The removal of nutrients, like phosphate and ammonium, from wastewater is crucial for controlling eutrophication and water reuse. Traditional methods have limitations and are often supplemented by additional treatment steps, having a large footprint, consuming energy, and incurring added costs. This study presents a solution with the design of highly permeable (>100 LMH/bar) adsorptive polyacrylonitrile membranes embedded with akageneite (PAN/Ak) and zeolite 13X (PAN/Z) with high affinities for phosphate and ammonium uptake, respectively. The chemical compatibility between polymer and inorganic fillers resulted in highly flexible membranes with dispersed particles. Additionally, the membranes were stable, with no leaching of filler particles and complete recovery of uptake capacities after 5 adsorption/desorption cycles. Batch tests demonstrated that the maximum uptake capacities of PAN/Ak and PAN/Z are 0.4 mmol P/g and 1.2 mmol N/g, respectively, with phosphate uptake attributed to ligand exchange and ammonium to ion exchange. Moreover, the membranes' ability to capture ions under dynamic flow conditions persists despite the presence of other competing ions, resulting in an initial removal of > 84% for ammonium and 100% for phosphate from a synthetic wastewater with initial concentrations of 2.1 mmol N/L and 0.1 mmol P/L. These membranes offer a unique solution for emerging water purification challenges, as they combine the high permeability of low-pressure membranes with high selectivity towards target ions.

This study describes the preparation and characterizationof apolydopamine-coated UF membrane with in situ grown akageneite usinga two-step mineralization process that employs NaOH for precipitation.This PAN-PDA-Ak/NaOH membrane showed superior phosphorus uptake capacity,higher wettability, and surface roughness compared to PAN-PDA-Ak/HClmembranes, which were fabricated using the conventional forced hydrolysiswith HCl and at elevated temperatures. The Langmuir model accuratelydescribed isotherm data, indicating a homogeneous adsorbent surfacewith a maximum phosphorus uptake capacity of 10.4 mg P/g. Under dynamicfiltration conditions using 0.3 bar pressure, the membrane removedover 64% of phosphorus from both single-contaminant and syntheticwastewater solutions. The PAN-PDA-Ak/NaOH membrane demonstrated ahigh affinity for phosphorus, excellent reusability, and stability,with complete restoration of its uptake capacity after five cyclesand negligible Fe leaching. This membrane also had a high permeability(199 LMH/bar), offering a unique opportunity to combine low-pressureoperations with the high selectivity of adsorbents.

The removal of natural organic matter (NOM) from water was studied using polyacrylonitrile (PAN) electrospun nanofibrous membrane (ENM) coated with HAOPs (heated aluminum oxide particles). The removal efficiencies of virgin PAN and HAOP-coated PAN were examined and the suitability of PAN as a support material for HAOPs was studied. The membranes were characterized with Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscope and energy dispersive X-ray spectrometer (SEM-EDS) as well as X-ray photoelectron spectroscopy (XPS). Several analytical techniques were applied to both the feed and the permeate to assess the effectiveness of NOM removal. In filtration of lake water, HAOPs efficiency in NOM removal was 56% measured by UV254 absorbance, but when it comes to virgin PAN membrane the removal efficiency was only 13%. In case of filtration of NOM's high molecular weight component, such as humic acid (HA), the rejection rate of HA was maintained above 97% of aromatic compounds of NOM, and above 43% of total organic carbon (TOC). Additionally, HA adsorption by HAOPs were fitted to isotherm models such as Langmuir and Freundlich models. The results showed that Langmuir model could fit the data better than Freundlich model. The kinetics of HA adsorption by HAOPs were also fitted to the pseudo-first order and pseudo-second order and for the initial HA concentration of 19.9 mg/L the pseudo-first order equation fitted the experimental data better with correlation coefficient of R2 = 0.8336. The results demonstrate that PAN ENM filtration has the potential to be employed as a pretreatment in water treatment and HAOP-coated PAN ENM can significantly enhance the removal of NOM.

Phosphorus (P) recovery from wastewater is essential for eutrophication control, water reuse initiatives, and recovery of this depleting non-renewable resource. Herein, a polyacrylonitrile (PAN) electrospun nanofiber membrane (ENM) was fabricated with akageneite (Ak), and modified with benzyldimethyldodecylammonium chloride (BDDA), a cationic surfactant, for phosphorus recovery from wastewater. We examined the influence of BDDA concentration on membrane properties, including fiber diameter, surface area, surface charge, and contact angle. Membrane performance was then evaluated using adsorption isotherms and kinetics, in the presence of competing ions such as Cl-, SO42- and CO32-, using synthetic wastewater and through a total of 7 adsorptiondesorption cycles. Akageneite was found to be the only active ingredient responsible for P removal by the membrane. We observed that the increase in BDDA concentration from 0 % to 3 % resulted in a linear increase in P adsorption capacity from 0.30 to 0.61 mmol P/g Ak. No increase in adsorption was observed at concentrations beyond 3 % BDDA. Membranes made of PAN and BDDA alone exhibited a negligible uptake of P at any concentration of BDDA. Since P uptake happened only in the presence of Ak, the improved performance with the addition of BDDA was attributed to increased hydrophilicity and influence of the Donnan membrane effect. The membranes had the highest affinity towards CO32- followed by P. The P adsorption capacity of PAN-Ak membrane was not affected by the presence of other competing ions (Cl-, SO42-). The results also confirmed the reusability of PAN-Ak without loss of adsorption capacity, even after seven cycles. This work demonstrated the potential of surface modification of adsorptive membranes for improved phosphorus recovery.

This study provides new insights and a fundamental understanding of the effect of particle size on the structure and performance of electrospun nanofiber membranes (ENMs) containing powdered activated carbon (PAC). PAC was fractionated into four size groups (<20, 32–45, 53–75, 90–125 μm) and incorporated into ENMs made of polyacrylonitrile. Scanning electron microscopy images of ENM samples revealed that PAC particles were covered by a thin and porous layer of PAN. The specific surface area (SSA) of PAC-containing ENMs decreased by increasing PAC particle size and was found to be directly proportional to the exterior surface area of PAC particles. Our findings suggest that only pores located near the surface of PAC were mainly accessible for adsorption. Isotherm studies showed that the Freundlich adsorption capacity for the removal of methylene blue was proportional to the SSA of these membranes and was controlled by pores in the range of 1.3–5.0 nm. Finally, a diffusion-based model was developed that described adsorption kinetics of PAC-containing ENMs. This model corroborated our findings that the pseudo-first order adsorption rate constant was a linear function of SSA of membrane and the inverse of PAC particle size.

In this work, the removal of arsenic (III) from contaminated water by means of electrospun nanofiber adsorptive membranes (ENAMs) has been reported. Polyvinylidene fluoride (PVDF) was used for preparation of the ENAMs incorporating titanium dioxide (TiO2)-halloysite nanotubes (HNTs) nanoparticles as adsorbents. Removal of arsenic (III) by the prepared ENAMs was studied at adsorbent to polymer ratios of 0, 0.25, and 0.5 w/w. The addition of TiO2-HNTs to the polymer left visible changes on the structural morphology and fibers properties of the membrane. The membrane samples were characterized by pure water permeability, contact angle measurement, TEM, SEM, XPS, and XRD. Results indicated that by increasing the TiO2-HNT content, the adsorption capacity of the membrane improved. A maximum of 31.2 mg/g of arsenic adsorption was achieved using TiO2-HNTto PVDF ratio of 0.5 w/w. The ENAMs were able to reduce the arsenic (III) concentration to less than 10 ppb, the level recommended by the World Health Organization (WHO). Moreover, the adsorptive properties of the nanocomposite fibers were restored to 94% of the original capacity by cleaning the membranes using sodium hydroxide solution followed by DI water flushing.

A functionalized adsorptive electrospun nanofiber membrane (ENM) was successfully prepared via the one-step electrospinning of polyacrylonitrile blended with powdered activated carbon (PAC). Addition of salt to the polymer blend resulted in thinner filaments and enhanced the specific surface area of the membrane. Membranes prepared with salt addition exhibited a 45% increase in Freundlich adsorption capacity and 1.9 times higher adsorption rate constant for the removal of methylene blue (MB), a surrogate micropollutant, from water. Furthermore, the total permeate volume at 20% breakthrough was 35% greater for NaCl-PAC-ENM compared to that of PAC-ENM. These results were supported by the BET analysis that confirmed the effective surface area of membranes increased by 75% upon salt addition. The dynamic breakthrough behaviour of these membranes closely followed the Yoon-Nelson model, while the percent removal of MB exhibited an exponential relationship with the contact time. Finally, assuming the rate of adsorption of MB was mass transfer-limited, a mathematical model was developed to predict MB removal rate.

While carbon nanotubes are known as efficient adsorbents for removal of a number of contaminants from water, the possibility of their leaching into drinking water has prevented their application in water treatment. In this study, single walled carbon nanotubes (SWCNT) were sandwiched between two electrospun nanofibre membranes (ENM). The relatively small pore size of the ENM prevented the mechanically entangled nanotubes from passing through and contaminating the water. The performance of the SWCNT-ENM was evaluated in a lab-scale setup for the removal of PPCPs. For this purpose, a feed solution spiked with known concentrations of six PPCPs was passed through the membrane system. The target substances included acetaminophen (ACT), bezafibrate (BZF), iopromide (IOP), diclofenac (DCF), carbamazepine (CBZ), and sulphamethoxazole (SMX). The same test was also conducted using a single contaminant (ACT). Results demonstrated a decrease in the overall percent removal of PPCPs as feed flow rate and PPCP concentration increased. For multi-component feeds containing equal amounts of the aforementioned PPCPs, the overall percent removal decreased from 90.8% to 71.0% when increasing the feed concentration from 30 to 600 mu g/L. Experiments using sandwiched powdered activated carbon (PAC) showed that the dynamic adsorption capacity of PPCPs by SWCNT-ENM was higher than that of PAC-ENM, and remained unaffected by the feed composition. In addition, the high porosity of this novel membrane allowed for flow of water with low resistance such that the trans-membrane pressure was found to be as low as 4 kPa at a pure water flux of 330 L/m(2)h.

This is part two of a paper about the potential environmental impacts of treated effluent from a wastewater treatment plant (WWTP) discharging to the Detroit River in Windsor, Ontario, Canada. The WWTP uses conventional activated sludge with nitrification. The assessment was conducted over six months using a variety of established tests, including in vitro cell-based screening assays, as well as acute, chronic and full-life cycle in vivo exposures. Effluent monitoring included pharmaceutically active compounds and endocrine disrupting compounds. No tests reported significant toxicity. However, enhanced algal growth was observed in a Pseudokerchneriella subcapitata growth inhibition test. In full life-cycle fathead minnow exposure, liver-somatic index changes were noted in exposed fish – increases for males, decreases for females – and production of viable fry decreased. Neither alteration is thought biologically significant. Because the effluent is diluted substantially by the receiving water, the level of risk posed to aquatic receptors and the environment is probably negligible.

Introduction There is growing environmental concern regarding the health impact of trace levels of pharmaceuticals and personal care products (PPCPs) in the environment. PPCPs and endocrine disrupting chemicals (EDCs) detected in surface and drinking waters, as well as in treated wastewater, are an issue of increasing international attention due to potential environmental impacts.1,2 These compounds are distributed widely in surface waters due to anthropogenic activities, improper disposal, and agricultural runoff. This presents a major challenge to drinking water treatment facilities, which are required to provide potable water that meets regulatory requirements for human consumption.

A comprehensive study was conducted at two wastewater treatment plants (WWTPs) and one water treatment plant (WTP) in Windsor, Ontario, Canada. The occurrence of 220 emerging and legacy compounds, their removal efficiencies by the existing treatment processes, and their potential environmental impacts were studied. The results are reported in a two part paper. In this part (I), the occurrence and removal efficiencies are presented. Three of the 47 target pharmaceutically active compounds (PhACs) and endocrine disrupting compounds (EDCs) contributed 89–96% of the total concentration of PhACs/EDCs in the WWTP influents. They were acetaminophen, ibuprofen, and naproxen. The existing treatment processes successfully removed between 95 and 98% of ‘all’ PhACs/EDCs, primarily due to the high removal rates of these three analgesics. Concentrations of PhACs/EDCs detected at the WTP intake were two to three orders of magnitude lower than those in the effluent of the upstream WWTP. These concentrations remained relatively unchanged in the finished drinking water, indicating the WTP's low removal efficiency for trace amounts of them. Polybrominated diphenyl ethers (PBDEs) were detected at concentrations as high as 150 ng/L (for PBDE-209) in the WWTPs’ influent, and removed at 86–96% efficiency. PDBE effluent concentrations were mostly below 1 ng/L at both WWTPs, with a maximum of 9 ng/L for PBDE-209. Octylphenol, nonylphenol, and nonylphenol ethoxylates concentrations were monitored in one WWTP's effluent, and ranged between undetectable and 286 ng/L (LoDs varied between 1.3 and 15.2 ng/L).

Oxidation kinetics of selected pharmaceutical compounds and their degradation during ozonation of secondary treated municipal wastewater effluent (MWWE) was investigated. The apparent second-order rate constants for the reaction between chlorotetracycline (CTC), enrofloxacin (ENR), gemfibrozil (GEM) and ozone ranged between 6.82 – 52.7 × 104 M−1s−1. The measured second-order hydroxyl radical rate constants were several orders of magnitude higher at 8.4 × 109 – 13.1 × 109 M−1s−1 with a reactivity sequence of GEM > CTC > ENR. Overall degradation of CTC, ENR and GEM in secondary treated municipal wastewater effluent was >76 % at ozone doses of 0.33 mg O3/mg DOC or higher.

The transformation of 41 target emerging contaminants in secondary treated municipal wastewater effluent in Canada was examined at pilot-scale, at transferred ozone doses of 2.8 mg/L (0.46 O3/mg DOC) and 4.4 mg/L (0.72 mg O3/mg DOC). In general, transformation efficiencies of CECs either increased or were retained at the higher ozone dose. The higher ozone dose of 0.72 mg O3/mg DOC (Zspec = 0.6 mg O3/mg DOC) was sufficient to transform 21 of the 31 detected CECs by over 80% as well as achieving the disinfection target of < 200 MPN E. coli per 100 mL.

Electrospun nanofiber membranes (ENMs) are cutting edge new generation of membranes that offer significantly higher flux at similar rejection rate compared with the conventional membranes. Electrospinning has allowed for fabrication of highly porous ENMs with controllable pore size in the range of microfiltration and ultrafiltration. ENMs could replace conventional water treatment membranes with smaller systems that operate at lower pressures. In this chapter, the fundamentals of ENMs are presented and characterization methods, properties, and applications are discussed.

The aim of this study was to develop novel surface-modified poly(ether sulfone) (PES) ultra-filtration (UF) membranes for removal of endocrine disrupting chemicals (EDCs) and pharmaceutical and personal care products (PPCPs). Seven tailor-made charged surface modifying macromolecules (CSMMs) were developed for use as additives in the preparation of PES UF membranes with a greater surface charge and improved PPCP and EDC removal through charge repulsion. Twenty three types of PES membranes were prepared using two amounts of different CSMMs and two drying (or evaporation) times. The experiments were designed to obtain the membranes' performances in terms of normalized standard flux (NSF), molecular weight cut-off (MWCO), surface charge (SC), static contact angle and their removal efficiency towards one EDC (bisphenol A) and three PPCPs (carbamazepine, ibuprofen, and sulfamethazine). The correlation between NSF versus SC, MWCO, pore density, and porosity was discussed. The filtration experiments showed an initial partial removal of the target compounds, but no removal in the later stages of operation, which indicated that charge repulsion was not the controlling removal mechanism. This is consistent with small changes in membrane surface charge achieved by addition of these additives. Given the decrease in the percent removal with time, removal by size exclusion was also not significant as expected because the membranes had a MWCO greater than 10 kilo-Dalton while the target compounds had molecular weights in the 200 to 300 Dalton range. Based on the decreasing level of removal with time, it appeared that adsorption was the main removal mechanism.

Ozonation and ozone-based advanced oxidation processes have been shown to be effective in the oxidation of several pharmaceutically active compounds (PhACs) routinely detected in surface waters. Under typical operating conditions of these processes, most of the parent compound oxidized is expected to lead to the formation of transformation products (TPs). For a target ozone exposure, the resulting hydroxyl radical exposure depends on the water matrix or process chosen (e.g. peroxone) which in turn may influence the degradation pathway and the TPs formed. This study was undertaken to examine the expected impact that varying ozone and hydroxyl radical exposures may have on TP formation from the oxidation of PhACs during typical drinking water ozonation. Two representative PhACs were selected for the study. Carbamazepine was chosen to represent PhACs with a fast reaction rate with ozone (kO3 > 104 M−1 s−1) and bezafibrate was chosen to represent PhACs with a slow to moderate reaction rate with ozone (kO3 < 104 M−1 s−1). The results show that under varying ozone and hydroxyl exposure scenarios examined, the major oxidation pathway for the parent compound was dominated by reaction with ozone for carbamazepine while for bezafibrate it varied.

Nanofiber membranes were fabricated by electrospinning poly(vinylidene fluoride). The electrospun nanofiber membranes were further modified by grafting of acrylic acid (AA) and methacrylic acid (MAA) over the surfaces of the membranes. Plasma AA graft was attempted only, and the results indicated the partial membrane pore filling with grafted AA. For MAA grafting, chemically induced polymerization using benzoyl peroxide and hydrogen peroxide was attempted. The combination of plasma and chemically induced MAA graft polymerization was also attempted. The membranes were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and static contact angle (SCA) measurement. SEM surface analysis indicated partial pore narrowing of grafted membranes. The average pore size was reduced from 0.97μm for the untreated membrane to 0.15μm for the two step plasma and chemically induced grafted membranes. XPS analysis confirmed that grafting has taken place on the top surface of the membranes. The surfaces of the grafted membrane were significantly hydrophilic as observed by SCA. It was also found that the combination of plasma and chemically induced grafting using hydrogen peroxide was the most effective in terms of flux and selectivity. The grafting reduced the pore size by filling the pores of the original membranes by the graft polymers. This practice resulted in producing tight micro-filtration (MF) membranes from loose MF ones. An impressive high water flux of 150kg/hm2 at an operating pressure of 4 psig, and a 79% removal of polyethylene oxide (molecular weight 400kilo-Daltons) were achieved.