Simultaneous Removal Of Multiple Pollutants Research Articles

Impact of Nitrate on the Removal of Pollutants from Water in Reducing Gas-Based Membrane Biofilm Reactors: A Review.

The membrane biofilm reactor (MBfR) is a novel wastewater treatment technology, garnering attention due to its high gas utilization rate and effective pollutant removal capability. This paper outlines the working mechanism, advantages, and disadvantages of MBfR, and the denitrification pathways, assessing the efficacy of MBfR in removing oxidized pollutants (sulfate (SO4-), perchlorate (ClO4-)), heavy metal ions (chromates (Cr(VI)), selenates (Se(VI))), and organic pollutants (tetracycline (TC), p-chloronitrobenzene (p-CNB)), and delves into the role of related microorganisms. Specifically, through the addition of nitrates (NO3-), this paper analyzes its impact on the removal efficiency of other pollutants and explores the changes in microbial communities. The results of the study show that NO3- inhibits the removal of other pollutants (oxidizing pollutants, heavy metal ions and organic pollutants), etc., in the simultaneous removal of multiple pollutants by MBfR.

Mechanisms of ammonia, calcium and heavy metal removal from nutrient-poor water by Acinetobacter calcoaceticus strain HM12

An Acinetobacter calcoaceticus strain HM12 capable of heterotrophic nitrification-aerobic denitrification (HN-AD) under nutrient-poor conditions was isolated, with an ammonia nitrogen (NH4+-N) removal efficiency of 98.53%. It can also remove heavy metals by microbial induced calcium precipitation (MICP) with a Ca2+ removal efficiency of 75.91%. Optimal conditions for HN-AD and mineralization of the strain were determined by kinetic analysis (pH = 7, C/N = 2.0, Ca2+ = 70.0 mg L−1, NH4+-N = 5.0 mg L−1). Growth curves and nitrogen balance elucidated nitrogen degradation pathways capable of converting NH4+-N to gaseous nitrogen. The analysis of the bioprecipitation showed that Zn2+ and Cd2+ were removed by the MICP process through co-precipitation and adsorption (maximum removal efficiencies of 93.39% and 80.70%, respectively), mainly ZnCO3, CdCO3, ZnHPO4, Zn3(PO4)2 and Cd3(PO4)2. Strain HM12 produces humic and fulvic acids to counteract the toxicity of pollutants, as well as aromatic proteins to increase extracellular polymers (EPS) and promote the biomineralization process. This study provides a experimental evidence for the simultaneous removal of multiple pollutants from nutrient-poor waters.

Dual crosslinking of low-methoxyl pectin by calcium and europium for the simultaneous removal of pharmaceuticals and divalent heavy metals

The contamination of water resources by heavy metals and pharmaceuticals is a significant threat to human health and the environment. Pectin is a promising material for removing heavy metals from water. However, its removal efficacy for other types of pollutants is limited. In this study, we developed a novel approach to enhance the remediation capacity of pectin (with a low degree of methylation) by crosslinking it with different agents: calcium, europium, and their combination. We performed scanning electron microscopy, infrared spectroscopy, and X-ray diffraction experiments to understand the molecular structure of pectin after gelation with the three agents. Our results showed that calcium, europium, and their combination all induce the gelation of pectin. However, the reticulated pectin structures exhibited significant structural differences depending on the type of crosslinking agent used, which affected the adsorption capacity. Specifically, calcium cations partially formed a crystalline “egg-box” structure, whereas europium cations produced a more homogeneous network without crystalline regions. The dual-crosslinking system comprising calcium and europium cations resulted in an intermediate network with both crystalline and amorphous regions. Our findings suggest that dual-cross-linked pectin is a highly effective adsorbent for the simultaneous removal of both heavy metals and pharmaceutical products. This novel approach of crosslinking pectin with multiple agents has the potential to significantly enhance its remediation capacity, offering a promising solution for the simultaneous removal of multiple pollutants from water.

Preparation of magnetic graphene/β-cyclodextrin polymer composites and their application for removal of organic pollutants from wastewater

Porous β-CD polymer (CDP) is a good adsorbent with broad spectrum for removal of micropollutants, preparation of composites of CDP with magnetic materials is highly expected. In this work, a composite of magnetic graphene and CDP (magGO-CDP) was prepared, it was fully characterized and was used as an adsorbent to remove model pollutants, including methylene blue (MB), rhodamine B (RhB), fleroxacin (Fler), enrofloxacin (Enr), bisphenol A (BPA), bisphenol S (BPS), nabumetone (NaB) and indomethacin (Ind) in wastewater. Factors influencing the removal efficiency were studied. The removal rates of the eight pollutants can reach 101± 0.7 %, 94.7±1.8 %, 83.3±1.1 %, 91.9±0.2 %, 58.9±0.9 %, 77.4±3.5 %, 96.2±0.3 % and 94.7±0.8 %, respectively. Their maximum adsorption capacities are 133, 178, 185, 34.8, 362, 247, 186 and 187 mg/g, respectively. Findings from kinetic studies suggest that the pseudo-second-order model can successfully describe the overall adsorption process. The adsorbent has good capability to resist fouling of natural organic matter, and it has good reusability and can be recycled for at least five times. It has a higher adsorption capacity than that of previously reported materials and could achieve good removal efficiency with smaller adsorbent dosage and shorter time. It was also used for simultaneous removal of multiple pollutants and removal of pollutants in simulated wastewater with satisfactory results. The magGO-CDP can serve as a promising candidate for wastewater remediation. The strategy for preparing the composite of CDP and magGO can be straightly extended to other matrixes to produce high performance adsorbents.

Novel ricinoleic acid highly functionalized hierarchical SiO2 with switchable superwettability for removal of oils, heavy metal ions, and organic dyes from water

It remains a challenge to explore a low-cost and green approach to prepare stimuli-responsive materials that can meet increasingly complicated separation demands. Herein, we report a facile method to prepare pH-responsive silica particles modified by abundant carboxyl groups (SiO2-COOH), which are introduced from bio-based ricinoleic acid via an efficient and mild thiol-ene click reaction. The hierarchical structure of SiO2-COOH can easily construct roughness that is essential for special wettability, which is demonstrated by the robust superhydrophobicity achieved synergistically with non-pH-responsive binder on different substrates and no significant change after 100 peels or extrusions. We also present the efficient separation of different oil–water mixtures by modified fabrics and sponges, respectively, based on their fast wettability transition within seconds at different pH. More importantly, benefiting from the chelation of carboxyl and hydroxyl groups from ricinoleic acid molecules and large specific surface area provided by the hierarchical structure, SiO2-COOH and its different alkali treatment products exhibit outstanding adsorption capacity to heavy metal ions and organic dyes, of which up to 180 mg/g for Pb2+. It is believed that the proposed novel and eco-friendly method is a promising candidate for the simultaneous removal of multiple pollutants from oily wastewater.

Experimental study on three additives used for the removal of nitrite, a byproduct of ozone oxidation denitration technology

Nitrogen oxides resulting from fossil fuel combustion are one of the major atmospheric pollutants. Ozone oxidation flue gas denitration technology has garnered significant attention for its benefits such as high efficiency, low temperature and simultaneous removal of multiple pollutants. However, the large amount of nitrite in the absorption products makes it prone to secondary pollution. A cost-effective and harmless treatment of the by-product nitrite will promote the ozone oxidation denitration technology. This study focused on investigating three different additives (ammonium chloride, ammonium carbonate, and urea) that can be added to react with nitrite and remove it in a harmless way. The effects of reaction temperature, initial nitrite ion concentration, reaction molar ratio, and initial pH on nitrite removal efficiency were explored. Combined with a wet spraying system, the synergistic removal of NOx/SO2 and by-product nitrite has also been studied. The experimental results revealed that with appropriate operating conditions and additives, the by-product nitrite can be efficiently removed while the system can achieve efficient removal of NOx/SO2. Among the three additives, ammonium carbonate was found to have the best overall removal effect. However, urea had an advantage over the other two additives in highly acidic and low-temperature slurry.

In situ doping lignin-derived carbon quantum dots on magnetic hydrotalcite for enhanced degradation of Congo Red over a wide pH range and simultaneous removal of heavy metal ions

A new N, S-CQDs@Fe3O4@HTC composite was prepared by loading N, S carbon quantum dots (N, S-CQDs) derived from lignin on magnetic hydrotalcite (HTC) via an in-situ growth method. The characterization results showed that the catalyst had a mesoporous structure. These pores facilitate the diffusion and mass transfer of pollutant molecules inside the catalyst, allowing them to approach the active site smoothly. The catalyst performed well in the UV degradation of Congo red (CR) over a wide pH range (3−11), with efficiencies over 95.43 % in all cases. Even at a high NaCl content (100 g/L), the catalyst showed extraordinary CR degradation (99.30 %). ESR analysis and free radical quenching experiments demonstrated that OH and O2− were the main active species governing CR degradation. Besides, the composite had outstanding removal efficiency for Cu2+ (99.90 %) and Cd2+ (85.08 %) simultaneously due to the electrostatic attraction between the HTC and metal ions. Moreover, the N, S-CQDs@Fe3O4@HTC had excellent stability and recyclability during five cycles, making it free of secondary contamination. This work provides a new environment-friendly catalyst for the simultaneous removal of multiple pollutants and a waste-to-waste strategy for the value-added utilization of lignin.

Mechanisms of N, N-dimethylacetamide-facilitated n-hexane removal in a rotating drum biofilter packed with bamboo charcoal-polyurethane composite

n-Hexane and N, N-dimethylacetamide (DMAC) are two major volatile organic compounds (VOCs) discharged from the pharmaceutical industry. To enhance DMAC-facilitated n-hexane removal, we investigated the simultaneous removal of multiple pollutants in a rotating drum biofilter packed with bamboo charcoal-polyurethane composite. After adding 800 mg·L−1 DMAC, the n-hexane removal efficiency increased from 59.4 % to 83.1 % under the optimized conditions. The maximum elimination capacity of 10.0 g·m−3·h−1n-hexane and 157 g·m−3·h−1 DMAC were obtained. The biomass of bamboo charcoal-polyurethane and the ratio of protein-to-polysaccharide in extracellular polymeric substances were significantly increased compared with the non-DMAC stage, which is attributed to increased carbon utilization. In addition, Na+ K+-ATPase was positively correlated with increasing electron transport system activity, which was 1.98 and 1.36 times greater. Hydrophilic DMAC improved the bioavailability of hydrophobic n-hexane and benefited bacterial metabolism. Co-degradation of n-hexane and DMAC system can be used for other volatile organic pollutants.

Synergizing Fenton oxidation and in-situ coagulation over a wide pH range for the simultaneous removal of multiple pollutants

Efficient removal of multiple pollutants from discharged antibiotic wastewater effluents by a single processing unit is highly desirable, yet challenging. In this study, intrinsically synergizing Fenton oxidation and in-situ coagulation were achieved in the tannic acid (TA)/Fe(III)/H2O2 process, demonstrating the simultaneous removal of multiple pollutants over a wide pH range. Under the optimal conditions (TA/Fe(III)/H2O2 = 25 mg/L/0.1 mM/0.5 mM), 95.43 % of SMR and 98.41 % of turbidity were simultaneously removed at pH = 7. Moreover, the applicability of this process was validated by treating a spiked actual secondary effluent. Compared with polymer ferric sulphate coagulation and conventional Fe(II)/H2O2 Fenton, TA/Fe(III)/H2O2 process exhibited significantly enhanced removal performance in terms of SMR, COD, UV254 and turbidity without any pH adjustment. The mechanism analysis revealed that the introduction of TA can not only promote the iron redox cycle for the production of ∙OH, but also neutralize the charge for the generation of the porous flocs. Due to the bridging of TA, the synergy of Fenton oxidation and in-situ coagulation was achieved in a single processing unit. Finally, the synergy mechanism proposed that a four-step process sequentially proceeded during the treatment. This study may provide new insights into the simultaneous removal of multiple pollutants in the advanced treatment of refractory industrial wastewater.

Solar-powered electrocoagulation treatment of wet flue gas desulfurization wastewater using dimensionally stable anode and induced electrode

Solar-powered electrocoagulation (EC) process is proven to be an alternative option for wet flue gas desulfurization (WFGD) wastewater treatment, due to simultaneous removal of multiple pollutants efficiently and reduce the operation costs significantly. Rapid and stable photoelectricity response is necessary for the removal efficiency of pollutants (eg. COD and turbudity), especially in low solar irradiation intensity. In this paper, dimensionally stable anode (DSA) and operation voltages in EC process driven by solar cells were investigated, for the purpose of the optimized removal of pollutants, including COD, turbidity, (free residual chlorine and chlorine dioxide). The results show that the removal efficiency of COD and turbidity can respectively reach 59.12% and 39.11% within 30 min of illumination time (the enhanced solar radiation = 915.8 W m-2), when Ti-based plates were adopted. The concentration of free residual chlorine and chlorine dioxide can reach 2.70 and 5.31 mg L-1, indicating that chlorine ions present in WFGD wastewater have been converted into active chlorine partly. Solar-powered EC equipped with Ti-based plates have a potential prospect in EC process for WFGD wastewater treatment.

Simultaneous electrochemical degradation of tetracycline and metronidazole through a high-efficiency and low-energy-consumption advanced oxidation process

With the increasing complexity of water environment pollution, it is becoming ever more practical to study the simultaneous removal of multiple pollutants in water. Electrochemical advanced oxidation technology is considered to be one of the most promising green approaches for the degradation of organic pollutants. Herein, Ti3+ and oxygen vacancies (VO) self-doped TiO2-x nanotube array electrodes are employed to investigate the simultaneous degradation and an energy consumption assessment for the effective removal of the antibiotics tetracycline (TC) and metronidazole (MNZ). The electrocatalytic performance of the nanotube arrays prepared at different reduction times is significantly different. The electrochemical reduction of TiO2 nanotube arrays for 10 min presents the best degradation performance for TC and MNZ. When a mixed solution of TC and MNZ is simultaneously degraded, the removal rate of TC (50 mg L−1) and MNZ (50 mg L−1) within 3 h reaches 100%, while the chemical oxygen demand (COD) removal rate is 79.1%. The energy consumption is significantly reduced compared to the degradation of a single substance. Simultaneously, the current utilization rate of the electrochemical degradation system is also significantly improved, with a specific energy consumption of only 85.78 kWh kg−1 and an average current efficiency that can reach 20.2%.

Kinetics and mechanism of synergistic adsorption and persulfate activation by N-doped porous carbon for antibiotics removals in single and binary solutions

Porous carbon serves as a green material for efficient wastewater purification by adsorption and advanced oxidation processes. However, a clear understanding of the simultaneous removal of multiple pollutants in water is still ambiguous. Herein, the synergistic effect of adsorption and peroxydisulfate (PS) activation on kinetics and mechanism of removing single and binary antibiotic pollutants, sulfamethoxazole (SMX) and ibuprofen (IBP), from water by biomass-derived N-doped porous carbon was investigated. Our findings suggest that adsorption contributed to efficient removals of SMX/IBP. Comparative quenching experiments and electrochemical analysis demonstrated that hydroxyl (•OH) and sulfate (SO4•−) radicals, as well as singlet oxygen (1O2) led to the catalytic degradation of SMX, while only 1O2 reacted for IBP oxidation. Superoxide ion (O2•−) radicals were not related to SMX/IBP degradation. Electron transfer pathway accounted for PS activation but was not involved in direct SMX/IBP oxidation. Only slight differences were found between the degradation kinetics of SMX and IBP in the binary and single SMX or IBP solutions. This arose from the non-selective effect of adsorption and 1O2 attack for SMX/IBP removal, and the weak selective oxidation process of SMX by •OH and SO4•−. This study provides a new viewpoint on the role of adsorption in catalysis and enriches the mechanistic study of multi-component antibiotic degradation.

Experimental research on heat transfer characteristics and temperature rise law of in situ thermal remediation of soil

With the advancement of industrialization, soil pollution has become a global environmental problem. In situ soil thermal remediation technology has attracted attention due to its wide application range, simultaneous removal of multiple pollutants and short time-consuming characteristics. In this study, using the principle of scale-down test, the law of temperature rise of the in situ thermal remediation of soil was experimentally studied; the heating construction period of the in situ soil remediation technology engineering application was predicted. The change law of temperature curve in different periods of soil heating is obtained. The results show that the soil temperature changes in three stages. Concentrated heating section: the temperature rises from the ambient temperature to the boiling point of water. Evaporation section: the water evaporates and the temperature maintains the boiling point temperature. Superheat section: the soil temperature continues to rise; the effect of heating power, water content and groundwater flow on heat transfer is studied. The results show that increasing the heating power, reducing the water content and preventing the seepage of surrounding water are all beneficial to the soil heating process. The research results provide favorable theoretical support for the laws of soil temperature rise, and the effect of heat transfer characteristics, simultaneously, provides a certain reference for actual soil remediation prediction, which is of great significance to the development of on-site soil thermal remediation technology.

A universal route to fabricate bacterial cellulose-based composite membranes for simultaneous removal of multiple pollutants.

A self-standing, robust bacterial cellulose (BC)-based multifunctional composite membrane embedded with desirable nano-adsorbents has been successfully fabricated via a facile versatile strategy. As expected, the developed BC-based composite membrane enables the simultaneous and efficient removal of multiple co-existing pollutants.

Simultaneous Desulfurization and Denitrification Using La-Ce-V-Cu-ZSM-5 Catalysts in an Electrostatic Precipitator.

Different catalysts were loaded onto the collecting plate of an electrostatic precipitator to achieve the simultaneous removal of multiple pollutants from coal-fired gas. The synergistic desulfurization and denitrification effect of the catalyst and the effect of corona discharge on the activity of the catalyst were studied. The La(6%)–Ce(8%)–V(7%)–Cu(8%)–ZSM-5 catalyst prepared by successive impregnation methods had the optimum simultaneous desulfurization and denitrification efficiency at a roasting temperature of 600 °C. The desulfurization and denitrification rates reached 97.09 and 83.30%, respectively. BET and SEM characterization results showed that the loading of active components and additives improved the pore structure of the molecular sieve, which contributed to the high stability of the catalyst’s internal structure and large surface area, as well as better desulfurization and denitrification efficiency. Corona discharge can significantly improve the catalytic effect.

Low pressure operated ultrafiltration membrane with integration of hollow mesoporous carbon nanospheres for effective removal of micropollutants

An effective way to remove micropollutants is desirable for water purification. In this work, a dual-functional ultrafiltration (DFUF) membrane was fabricated by loading hollow mesoporous carbon nanospheres (HMCNs) into the finger-like support layer pores of the polymeric ultrafiltration (UF) membrane. The designed DFUF membrane combines the high selectivity of ultrafiltration that removes macromolecules based on size exclusion mechanism, and excellent adsorption capacity of HMCNs towards micropollutants in water. When tetracycline (TCN) and 17β-Estradiol (E2) were selected as model micropollutants, corresponding 97 % and 94 % removal were achieved at a low pressure less than 0.15 bar and a flux of 50 and 64 L h−1 m-2 (estimated residence time less than 6 s), respectively. Moreover, simultaneous removal of multiple pollutants was demonstrated by filtering a mixture containing TCN and polyethylene glycols (PEG) 600 kDa macromolecules. Over a long filtration period (more than 60 h) that produced 3180 L/m2 of permeate, the TCN concentration reduced from 100 μg/L in the feed to less than 10 μg/L in the permeate. The above results indicate that the DFUF membrane is capable of removing the small molecular and macromolecular pollutants simultaneously at low pressure, and hence offers remarkable potential in water treatment applications.

Research on Desulfurization and Denitration Technologies of Ship Exhaust

Ship exhaust is one of the main sources of air pollution, at present; there are three methods for treating ship exhaust, including desulfurization, denitration, and desulfurization-denitration integration. This paper introduces the mainstream desulfurization and denitration technologies, and the desulfurization-denitration integration technology can achieve the simultaneous removal of multiple pollutants, which will become the main method of ship exhaust treatment in the future and has broad development prospects. This paper introduces some treatment methods and advantages and disadvantages of ship exhaust, and hopes to provide some references for the treatment of ship exhaust.

Hg0 oxidation and SO3, Pb0, PbO, PbCl2 and As2O3 adsorption by graphene-based bimetallic catalyst ((Fe,Co)@N-GN): A DFT study

As important parts of simultaneous removal of multiple pollutants in flue gas, catalytic oxidation of Hg0 and adsorption removal of SO3, Pb species and As2O3 on the surface of (Fe,Co)@N-GN catalyst were systematically investigated in this work, using density functional theory. As a result, we found (Fe,Co)@N-GN not only showed great performance on Hg0 oxidation, but also exhibited outstanding removal capacity for SO3, Pb species and As2O3 molecules. Besides, PDOS and EDD analysis were carried out and the result indicated that electron transfer and orbit hybridization played key roles in gas adsorption. In addition, thermodynamics analysis further evidenced (Fe,Co)@N-GN was a qualified sorbent under 550 K, and competitive analysis suggested that the adsorption order of pollution gas was determined by adsorption energy, rather than the volume fraction of corresponding gases in flue gas. We hoped this work can not only lay a foundation for theoretical investigation of Hg0 oxidation, but also provide an important guideline for simultaneous removal of multiple pollutants released from coal-fired power plants.

Bacterial cellulose derived paper-like purifier with multifunctionality for water decontamination

Contaminated water contains various types of pollutants, the removal of which requires two or more technologies. It is imperative but challenging to develop water purifier for simultaneous removal of multiple pollutants for the sake of easy operation, low cost, and etc. Previously reported multifunctional purifiers are normally nanoparticles which require caution during use. Here, we describe a design of paper-like multifunctional purifier, which has biomass-based structure by grafting polyethylenimine derived quaternary ammonium compounds onto three-dimensional bacterial cellulose substrate. Compared to similar materials reported previously, our product exhibited strikingly higher adsorption capacities towards various metal ions including Pb2+, Cu2+, and Cr6+, anionic organic dyes including congo red, methyl orange and methyl red, and excellent disinfection efficiency towards both Gram-negative and Gram-positive bacteria. Remarkably, this purifier also demonstrated effective removal of the three contaminative species simultaneously from both simulated and local polluted water. With more virtues of superior reusability and extreme handy convenience, we hope our molecular design could inspire further efforts on the rational construction of multifunctional water purifier with easy operation. We reckon our material to have strong potential for the possible use in water treatment, especially in regions that are short of environmental infrastructures.

Simultaneous Adsorption of Heavy Metals from Roadway Stormwater Runoff Using Different Filter Media in Column Studies

Stormwater runoff from roadways often contains a variety of contaminants such as heavy metals, which can adversely impact receiving waters. The filter media in stormwater filtration/infiltration systems play a significant role in the simultaneous removal of multiple pollutants. In this study, the capacity of five filter media—natural quartz sand (QS), sandy soil (SS) and three mineral-based technical filter media (TF-I, TF-II and TF-III)—to adsorb heavy metals (Cu, Pb and Zn) frequently detected in stormwater, as well as remobilization due to de-icing salt (NaCl), were evaluated in column experiments. The column breakthrough data were used to predict lifespan of the filter media. Column experiment operated under high hydraulic load showed that all technical filters and sandy soil achieved >97%, 94% and >80% of Pb, Cu and Zn load removals, respectively, while natural quartz sand (QS) showed very poor performance. Furthermore, treatment of synthetic stormwater by the soil and technical filter media met the requirements of the Austrian regulation regarding maximum effluent concentrations and minimum removal efficiencies for groundwater protection. The results showed that application of NaCl had only a minor impact on the remobilization of heavy metals from the soil and technical filter media, while the largest release of metals was observed from the QS column. Breakthrough analysis indicated that load removal efficiencies at column exhaustion (SS, TF-I, TF-II and TF-III) were >95% for Cu and Pb and 80–97% for Zn. Based on the adsorption capacities, filtration systems could be sized to 0.4 to 1% (TF-I, TF-II and TF-III) and 3.5% (SS) of their impervious catchment area and predicated lifespan of each filter media was at least 35, 36, 41 and 29 years for SS, TF-I, TF-II and TF-III, respectively. The findings of this study demonstrate that soil—based and technical filter media are effective in removing heavy metals and can be utilized in full-stormwater filtration systems.