Secondary Effluent Water Research Articles

Degradation kinetics and transformation products of chlorophene by aqueous permanganate

This paper evaluates the oxidation of an antibacterial agent, chlorophene (4-chloro-2-(phenylmethyl)phenol, CP), by permanganate (Mn(VII)) in water. Second-order rate constant (k) for the reaction between Mn(VII) and CP was measured as (2.05 ± 0.05) × 101 M−1 s−1 at pH 7.0 for an initial CP concentration of 20.0 μM and Mn(VII) concentration of 60.0 μM. The value of k decreased with increasing pH in the pH range of 5.0–7.0, and then increased with an increase in solution pH from 7.0 to 10.0. The presence of MnO2 and Fe3+ in water generally enhanced the removal of CP, while the effect of humic acid was not obvious. Fourteen oxidation products of CP were identified by an electrospray time-of-flight mass spectrometer, and direct oxidation, ring-opening, and decarboxylation were mainly observed in the reaction process. The initial reaction sites of CP by Mn(VII) oxidation were rationalized by density functional theory calculations. Toxicity changes of the reaction solutions were assessed by the luminescent bacteria P. phosphoreum, and the intermediate products posed a relatively low ecological risk during the degradation process. The efficient removal of CP in secondary clarifier effluent and river water demonstrated the potential application of this Mn(VII) oxidation method in water treatment.

Simultaneous analysis of opioid analgesics and their metabolites in municipal wastewaters and river water by liquid chromatography–tandem mass spectrometry

Although published literature provides a clear demonstration of widespread occurrence of opioid analgesics (OAs) in the aquatic environment, analytical methods suitable for a systematic study of this pharmaceutical class, which would include a broad spectrum of opioid analgesics and their metabolites, are still missing. In this work, a comprehensive multiresidue method for quantitative analysis of 27 opioid analgesics and their metabolites, including 2 morphine glucuronide conjugates, was developed and validated for three matrices: raw wastewater (RW), secondary effluent (SE) and river water. The method comprised different classes of opioid analgesics, including natural opiates (morphine and codeine), their semi-synthetic derivatives (hydrocodone, hydromorphone, oxycodone, oxymorphone and buprenorphine) as well as fully synthetic opioids such as methadone, fentanyl, sufentanil, propoxyphene and tramadol. The optimized enrichment procedure involved mixed-mode, strong cation-exchange sorbent in combination with a sequential elution procedure. The extracts were analyzed by reversed-phase liquid chromatography using a Synergy Polar column coupled to electrospray ionization tandem mass spectrometry (LC–MS/MS). Accurate quantification of target OAs was achieved using 19 deuterated analogues as surrogate standards. Method accuracies for RW, SE and river water varied in the range from 91 to 126%, 74 to 120% and 75 to 116%, respectively. Careful optimization of the procedure allowed reliable determination of OAs with method quantification limits in the low ng/L range (RW: 0.3-3.5 ng/L; SE: 0.2-1.9 ng/L, river water: 0.1-0.8 ng/L. The developed method was applied for analysis of RW, SE and river water samples from Croatia. The concentrations of individual OAs in municipal wastewater varied in a wide range (from < QL to 859 ng/L) and the most prevalent representatives were tramadol, codeine, morphine and methadone and their derivatives. Elevated concentrations of morphine glucuronides (up to 370 ng/L) found in raw municipal wastewater indicated their importance in the overall morphine mass balance.

Removal of PhACs and their impacts on membrane fouling in NF/RO membrane filtration of various matrices

The removal of pharmaceutically active compounds (PhACs) by fouled nanofiltration (NF) and reverse osmosis (RO) membranes has been extensively studied. Investigations on the effects of PhACs on organic fouling or biofouling in the NF/RO membrane application are still lacking. In this study, NF/RO membranes were fed with both synthetic (SRNOM solution and synthetic wastewater containing pure culture inoculum) and real (secondary effluent) water matrices spiked with three PhACs to elucidate the impact of PhACs on membrane fouling in comparison with control experiments in the absence of PhACs. Results showed that the PhACs mitigated flux decline during NF/RO filtration of SRNOM solution. The total organic foulants on both membrane surfaces decreased in the presence of PhACs due to the increased negative charges of the membranes and the enhanced size and charge effects of PhAC–macromolecule complexes in SRNOM solution. PhACs appeared to inhibit cell growth in the early stages of biofouling, causing a decline in total biomass, and then induced cell lysis, releasing EPS to protect from chemical stress in the later stages of biofouling, especially protein-like materials, causing more severe biofouling. The alleviation of declines in flux and salt rejection during the filtration of secondary effluent were found in the presence of PhACs. Therefore, we hypothesized that organic fouling or early-stage biofouling occurred during 100h of filtration of secondary effluent. The decrease in PhAC retention was more obvious due to the higher ionic strength in the secondary effluent. This study may aid understanding of PhAC removal from various matrices and the effects of PhAC mixtures on membrane fouling by in practical NF/RO membranes applications.

Domestic sewage and secondary effluent treatment using vertical submerged biological filter

Biological filter (bio-filter) exhibits a high potential for sustainability because construction and maintenance cost are low. When bio-filters are used as pre-treatment or post-treatment technology, other treat steps in the combined treat process could prevent clogging and get better process stability and performance efficiency. This study considered bio-filters for reducing the amounts of various wastewaters, i.e., high-strength sewage, municipal wastewater and secondary effluent water, using five kinds of media. The results obtained indicate significant improvement in organics removal when influent COD are 1500 mg/L and 2500 mg/L for anaerobic and aerobic biofilters, respectively. Sufficient alkalinity would obviously improve the substrate removal in an anaerobic bio-filter, when treating high-strength wastewater. The performances of bio-filters are adequate for further removal of the residual organic material and nutrient elements for tertiary domestic wastewater treatment.

Drip Irrigation with Sewage Effluent Increased Salt Accumulation in Soil, Depressed Sap Flow, and Increased Yield of Tomato

AbstractSewage application is a cost‐effective method for meeting the challenge of irrigation in water‐short regions. However, there is concern about the accumulation of salt from sewage effluent in soil. Experiments were conducted for 3 years in a greenhouse to investigate the effects of water quality on salt accumulation in soil and on sap flow for drip‐irrigated tomato. The types of irrigation water used in the experiments included secondary sewage effluent, groundwater, and blended water that was obtained by mixing the secondary sewage effluent and the groundwater in equal volumes. The results demonstrated that soil bulk electrical conductivity (ECb) increased with irrigation rates, and sewage application produced a more rapid increase than did blended water and groundwater treatments. Irrigation throughout the growing season could produce a 21–44% increase in salt content from its initial values to values at harvest, and salt accumulation occurred mainly at the 30–45 cm depth of soil. Sewage irrigation was likely to decrease sap flow but increased tomato yield and improved fruit quality parameters excluding ascorbic acid compared with groundwater irrigation. These results suggest that secondary sewage application using drip irrigation increases salt accumulation in the root zone, and depresses crop transpiration to some extent, but does not have a negative influence on tomato yield and fruit quality. Copyright © 2017 John Wiley &amp; Sons, Ltd.

Identification, Mechanisms and Kinetics of Macrolide Degradation Product Formation under Controlled Environmental Conditions

Erythromycin, azithromycin, clarithromycin and roxithromycin are antibiotics belonging to the widely used macrolide group. Their presence in the environment has been much investigated, despite the rapid degradation of Erythromycin to its spiroketal degradation product. In this study, the formation of macrolide degradation products was investigated in various aqueous solutions, each containing 100 μg/mL of the respective macrolide, under controlled artificial conditions: three phosphate buffer solutions (pH 5, pH 7 and pH 8.5), and a buffer solution at pH 7 with the addition of humic acids. Two solutions from natural sources were also examined: secondary effluent and tap water. The obtained degradation products were identified by their HRMS and NMR spectra (for Erythromycin-spiroketal, obtained from pure compounds isolated by preparative HPLC) as: N-oxide, N-desmethyl and N-didesmethyl forms of all examined macrolides. These degradation products were obtained only under irradiation by sunlight, while the Erythromycin-H2O degradation products were also obtained in the shade. The secondary effluent was the most significant medium for achieving macrolide degradation products. According the degradation product’s t1/2 values obtained in the secondary effluent, the azithromycin was most rapidly degraded (23 hours). Furthermore, results suggested that the degradation process was activated by sunlight irradiation energy, and that the degradation mechanism started with the transfer of an electron from the amine group to O2 to produce the radical ions RMe2N·+ and O2 ·- as intermediates and production of the N-oxide and N-desmethyl macrolide degradation products. The kinetics of macrolide degradation was calculated as a first-order reaction.

Multiresidual analysis of emerging amphetamine-like psychoactive substances in wastewater and river water

Besides the common illicit drugs, such as cocaine, heroin, and marijuana, there is a growing concern about the use of modern “designer drugs” that have emerged in large numbers over the past few years. In this work, a sensitive and selective method for simultaneous determination of 25 synthetic amphetamine-like psychoactive compounds, including amphetamine, sympathomimetic substituted amphetamines, synthetic cathinones and ketamine, in raw wastewater (RW), secondary effluent (SE) and river water was developed. Samples were enriched by solid-phase extraction (SPE) on mixed-mode reversed-phase/strong cation-exchange sorbent (Oasis MCX) and analysed by reversed-phase liquid chromatography coupled to electrospray ionisation tandem mass spectrometry (LC-MS/MS). The target compounds were separated on a Synergi Polar column and detected using multiple reaction monitoring (MRM) in positive ionisation mode. Accurate quantification was achieved by using several deuterated analogues as surrogate standards. Careful optimisation and validation of the procedure resulted in a reliable determination of all target analytes in low ng/L range for all matrices, which makes the method suitable for the application in wastewater-based epidemiology. The method was applied for assessment of selected compounds in municipal wastewater and river water from Croatia. It was shown that most of the wastewater samples contained detectable levels of the well-known synthetic illicit drugs, amphetamine and 3,4-methylenedioxy-methamphetamine (MDMA) (concentrations up to 545ng/L and 55ng/L in RW, respectively), as well as ephedrine (up to 108ng/L) and pseudoephedrine (up to 698ng/L), which are used as ingredients of popular over-the counter cough and cold medications. Other target amphetamine-like psychoactive substances, recently reported for their potential abuse, were detected only occasionally and in low concentrations (<10ng/L).

Analysis of organophosphate flame retardants and plasticisers in water by isotope dilution gas chromatography–electron ionisation tandem mass spectrometry

The widespread use of organophosphate flame retardants (PFRs) in commercial products have led to their increased presence in the environment. In this study, a rapid and reliable analytical method was developed for the analysis of five PFRs in water using gas chromatography tandem mass spectrometry (GC–MS/MS) with electron ionisation (EI) and a run time of 13min. The PFRs investigated were tributyl phosphate (TBP), tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), tris(1,3-dichloro-2-propyl) phosphate (TDCP) and triphenyl phosphate (TPP). Solid phase extraction (SPE) was undertaken to extract and concentrate target analytes from aqueous matrices. All water samples were extracted from a volume of 500mL. Isotopically labelled compounds were used to account for analytical variability and for accurate quantification by isotope dilution. Method recoveries for all compounds were above 80% in all tested water samples. Method detection limits for all target analytes ranged from 0.3 to 24ng/L in ultrapure water, tap water, seawater, surface water, secondary effluent and swimming pool water. Validation of this method confirmed satisfactory method stability with less than 1% coefficients of variation, verifying that this approach produced good reproducibility.

Electrochemical degradation of N,N-diethyl-m-toluamide on a boron-doped diamond electrode

This study investigates the electrochemical oxidation of N,N-diethyl-m-toluamide (DEET) on a boron-doped diamond (BDD) anode under different temperatures, current densities, and sample matrixes. For comparison, a commercial Pt electrode and a lab-prepared PbO2 anode were also tested. The oxidation of DEET on BDD was found to be electrochemically irreversible. The degradation of DEET increased with the increase of current density, but was slightly influenced by temperature (25–75°C). Furthermore, the BDD anode was superior to the Pt and PbO2 electrodes with regard to DEET abatement and total organic carbon (TOC) removal. At 0.75A/cm2 and 50°C, the pseudo-first-order rate constants of DEET oxidation were 5.00×10−3–8.98×10−3s−1 in DEET-spiked 1M Na2SO4 solution, municipal wastewater treatment plant secondary effluent (MWTPSE), groundwater (GW), and river water (RW), significantly greater than that (4.73×10−4s−1) in DEET-spiked industrial wastewater (IW). The TOC removal in the real environmental matrixes followed the order MWTPSE>GW≈RW≫IW. Through electrochemical oxidation, DEET was completely mineralized in the DEET-spiked MWTPSE.

The impact of EfOM, NOM and cations on phosphate rejection by tight ceramic ultrafiltration

Reverse osmosis (RO) systems for secondary effluent water reuse frequently encounter severe biofouling due to the high nutrient concentration in the RO feed water. Deployment of negatively charged tight ceramic ultrafiltration (UF) may restrict biofouling in RO by phosphate limitation, since the tight ceramic UF can reject dissolved phosphate by electrostatic interactions. However, the organic matter and cations can potentially impact phosphate rejection by tight ceramic UF. In this study, the effects of organic matter and Ca2+ on phosphate rejection by the 3kDa tight ceramic UF membrane were investigated, using synthetic water containing natural organic matter (NOM) and effluent organic matter (EfOM), as well as secondary effluent water. Phosphate rejection was found to be linearly correlated to the zeta potential of the organics in the membrane feed water when the membrane was fouled by NOM. Furthermore, the EfOM-fouled membrane yielded higher phosphate rejection than the membrane fouled by the NOM due to additional adsorption of phosphate by the biopolymers. A preferential phosphate rejection was observed during effluent water filtration by the 3kDa tight ceramic UF membrane.

In-depth characterization of secondary effluent from a municipal wastewater treatment plant located in Northern China for advanced treatment

This study provided insight into the characterization of secondary effluent from a wastewater treatment plant located in northeastern China. The secondary effluent was separated into three fractions, the dissolved, the near-colloidal and the suspended, to study their individual characteristics. It revealed that most of the organics in the secondary effluent existed in the dissolved form, accounting for 78.1-86.5% of the total chemical oxygen demand and 82.6-86.6% of the total organic carbon. Results from the molecular weight distribution study further indicated that organics with MW < 1k Da constituted 56.3-62.7% of total organics. Moreover, the particle size distribution study suggested that particles between 2.0 and 6.8 μm in diameter made up 80.0% of the total suspended solids. Both biological oxygen demand/chemical oxygen demand and biological dissolved organic carbon/dissolved organic carbon were measured ranging from 0.2 to 0.3, suggesting the most secondary effluent organics were biologically refractory. This conclusion was further strengthened by the functional groups information obtained from the GC/MS (gas chromatography/mass spectrometry) analysis. The characteristics information revealed from this study will help the design and selection of water quality-specific tertiary treatment technologies for secondary effluent water purification and reuse.

Effect of sludge return ratio on the treatment characteristics of high-efficiency sedimentation tank

An advanced treatment experiment on secondary effluent water of the municipal wastewater treatment plant by utilizing a high-efficiency sedimentation tank was conducted. The removal efficiencies of suspended solids (SS), total phosphorus (TP) and chemical oxygen demand (COD) as well as the characteristics of sludge settling under different sludge reflux ratios were studied. In addition, the optimal working conditions were analyzed in this experiment. The experimental results show that sludge reflux ratio plays an influential role in contaminant removal and sludge settling. In case the reflux ratio is 50%, concentrations of SS, TP and COD in effluent water are 10, 0.48 and 49 mg/L, respectively. The effluent water is up to Grade 1A of the Standard (GB18918-2002), and the sludge can be settled well. The high-efficiency sedimentation tank presented a remarkable effect in removing suspended particles, as suspended substances with particle diameters above 3μm could be removed effectively and those with particle size(s) of or above 12μm could be completely removed. Experimental results show that the adoption of high-efficiency sedimentation tank significantly improves the treatment effects of SS, TP and COD in sewage. The experimental parameters acquired under the optimal working conditions can be served as references for the actual running of high density sedimentation tank in the municipal sewage treatment plant.

A Natural Driven Membrane Process for Brackish and Wastewater Treatment: Photovoltaic Powered ED and FO Hybrid System

In isolated locations, remote areas, or islands, potable water is precious because of the lack of drinking water treatment facilities and energy supply. Thus, a robust and reliable water treatment system based on natural energy is needed to reuse wastewater or to desalinate groundwater/seawater for provision of drinking water. In this work, a hybrid membrane system combining electrodialysis (ED) and forward osmosis (FO), driven by renewable energy (solar energy), denoted as EDFORD (ED-FO Renewable energy Desalination), is proposed to produce high-quality water (potable) from secondary wastewater effluent or brackish water. In this hybrid membrane system, feedwater (secondary wastewater effluent or synthetic brackish water) was drawn to the FO draw solution while the organic and inorganic substances (ions, compounds, colloids and particles) were rejected. The diluted draw solution was then pumped to the solar energy driven ED. In the ED unit, the diluted draw solution was desalted and high-quality water was produced; the concentrate was recycled to the FO unit and reused as the draw solution. Results show that the water produced from this system contains a low concentration of total organic carbon (TOC), carbonate, and cations derived from the feedwater; had a low conductivity; and meets potable water standards. The water production cost considering the investment for membranes and solar panel is 3.32 to 4.92 EUR m(-3) (for 300 days of production per year) for a small size potable water production system.

Sustainable biodegradation of phenolic endocrine-disrupting chemicals by Phragmites australis–rhizosphere bacteria association

The efficacy of two rhizobacteria (Sphingobium fuliginis TIK1 and Sphingobium sp. IT4) of Phragmites australis for the sustainable treatment of water polluted with phenolic endocrine-disrupting chemicals (EDCs) was investigated. Strains TIK1 and IT4 have recently been isolated from Phragmites rhizosphere and shown to degrade various 4-alkylphenols-TIK1 via phenolic ring hydroxylation and meta-cleavage and IT4 via ipso-hydroxylation. The two strains also degraded bisphenol A (BPA), bisphenol B, bisphenol E, bisphenol F, bisphenol P and bisphenol S (BPS). Thus, strains TIK1 and IT4 have wide degradation spectra for phenolic EDCs. The two strains utilized Phragmites root extracts as a sole carbon source and sustainably colonized Phragmites roots, where they degraded phenolic EDCs. In sequencing batch reactor experiments using Phragmites in association with TIK1 or IT4, both associations repeatedly removed phenolic EDCs from polluted secondary effluent water (BPA, BPS, 4-tert-butylphenol, 4-tert-octylphenol and 4-nonylphenol) from polluted secondary effluent water. The results suggest that hydroponic systems using Phragmites-TIK and Phragmites-IT4 associations would be useful for sustainable treatment of polluted waters containing various phenolic EDCs.

A novel hybrid process of reverse electrodialysis and reverse osmosis for low energy seawater desalination and brine management

This paper introduces a novel concept for a hybrid desalination system that combines reverse electrodialysis (RED) and reverse osmosis (RO) processes. In this hybrid process the RED unit harvests the energy in the form of electricity from the salinity gradient between a highly concentrated solution (e.g., seawater or concentrated brine) and a low salinity solution (e.g., biologically treated secondary effluent or impaired water). The RED-treated high salinity solution has a lower salt concentration and serves as the feed solution for the RO unit to reduce the pump work. The concentrated RO brine provides the RED unit a better high salinity source for the energy recovery compared to seawater. In addition, the concentration of the discharged brine can be controlled by the RED unit for improving the water recovery and minimizing the impact on the environment. Different configurations of the hybrid RED–RO processes are presented for a comparative study on the basis of mathematical modeling. Specifically, various operating conditions for the RED unit are investigated for better adaptation to the hybrid system. The variations of the total specific energy consumption and the discharge brine concentration for various hybrid modes are simulated to verify the conceptual designs. The modeling results indicate that the RED–RO hybrid processes could substantially reduce the specific energy consumption and provide a better control of the discharge brine concentration in comparison to conventional seawater desalination RO processes.

Antibacterial activity of heavy metal-loaded natural zeolite

The antibacterial activity of natural zeolitized tuffs containing 2.60 wt.% Cu 2+, 1.47 Zn 2+ or 0.52 Ni 2+ were tested. Antibacterial activities of the zeolites against Escherichia coli and Staphylococcus aureus were tested after 1 h and 24 h of exposure to 1 g of the zeolite in 100 mL of three different media, namely Luria Bertani, synthetic wastewater and secondary effluent wastewater. The antibacterial activities of the zeolites in Luria Bertani medium were significantly lower than those in the other media and negatively correlated with the chemical oxygen demand of the media. The Ni-loaded zeolite showed high leaching of Ni 2+ (3.44–9.13 wt.% of the Ni 2+ loaded) and weak antibacterial activity in the effluent water. Since Cu-loaded zeolite did not leach Cu 2+ and the leaching of Zn 2+ from Zn-loaded zeolite was low (1.07–1.61 wt.% of the Zn 2+ loaded), the strong antibacterial activity classified the Cu- and Zn-loaded zeolite as promising antibacterial materials for disinfection of secondary effluent water.

AN EMPIRICAL MODEL FOR BUILD-UP OF SODIUM AND CALCIUM IONS IN SMALL SCALE REVERSE OSMOSIS

A simple models for predicting build-up of solute on membrane surface were formulated in this paper. The experiments were conducted with secondary effluent, groundwater and simulated feed water in small-scale of RO with capacity of 2000 L/d. Feed water used in the experiments contained varying concentrations of sodium, calcium, combined sodium and calcium. In order to study the effect of sodium and calcium ions on membrane performance, experiments with ground water and secondary effluent wastewater were also performed. Build-up of salts on the membrane surface was calculated by measuring concentrations of sodium and calcium ions in feed water permeate and reject streams using Atomic Absorption Spectrophotometer (AAS). Multiple linear regression of natural logarithmic transformation was used to develop the model based on four main parameters that affect the build-up of solute in a small scale of RO namely applied pressure, permeate flux, membrane resistance, and feed concentration. Experimental data obtained in a small scale RO unit were used to develop the empirical model. The predicted values of theoretical build-up of sodium and calcium on membrane surface were found in agreement with experimental data. The deviation in the prediction of build-up of sodium and calcium were found to be 1.4 to 10.47 % and 1.12 to 4.46%, respectively. Keywords: build-up, membrane, model, osmosis, water

A Comparative Analysis of Odour Treatment Technologies in Wastewater Treatment Plants

Biofiltration, activated sludge diffusion, biotrickling filtration, chemical scrubbing, activated carbon adsorption, regenerative incineration, and a hybrid technology (biotrickling filtration coupled with carbon adsorption) are comparatively evaluated in terms of environmental performance, process economics, and social impact by using the IChemE Sustainability Metrics in the context of odor treatment from wastewater treatment plants (WWTP). This comparative analysis showed that physical/chemical technologies presented higher environmental impacts than their biological counterparts in terms of energy, material and reagents consumption, and hazardous-waste production. Among biological techniques, the main impact was caused by the high water consumption to maintain biological activity (although the use of secondary effluent water can reduce both this environmental impact and operating costs), biofiltration additionally exhibiting high land and material requirements. From a process economics viewpoint, technologies with the highest investments presented the lowest operating costs (biofiltration and biotrickling filtration), which suggested that the Net Present Value should be used as selection criterion. In addition, a significant effect of the economy of scale on the investment costs and odorant concentration on operating cost was observed. The social benefits derived from odor abatement were linked to nuisance reductions in the nearby population and improvements in occupational health within the WWTP, with the hybrid technology exhibiting the highest benefits. On the basis of their low environmental impact, high deodorization performance, and low Net Present Value, biotrickling filtration and AS diffusion emerged as the most promising technologies for odor treatment in WWTP.

Evaluation of Biological Activated Carbon (BAC) process in wastewater treatment secondary effluent for reclamation purposes

The effects of two different granular activated carbon (GAC) types (steam activated, PK1–3 and chemically activated, CAgran) on dissolved organic carbon (DOC) removal, nitrification and denitrification were evaluated in BAC columns for wastewater reclamation/reuse purposes. Continuous-flow laboratory-scale BAC columns were operated for 320 days using the secondary effluent water of Pasakoy Advanced Wastewater Treatment Plant. During the first 83 days of column operation, when adsorption was the dominant mechanism, the average DOC removal efficiency was 81% for PK1–3 and 64.5% for CAgran. Later on, the efficiencies dropped to 45.9% for PK 1–3 and 37.8% for CAgran, which shows the operational time period when breakthrough is reached and DOC removal is dominantly due to biodegradation. BAC columns were also capable of removing total nitrogen; removal efficiencies were observed to be 54.0% for the biofilter packed with PK1–3 and 51.5% for the one packed with CAgran. The results also showed that DOC and ammonia nitrogen concentrations immediately decrease due to dilution and biodegradation at the top of the BAC columns. This study establishes that a carefully operated BAC system, which was used for tertiary treatment of a secondary effluent, can remove organic carbon and total nitrogen to a significant extent.

Flow-through immunomagnetic separation system for waterborne pathogen isolation and detection: Application to Giardia and Cryptosporidium cell isolation

Simultaneous sample washing and concentration of two waterborne pathogen samples were demonstrated using a rotational magnetic system under continuous flow conditions. The rotation of periodically arranged small permanent magnets close to a fluidic channel carrying magnetic particle suspension allows the trapping and release of particles along the fluidic channel in a periodic manner. Each trapping and release event resembles one washing cycle. The performance of the magnetic separation system (MSS) was evaluated in order to test its functionality to isolate magnetic-labelled protozoan cells from filtered, concentrated tap water, secondary effluent water, and purified water. Experimental protocols described in US Environmental Protection Agency method 1623 which rely on the use of a magnetic particle concentrator, were applied to test and compare our continuous flow cell separation system to the standard magnetic bead-based isolation instruments. The recovery efficiencies for Giardia cysts using the magnetic tube holder and our magnetic separation system were 90.5% and 90.1%, respectively, from a tap water matrix and about 31% and 18.5%, respectively, from a spiked secondary effluent matrix. The recovery efficiencies for Cryptosporidium cells using the magnetic tube holder and our magnetic separation system were 90% and 83.3%, respectively, from a tap water matrix and about 38% and 36%, respectively, from a spiked secondary effluent matrix. Recoveries from all matrices with the continuous flow system were typically higher in glass tubing conduits than in molded plastic conduits.