Powdered Activated Carbon Research Articles

Empowering powdered activated carbon (PAC) with 3D printing: Achieving highly efficient and reusable cationic dye removal

Powdered activated carbon (PAC) has been extensively used as an effective adsorbent. Despite its excellent adsorption ability, PAC has drawbacks, including difficulty in filtration and reactivation after use, limitations of mass transfer in deeper areas because of its aggregated powder form, and limited applicability in high-flow systems. To overcome these limitations, we used a three-dimensional (3D) printing system to fabricate PAC into a 3D structure. Spectral and microscopic analyses indicated that PAC was embedded into 3D monolith and exhibited high porosity suitable for facile mass transfer. The designed 3D PAC filter effectively removed 200 ppm-methylene blue (MB) within 8 h and showed an adsorption efficiency of 93.4 ± 0.9%. The adsorption of MB onto the 3D PAC filter was described by the pseudo-first-order kinetic and Freundlich isotherm models. The negatively charged 3D PAC filter might attract the positively charged MB, thus favoring the physical adsorption of MB onto the 3D PAC filter. The adsorption performance of the 3D PAC filter was tested at various pH levels of 4–10 and against MB spiked in seawaters and freshwaters to evaluate its feasibility for use in real environments. Finally, the reproducibility and reusability of the 3D PAC filter were demonstrated through repeated adsorption and desorption processes against MB.

Scattered and transmitted light as surrogates for activated carbon residual in advanced wastewater treatment processes: Investigating the influence of particle size

The use of powdered activated carbon (PAC) is a common process in advanced wastewater treatment to remove micropollutants. Retention and separation of PAC is essential as PAC loaded with micropollutants should not be released into the environment. Determining the activated carbon (AC) residual in the effluent poses a challenge, as there is currently no on-line measurement method. In this study, the correlation between turbidity, measured by scattered light, and absorption at wavelength of 550 nm (Absorption550 nm), measured by transmitted light, was investigated in relation to the AC residue. Linear correlations for turbidity (R2 = 0.95) and Absorption550 nm (R2 = 1.00) to AC concentrations were observed in both laboratory and full-scale experiments in a pilot plant where superfine PAC was added prior to Pile Cloth Media Filtration (PCMF). Decreasing the particle size (d50) while maintaining the same AC concentration leads to increased turbidity: Therefore, a fourfold reduction in d50 results in a 2- to 3-fold increase in turbidity, whereas a 30-fold reduction in d50 leads to a 6-to 8-fold increase. Furthermore, the original wastewater turbidity led to a parallel shift in the linear correlation between turbidity and AC. Coagulant doses of up to 400 mg Me3+/g AC resulted in a 50% reduction in turbidity. However, higher concentrations from 400 to 1,000 mg Me3+/g AC resulted in increased turbidity with only a 30% reduction compared to the initial turbidity. The study also highlights the significance of AC particle size in optical measurements, impacting result accuracy.

Sol-gel synthesis of composite adsorbent coating from Prosopis juliflora–activated carbon for simultaneous adsorptive removal of Cd2+ and Cr2O72- from wastewater

ABSTRACT To overcome the challenges associated with powdered activated carbon (PAC) in water and wastewater treatment, the efficacy of composite adsorbent coating (CAC) synthesized using a simple sol-gel method with Prosopis juliflora-activated carbon for the simultaneous reduction of Cd2+ and Cr2O72− was investigated. The CAC was characterized by FTIR (C-H, C = O, and O-H stretching), pHPZC (6 -6.6), SEM (porous-rough surface), and BET surface area (10.6 m2/g) techniques. Statistical analysis confirmed that pH and contact time significantly (p < 0.0001) affected both metal ions removal, with Cd2+ removal generally exceeding that of Cr2O72− due to better ionic properties. Using the optimized conditions (8.5 pH, 0.25 dosage, 5 mg concentration, 105 minutes contact time and 23.73 °C temperature), the predicted and experimental ion removal efficiencies were 86.86 and 83.98% for Cd2+ and 94.26 and 58.08% for Cr2O72−, respectively. The Langmuir adsorption isotherm was the best-suited model (R2 > 0.99), while the metal ions removal was regulated by the PSO kinetic model (R2 > 0.999). The adsorption process was endothermic and spontaneous, as indicated by thermodynamic values (−ΔG°, +ΔH°, +ΔS°). The study demonstrates CAC's effectiveness as an alternative to PAC, offering significant advantages in removing metal ions from wastewater.

Potential Nanoparticles to Integrate with Ceramic Membranes for Treating Industrial Wastewater: A Review

Due to human indifference and reckless oily wastewater production from industry, environmental or ecological pollution has become a challenge for our planet. Oily industrial wastewater mostly released by oil fields, refineries, cars, palm oil sectors, and many others is one of the biggest dangers. Oil and water can be virtually completely separated using membrane-based technologies. However, these technologies still face challenges in upholding efficiency over extended periods due to membrane fouling induced by oil droplets mixing with the membranes. Therefore, to overcome these challenges, the creation of polymeric, ceramic, and metallic-based membrane materials with enhanced performance is the focus of research in this field. In this review, various published approaches applied for treating industrial wastewater by using Ceramic Membranes integrated with nanoparticles were focused initially. Then, a modified experimental procedure from the literature for wastewater treatment process by using ceramic membranes is discussed. The majority of studies indicate nearly total oil rejection and increased outputs. Silicon carbide (SiC), Titanium dioxide (TiO2), Aluminum Oxide (Al2O3), Iron Oxide (Fe2O3) Powdered Activated Carbon (PAC), Zirconium dioxide (ZrO2), Alumina powder (Al), Silica (SiO2), Graphene Oxide (GO), and Silver (Ag) are identified potential nanoparticles to mix with ceramic membranes for wastewater treatment application.

Comparison on molecular transformation of dissolved organic matter during Fenton and activated carbon adsorption processes for chemical cleaning wastewater treatment

This study employed Fenton oxidation and powdered activated carbon (PAC) adsorption processes for the removal of recalcitrant dissolved organic matter (DOM) in chemical cleaning wastewater (CCW) to meet discharge standards. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to identify resistant compounds and investigate the transformation characteristics of DOM. CCW mainly contained surfactant exhibiting heteroatom-rich characteristics, and both processes exhibited effective DOM removal but distinct selectivity towards different subclasses of formulas. PAC adsorption significantly decreased the number of DOM compounds and more effective in aromatic compounds than Fenton oxidation. The aliphatic compounds (AImod ≤ 0.5, 1.5 ≤ H/C ≤ 2.0) predominantly with saturated and reduced states were resistant to PAC adsorption, and particularly a specific CHONSP formula was the predominant contributor to residual DOM in the effluent. In contrast, Fenton oxidation degraded most substances in the CCW except for a few saturated and reduced compounds primarily consisting of CHO, resulting in an increase in DOM number. Two unsaturated subclasses, carboxylic-rich alicyclic molecules/lignin-like structures (primarily CHON) and carbohydrates (primarily CHONP and CHONSP), were prominently produced after Fenton oxidation. The major mechanisms governing Fenton oxidation of surfactant in CCW primarily involved dealkylation (25.2 %), oxygen addition (21.2 %), and decarboxylation (19.8 %). Given the unique removal preferences and resistance observed in Fenton and PAC processes, a combination approach could be explored in the future to achieve advanced overall performance.

Improved performance of flow-electrode capacitive mixing through N-doping of activated carbon

Flow electrodes, which are integral to flow-electrode capacitive mixing (F-CapMix), primarily consist of activated carbon (AC), conductive additive and an aqueous electrolyte with a salt. For the better performance of F-CapMix, the AC must have a high surface area and excellent electrical conductivity to facilitate efficient charge percolation and electron transport between the AC particles within the flow electrode. In this study, nitrogen-doped activated carbon (N-doped AC) was synthesized through a straightforward process involving the heating of a mixture of raw AC and melamine in a covered container. The resulting N-doped AC powder exhibited an average of 20 % higher electrical conductivity than raw AC powder without sacrificing the surface area (AC: 2284.7 m2/g vs N-doped AC: 2125.6 m2/g) owing to the incorporation of graphitic nitrogen and oxidized nitrogen into the raw AC surface. The surface characteristics of N-doped AC were found to be similar to those of raw AC. Electrochemical impedance spectroscopy analysis of F-CapMix utilizing N-doped AC in the flow electrode revealed reduced resistance and increased capacitance, leading to an enhancement in power density from 0.706 to 0.828 W/m2. Consequently, integrating N-doped AC into the flow electrode can contribute to the improved performance of F-CapMix.

Reusable and inductively regenerable magnetic activated carbon for removal of organic micropollutants from secondary wastewater effluents

This work introduces a new sustainable alternative of powdered activated carbon (PAC) - magnetically harvestable and reusable after regeneration via inductive heating - for the adsorptive removal of organic micropollutants (OMP) from secondary wastewater effluents. For this purpose, two commercial PACs - lignite “L” (1187 m2/g) and coconut “C”-based (1524 m2/g) - were modified with magnetic iron oxide following two different synthesis approaches: infiltration (“infiltr”) and surface deposition (“depos”) route. The resulting magnetic powdered activated carbons (mPAC) and their precursor PACs were fully characterized before application. The iron oxide content of the modified “L” and “C” samples was ∼30 % and ∼20 %, respectively. Iron oxide gives the PAC beneficial magnetic properties for easy magnetic separation and simultaneously acts as an inductively heatable agent for the carbon regeneration. The infiltrated samples displayed better inductive heating performance and regeneration than their deposited counterparts. Tests with real wastewater showed fast adsorption kinetics of the organic load following the pseudo-second-order kinetic model. Adsorption isotherms were compliant with the Freundlich isotherm model. Sample “L-infiltr” had the best overall adsorption performance throughout 5 reuse cycles when intermediately inductively regenerated (<3 % drop in organics removal per cycle with intermediate regeneration vs. ∼10 % drop per cycle without regeneration). The treated supernatant was additionally tested for 31 representative organic micropollutants and their transformation products (pharmaceuticals, personal care products, industrial chemicals, etc.), where 26 OMPs had consistently high removal (>85 %) throughout 5 cycles with intermediate regeneration and for 28 OMPs the total adsorption efficiency dropped by <5 % after 5 cycles.

Operational mode and powdered activated carbon promoting syntrophic propionate oxidation during anaerobic digestion of complex organic substances

Operational mode and powdered activated carbon (PAC) are key factors facilitating microbial syntrophy and interspecies electron transfer during anaerobic digestion, consequently benefiting process stability and efficient methanogenesis. In this study, continuous-flow reactor (CFR) and sequencing batch reactor (SBR), with and without the addition of PAC, respectively, were operated to examine their effects on system performance and methanogenic activity. Based on the cycle-test result, the PAC-amended CFR (CFRPAC) recorded both the highest methane yield (690.1 mL/L) and the maximum CH4 production rate (28.8 mL/(L·h)), while SBRs exhibited slow methanogenic rates. However, activity assays indicated that SBRs were beneficial for organics removal in batch experiments fed with peptone. Taxonomic and functional analysis confirmed that CFRs were optimal for proliferating oligotrophs (e.g., Geobacter) and SBRs were more suitable for copiotrophs (e.g., Desulfobulbus). Metagenomic analysis revealed that CFRs had efficient acetate metabolic pathways from propionate and ethanol, whereas SBRs did not, resulting in the buildup of propionate. Furthermore, Methanobacterium and Methanothrix were acclimated to the different operational conditions, while acetoclastic Methanosarcina and hydrogenotrophic Methanolinea were acclimated in SBRs (5.1–13.4%) and CFRs (0.3–1.7%), respectively. This study confirmed the enhancement of microbial syntrophy by the addition of PAC as well as the acclimation of electroactive bacteria (e.g., Geobacter) with complex organic substances.

Treatment of real textile effluent containing indigo blue dye by hybrid system combining adsorption and membrane processes

The rapid expansion of the textile industry in Tunisia has resulted in ever-increasing discharges of wastewater, making it necessary to set up treatment systems allowing i) its discharge into the environment or ii) to recycle the water in the textile plant. In this study, several unitary operations were tested in order to improve the treated water quality. Thus, the following unit operations were applied: adsorption using Natural Clay (NC) and Powdered Activated Carbon (PAC), ultrafiltration (UF) and nanofiltration (NF) individually or in synergy: UF, nanofiltration, PAC-UF, NC-UF, UF-NF et Adsorption-UF/NF. The experiments were carried out on real textile effluent containing Indigo blue dye. A threshold concentration was observed above which performance no longer increases. NF alone showed better reduction of COD (67%), color (78%), and turbidity (98%) than UF alone (26%, 48%, 95%, respectively). The coupling UF–NF showed a clear improvement in water quality in terms of color (99%) and COD (98%) with an improvement in the NF flux from 67.81 L/h.m2 to 90.62 L/h.m2. No fouling was observed for NF while it is significant during UF. The used of adsorption as pretreatment to filtration leads to an enhancement of the treatment performances with a removal of 99.9%, 99.5% and 79.5% respectively for turbidity, color and COD for NC-UF and a removal of 100%, 99.4% and 79.6% respectively for turbidity, color and COD for PAC-UF. Moreover, the addition of adsorbent controls the fouling and a constant and high flux is quickly attained and remains stable over time. The use of natural clay as adsorbent represents an economically profitable solution since it can be obtained locally and the clay used can be reused in the ceramic industry as an additive for road surfacing without the need for regeneration.

Solar interfacial evaporation for efficient treatment of sewage containing volatile organic compounds and toxic heavy metal ions: A sequential process of adsorption, coagulation, and evaporation

Solar interfacial evaporation (SIE) is an eco-friendly and sustainable technology for addressing water pollution and freshwater scarcity. However, treating wastewater containing volatile organic compounds and heavy metal ions with a single SIE method is inefficient. The combination of adsorption, coagulation, and evaporation process provides an alternative solution for treating this type of wastewater. In this study, activated carbon powder (C) is introduced as an adsorbent and an integral part of photothermal conversion material, which is coagulated with polyvinyl alcohol (PVA) and polyethylene glycol (PEG) through a mold press process to fabricate PVA/C/PEG composite hydrogels. The volatile organic compounds and heavy metal ions in the wastewater are adsorbed by the activated carbon powder and the wastewater is then further purified into freshwater through SIE. This stepwise “adsorption first, then coagulation and evaporation” method can not only rapidly remove pollutants from the raw water, but also provides a much higher removal efficiency than the adsorption-evaporation synergetic process. This work demonstrates a successful attempt to utilize the SIE method for treating wastewater containing volatile organic compounds and heavy metal ions.

Effects of different acidification-resisting strategies on anaerobic digestion of kitchen waste: Methanogenic properties and microbial community shift

Anaerobic digestion (AD) has been widely used as a promising technology for the treatment of kitchen waste (KW). The effects of several acidification-resisting methods were compared, which included the supplementation of trace elements (TEs) and zero-valent iron (ZVI) / powdered activated carbon (PAC), and the application of the sludge domesticated by acetic acid (HAc) and KW as inoculum. The results showed that the supplementation of TEs and ZVI/PAC at total solid (TS) content of 6% and optimal addition doses resulted in an increase in methane yield to 346 and 366 mL/g VS, respectively. In addition, the methane yields of 327 and 241 mL/g VS were obtained by applying the sludge domesticated with KW and HAc as inoculum, while the methane yield of the control was only 89.2 mL/g VS, representing a relative increase of 288%, 311%, 267%, and 170%. The acidification could be alleviated by applying these methods, and also the methanogenic profile was improved. Furthermore, microbial community analysis revealed that the enrichment of Methanosarcina, which enhanced the substrate utilization capacity and subsequently increased methane production, was achieved through the addition of TEs and ZVI/PAC, along with the application of sludge domesticated by KW.

Powdered activated carbon (PAC)-assisted peroxymonosulfate activation for efficient urea elimination in ultrapure water production from reclaimed water

Urea is a problematic pollutant in reclaimed water for ultrapure water (UPW) production. The sulfate radical-based advanced oxidation process (SR-AOP) has been recognized as an effective method for urea degradation. However, conventional metal-based catalysts for peroxymonosulfate (PMS) activation are unsuitable for UPW production due to issues related to metal ion leaching. In this study, the use of powdered activated carbon (PAC) was investigated for the removal of urea from reclaimed water. The PAC exhibited a high degree of defects (ID/IG = 1.709) and various surface oxygen functional groups (C–OH, C=O, and C–O), which greatly enhanced its catalytic capability. The PAC significantly facilitated PMS activation in the PMS + PAC system, leading to the complete urea decomposition. The PMS + PAC system demonstrated excellent urea removal efficiency within a wide pH range, except for pH < 3. Among the various anions present, the CO32− and PO43− inhibited urea degradation, while the coexistence of Cl− promoted urea removal. Furthermore, the feasibility test was evaluated using actual reclaimed water. The quenching test revealed that SO4−·, ·OH, and O2−· played crucial roles in the degradation of urea in the PAC-assisted SR-AOP. The oxygen functional groups (C–OH and O–C=O) and defect sites of PAC clearly contributed to PMS activation.

A comprehensive evaluation of asphalt concrete modified with ACP based on improved AHP and radar chart method

Microwave heating, as an efficient and environmentally friendly heating technology, is used in solving rapid deicing issues of asphalt pavement. In this study, activated carbon powder (ACP) was adopted to partly replace mineral powder and improve the microwave heating efficiency of asphalt concrete. Some tests of key indexes about deicing, microwave heating, asphalt concrete and asphalt mastic were conducted in laboratory. In order to comprehensively compare and analyze the performance of asphalt concrete at different replacements and recommend the best type of asphalt concrete with laboratory data, an advanced data processing and mathematical model was established based on improved Analytic Hierarchy Process (AHP) and radar chart method. The results show that the fi representing the comprehensive performance of each type of asphalt concrete can be ranked as f6&amp;gt;f5&amp;gt;f4&amp;gt;f3&amp;gt;f2&amp;gt;f1. Therefore, it can be easily recommended that the type of asphalt concrete that meets the expected requirements is that with 100% ACP replacement amount. Additionally, the established model has proved feasible and effective through the application of this research. Finally, this research’s process and results can provide a new idea and reference for resolution of similar problems in the future.

Rheological performance evaluation of activated carbon powder modified asphalt based on TOPSIS method

In this study activated carbon powder (ACP) was incorporated into asphalt to substitute a portion of the conventional filler (mineral powder, MP). The dynamic modulus at elevated temperatures, temperature-dependent viscosity sensitivity, low-temperature creep, and the interaction between asphalt and ACP were examined through dynamic shear rheometer testing, viscosity testing, and bending beam rheometer testing. Moreover, statistical methodologies such as the entropy weight method (EWM) and the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) were employed to optimize the proportion of ACP by evaluating the comprehensive rheological behavior of asphalt mastic (including high temperature performance, low temperature performance, flowability, and asphalt-ACP interaction). The findings demonstrate that ACP can enhance the resistance of asphalt mastic to high-temperature deformation to a certain degree. The ratio of creep rate to stiffness (m/S) decreases with the addition of ACP, indicating that ACP may exacerbate the occurrence of low-temperature thermal cracking in asphalt mastic. The interaction ability of asphalt mastic is significantly enhanced when a portion of the filler is replaced with ACP. The loss factor shows significant impact on the comprehensive evaluation. According to TOPSIS analysis, asphalt mastic with a blending proportion of 40% ACP and 60% MP performs better in terms of comprehensive rheological properties.

Preparation of Nickel-Based Bimetallic Catalyst and Its Activation of Persulfate for Degradation of Methyl Orange

In this research, a new catalyst for activating persulfate was developed by loading iron and nickel ions onto powdered activated carbon (PAC) for treating methyl orange, and the preparation process was optimized and characterized. The efficacy of the treatment was evaluated using the Chemical Oxygen Demand (COD) removal rate, which reflects the impact of various process parameters, including catalyst dosage, sodium persulfate dosage, and reaction pH. Finally, the recovery and reuse performance of the catalyst were studied. The optimal conditions for preparing the activated sodium persulfate catalyst were determined to be as follows: a molar ratio of Fe3+ and Fe2+ to Ni of 4:1, a mass ratio of Fe3O4 to PAC of 1:4, a calcination temperature of 700 °C, and a calcination time of 4 h. This preparation led to an increase in surface porosity and the formation of a hollow structure within the catalyst. The active material on the surface was identified as nickel ferrite, comprising the elements C, O, Fe, and Ni. The magnetic property is beneficial to recycling. With the increase in catalyst and sodium persulfate dosage, the COD removal efficiency of the oxidation system increased first, and then, decreased. The catalyst showed good catalytic performance when the pH value was in the range of 3~11. Furthermore, Gas Chromatography–Mass Spectrometry (GC-MS) analysis indicated the complete oxidation of methyl orange dye molecules in the system. This result highlights the important role of the newly developed catalyst in activating persulfate.

Water-based Synthesis of MIL-53(Al) at Room Temperature: An Eff ective Adsorbent for Oxytetracycline (OTC) Antibiotic Removal from Water

MIL-53(Al), a fl exible metal-organic framework, was synthesized by a facile method through a water-based method at room temperature, aligning with the principles of green chemistry. The objective was to investigate its effectiveness in removing pharmaceuticals and personal care products (PPCPs), specifi cally focusing on oxytetracycline (OTC). Our fi ndings revealed that MIL-53(Al) possesses a structure with both micropores and mesopores, with a specifi c surface area of 916 m2/g. MIL-53(Al) notably exhibited a higher OTC adsorption capacity than commercially available powder activated carbon (PAC). The adsorption kinetics followed a pseudo-second-order model, while the Langmuir model accurately described the experimental isotherms for OTC adsorption. MIL-53(Al) outperformed previously reported MOF-based adsorbents with a maximum of 1005 mg/g capacity at pH 7. The fl exible structure induces a breathing effect that signifi cantly improves intraparticle diffusion for OTC, contributing to its adsorption effi ciency. The adsorption of OTC was infl uenced by the solution pH, the acid dissociation constants of OTC, and the charged surface of the adsorbent. Pore fi lling, hydrogen bonding, π-π interaction, electrostatic interaction, and hydrophobic interaction were all associated with the adsorptive interaction between OTC and MIL-53(Al). The MIL-53(Al) also demonstrated good regeneration and reuse, with just a little decreased adsorption capacity after three reuse cycles. These fi ndings indicate that green material MIL-53(Al) has the potential to be an effective adsorbent for removing OTC from water matrices

The dependence in microcystin removal with powdered activated carbon on variant properties, carbon properties, and dissolved organic matter

Powdered activated carbon (PAC) is commonly used by water treatment plants to remove harmful cyanotoxins such as microcystins (MCs) produced during seasonal harmful algal blooms. MC removal by PAC depends upon the properties of the PAC, the properties of the MC variant, and the presence and properties of dissolved organic matter (DOM). To identify which of these factors has the greatest impact on the removal of MC by PAC, we evaluated the removal of four different MC variants (MC-LR, MC-LA, MC-RR and desmethylated MC-RR) by three different PAC types (wood-based, coal-blend and coal-based). The role of DOM properties was evaluated using DOM isolated from two different sources, a terrestrial source (Suwannee River Fulvic Acid, SRFA) and a microbial source (Grand Lake St Marys DOM, GLSM). The results of adsorption experiments conducted over a period of 72 h demonstrated the wood-based PAC, which had the highest surface area and mesopore volume of the PAC tested, had the highest adsorption rate and capacity for all four MC variants. Of the variants studied, neutrally charged MC-RR was adsorbed more rapidly and to a greater extent on all of the PAC types than were the other variants. Although MC-LA and MC-LR had the greatest hydrophobicity, their negative charges resulted in their being adsorbed the least. As expected, DOM inhibited microcystin adsorption to PAC. The degree of inhibition, however, did not significantly vary for the two DOM types evaluated, indicating the properties of the DOM on MC adsorption to PAC was less important than the PAC properties or MC variant properties. Overall, PAC properties were a more important factor in MC removal than were the MC properties or DOM conditions.

Co-Action of Ionic Liquids with Alternative Sorbents for Removal of Reactive Azo Dyes from Polluted Wastewater Streams

In this study, the facile removal of the chromium-complex-based reactive azo dye C. I. Reactive Black 8 (RB8) from model wastewaters by the co-action of alternative sorbents—biochar (BC) and bentonite (BT)—with ionic liquids such as benzalkonium chloride (BAC) or Aliquat 336 (A336) was studied. The experiments using model RB8-containing wastewater proved that the co-action of BAC with BC is the most promising method of RB8 separation from wastewater containing 1 g L−1 of RB8 dye. The application of 2 g L−1 BC in co-action with 1.5 g L−1 BAC or 1 g L−1 BT in co-action with 2 g L−1 BAC enables the removal of more than 98% of contaminant RB8 after 30 min of action. Similar removal efficiency (RE) was achieved using 40 g L−1 of powdered activated carbon (PAC) after 180 min of action. To reach the same RE using real RB8-containing wastewater, a four times higher dose of BC and a four times higher dose of BAC per gram of removed RB8 were required. The proposed mechanism of RB8 removal by the co-action of alternative sorbents with BAC comprises a parallel effect of (i) sorption, (ii) the formation of less polar ion pairs accompanied by their sorption on an alternative sorbent and (iii) the separation of used alternative sorbents covered with ion pairs. The removal efficiency of organic contaminant(s) from both model and real wastewater was evaluated by VIS spectroscopy applying the Lambert–Beer law and by the determination of chemical oxidation demand (COD) and/or adsorbable organically bound halogen (AOX) parameters.

Methods for eliminating micropollutant from wastewater: A review

The amount of suspended solid and medicinal micropollutants, such as fungicides, personal care products, contraceptive medications, antibiotics and aromatic hydrocarbons are increasing daily and has reached an alarming level. The micropollutant present in wastewater must be treated before its release because it forms adverse effect on mortal health. Because some harmful micropollutants are incredibly difficult to remove from WWTPs because of their nonbiodegradability, poor adsorption capability, complex nature and traditional wastewater treatments are precious or insufficient for decontamination. For the micropollutant declination some of the conventional physicochemical has been used. The use of powdered activated carbon (PAC) for water purification has been proven to be effective without harming the environment. Advanced oxidation technologies (AOTs), typically applied after natural processes have recently emerged as effective tertiary treatments for the withdrawal of micropollutants at high concentrations. Various methods have been developed and studied for the removal of these micropollutants from wastewater. This review aims to provide a comprehensive overview of the different methods employed, including physical, chemical, and biological processes, highlighting their effectiveness and limitations in micropollutant removal. As well as improving treatment efficiency, they can also remove any accumulation of dangerous byproducts produced during treatment.

A thorough analysis of the occurrence, removal and environmental risks of organic micropollutants in a full-scale hybrid membrane bioreactor fed by hospital wastewater

The Urban Wastewater Treatment Directive recent draft issued last October 2022 pays attention to contaminants of emerging concern including organic micropollutants (OMPs) and requires the removal of some of them at large urban wastewater treatment plants (WWTPs) calling for their upgrading. Many investigations to date have reported the occurrence of a vast group of OMPs in the influent and many technologies have been tested for their removal at a lab- or pilot-scale. Moreover, it is well-known that hospital wastewater (HWW) contains specific OMPs at high concentration and therefore its management and treatment deserves attention. In this study, a 1-year investigation was carried out at a full-scale membrane bioreactor (MBR) treating mainly HWW. To promote the removal of OMPs, powdered activated carbon (PAC) was added to the bioreactor at 0.1 g/L and 0.2 g/L which resulted in the MBR operating as a hybrid MBR. Its performance was tested for 232 target and 90 non-target OMPs, analyzed by UHPLC-QTOF-MS using a direct injection method. A new methodology was defined to select the key compounds in order to evaluate the performance of the treatments. It was based on their frequency, occurrence, persistence to removal, bioaccumulation and toxicity. Finally, an environmental risk assessment of the OMP residues was conducted by means of the risk quotient approach. The results indicate that PAC addition increased the removal of most of the key OMPs (e.g., sulfamethoxazole, diclofenac, lidocaine) and OMP classes (e.g., antibiotics, psychiatric drugs and stimulants) with the highest loads in the WWTP influent. The hybrid MBR also reduced the risk in the receiving water as the PAC dosage increased mainly for spiramycin, lorazepam, oleandomycin. Finally, uncertainties and issues related to the investigation being carried out at full-scale under real conditions are discussed.