Effluent Organic Matter Removal Research Articles

Cu2(OH)3NO3/γ-Al2O3 catalyzes Fenton-like oxidation for the advanced treatment of effluent organic matter (EfOM) in fermentation pharmaceutical wastewater: The synergy of Cu2(OH)3NO3 and γ-Al2O3

The secondary effluent of fermentation pharmaceutical wastewater exhibits high chromaticity, elevated salinity, and abundant refractory effluent organic matter (EfOM), presenting significant treatment challenges and environmental threats. Herein, Cu2(OH)3NO3/γ-Al2O3 was fabricated through ultrasound-assisted impregnation and calcination to catalyze the Fenton-like oxidation for degrading organic pollutants in this secondary effluent. Under neutral conditions, with 400.00 mg/L H2O2, 8 g/L catalyst, and at 30 ℃, the EfOM and CODCr removal efficiencies can reach 96.90 % and 51.56 %, respectively. The Cu2(OH)3NO3/γ-Al2O3 catalyst possesses ideal reusability, maintaining CODCr, chromaticity, and EfOM removal efficiencies at 44.44 %-64.59 %, 85.45 %-93.45 %, and 61.00 %-95.00 % over 220 h in a continuous-flow catalytic oxidation system operated at room temperatures (15–25 ℃). Electron paramagnetic resonance results and density functional theory calculations indicate that •OOH may be the predominant reactive oxygen species, facilitated by the easier elongation of the OH bond in H2O2 compared to the OO bond. The adjusted electronic structure endows Cu2(OH)3NO3/γ-Al2O3 composite sites with superior catalytic selectivity for H2O2 activation compared to Cu2(OH)3NO3 single crystal sites, with γ-Al2O3 additionally facilitating H2O2 activation through electron donation. This research highlights the efficacy of Cu2(OH)3NO3/γ-Al2O3 in the advanced treatment of complex industrial wastewater, elucidating its catalytic mechanisms and potential applications.

Spectroscopic analysis on effluent organic matter (EfOM) evolution in different UV-based advanced oxidation processes

The effluent organic matter (EfOM) removal performance of the advanced wastewater treatment process has drawn great attention owing to the potential ecological risk of EfOM in the receiving aquatic environments. However, the EfOM evolution process is still unclear in the various advanced wastewater treatment processes. In this study, the EfOM evolution process in terms of components, structures, and functional groups was investigated in four kinds of UV-based advanced oxidation processes (AOPs). The overall EfOM removal performances were in the order: UV/NaClO > UV/PMS > UV/H2O2 > UV. According to the spectroscopic analysis results, simple aliphatics/aromatic/acetylenes compounds with C–O, =C–H, amides, or amino structures deriving from protein-like substances, are easily destroyed under UV irradiation. Apart from these structures, microbial metabolic was strongly sensitive to a reactive chlorine species (RCS)-dominated system, especially nutrients, amino acids, and small peptides with ester. Total of 22 species of halogen by-products with high biotoxicity (acetonitrile-based chlorinated EfOM, chlorinated acetate, chlorinated methane) were detected in the UV/NaClO group. In contrast, the reactive oxygen species (ROS)-dominated systems exhibited strong structure selectivity for ester (UV/H2O2) and carbonyl (UV/PMS) in all of the EfOM components, exhibiting strong reaction activity with EfOM at different stages. The results reveal the EfOM evolution in different UV-based AOPs, providing a strategy for selecting suitable UV-based AOPs in the advanced wastewater treatment process in terms of high-efficiency removal of EfOM.

Performance of a pilot-scale EGSB-Bardenpho process treating fresh leachate from municipal solid waste incineration plant

The fresh leachate of municipal solid waste incineration plant (FLIP) has different characteristics from that of sanitary waste landfill plant (LSL), so attention should be paid to the development of FLIP treatment technology. This study proved that EGSB-Bardenpho process with massive effluent reflux could achieve better COD and TN removals. Through the reflux, the effluent organic matter (EfOM) and dissolved organic nitrogen (DON) could be further removed, thus improving the effluent quality. The effluent reflux effectively overcame the inhibition of ammonia nitrogen, and increased the COD removal of the process by about 7.8%, which was attributed to the additional 73% removal of EfOM. The average methane yield of EGSB reactor was 309 N ml·(g COD removed) −1 but the methane production did not timely reflect the state of the reactor. The inhibition threshold of total ammonia nitrogen (TAN) and free ammonia nitrogen (FAN) on the expanded granular sludge bed (EGSB) reactor was 250–360 and 7–10 mg N·L−1, respectively. 20% of the total influent entering the Bardenpho system could provide the carbon source enough for the denitrification when the TN removal rate was about 98%. In the case of 80% of the FLIP treated by the EGSB reactor, its contribution to the total system COD removal was approximately 71%. The presence of TAN appeared to promote the formation of cocci-dominated granular sludge in EGSB reactor.

Evaluation of secondary effluent organic matter removal by an in-series forward osmosis-ultrafiltration hybrid process using parallel factor analysis with self-organizing maps

This study explores removal of effluent organic matter (EfOM) from secondary municipal wastewater effluent by a custom-devised in-series forward osmosis-ultrafiltration (FO-UF) hybrid system in which naturally-driven osmotic pressure, induced by the concentration difference between the feed solution and the draw solution, is a sole driving force for post UF filtration. Water flux and reverse salt flux are greatly affected by concentration and type of draw solution as well as different FO membrane configurations of the active layer facing feed solution (AL–FS) and the active layer facing draw solution (AL–DS). Maximum fluorescence intensity values obtained from parallel factor analysis (PARAFAC) revealed that the FO-UF hybrid process removes EfOM up to 97% of initial concentration over 2 h experimentation, owing to 6–8% of additional removal by post UF membrane. PARAFAC and self-organizing maps (SOM) modeling revealed that humic-like substances are removed preferentially over protein-like and smaller-sized organics in both AL–FS and AL–DS modes. However, in AL–DS mode, fouling, possibly due to humic-like substances, followed by deteriorating water quality, is observed earlier than in AL–FS mode. During the FO-UF processes, overall properties of EfOM in feed solution are shifted to hydrophilic and smaller-sized organic matter. This work provides a concept of pump-less FO-UF hybrid filtration and demonstrates the proposed system as a feasible option for EfOM removal in water reuse. As the first of its kind, the incorporation of PARAFAC with SOM modeling in FO process gives an insight into the fouling and transport of EfOM in the AL-FS and AL-DS modes.

Ultrasound-assisted H2O2 directional-modification of powdered activated carbon for the enhanced adsorption of secondary effluent organic matter from printing and dyeing processes

The physicochemical properties of powdered activated carbon (PAC) are important factors affecting its adsorption performance, which is also related to the characteristics of target organic pollutants. In this study, the key indicators affecting the adsorption performance of PAC were identified, and the physicochemical properties of PACs were modified by hydrogen peroxide and/or ultrasound in a targeted manner to improve the adsorption performance. The results indicated the adsorption properties of printing and dyeing secondary effluent organic matter (EfOM) in terms of CODcr and UV absorbance at 254 nm (UV254) positively correlated with mesoporous volume, average pore size and acid group content of PAC. After modification, the mesoporous volume and average pore size of PAC increased, and the number of acidic groups increased, thus enhancing the adsorption efficiency. EfOM removal characteristics showed that PAC preferentially adsorbed unsaturated bonds or aromatic compounds, tryptophan-like proteins, soluble microbial metabolites and low molecular weight fractions below 1 kDa. In addition, the relative contents of specific surface area, pore volume and oxygen-containing functional groups (O-CO, C-OH, CO/O-C-O) of PAC decreased after adsorption, indicating that EfOM adsorption was a physical and chemical process, including pore filling, hydrophobic interaction and chemical bond force interaction. In general, PACs with larger mesoporous volume, average pore size and abundant acid groups possessed good adsorption performance towards EfOM.

Identifying the critical activated carbon properties affecting the adsorption of effluent organic matter from bio-treated coking wastewater

Activated carbon is widely used to remove effluent organic matter (EfOM) from bio-treated coking wastewater. However, the critical carbon properties affecting adsorption performance are still unclear. Nine commercial powdered activated carbons (PACs) with different pore structures, surface functional groups, and surface charges were used to adsorb EfOM from bio-treated coking wastewater, which was fractionated according to their molecular weight (MW) and hydrophobicity. Good correlations were observed between the adsorption of biopolymers (MW > 20,000 Da, 7 %) and macropore volume (>50 nm), as well as between the adsorption of humics (MW = 1000 ~ Da, 36 %) and mesopore volume (2–50 nm), suggesting that the adsorption sites of EfOM depended on their molecular size. Higher isoelectric points and fewer acidic groups promoted the adsorption of the most negatively charged hydrophobic acids (HPOA, 39.5 %). According to variation partitioning analysis (VPA), mesopore-macropore greatly contributed to the adsorption capacities of EfOM (71.3 %), whereas the sum of phenolic hydroxyl and carboxyl (26.3 %) and isoelectric point (12.2 %) affected the normalized adsorption capacities of EfOM. In conclusion, PAC with a higher mesopore volume, fewer acidic groups, and a higher isoelectric point was desirable for removing EfOM from bio-treated coking wastewater. This study provides guidance for the selection of PAC for the removal of EfOM from bio-treated coking wastewater.

Advanced technique of catalytic ozonation-enhanced coagulation for the efficient removal of low coagulability refractory organics from secondary effluent.

The novel cascaded catalytic ozonation-enhanced coagulation process (FeCeAC/O3-PAC) was developed with much success towards second effluent organic matter (EfOM) in chemical industrial wastewater. Compared with the conventional techniques, FeCeAC/O3-PAC exhibited remarkable performances in the advanced removal of EfOM. The characteristics of EfOM and interactivities of reaction process played the crucial roles. Especially, the removal rate constant of soluble microbial products (SMPs) with FeCeAC/O3-PAC exceeded 55.38% versus FeCeAC/O3. The outstanding synergistic effect was contributed to the enhanced generation of active oxygen species by FeCeAC and PAC, which increased the content of oxygen-containing functional groups of EfOM and thus facilitated the interaction between PAC and EfOM. As the result, the larger-sized flocs could be formed and separated easily. Herein, this work found a far more effective way to remove EfOM especially low-coagulability refractory organics (LCRO) in chemical sewage plant.

New insights into the transformation of effluent organic matter during Fe(II)-assisted advanced oxidation processes: Parallel factor analysis coupled with self-organizing maps

The negative effects of effluent organic matter (EfOM) on receiving aquatic environments and advanced treatment facilities pose significant concerns. However, the effective removal of EfOM is challenging due to its chemically complex nature and its refractory characteristics. In this study, two Fe(II)-assisted oxidation processes including UV/Fe(II)/H2O2 and UV/Fe(II)/persulfate (UV/Fe(II)/PS) were investigated to promote EfOM reduction. Fe(II) was essential for promoting EfOM degradation. The mineralization rate of EfOM increased from 7 to 29% with 2 mM Fe(II) addition in the UV/H2O2 process and to 23% with 0.8 mM Fe(II) addition in the UV/PS process. A preliminary experiment was conducted to obtain the optimal molar ratio of oxidant to Fe(II) for practical applications based on different indicators. The form of Fe(III) prevalent at different pH values strongly affected Fe(II)/Fe(III) cycling, thus determining the progress of EfOM degradation. A machine learning approach consisting of parallel factor analysis coupled with self-organizing maps (PARAFAC-SOM) was employed with fluorescence spectra to visualize the degradation behavior of EfOM in the different reaction systems. Four components (i.e., two humic-like substances, one fulvic acid, and one tryptophan-like substance) were eventually identified, and their reductions reached more than 62% during the Fe(II)-assisted oxidation processes. The degradation orders for each component in the different oxidation processes were initially evaluated by SOM analysis with Fmax percentage data. The degradation behavior of EfOM in the UV/Fe(II)/H2O2 and UV/Fe(II)/PS systems exhibited different trends based on the best matching unit map and component planes. The humic-like component was more refractory than the other three components in both oxidation processes. The microbial humic-like and high-molecular-weight fulvic acid substances showed higher reactivity with SO·4- than with ·OH, while the tryptophan-like substance was more reactive in the UV/Fe(II)/H2O2 system than in the UV/Fe(II)/PS system. The outcomes of this study provide new insights into the degradation behavior of EfOM, promoting the development of advanced wastewater treatments.

Secondary wastewater treatment using peroxymonosulfate activated by a carbon nanofiber supported Co3O4 (Co3O4@CNF) catalyst combined with ultrafiltration

In this study, a heterogeneous carbon nanofiber supported Co3O4 (Co3O4@CNF) catalyst was prepared, and peroxymonosulfate (PMS) oxidation activated by Co3O4@CNF integrated with ultrafiltration (UF) membranes was proposed for treating secondary wastewater. The micromorphology and chemical composition of Co3O4@CNF were characterized by various techniques, demonstrating the successful synthesis of Co3O4@CNF. The prepared catalyst exhibited superior catalytic performance for PMS, accompanied by the formation of various reactive oxygen species, including •OH, SO4•−, 1O2 and O2•−. The Co3O4@CNF/PMS system substantially enhanced the removal of effluent organic matter (EfOM), and the DOC and UV254 values were decreased to 3.8 mg/L and 0.032 cm−1, with removal rates of 46.5% and 58.4%, respectively. The reduction efficiency of various fluorescent components was also improved, while macromolecular and humic substances were significantly reduced, accompanied by the generation of some small molecular organics. For both polyether sulfone and ceramic membranes, the fouling caused by EfOM was effectively mitigated, with the irreversible fouling resistance reduced by 65.6% and 83.9%, individually. The main fouling mechanism was also changed by increasing the specific filtration volume for the formation of cake filtration. The effectiveness of Co3O4@CNF/PMS for fouling mitigation was verified through the characterization of the surface morphology and functional groups of the membranes. The results suggest that the process of PMS activated by Co3O4@CNF integrated with UF has an application potential for secondary wastewater treatment.

Evaluation of Fe(VI)/Fe(II) combined with sludge adsorbents in secondary effluent organic matter removal

Wastewater reclamation and reuse are important methods that help to achieve an equilibrium within demand and offer, and also one of the important ways to reduce carbon emission. The existence of secondary effluent organic matter (EfOM) will bring potential threat to the environment in reuse process. Therefore, it is important to develop reclaimed water reuse technology that effectively remove EfOM. In this study, the removal of EfOM performance of ferrates enhanced by FeCl2 (Fe(VI)/Fe(II)) combined with sludge adsorbents (SAs) was evaluated by using the continuous-flow process (FeSDF), which was composed of Fe(VI)/Fe(II), SAs, densadeg and filtration. The results showed that when the inflow rate was 1 L/h, the optimal operating conditions of FeSDF including 5 mg/L of Fe(VI), 1 mg/L of Fe(II), 1 g/L of SA and 50% of the reflux ratio. Bulk organic indicators, including chemical oxygen demand, dissolved organic carbon, ammonia, total nitrogen, total phosphorus, turbidity, and ultraviolet absorbance at 254 nm in the effluent met the water quality standard for scenic environment use (GB/T 18921-2019 in China). The addition of Fe(II) makes the coagulation process by Fe(VI) produce more Fe(III) and produce more quality of sedimentary flocs and improve the removal efficiency of EfOM. The removal of organic micro-pollutants (OMPs) was mainly due to ferrate oxidation and SA adsorption in FeSDF, and the removal of most of the OMPs was more than 90%. The total fluorescence intensity removal efficiency in FeSDF was 63.8%. Moreover, the genotoxicity of the FeSDF effluent decreased to 0.73 μg 4-nitroquiniline-N-oxide/L, and the reduction efficiency reached 97.6%. The actual efficiency of most of the indicators is greater than the expected efficiency, indicating that there is a synergistic comprehensive effect during the whole process operation of FeSDF.

Optimizing biological effluent organic matter removal for subsequent micropollutant removal

Wastewater treatment plant effluent is an important point source for micropollutants emissions into the environment. These micropollutants can pose risks for ecosystems and humans; therefore, wastewater treatment plants should be upgraded to improve their micropollutant removal. Micropollutant removal can be improved by implementing tertiary treatment such as ozonation or activated carbon filtration. However, organic matter in the wastewater treatment plant effluent interferes with the micropollutant removal in these tertiary treatments, resulting in high energy demand and costs. To decrease the energy demand of tertiary treatment, biological pre-treatment can be introduced to remove effluent organic matter in an energy efficient manner. This biological pre-treatment was optimized by comparing three types of bioreactors; biological activated carbon, sand filter, and moving bed bioreactor. The reactors were operated at five flow rates (0.25, 0.5, 1, 2 and 4 L/h) in a continuous setup. The biological activated carbon filter achieved higher effluent organic matter removal than the sand filter and moving bed bioreactor (up to 72%, 41%, and 21% respectively). Additionally, effluent organic matter removal was negatively correlated to the flow rate in the biological activated carbon filter and the sand filter. The biological activated carbon filter also achieved average removal of 85% for the 18 analyzed micropollutants, although how long this high micropollutant removal can be sustained is unclear. To conclude, the biological activated carbon filter as pre-treatment can achieve high effluent organic matter removal, which would decreases the energy demand and cost of subsequent treatment for micropollutant removal.

Interaction-sedimentation strategy for highly efficient removal of refractory humic substances in biologically treated wastewater effluent: from mechanistic investigation to full-scale application

Based on the accurate characterization of the binding sites of humic substances (HS) and their binding coefficients with ferric ions (Fe(III)), a coupled interaction-sedimentation (CIS) technology was proposed for dealing with HS in the biologically treated wastewater effluent (BTWE) from a full-scale antibiotic production wastewater treatment plant. The infrared spectral and carbon-13 nuclear magnetic resonance characteristics showed that (i) protonated carboxyl groups in HS were the main binding sites for Fe(III) and HS, (ii) one carboxyl group of HS interacted with one ferric ion, (iii) the Fe(III)-binding ability of fulvic acids (FA) was 2.8 times as much as that of humic acids (HA) when FA and HA coexisted, and (iv) the presence of non-humic substances in the effluent organic matter (EfOM) amplified the Fe(III)-binding ability difference between FA and HA to 4.9 times. Afterwards CIS technology was successfully optimized and applied in engineering-scale and superior HS and EfOM removal efficiencies of 94.2% and 84.0% were reached, respectively. The CIS technology and its engineering application in this study not only fulfill the direct discharging standard for antibiotic production wastewater, but also have the potential for replication in broader advanced treatments for BTWE.

Visible light-activated NGQD/nsC3N4/Bi2WO6 microsphere composite for effluent organic matter treatment

The diminishing availability of clean water resources has led to a high demand for advanced, effective wastewater effluent reclamation techniques. In this study, a new microsphere composite of nitrogen-doped graphene oxide quantum dots, nanosheet C3N4, and Bi2WO6 was synthesized and characterized to examine its feasibility as a visible light-activated photocatalyst for wastewater reclamation. At the optimal dose of 1 g•L−1 under 6 h of illumination, the composite exhibited a high removal capability for effluent organic matter (82.8 ± 1.6%). Its high performance and stability over multiple cycles are attributed to two factors: (1) its harvesting ability over a wide range of the visible light region and (2) its ability to separate photoinduced charge carriers effectively, which is driven by the efficient interfacial contact of the hosts and inclusion of the photosensitized nitrogen-doped graphene oxide quantum dots in the structural network. The complex effluent organic matter removal process of the compound was further examined by fluorescence spectroscopy and size exclusion chromatography. Fluorescence spectroscopy showed that humic-like components with a higher degree of aromatic condensation and greater molecular size were preferentially removed by photocatalysis. Protein-like components were removed more rapidly than the humic-like components due to the synergetic effects of OH and 1O2 on the rapid decomposition of low-molecular-weight compounds. Size exclusion chromatography revealed that the photocatalytic system preferentially removed larger molecules via adsorption and oxidation; however, smaller size fractions might be produced via the breakdown of biopolymer and humic substance fractions in effluent organic matter.

Recent advances in the characterization and the treatment methods of effluent organic matter

There are many previous review articles are available to summarize either the characterization methods of effluent organic matter (EfOM) or the individual control treatment options. However, there has been no attempt made to compare in parallel the physicochemical treatment options that target the removal of EfOM from biological treatments. This review deals with the recent progress on the characterization of EfOM and the novel technologies developed for EfOM treatment. Based on the publications after 2010, the advantages and the limitations of several popularly used analytical tools are discussed for EfOM characterization, which include UV-visible and fluorescence spectroscopy, Fourier transform infrared spectroscopy (FTIR), size exclusion chromatography (SEC), and Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS). It is a recent trend to combine an SEC system with various types of detectors, because it can successfully track the chemical/functional composition of EfOM, which varies across a continuum of different molecular sizes. FT-ICR-MS is the most powerful tool to detect EfOM at molecular levels. However, it is noted that this method has rarely been utilized to understand the changes of EfOM in pre-treatment or post-treatment systems. Although membrane filtration is still the preferred method to treat EfOM before its discharge due to its high separation selectivity, the minimum requirements for additional chemicals, the ease of scaling up, and the continuous operation, recent advances in ion exchange and advanced oxidation processes are greatly noteworthy. Recent progress in the non-membrane technologies, which are based on novel materials, are expected to enhance the removal efficiency of EfOM and even make it feasible to selectively remove undesirable fractions/compounds from bulk EfOM.

Evaluation of a hybrid process of magnetic ion-exchange resin treatment followed by ozonation in secondary effluent organic matter removal

The presence of effluent organic matter (EfOM) and organic micro-pollutants (OMPs) in secondary effluent is receiving increasing concern due to their potential impacts on the aquatic environment and human health. In this study, the removal characteristics of EfOM by magnetic ion-exchange resin (MIEX), ozonation, and the hybrid process of MIEX followed by ozonation (M + O) were compared by measuring the bulk organic indicators (BOIs), OMPs, bio-toxicity, and fluorescence. Furthermore, the desorption characteristics of MIEX were comprehensively studied. Ozonation could reduce the OMPs, total fluorescence (TF), genotoxicity, and oestrogenic activity more effectively than MIEX, with reductions of 80.3%, 97.8%, 98.9%, and 94.6%, respectively. The M + O process was capable of removing more EfOM than the individual MIEX or ozonation processes and could reduce the genotoxicity and oestrogenic activity to the detection limit. By implementing MIEX as a pre-treatment, the generation of ammonia–nitrogen and nitrate–nitrogen was effectively reduced in the subsequent ozonation process as MIEX adsorbed organic nitrogen and nitrite-nitrogen. The different regenerants influenced the OMP desorption performance of MIEX by changing the desorption mechanisms, and NaCl + NaOH was the best regenerant due to its high total OMP desorption efficiency. Parallel factor analysis coupled with self-organising maps further explained the differences in fluorescence desorption due to the addition of NaOH to the regenerated solution. Pearson correlation analysis indicated the potential of using spectroscopic indicators, such as ultraviolet absorbance and TF, to assess the evolution of OMPs and bio-toxicity during the M + O and MIEX desorption processes.

Variation of effluent organic matter (EfOM) during anaerobic/anoxic/oxic (A2O) wastewater treatment processes

Here, we studied seasonal variation of effluent organic matter (EfOM), based on molecular weight distribution and fluorescent components, during the traditional anaerobic/anoxic/oxic (A2O) wastewater treatment processes. Microbial community structure and effect of temperature on some isolated pure strains were analyzed to explain the related mechanism. Results showed that the anaerobic process played a key role in EfOM removal by removing building blocks, low molecular weight (LMW) neutrals, biopolymers, and protein-related substances (C4 and C5), thus determining the fate of EfOM during the A2O processes. On the other hand, humic substances, LMW neutrals, large molecular-sized hydrophobic humic-like compounds (C3), and aromatic proteins (C4) were generated during the anoxic process in summer and winter. Proteobacteria (Gamma-, Beta-, and Alpha-proteobacteria) and Bacteroidetes constituted over 50% of the sludge community. Temperature was found to be positively correlated with the generation of soluble microbial products (SMP) based on the performance of the mixture of isolated Herbaspirillum sp. (Beta-proteobacteria) and Pseudomonas sp. (Gamma-proteobacteria). Through comprehensive analysis of the co-action of Proteobacteria and temperature, we proposed the Synergetic Effect of Temperature and Proteobacteria as a possible mechanism of the seasonal variation of EfOM. These findings are important for understanding the fate of EfOM during the wastewater treatment processes and therefore be helpful for better EfOM control.

Effect of pH on effluent organic matter removal in hybrid process of magnetic ion-exchange resin adsorption and ozonation.

It is essential to mitigate the risk of exposure to effluent organic matter (EfOM) in aquatic environments to ensure safe wastewater recycling. Magnetic ion-exchange (MIEX) resin adsorption combined with ozonation could provide EfOM removal. However, the poor understanding of the influences of the parameters and mechanisms in the hybrid process has restricted the applications. In this study, the response surface methodology was used to reveal the interactions of the major operation parameters. The degradation behaviour of the EfOM was investigated by using spectroscopy combined with mathematical methods. The effect of the pH on the EfOM removal was also analysed. The maximum efficiency of the removal of dissolved organic carbon (DOC) was 59.77% at the optimal MIEX resin dosage of 7.97 mL/L, ozone concentration of 8 mg/L, agitation speed of 199.84 r/min, and pH of 9.98. The ozonation was superior to resin adsorption in the removal of 1054-Da compounds, while the resin adsorption was advantageous in the removal of 4168-Da compounds. Three fluorescent components (C1, C2, and C3) were more easily subjected to external perturbation than the DOC and ultraviolet absorbance at 254 nm in the oxidation processes. The MIEX resin exhibited low efficiencies of removal of the fluorescent substances. A synchronous fluorescence analysis coupled with a two-dimensional correlation analysis revealed that the variation in EfOM followed the order of fulvic-to humic-like substances in the hybrid process of MIEX and the following ozonation. The pH was the most significant influencing factor in the hybrid process.

Fouling control in ultrafiltration of secondary effluent using polyaniline/TiO2 adsorption and subsequent treatment of desorption eluate using electrochemical oxidation

Performance of three adsorbents, polyaniline-modified TiO2 (PANI/TiO2), Dow resin IRA(a) and Dow resin IRA(b), in removing organics from secondary effluent (SE) was evaluated, and the objective of this study is to deliver a treatment loop including membrane fouling control using adsorption and treatment of correspondingly formed desorption eluate using electrochemical oxidation, so that the contaminants could be effectively handled within a wastewater treatment plant. Results show that PANI/TiO2 is a promising adsorbent in the removal of effluent organic matter (>55%) and its regeneration was superior to the two others. Specifically, PANI/TiO2 could remove over 70% of the fraction of biopolymers from the SE and therefore alleviated subsequent membrane fouling to a large extent, while the other two presented less antifouling effect due to limited removal of the major foulants, though they both showed comparable effect as PANI/TiO2 in the removal of other organic fractions. BOD5/COD of the concentrated desorption eluate was gradually increasing along with the extension of the electrochemical oxidation. It reached >0.4 after 4.5 h of treatment, which is of suitable biodegradability for recycling to the influent of the wastewater treatment plant. The improvement on BOD5/COD was due to the mineralization of effluent organic matter and simultaneous minifying of their molecular size. Moreover, the operation cost of the treatment loop was estimated at about 0.12–0.15 USD/m3 for delivering effect fouling control and significant improvement on effluent quality.

Origin, Fate and Control of Pharmaceuticals in the Urban Water Cycle: A Case Study

The aquatic environment and drinking water production are under increasing pressure from the presence of pharmaceuticals and their transformation products in surface waters. Demographic developments and climate change result in increasing environmental concentrations, deeming abatement measures necessary. Here, we report on an extensive case study around the river Meuse and its tributaries in the south of The Netherlands. For the first time, concentrations in the tributaries were measured and their apportionment to a drinking water intake downstream were calculated and measured. Large variations, depending on the river discharge were observed. At low discharge, total concentrations up to 40 μg/L were detected, with individual pharmaceuticals exceeding thresholds of toxicological concern and ecological water-quality standards. Several abatement options, like reorganization of wastewater treatment plants (WWTPs), and additional treatment of wastewater or drinking water were evaluated. Abatement at all WWTPs would result in a good chemical and ecological status in the rivers as required by the European Union (EU) Water Framework Directive. Considering long implementation periods and high investment costs, we recommend prioritizing additional treatment at the WWTPs with a high contribution to the environment. If drinking water quality is at risk, temporary treatment solutions in drinking water production can be considered. Pilot plant research proved that ultraviolet (UV) oxidation is a suitable solution for drinking water and wastewater treatment, the latter preferably in combination with effluent organic matter removal. In this way >95% of removal of pharmaceuticals and their transformation products can be achieved, both in drinking water and in wastewater. Application of UV/H2O2, preceded by humic acid removal by ion exchange, will cost about €0.23/m3 treated water.

Polycyclodextrin-Clay Composites: Regenerable Dual-Site Sorbents for Bisphenol A Removal from Treated Wastewater.

The greatest challenge of wastewater treatment is the removal of trace concentrations of persistent micropollutants in the presence of the high concentration of effluent organic matter (EfOM). Micropollutant removal by sorbents is a common practice, but sorbent employment is often limited because of fouling induced by EfOM and challenging sorbent regeneration. We directly addressed these two issues by designing regenerable dual-site composite sorbents based on polymerized β-cyclodextrin, modified with a cationic group (pCD+) and adsorbed to montmorillonite (pCD+-MMT). This dual-site composite was tailored to simultaneously target an emerging micropollutant, bisphenol A (BPA), through inclusion in β-cyclodextrin cavities and target anionic EfOM compounds, through electrostatic interactions. The removal of BPA from treated wastewater by the composite was not compromised despite the high removal of EfOM. The composites outperformed many recently reported sorbents. Differences in composite performance was discussed in terms of their structures, as characterized with TGA, XRD, BET and SEM. The simultaneous filtration of BPA and EfOM from wastewater by pCD+-MMT columns was demonstrated. Furthermore, successful in-column regeneration was obtained by selectively eluting EfOM and BPA, with brine and alkaline solutions, respectively. Finally, the composites removed trace concentrations of numerous high priority micropollutants from treated wastewater more efficiently than commercial activated carbon. This study highlights the potential to design novel dual-site composites as selective and regenerable sorbents for advanced wastewater treatment.