Treatment Of Micropollutants Research Articles

Removal of bisphenol a micropollutants released from plastic waste using Pt-ZnO photocatalyst.

Plastic pollution is becoming increasingly severe and is attracting global attention. One of its consequences is the recent discovery of micropollutant discharge into water, with Bisphenol A (BA-MP) being a typical example. This study utilizes an advanced oxidation process based on Pt-doped ZnO photocatalyst to remove BA-MP. Health concerns related to the release of BA-MP from plastic waste are discussed. Besides, the results of the photodegradation experiment show that the Pt-ZnO photocatalyst can remove 94.1% of BA-MP within 60min when exposed to solar light. Moreover, after five reuse cycles, Pt-ZnO retains a high BA-MP removal efficiency of 71.2%, and its structure remains largely unchanged compared to the original material. The removal efficiency of BA-MP leaching from plastic waste was measured at 98.8%, confirming the suitability of Pt-ZnO for the treatment of micropollutants. Furthermore, this study also highlights the prospects and challenges of using Pt-ZnO for the treatment of micropollutants discharged from plastic waste.

Analysis of the steady-state concentrations of reactive species and their role in contaminant degradation by the iron-biochar/persulfate advanced oxidation process: Comparison of probe compound and quenching agent methods

Reactive species, including hydroxyl radicals (OH), sulfate radicals (SO4−), singlet oxygen (1O2), superoxide radicals (O2−), and Fe(IV), are generated by the iron-biochar activated persulfate (Fe-BC/PS) process. These reactive species can be leveraged for treatment of micropollutants, such as the sulfamethoxazole antibiotic. In this study, the steady-state concentrations and contributions of OH, SO4−, 1O2, O2−, and Fe(IV) to sulfamethoxazole degradation were calculated for different operating conditions in the iron-biochar/persulfate (Fe-BC/PS advanced oxidation process. Electron paramagnetic resonance was employed to confirm the production of each reactive species. The nitrobenzene, benzoic acid, furfuryl alcohol, p-chlorobenzoic acid or p-benzoquinone, and phenyl methyl sulfoxide probe compounds were added to experimental solutions in isolation, as mixtures, and at different concentrations to calculate the steady-state concentrations of OH, SO4−, 1O2, O2−, and Fe(IV) and determine their contributions to sulfamethoxazole degradation at variable pH conditions. The results not only informed the primary mechanisms of sulfamethoxazole degradation by the Fe-BC/PS system, but also highlighted best practices for the use of probe compounds and quenching agents in persulfate-based advanced oxidation processes. In particular, the initial concentration of the probe compounds should be as low as possible to avoid impacts on target contaminant degradation and misinterpretation of the role of each reactive species. Furthermore, quenching-based approaches to determination of the key reactive species were less consistent than evaluation by probe compounds. The overall outcomes of this work inform sulfamethoxazole treatment by the Fe-BC/PS system and emphasize the need for internal validation of kinetics results using a multi-pronged approach.

Matching periodate peak absorbance by far UVC at 222 nm promotes the degradation of micropollutants and energy efficiency

Periodate (PI)-based advanced oxidation processes have gained increasing interest. This study for the first time elevates the light-activation capacity of PI by using far UVC at 222 nm (UV222/PI) without extra chemical inputs. The effectiveness and the underlying mechanisms of UV222/PI for the remediation of micropollutants were studied by selecting atenolol (ATL) as a representative. PI possessed a high molar absorption coefficient of 9480–6120 M−1 cm−1 at 222 nm in the pH range of 5.0–9.0, and it was rapidly decomposed by UV222 with first-order rate constants of 0.0055 to 0.002 s−1. ATL and the six other organic compounds were effectively degraded by the UV222/PI process under different conditions with the fluence-based rate constants generally two to hundred times higher than by UVA photolysis. Hydroxyl radical and ozone were confirmed as the major contributors to ATL degradation, while direct photolysis also played a role at higher pH or lower PI dosages. Degradation pathways of ATL were proposed including hydroxylation, demethylation, and oxidation. The high energy efficiency of the UV222/PI process was also confirmed. This study provides a cost-effective and convenient approach to enhance PI light-response activity for the treatment of micropollutants.

Comprehensive two-dimensional liquid chromatography with high resolution mass spectrometry to investigate the photoelectrochemical degradation of environmentally relevant pharmaceuticals and their degradation products in water

The widespread presence of organic micropollutants in the environment reflects the inability of traditional wastewater treatment plants to remove them. In this context, advanced oxidation processes (AOPs) have emerged as promising quaternary wastewater treatment technologies since they efficiently degrade recalcitrant components by generating highly reactive free radicals. Nonetheless, the chemical characterization of potentially harmful byproducts is essential to avoid the contamination of natural water bodies with hazardous substances. Given the complexity of wastewater matrices, the implementation of comprehensive analytical methodologies is required. In this work, the simultaneous photoelectrochemical degradation of seven environmentally relevant pharmaceuticals and one metabolite from the EU Watch List 2020/1161 was examined in ultrapure water and simulated wastewater, achieving excellent removal efficiencies (overall >95%) after 180 min treatment. The reactor unit was linked to an online LC sample manager, allowing for automated sampling every 15 min and near real-time process monitoring. Online comprehensive two-dimensional liquid chromatography (LC × LC) coupled with high resolution mass spectrometry (HRMS) was subsequently used to tentatively identify degradation products after photoelectrochemical degradation. Two reversed-phase liquid chromatography (RPLC) columns were used: an SB-C18 column operated with 5 mM ammonium formate at pH 5.8 (1A) and methanol (1B) as the mobile phases in the first dimension and an SB-Aq column using acidified water at pH 3.1 (2A) and acetonitrile (2B) as the mobile phases in the second dimension. This resulted in a five-fold increase in peak capacity compared to one-dimensional LC while maintaining the same total analysis time of 50 min. The LC x LC method allowed the tentative identification of 12 venlafaxine, 7 trimethoprim and 10 ciprofloxacin intermediates. Subsequent toxicity predictions suggested that some of these byproducts were potentially harmful.This study presents an effective hybrid technology for the simultaneous removal of pharmaceuticals from contaminated wastewater matrices and demonstrates how multidimensional liquid chromatography techniques can be applied to better understand the degradation mechanisms after the treatment of micropollutants with AOPs.

Ancient terminal water treatment methods still work: Removing micropollutants in drinking water by simultaneous boiling and VUV

Micropollutant in drinking water may not be effectively removed during centralized treatment. To reduce potential health risks, water treatment at the user terminal is warranted. This study investigated the performance of VUV coupled with boiling to simultaneously remove contaminants, a common household water treatment method in developing countries, for the treatment of micropollutants. Compared to individual boiling or VUV treatment, the VUV/BO process was more effective in improving the degradation of micropollutants. The results showed that heating promoted the direct photolysis and HO oxidation capabilities in the VUV process, with the HO generation increasing from 36.56 μM at 30 °C to 80.48 μM at 90 °C. At a reaction temperature of 100 °C, the degradation rates of malathion (MAL), dimethoate (DMT), trichloroacetic acid (TCAA), and dichloroacetic acid (DCAA) by VUV were increased by 0.81, 1.19, 1.34, and 0.90 times respectively compared to 25 °C. Analysis of the organic composition of actual water samples showed that the total fluorescence intensity of organic matter decreased significantly after VUV oxidation, mainly degrading humic-like substances. Using GC–MS analysis, this study identified 11 oxidative products of the DMT, and proposed two possible degradation pathways. Toxicity evaluation of the intermediate products of DMT demonstrated that they were less toxic than the parent contaminants. The results indicate that the heating-coupled water treatment process provides an effective technology for the treatment of micropollutants in terminal drinking water, and this process is worth promoting in the future.

Electrogeneration of H2O2 through carbon-based ink on Al foam for electro-Fenton treatment of micropollutants in water

In the present work, the catalytic efficiency of inks based on different carbon materials, namely activated carbon (AC), carbon graphite (CG), and carbon black (CB) was investigated for the oxygen reduction reaction (ORR). Additionally, we explored the feasibility of using this ink as a coating for an Aluminum foam (Alfoam) cathode in an electrochemical cell. The goal was to utilize this setup to produce hydrogen peroxide (H2O2) in the electro-Fenton (EF) process, targeting for treating water contaminated with contaminants of emerging concern (CECs).Among the materials investigated, all of them exhibited the ability to facilitate the ORR. However, AC proved to be the most suitable material due to its optimal balance between physical and electrocatalytic properties, thus enabling the formation of H2O2. When the different inks were applied to the surface of aluminum foam, it was observed that only the ink based on carbon black CB achieved a homogeneous distribution with the same ink quantity. As a result, it was observed that the Alfoam/CB electrode exhibited the highest H2O2 generation capacity, producing 45.6 mg L-1, followed by electro-generation of 5.1 mg L-1 using Alfoam/AC and 11 mg L-1 using Alfoam/CG. Furthermore, the application of Alfoam/CB in EF processes allowed for the almost complete degradation of 15 emerging contaminants of concern (CECs) present in secondary effluent. The innovative outcome of this study positions the developed technology as a promising and effective alternative for the treatment of water contaminated with CECs, demonstrating significant potential for industrial-scale application.

A realistic approach to radiation-induced treatment of micropollutants in wastewater

A realistic approach to radiation-induced treatment of micropollutants in wastewater

Advanced Oxidation Processes Coupled to Nanofiltration Membranes with Catalytic Fe0 Nanoparticles in Symmetric and Asymmetric Polyelectrolyte Multilayers.

The in situ synthesis of Fe0 particles using poly-(acrylic acid) (PAA) is an effective tool for fabricating catalytic membranes relevant to advanced oxidation processes (AOPs). Through their synthesis in polyelectrolyte multilayer-based nanofiltration membranes, it becomes possible to reject and degrade organic micropollutants simultaneously. In this work, we compare two approaches, where Fe0 nanoparticles are synthesized in or on symmetric multilayers and asymmetric multilayers. For the membrane with symmetric multilayers (4.0 bilayers of poly (diallyldimethylammonium chloride) (PDADMAC)/PAA), the in situ synthesized Fe0 increased its permeability from 1.77 L/m2/h/bar to 17.67 L/m2/h/bar when three Fe2+ binding/reducing cycles were conducted. Likely, the low chemical stability of this polyelectrolyte multilayer allows it to become damaged through the relatively harsh synthesis. However, when the in situ synthesis of Fe0 was performed on top of asymmetric multilayers, which consist of 7.0 bilayers of the very chemically stable combination of PDADMAC and poly(styrene sulfonate) (PSS), coated with PDADMAC/PAA multilayers, the negative effect of the Fe0 in situ synthesized can be mitigated, and the permeability only increased from 1.96 L/m2/h/bar to 2.38 L/m2/h/bar with three Fe2+ binding/reducing cycles. The obtained membranes with asymmetric polyelectrolyte multilayers exhibited an excellent naproxen treatment efficiency, with over 80% naproxen rejection on the permeate side and 25% naproxen removal on the feed solution side after 1 h. This work demonstrates the potential of especially asymmetric polyelectrolyte multilayers to be effectively combined with AOPs for the treatment of micropollutants (MPs).

Inhibition caused by adsorption of organic micropollutants (MPs) on PES@CoFe2O4 polymeric ultrafiltration membranes and the enhanced MPs degradation by a continuous pH regulation

In this work, catalytic membranes were fabricated by blending CoFe2O4 catalysts into polyethersulfone (PES) and then used to treat naproxen with the addition of peroxymonosulfate (PMS). It was found that the addition of PMS results in a decrease in pH, which increases the adsorption of naproxen. This often overlooked phenomenon is demonstrated here to have an important role since the adsorption of naproxen on the polymeric matrix and catalytic particles decreases the degradation efficiency of naproxen. To verify this hypothesis and rule out the decrease in pH after the addition of pH, two ways of controlling the pH of the naproxen solution were compared: adjusting pH before and after the addition of PMS, respectively. Our results indicate that in the batch experiment, adjusting the pH of naproxen solution after adding PMS led to a dramatic 23-fold increase in the kinetic constant of the naproxen oxidation (0.42/min, pH6) compared to when pH was adjusted before adding PMS (0.018/min, pH 6). This enhancement in the overall kinetics was attributed to the elimination of the inhibition caused by MPs adsorption at low pH. In a dead-end cell, the catalytic membranes with 2.0 % of CoFe2O4 achieved quantitative conversion of naproxen, bisphenol A, and atrazine, with values of 98 %, 97 %, and 74 %, respectively, demonstrating the efficacy of this approach to convert multitype of MPs in wastewater streams. In a reusability study, the naproxen removal of the catalytic membranes with 2.0 % of CoFe2O4 decreased by 81 % and 45 % after 5 rounds in the batch experiment and dead-end cell, respectively. However, with a chemical cleaning process between each round, the degradation efficiency can be effectively recovered, proving the negative effects of the adsorption of MPs or their intermediates during the SR-AOPs. Our work demonstrates that pH in SR-AOP-based catalytic membrane processes determined both the reaction rate and the adsorption of MPs or their intermediates on the membrane and its reactive sites. We envision that these results will be valuable in developing efficient catalytic membranes for the treatment of MPs in wastewater streams.

Floating immobilized TiO2 catalyst for the solar photocatalytic treatment of micro-pollutants within the secondary effluent of wastewater treatment plants

Floating immobilized spherical titanium dioxide catalysts were used to degrade micro-pollutants by solar photocatalysis. The degradation of the micro-pollutants was performed in the secondary effluent of a wastewater treatment plant. During the experimental period, the continuous measurement of the solar ultraviolet (UV) radiation intensity was performed. The micro-pollutants were degraded to an average of 55% after 9 h of irradiation. A substance-specific degradation affinity was found, whereby degradation rates varied by a factor of up to 3.5. The substance-specific adsorption behavior was identified as a major limitation of the reaction performance. With an increasing influence of adsorption limitation, the degradation kinetics changed from the pseudo-first order to pseudo-zero order. A correlation between degradation rate and solar irradiance could only be found for substances with high degradation/adsorption affinity. For diclofenac, a 95% degradation rate could be achieved at a radiation dose of approximately 190 mWh/m². The investigated technology represents a promising possibility for a minimally invasive extension of wastewater treatment plants. Possibilities of implication were estimated and discussed within this work, whereby possibilities arise for large-scale as well as decentral treatment plants.

Ozone- and Hydroxyl Radical-Induced Degradation of Micropollutants in a Novel UVA-LED-Activated Periodate Advanced Oxidation Process.

In this study, novel light emitting diode (LED)-activated periodate (PI) advanced oxidation process (AOP) at an irradiation wavelength in the ultraviolet A range (UVA, UVA-LED/PI AOP) was developed and investigated using naproxen (NPX) as a model micropollutant. The UVA-LED/PI AOP remarkably enhanced the degradation of NPX and seven other selected micropollutants with the observed pseudo-first-order rate constants ranging from 0.069 ± 0.001 to 4.50 ± 0.145 min-1 at pH 7.0, demonstrating a broad-spectrum micropollutant degradation ability. Lines of evidence from experimental analysis and kinetic modeling confirmed that hydroxyl radical (•OH) and ozone (O3) were the dominant species generated in UVA-LED/PI AOP, and they contributed evenly to NPX degradation. Increasing the pH and irradiation wavelength negatively affected NPX degradation, and this could be well explained by the decreased quantum yield (ΦPI) of PI. The degradation kinetics of NPX by the UVA-LED/PI AOP in the presence of water matrices (i.e., chloride, bicarbonate, and humic acid) and in real waters were examined, and the underlying mechanisms were illustrated. A total of nine transformation products were identified from NPX oxidation by the UVA-LED/PI AOP, mainly via hydroxylation, dealkylation, and oxidation pathways. The UVA-LED/PI AOP proposed might be a promising technology for the treatment of micropollutants in aqueous solutions. The pivotal role of ΦPI during light photolysis of PI may guide the future design of light-assisted PI AOPs.

Ultra-uniform MIL-88B(Fe)/Fe3S4 hybrids engineered by partial sulfidation to boost catalysis in electro-Fenton treatment of micropollutants: Experimental and mechanistic insights

Fe-based metal–organic frameworks are promising catalysts for water treatment, although their viability is hampered by the slow regeneration of active Fe(II) sites. A facile sulfidation strategy is proposed to boost the catalytic activity of MIL-88B(Fe) in heterogeneous electro-Fenton (HEF) treatment of organic micropollutants at mild pH. The synthesized MIL-88B(Fe)/Fe3S4 hybrids possessed numerous and durable unsaturated iron sites, acting the S2− atoms as electron donors that enhanced the Fe(II) recycling. The sulfidated catalyst outperformed the MIL-88B(Fe), as evidenced by the 7-fold faster degradation of antibiotic trimethoprim by HEF and the fast destruction of micropollutants in urban wastewater. The hybrid catalyst was reused, obtaining >90% drug removal after four runs and, additionally, its inherent magnetism facilitated the post-treatment recovery. Electrochemical tests and DFT calculations provided mechanistic insights to explain the enhanced catalysis, suggesting that the accelerated Fe(III)/Fe(II) cycling and the enhanced mass transport and electron transfer accounted for the efficient trimethoprim degradation.

Phase transformation-driven persulfate activation by coupled Fe/N–biochar for bisphenol a degradation: Pyrolysis temperature-dependent catalytic mechanisms and effect of water matrix components

Fe–N co-doped biochar is recently an emerging carbocatalyst for persulfate activation in situ chemical oxidation (ISCO). However, the involved catalytic mechanisms remain controversial and distinct effects of coexisting water components are still not very clear. Herein, we reported a novel N-doped biochar-coupled crystallized Fe phases composite (Fe@N-BC800) as efficient and low-cost peroxydisulfate (PDS) activators to degrade bisphenol A (BPA), and the underlying influencing mechanism of coexisting inorganic anions (IA) and humic constituent. Due to the formation of graphitized nanosheets with high defects (AI index>0.5, ID/IG = 1.02), Fe@N-BC800 exhibited 2.039, 5.536, 8.646, and 23.154-fold higher PDS catalytic activity than that of Fe@N-BC600, Fe@N-BC400, N-BC, BC. Unlike radical pathway driven by carbonyl group and pyrrolic N of low/mid-temperature Fe@N–BCs. The defective graphitized nanosheets and Fe-Nx acted separately as electron transfer and radical pathway active sites of Fe@N-BC800, where π-π sorption assisted with pyrrolic N and pore-filling facilitated BPA degradation. The strong inhibitory effects of PO43− and NO2− were ascribed to competitive adsorption of phosphate (61.11 mg g−1) and nitrate (23.99 mg g−1) on Fe@N-BC800 via electrostatic attraction and hydrogen bonding. In contrast, HA competed for the pyrrolic-N site and hindered electron delivery. Moreover, BPA oxidation pathways initiated by secondary free radicals were proposed. The study facilitates a thorough understanding of the intrinsic properties of designed biochar and contributes new insights into the fate of degradation byproducts formed from ISCO treatment of micropollutants.

Efficient degradation of bisphenol A over facilely optimized ternary Ag/ZnO/ZnAl‒LDH composite with enhanced photocatalytic performance under visible light irradiation

For the advanced treatment of micropollutants from wastewater, this study synthesized a ternary Ag/ZnO/ZnAl‒LDH composite photocatalyst with performance optimization based on the Taguchi approach. The optimal synthesis parameters were statistically determined as the Ag doping amount of 5 wt%, Zn2+ and Al3+ with a molar ratio of 3:1, Ag/ZnO and ZnAl‒LDH with composite ratio of 3:2, and PEG-200 dosage of 25 mL. The optimally synthesized Ag/ZnO/ZnAl‒LDH achieved the efficient degradation of bisphenol A (BPA) under visible light irradiation, and the reaction rate constant was about 4.8-, 2.2- and 12.0-fold higher than that of ZnO, Ag/ZnO and ZnAl‒LDH, respectively. As proved by various characterizations, the enhanced photocatalytic performance of Ag/ZnO/ZnAl‒LDH can be attributed to the improvements of optoelectronic properties, such as the widened visible light responsivity and facilitated charge transfer, thus resulting in a significant increase of hydroxyl radicals (·OH) formation. Fluorescence measurements and radical quenching experiments indicated that ·OH mainly contribute to the degradation of BPA, and the oxidation of H2O by holes was the dominant formation pathway. According to the above results, this study summarized and proposed the enhanced photocatalytic mechanism of Ag/ZnO/ZnAl‒LDH for ·OH production and BPA removal.

Treatment of micropollutants in wastewater: Balancing effectiveness, costs and implications

In this contribution, we analyse scenarios of advanced wastewater treatment for the removal of micropollutants. By this we refer to current mainstream, broad spectrum processes including ozonation and sorption onto activated carbon. We argue that advanced treatment requires properly implemented tertiary (nutrient removal) treatment in order to be effective. We review the critical aspects of the main advanced treatment options, their advantages and disadvantages. We propose a quantification of the costs of implementing advanced treatment, as well as upgrading plants from secondary to tertiary treatment when needed, and we illustrate what drives the costs of advanced treatment for a set of standard configurations. We propose a cost function to represent the total costs (investment, operation and maintenance) of advanced treatment. We quantify the implications of advanced treatment in terms of greenhouse gas emissions. Based on the indicators of total toxic discharge, toxicity at the discharge points and toxicity across the stream network discussed in Pistocchi et al. (2022), we compare costs and effectiveness of different scenarios of advanced treatment. In principle the total toxic load and toxicity at the points of discharge could be reduced by about 75 % if advanced treatment processes were implemented virtually at all wastewater treatment plants, but this would entail costs of about 4 billion euro/year for the European Union as a whole. We consider a “compromise” scenario where advanced treatment is required at plants of 100 thousand population equivalents (PE) or larger, or at plants between 10 and 100 thousand PE if the dilution ratio at the discharge point is 10 or less. Under this scenario, the length of the stream network exposed to high toxicity would not increase significantly compared to the previous scenario, and the other indicators would not deteriorate significantly, while the costs would remain at about 1.5 billion Euro/year. Arguably, costs could be further reduced, without a worsening of water quality, if we replace a local risk assessment to generic criteria of plant capacity and dilution in order to determine if a WWTP requires advanced treatment.

Acute ecotoxicological effects on daphnids and green algae caused by the ozonation of ibuprofen

Due to its ubiquitous presence in wastewaters, wastewater treatment plant effluents and even surface waters, the removal of the pharmaceutical ibuprofen from water is of special interest. Ozonation is widely applied for the treatment of micropollutants in wastewater treatment plants and is already known to also degrade ibuprofen. However, the formation of a wide range of transformation products during such oxidation steps might affect the aquatic environment. This study focuses on the acute ecotoxicological impact of the ibuprofen ozonation products on the two model organisms Daphnia magna and Desmodesmus subspicatus. For the identification of possibly ecotoxic products, a new workflow combining ecotoxicological testing, analytical methods and toxicity prediction was applied. Examination at different pH conditions with increasing ozone doses can point to respective products for further systematic examination.Seven ozonation products were confirmed in this study, two of them for the first time. Five previously postulated products were rejected. For pH 7 the inhibition of green algae growth was observed for mixtures oxidized with low ozone doses, while at pH 3 the mixtures with higher ozone doses caused toxic effects on the mobility of daphnids. Together with the analytical measurements in combination with ecotoxicity prediction, six products were identified which might have caused the toxic effect on green algae. However, no assignment to the observed toxic effects on daphnids was possible. The gained results indicate that mixture toxicity might play a role in oxidation processes and needs to be considered in ozonation studies concerning the ecotoxicological impact. Furthermore, the different observed toxicity for the two organisms underlines the importance of using multiple test systems for a comprehensive evaluation of the ecotoxicity during ozonation processes.

Laminated PAA nanofibers as a practical support for crude laccase: A new perspective for biocatalytic treatment of micropollutants in wastewaters

Increasing concentrations of endocrine disrupting pollutants from countless human activities represent an increasingly serious threat to the environment. However, crude microbial enzymes that are easily obtained from nature may serve as eco-friendly and cost-effective biocatalysts for polluted wastewater treatment. In this work, crude laccase, obtained from white-rot fungi Trametes versicolor , was covalently immobilized onto laminated poly(acrylic acid) nanofibers and its biocatalytic activity and stability tested on real wastewater effluent. The immobilized crude laccase retained almost 80% of its initial activity after 35 days of storage in wastewater, with no significant inhibition of enzymatic activity caused by the high concentrations of inorganic salts or cations. Most importantly, immobilized laccase proved highly effective in degrading a mixture of bisphenol A, 17 α -ethinylestradiol, triclosan and diclofenac in wastewater effluent over 14 days. Based on these results, crude laccase from T. versicolor could represent an important new perspective for wastewater treatment. • Crude laccase successfully immobilized onto laminated PAA support. • PAA-laccase displayed excellent activity, stability and reuse. • Exceptional stability against inorganic salts in wastewater confirmed. • Laminated PAA-laccase is suitable for real wastewater application.

Functionalization of MXene-based nanomaterials for the treatment of micropollutants in aquatic system: A review

The increased industrialization and urbanization generate a larger quantity of effluent that is discharged into the environment regularly. Based on the effluent composition produced from various industries, the number of hazardous substances such as heavy metals, hydrocarbons, volatile organic compounds, organic chemicals, microorganisms introduced into the aquatic systems vary. The conventional wastewater treatment systems do not meet the effluent standards before discharge and require a different treatment system before reuse. Adsorption is an eco-friendly technique that uses selective adsorbents to remove hazardous pollutants even at microscale levels. MXene, a 2-Dimensional nanomaterial with resplendent properties like conductivity, hydrophilicity, stability, and functionalized surface characteristics, is found as a potential candidate for pollutant removal systems. This review discusses the fabrication, characterization, and application of MXene based nanoparticles to remove many pollutants in water treatment systems. The improvement in surface properties and adsorption capacity of MXene based NPs, when modified using different modification agents, has also been discussed. Their feasibility in terms of economic and environmental aspects has been evaluated to understand their scope for practical application in large-scale industries. The challenges towards the synthesis and toxicity's importance have been discussed, with the appropriate recommendations.

Advanced wastewater treatment of micropollutants – state of the art

PurposeMicropollutants in the aquatic environment pose threats to both ecosystems and human health. Traditional wastewater treatment plants (WWTP) reduce some micropollutants, especially those who adhere to sludge or suspended matter. The hydrophilic micropollutants, on the other side, which may be non-biodegradable and resistant to UV-treatment etc. are typically transported untreated into the water recipients. This paper contains a literature study on the state of the art of advanced wastewater treatment technologies for reducing micropollutants such as pharmaceutical degradation products, personal care products, surfactants and industrial chemicals including heavy metals.Design/methodology/approachThis literature study is completed using the most extensive and expansive literature database in the World to date, Google Scholar (GS). Published papers in recognized scientific journals are sought out in GS, and for relevance for this literature study, papers published here from 2016 and onwards (the last 5 years) have been chosen to eliminate irrelevant studies.FindingsThe result of the study is that there are many promising technologies on the market or emerging; however, no one solution treats every micropollutant equally well. Since advanced technologies often require expensive investments for municipalities and companies, it is important to identify which micropollutants pose the highest risk towards human health and the environment, because choosing systems to eliminate them all is not economically wise, and even choosing a system combining the existing technologies can be more expensive than states, municipalities and private companies are capable of investing in.Research limitations/implicationsThe research is limited to published papers on GS, which may omit certain papers published in closed databases not sharing their work on GS.Practical implicationsThe practical implications are that practitioners cannot find go-to solutions based on the conclusions of the research and thus need to use the results to investigate their own needs further in order to make the wisest decision accordingly. However, the paper outlines the state of the art in advanced wastewater treatment and explains the benefits and downsides of the technologies mentioned; however, more research in the field is required before practitioners may find a proper solution to their specific issues.Social implicationsThe social implications are that the consequences of introducing a removal of micropollutants from the water environment can ultimately effect the citizens/consumers/end-users through added costs to the tariffs or taxes on advanced wastewater treatment, added costs on everyday goods, wares and products and added costs on services that uses goods, wares and products that ultimately produces micropollutants affecting the water environment.Originality/valueThis paper presents a much needed state of the art regarding the current advanced technologies to mitigate micropollutants in wastewater. The overview the paper provides supports politics on national as well as international levels, where larger unions such as the EU has stated that advanced wastewater treatment will be the next step in regulating pollutants for aquatic outlet.

Treatment of Micropollutants in Wastewater: Balancing Effectiveness, Costs and Implications

Treatment of Micropollutants in Wastewater: Balancing Effectiveness, Costs and Implications