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International Journal of Innovation, Management and Technology, Vol. 5, No. 2, April 2014 Ampicillin Removal by Polyvinylidene Difluoride (PVDF), Polyethersulfone (PES) and Nylon for Membrane Bioreactor Application Ruby S. Labinghisa and Analiza P. Rollon 1
oxidation processes (AOPs) and adsorption. Though high Abstract—Micropollutants comprising of pharmaceutically
drug and COD removal rates were achieved in these bench- active compounds (PhACs) are usually not degraded or
scale experiments, they are not suitable for full-scale removed in conventional wastewater treatment systems and
wastewater treatment plant (WWTP) due to their high cost. are persistent in aquatic environment. This study determined
Pharmaceutical wastewater may contain diverse refractory the rejection of ampicillin by hydrophobic and hydrophilic
membranes, the effects of operational parameters such as flow
organic materials that cannot be readily degraded. rate (1.4 and 2.2 mL/min), influent concentration (40, 70 and
Biological treatment is still a viable choice for treatment in 100 ppb) and the extent of biodegradation and adsorption of
addition to physicochemical processes [1]. Existing ampicillin in batch membrane bioreactor with and without
wastewater-treatment facilities should be upgraded and nitrification. Ampicillin (AMP) removal was higher in the
implementation of new technologies is envisaged as the next bioreactor where nitrification occurred and at lower
step in improvement of wastewater treatment. Interest in concentration and flow rates. The results showed that
membrane bioreactor (MBR), with combined biological
membrane bioreactor (MBR) technology for wastewater is degradation and membrane filtration is a viable system for
rapidly increasing worldwide [2]. Although efficient, ampicillin removal. Besides biodegradation in the bioreactor,
common drawbacks of membrane filtration for wastewater the cake layer deposited over the membrane surfaces played an
treatment are the high operating costs and membrane important role in AMP rejection. A big part of the removal by
fouling. Many researchers have recently devoted their the membrane system was attributed to the sieving and
efforts in significantly reducing the operation cost for adsorption onto the cake layer.
membrane systems. However, fouling problem remains to be a major obstacle to membrane technology [3]. Factors considered to be related to fouling and efficiency of MBRs that this study aims to examine are the hydrophobicity of the pollutant as well as the membrane used and several operational parameters such as flow rate and influent Antibiotics are drugs specifically designed to treat or concentration. The main removal mechanisms for micropollutants such as endocrine disrupting compounds prevent infective diseases in human or animal body. Its use (EDCs) and pharmaceutically active compounds (PhACs) has become indispensable in human life and the global are through biological degradation and sorption to particles market consumption increase steadily every year. Human [4]. Knowledge on factors affecting PhAC removal is environments, medical wastes, farms, pharmaceutical and important as wastewater treatment plants (WWTPs) are not hospital sewage residues may contain various antibiotics specifically designed to reduce them. Commonly cited and antibiotic resistance genes that can contaminate natural factors are hydrophobicity or hydrophilicity of pollutant and environments. Its exposure in aquatic environment may characteristics, increase the number of antibiotic resistant bacteria, posing a biodegradability of pollutant, operational parameters (e.g. serious threat to public health in that more and more sludge retention time, hydraulic retention time, pollutant infections may no longer be treatable with known antibiotics. influent concentrations, pH and temperature) as mentioned Ampicillin (AMP) is one of the most widely used in the studies conducted by Paetkau. Biological degradation antibiotics. Though quite expensive, this wastewater must particularly in nitrifying conditions was recommended for be treated properly prior to the release into environment. these compounds. As suggested by Gaulke, current trend on The present studies to treat the chemical synthesis-based EDC such as estrogen degradation highlights the need for pharmaceutical wastewaters mainly focus on physical and nitrification to achieve high removal. Their study showed chemical treatment, such as UV/ZnO photo-catalytic that chemical reaction through the transformation of process, photo-Fenton process, ultrasonic process, advanced estrogen with ammonia oxidizing bacteria is seen as estrogen degradation in wastewater treatment. As sorption Manuscript received November 22, 2013; revised February 13, 2014. and biodegradation are considered significant removal This work was supported in part by the Department of Science and mechanism, hydrophobicity of both pollutant and membrane Technology-Engineering Research and Development for Technology. Analiza P. Rollon is with the Department of Chemical Engineering, are important [5]. Discussed in the study by Schuman, College of Engineering, University of the Philippines 1101, Philippines (e- hydrophobic character of a compound can be indicated by mail: [email protected]). Ruby S. Labinghisa is with the Environmental Engineering Program, ow value [6]. This is the partition coefficient between University of the Philippines Diliman 1102, Philippines (e-mail: octanol and water for a given compound. Gaulke also [email protected]). International Journal of Innovation, Management and Technology, Vol. 5, No. 2, April 2014 mentioned that sorption to biosolids is dependent on solid- through the membrane filter in a time interval was water distribution coefficient, Kd [5]. Study on solute determined by measuring the weight of the effluent rejection during membrane filtration of activated sludge, receiving flask before and after the time interval. Volume showed that hydrophobic membrane always have greater was also measured using 10 and 100mL graduated cylinders. solute rejection than that of hydrophilic membrane [7]. Thus, C. Reactor Operation and Monitoring the effects of different membranes and their hydrophobicity is included in this study. To start up, the reactor was seeded with a sludge taken This study aims to determine the applicability of aerobic from an aerobic wastewater treatment system of a shopping membrane bioreactors in removing ampicillin (AMP) in mall. At the start, these were fed with sodium acetate (400 wastewater. Specifically, this study aimed to determine: (1) mg TCOD/L) as the organic substrate for 2 weeks until a the effect of nitrification on biological ampicillin removal, stable sludge was achieved at around 3.5 – 4 g/L. Presence (2) the effects of influent flow and AMP concentration on and extent of nitrification was also monitored. Sample (200 AMP removal, (3) the AMP removal behavior by different mL) was taken from the reactor every 3-4 days for the membrane materials as characterized by their rejection and analysis of ammonium-nitrogen (NH3-N) and nitrate- their hydrophilicity or hydrophobicity, and (4) the removal nitrogen (NO3-N). MLSS, MLVSS, NH3-N, NO3-N was mechanism of AMP in the system, either by biodegradation measured every 3-4 days, TCOD, SCOD every 2 days, and or adsorption to cake sludge and to membrane. pH was monitored everyday using standard procedure. The target pollutant, AMP was spiked starting 1 μg/L until 100 II. MATERIALS AND METHODS D. Analytical Methods A. Overview The measurements of MLSS, MLVSS, TCOD, SCOD, The system was first acclimatized by feeding the NH3-N, NO3-N were based on standard procedure. TCOD and SCOD was measured using dichromate digestion high micronutrients until stable mixed liquor suspended solids range. Hach colorimeter D-790 was used in measuring. (MLSS), mixed liquor volatile suspended solids (MLVSS), AMP used was Sodium ampicillin and was measured using and consistent COD removal were achieved. The minimal spectrophotometric method according to Khan et al. on incubation medium used in the batch tests was based on Shimadzu UV-VIS [9]. Stanier medium as also used by De Gusseme [8]. Once nitrification was achieved as shown by regular ammonia-nitrogen and nitrate-nitrogen monitoring, target pollutant (ampicillin) was spiked in both systems without A. Bioreactor Performance during Acclimatization (system A) and with (system B) nitrification. Ampicillin without Filter (AMP) was monitored every 3-4 days. When the systems During acclimatization of the system with nitrification, were already acclimatized as shown by AMP removal, batch from the 9th day of the run, conversion of ammonia to nitrate mode of experiment was started to determine the effect on began to occur as indicated by a decrease in NH3-N and AMP removal by nitrification, varying the influent increases in NO3-N. To maintain the pH in the range 7.5-8.0, concentration, flowrate, and membranes (hydrophobic sodium hydroxide was added. Nitrification generates H+ as polyethersulfone and polyvinylidene difluoride, and shown in (1) and (2). hydrophilic nylon). Also removal mechanism was studied by measuring the biodegraded AMP in the influent before NO2 + 3H+ + 2e- (1) passing the membranes and the AMP removed by measuring the effluent after passing the wastewater through NO3 + 2H+ + 2e- (2) the membranes (sorption). Kinetics of AMP removal was The pH decrease accompanying the conversion of also determined at various influent concentrations, flowrates ammonia to nitrate supports the occurrence of nitrification and signifies growth of nitrifying bacteria in the bioreactor.
B. Experimental Set-up Systems A (without nitrification) and B (with nitrification) A 4 L Erlenmeyer flask reactor was aerated using air were acclimatized. The systems began stabilizing in terms diffuser stones and the silicon tubing was used since plastics of conversion rates around day 19. From this day, the MLSS could affect the compounds. The system was operated in and MLVSS levels were 3.5 - 4 g/L MLSS and 1-2 g/L batch mode. It was mixed during feeding and sampling of MLVSS. At this time, the ammonium-nitrogen (NH3-N) and MLSS using magnetic stirrer regulated at 180 rpm based on nitrate-nitrogen (NO3-N) was then monitored at System B to Chang et al. [7]. determine if nitrification was taking place. Sodium acetate The syringe filters used had the same specifications, was fed as organic substrate (400 mg COD/L) to maintain a Whatman Puradisc 0.45 μm pore size, 25 mm diameters and stable sludge concentration at the range 3,000-4,000 mg/L filter areas of 4.2 cm2. Only the membrane materials differ MLSS, which is a typically applied value for membrane using hydrophilic Nylon, slightly hydrophobic (60%) bioreactors [10]. As shown in Fig. 1, TCOD values in Polyethersulfone (PES) and hydrophobic Polyvinylidine succeeding batch gradually decreased starting from 505.33 difuoride (PVDF). mg/L TCOD and 339 mg/L SCOD, the value dropped to The permeate flux was manually measured in relation to 26.5 mg/L TCOD and 47.33 mg/L SCOD at the end of membrane fouling. The mass of the effluent that passed acclimatization period. International Journal of Innovation, Management and Technology, Vol. 5, No. 2, April 2014 There were previous studies that explored ways to enhance the removal, degradation or both of micropollutants such as endocrine disrupting compounds (EDCs). De Gusseme et al. on using nitrifier enriched culture (NEC) for 17α–ethinylestradiol (EE2) concluded that nitrifying MBR offers opportunities as a promising add-on technology for WWTP effluent polishing [8]. The study by Clara et al. demonstrated degradation of EE2 by a nitrifying sludge with a high ammonium (NH + 4 ) oxidizing activity [11]. These authors brought forward the concept that nitrifiers initially Fig. 1. TCOD and SCOD levels in the system with nitrification (B) during degrade EE2 into intermediates that subsequently serve as a acclimatization at sequencing batch mode. substrate for heterotrophic microorganisms. On the other These decreases in TCOD and SCOD showed that hand, De Gusseme et al. suggested that the primary microorganisms present in the system were able to feed on mechanism for EE2 degradation is more likely linked to the acetate, the organic substrate. AMP was then spiked to the activity of heterotrophic bacteria [8]. They suggested that bioreactor beginning at 1 µg/L and AMP concentration was the EE2 removal by axenic cultures of ammonia-oxidizing gradually increased to a final concentration of 100 µg/L (or bacteria (AOB) is only due to the abiotic nitration reaction 100 ppb). The AMP levels during sequencing batch runs in with EE2, which is governed by the high NO2-N levels after systems without (A) or with nitrification (B) decreased from oxidation of the high NH4-N concentrations in batch tests. 100 ppb at the beginning of each new batch to below 10 Besides the application of nitrifiers in EDC removal, studies µg/L (Fig. 2). This AMP decrease indicates that both on PhACs mainly focused on AOPs and some are coupled systems were able to degrade the added AMP in the one- with biological treatment. In this study nitrification was month duration of acclimatization. found to enhance ampicillin removal. B. Effect of Nitrification on AMP Removal Simultaneous sequencing MBR runs with and without nitrification were done for two weeks. The TCOD and SCOD removal values without nitrification (system A) were 37.32% and 27.89%, respectively (Fig. 3). The TCOD and SCOD removal values were higher with nitrification (system B), i.e., 59.97% and 60.04%, respectively. The systems had a stable sludge concentration throughout the runs, i.e., in the range 3,000-4,000 mg/L, which is typically maintained in MBRs [10]. For AMP removal, the average was 78.13% and 87.60% in systems A and B, respectively. Ampicillin and COD removal was greater in the system with nitrification than without nitrification. The nitrifiers could have initially degraded AMP into intermediates that subsequently serve as a substrate for heterotrophic organisms. Fig. 3. TCOD and SCOD levels in the MBR without nitrification (A) and system with nitrification (B). Vertical lines denote the time of feeding the reactor with fresh influent. C. Ampicillin (AMP) Removal via Membrane Filtration 1) Effects of influent AMP concentrations removal for PES, nylon and PVDF membranes In general, the percent AMP removal at the same duration of run (250 min) increased as the influent concentration decreased from 100 ppb to 40 ppb. The total amounts of AMP removed within 250 min were similar at different Fig. 2. Ampicillin level in system A without nitrification (a) and system B initial AMP concentrations. The AMP removal rates were with nitrification (b). Vertical lines denote the time of feeding the reactor the same for a given membrane regardless of initial with fresh influent. International Journal of Innovation, Management and Technology, Vol. 5, No. 2, April 2014 concentration. Hence, the concentration of AMP after 250 different influent AMP concentration study could not give minutes decreased as initial concentration decreased (Fig. 4). indications on whether AMP has inhibitory or limiting Among membranes the removal rates were 35-45, 30-40 effects on the microorganisms present in the MBR system. and 35-60 g/L/250 min for PES, Nylon and PVDF 2) Effects membranes, respectively. It is interesting to note that PES The rates of decrease in AMP concentration with time and PVDF are hydrophobic while the Nylon membrane used were higher at lower flow rate (1.4 mL/min) than those at was hydrophilic. The latter membranes are suitable for use higher flow rate (2.2 mL/min) as shown in Fig. 5. The with a wide range of biological preparations and can be used removal rates among the three membranes were higher where other membranes are unsuitable or difficult to use using PES and PVDF membrane materials (Fig. 6). The due to its characteristic. mass flow rate for Nylon is the highest among the other The cake sludge formed through time on the membrane membranes, considering that the same filter area was used probably aided in removing AMP as the reactor broth in all runs. This was probably because Nylon is hydrophilic, passed through the membrane filter. allowing higher permeates across its membrane. The higher AMP removal at lower flow rate was probably due to the corresponding longer hydraulic retention time (HRT), i.e., longer time that the wastewater remained in the bioreactor prior to its flow through the membrane filter. Paetkau suggested that longer HRTs (greater than 10 hours) are associated with high micropollutant levels [4]. At longer HRT, the microorganisms present in the system have greater time to grow and consume or degrade the pollutant (substrate) and become better adapted in degrading the micropollutants. Moreover, lower flow rate probably enabled enough time for formation of sludge cake on the filter, thereby aiding the removal of the pollutant (AMP in this study). As corroborated by the mass permeate data for each flow rate, the lower flow rate would also enable AMP to be adsorbed to the sludge/filter membrane. 3) Effects of membrane materials As earlier mentioned, the highest AMP removal (thus, lowest effluent AMP effluent concentration) was that by hydrophobic PVDF, followed by slightly (60% based on hydrophobic PES, and then that of hydrophilic Nylon [2]. The mass permeate of each membrane, which was highest for Nylon and lowest for PES, had an effect on the AMP removal. The effect was probably due to sludge cake formation on the membrane. Maximous et al. [2] suggested that the relatively higher cake resistance (a factor of permeate flux) of the membranes rationalize the increased solute rejection in the hydrophobic membrane. This means that the deposited cake layer plays an important role in solute rejection. Choi and Ng determined the effect of membrane types and material on performance of submerged membrane bioreactor [12]. Fig. 4. AMP in MBR at 2.2 mL/min flow through (a) PES, (b) PVDF and (c) nylon membrane (top to bottom). At 4 hours duration of each runs, the membrane filter and probably also the cake sludge formed on the membranes were only able to almost completely remove the AMP at lower influent concentration. If the run duration is extended to several days or weeks, the microorganisms that attached, retained and developed on the cake sludge could have adapted to the prevailing influent AMP. The results of the above MBR runs using different membrane materials and at International Journal of Innovation, Management and Technology, Vol. 5, No. 2, April 2014 The removal across the membrane in the first hour was 7 ppb, and as the cake sludge formed, the AMP removed increased until the removal reached 84 ppb in 8 hours. Hence, besides filtration, the adsorbed colloids and sludge on the membrane enhanced the AMP rejection over time. Espinasse et al. suggested that besides the obvious rejection of pollutant, the formation of a deposit on the membrane surface generally changes its properties, which would later affect membrane fouling and solute rejection [13]. This is an important problem for applications that are very sensitive to the surface properties, as in food and pharmaceutical industries. Fouling happens when a natural dispersion is ultra-filtered. In this study the colloidal range was only in macrofiltration level. Fouling is often the consequence of the concentration of colloids (macromolecules or sub-micronic particle). However, these adsorption of suspended particles on the membrane also lessens the permeate flux and can cause fouling. The cumulative removal in the influent of the reactor was 6 ppb AMP for the first hour until it reached 47 ppb at the end of the run. Thus, while there was a removal after filtration, biodegradation was also taking place, and aided removal even before membrane filtration. For nylon, the run was done for 13 hours. Across the membrane filters, removals were 9 ppb for the first hour, and continued to increase at the succeeding time intervals. This increase was Fig. 5. Effect of flow rate on AMP removal in MBR using PES, PVDF and probably mainly due to possible formation of sludge cake nylon membrane (top to bottom). on the membrane surface. After 13 hours, the cumulative AMP removal across nylon was 72 ppb. They found a lower Total Organic Carbon (TOC) level in In PES, the removal across the membrane in the first hour the permeate compared to the supernatant and they was 7 ppb, and as the cake sludge formed, the AMP attributed this to a possible combination of biodegradation removed increased until the removal reached 84 ppb in 8 h. by the biofilm (cake layer) developed on the membrane For PVDF, the run was done for 14 hours. The surface and further filtration by cake layer and narrowed cumulative AMP removal across the PVDF membrane pores. Hydrophobic membranes tend to have lower started with 7 ppb until 19 ppb for the first hour. After 14 permeate as discussed in previous section, thus cake sludge hours, the cumulative AMP removal across PVDF was 85 is formed resulting in higher cake sludge resistance and higher rejection of micropollutant. Summarizing the results, the effect of varying operational parameters such as flow rate and influent concentration had a significant effect on the AMP removal. Lower flow rates resulted in higher AMP removal due to longer time for the sludge cake to be formed and for solutes to be adsorbed on the sludge cake and membrane layers. The study also found that higher influent concentration resulted in higher AMP effluent concentrations. This study however was not able to determine if the higher AMP concentration had a limiting effect on the substrate removal and growth of microorganisms present in the reactor. The results of this study also suggest that cake layer and fouling resistances of hydrophobic membranes such as Fig. 6. AMP effluent of different membrane materials at 100 ppb and 2.2 PVDF and that of slightly hydrophobic PES are always higher than those for hydrophilic membranes such as nylon. 4) AMP removal mechanism: biodegradation and Since cumulative AMP removal through time was adsorption increasing, adsorption to cake sludge played an important For PES membrane, the cumulative removal of AMP was role in AMP removal mechanism. AMP is removed partly monitored and for this membrane material, the mass via adsorption onto the membranes and through membrane permeate became constant after nine hours. The cumulative AMP removal (as indicated by the decreasing AMP concentration in the reactor and prior to the membrane) increased in time suggesting that biodegradation was taking place inside the bioreactor. This study has found that MBRs using suitable membrane

International Journal of Innovation, Management and Technology, Vol. 5, No. 2, April 2014 materials is a promising option for AMP removal from Department of Water and Sanitation in Developing Countries effluents of treatment systems treating domestic or municipal sewage. This study has shown the effects of the [6] E. Schuman, "Fate of human pharmaceuticals in biological treatment parameters and type of membrane materials on ampicillin environmental conditions," M.Sc. Thesis, Sub-department of (AMP) removal in membrane bioreactor application. It has also determined the type of kinetic equation that describes Netherlands, July 2008. AMP removal via biodegradation and via combined [7] I. S. Chang, S. O. Bag, and C. H. Lee, "Effects of membrane fouling on solute rejection during membrane filtration of activated sludge," biodegradation and membrane filtration system. Process Biochemistry, vol. 36, pp. 855–860, March 2001. [8] B. de Gusseme, B. Pycke, T. Hennebel, A. M. Siegfried, E. A. Effect of Nitrification Vlaeminck, H. Noppe, N. Boon, and W. Verstraete. (May 2009). The occurrence of nitrification or the presence of Biological removal of 17α -ethinylestradiol by a nitrifier enrichment culture in a membrane bioreactor. Bioscience Engineering, Ghent University, Gent, Belgium. Water Research. [Online]. 43. pp. 2493– biodegradation. AMP degradation takes place with or 2503. Available: http://www.elsevier.com/locate/waters. 2009.
without nitrification but its rate and extent are higher when [9] A. A. P. Khan et al. (May 2011). Spectrophotometric methods for the nitrification is present. The average AMP removal was determination of ampicillin by potassium permanganate and 1-chloro-2, 4-dinitrobenzene in pharmaceutical preparations. Arabian Journal 78.13% and 87.60% in systems A (without nitrification) and Chemistry. B(with nitrification) , respectively. [10] L. Patacsil, "Evaluation of the performance of a lab-sclae submerged B. Effect of Operational Parameters at Different membrane bioreactor for the continuous removal of 17β-estradiol (E2) Membrane Materials and 17α-ethinylestradiol (EE2)," Ph.D. dissertation, Environmental Engineering Program, University of the Philippines-Diliman, Quezon The percent AMP removal was lower at higher influent City, Philippines, May 2012. concentration. However, the amounts of AMP removed [11] M. Clara, B. Strenn, O. Gans, E. Martinez, N. Kreuzinger, and H. were the same regardless of initial influent concentration. Removal of selected pharmaceuticals, fragrances and endocrine disrupting compounds in a membrane bioreactor and That is, the AMP removal rates were the same for a given conventional wastewater treatment plants," Water Research, vol. 39, membrane material regardless of initial AMP concentration. pp. 4797-4807, November 2005. Higher AMP removal rates were achieved at lower flow [12] J. H. Choi and H. Y. Ng, "Effect of membrane type and material on performance of a submerged membrane bioreactor," Chemosphere, rates. Among the three membranes evaluated in this study, vol. 71, pp. 853–859, March 2008. the PES and PVDF membranes, which are hydrophobic and [13] B. Espinasse, P. Bacchin, and P. Aimar, "Filtration method slightly hydrophobic achieved higher AMP removal at 47% characterizing the reversibility of colloidal fouling layers at a membrane surface: analysis through critical flux and osmotic and 54%, respectively. Nylon, which is hydrophilic, pressure," Journal of Colloid and Interface Science, vol. 320, pp. achieved lower AMP removal of 32%. Hydrophobic 483-490, April 2008. membranes (PES and PVDF) showed greater solute and Analiza P. Rollon was born in Manila,
AMP rejection than hydrophilic membrane (Nylon). Philippines on April 10, 1963. She obtained degrees on bachelor of science in chemical C. AMP Removal Mechanism engineering in 1985 and M.S. chemical In the MBR system, AMP is removed via biodegradation, engineering in 1992 from the University of the filtration by the membrane material and the sludge cake Philippines, Diliman, and M.S. environmental science and technology in 1993 and Ph.D. in formed. The predominant removals were attributed to the environmental technology in 1999 at the sieving and/or adsorption onto the cakes as higher removal was observed until constant permeate flux (PES was Institute of Infrastructural, Hydraulic and Environmental Engineering, The Netherlands. She is an associate professor of the Department of 9.33µg/L-hr, Nylon was 5.54µ/L-hr and PVDF was Chemical Engineering, University of the Philippines, Diliman, Quezon 6.07µg/L-hr). Some parts of the pollutant were adsorbed City. Her research works are mainly on liquid and solid waste treatment into the membrane pores and surfaces. In time, as the latter technologies. She is a member of the Asian Society of Environmental Biotechnology. thickens, the cake layer resistance slows down AMP Ruby S. Labinghisa was born on July 20, 1987
in Iloilo City, Philippines. The author finished
her bachelor's degree in agricultural engineering [1] P. Zhou, C. Su, B. W. Li, and Y. Qian, "Treatment of High-Strength major in Land and Water Resources Engineering Pharmaceutical Wastewater and Removal of Antibiotics in Anaerobic at the University of the Philippines Los Baños, and Aerobic Biological Treatment Processes," Journal of Laguna last April 2009, Philippines and her Environmental Engineering, vol. 132, pp. 129-136, January 2006. master's degree in environmental engineering at [2] N. Maximous, G. Nakhla, and W. Wan, "Comparative assessment of the University of the Philippines Diliman, hydrophobic and hydrophilic membrane fouling in wastewater Quezon City, Philippines last November 2013. applications," Journal of Membrane Science, vol. 339 pp. 93–99, She previously worked as a technical staff in Philippine Center for Postharvest Development and Mechanization, Science City of Muñoz, [3] M. Wan, H. Yang, C. Chang, F. Reguyal, and C. Kan, "Fouling Nueva Ecija, Philippines and as an engineer in National Irrigation Elimination of PTFE Membrane under Precoagulation Process Administration Province of Iloilo, Philippines. Currently, she is an Combined with Ultrasound Irradiation," Journal of Environmental environmental management specialist in Environmental Management Engineering, vol. 138, pp. 337-343, March 2012. Bureau of Region VI, Philippines. [4] M. R Paetkau, "Comparison of Ethinylestradiol and Nitrogen Ms. Labinghisa recently became a member (M) of Asia-Pacific Removal in a Conventional and Simultaneous Nitrification - Chemical, Biological and Environmental Engineering Society Denitrification Membrane Bioreactor," M.Sc Thesis, Biosystems (APCBEES). She is also a member of Philippine Society of Engineering, University of Manitoba, Winnipeg, March 2011. Agricultural Engineers. [5] Gaulke, Linda S. (March 25, 2010). How are endocrine disrupting compounds removed in wastewater treatment facilities? the Swiss Federal Institute of Aquatic Science and Technology (EAWAG).

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