materials. Our findings showed that the antibiotic-biochar interactions can be well interpreted with site energy distribution and XPS analysis results. Polar interactions between CS-300, CS-500, and CS-800 and SDZ and SMX occurring at the high-energy sites dominated their removal. However, TC and CFX removal by these biochars was driven by their polar interactions occurring at high-energy sites and π-π interactions at low-energy sites. The π-π stacking mechanism tended to dominate their removal with increasing charring temperature. Abundance of polar functionalities on CS-500, BS-500, and MBM-500 and TC removal efficiency of these materials consistently followed an order of MBM-500 > CS-500 > BS-500, highlighting importance of precursors for making biochars and polar interactions in its removal.