Ogni antibiotico è efficace in relazione a un determinato gruppo di microrganismi
comprare ciprofloxacina online in italiain caso di infezioni oculari vengono scelte gocce ed unguenti.
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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
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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).
Source: http://www.ijimt.org/papers/495-H0010.pdf
11402 • The Journal of Neuroscience, December 10, 2003 • 23(36):11402–11410 Imaging Reveals Synaptic Targets of a Swim-TerminatingNeuron in the Leech CNS Adam L. Taylor,1,2 Garrison W. Cottrell,1 David Kleinfeld,3 and William B. Kristan Jr21Department of Computer Science and Engineering, 2Neurobiology Section, Division of Biological Sciences, and 3Department of Physics, University ofCalifornia, San Diego, La Jolla, California 92093
Journal ofApplied Ichthyology J. Appl. Ichthyol. 27 (2011), 796–798 Received: March 28, 2010 2011 Blackwell Verlag, Berlin Accepted: December 18, 2010 Effects of the prebiotics Immunoster and Immunowall on growth performance ofjuvenile beluga (Huso huso) By R. TaÕati1, M. Soltani2, M. Bahmani3 and A. A. Zamini4 1Department of Fisheries, Islamic Azad University, Talesh Branch, Talesh, Iran; 2Department of Aquatic Animal Health, Faculty ofVeterinary Medicine, University of Tehran, Tehran, Iran; 3International Sturgeon Research Institute, Rasht, Iran; 4Department ofFisheries, Islamic Azad University, Lahijan Branch, Lahijan, Iran