In addition, when 10 ppm or 100 ppm PAC was added, the LP culture caused less total resistance of the membrane compared to the NP culture. Membrane resistances for both the NP and LP cultures using the Resistance-in-Series model at various concentrations of the PAC such as 0, 10 and 100 ppm; (a) Total resistance (Rt), (b) Resistance of cake layer (Rc), (c) Resistance of pore block (Rp. Scanning electron microscopy (SEM) images of the MF membranes filtered both the NP and LP cultures after treatment with different concentrations of the PAC.
Original and normalized flux point at 1 min for both the NP and LP cultures after treatment with different concentrations of PAC. Fouling resistance of membranes filtered both the NP and LP cultures after the treatment using different concentrations of PAC.
INTRODUCTION…
Research background
For example, the chlorine has a detrimental impact on the polyamide membrane because amide bonds (-CO-NH-) of the commercial membrane are extremely susceptible to chlorine (Kwon et al., 2011b). In addition, the oxidation treatments using ozone destructive disinfection by-products (DBPs) produced such as aldehydes, brominated, carcinogenic haloacetic acids (HAs) and trihalomethanes (THMs) (Boorman et al., 1999, Huang et al., 2005). With the increasing interest in finding effective, novel and environmentally safe tools to alleviate membrane biofouling, researchers have begun to explore the use of biological treatments such as eukaryotic predators as alternatives (Derlon et al., 2012).
However, those predators could not penetrate the clusters of bacterial cells (microcolonies) within biofilms; therefore their abilities were limited (Bohme et al., 2009, Derlon et al., 2012). At this stage, the predatory bacterium breaks its flagellum and enters the periplasm of the prey, where it lies, lyses, and cleaves the prey internally before the progeny eventually emerge and attack other prey in the environment (Dwidar et al., 2012a, Sockett and Lambert, 2004).
Objectives of the study
EXPERIMENTAL METHODS & MATERIALS
- Bacterial strains, media and culture conditions
- Preparation of the experimental culture medium
- Investigation of Pre-treatment using Bdellovibrio-and-like-organisms (BALOs) on the dead-
- Combined pre-treatments of bacterial predation and alum coagulation to reduce membrane
- Pretreatments
- Combined pre-treatments of bacterial predation and alum coagulation to reduce membrane
- Combined pre-treatments of bacterial predation and powdered activated carbon (PAC) to
- Membrane filtration system
- Microbial solution analysis and Membrane morphology
- Analysis of membrane performance
- Investigation of Pre-treatment using Bdellovibrio-and-like-organisms (BALOs) on the dead-
Combined pretreatments of bacterial fouling and powdered activated carbon (PAC) to reduce membrane biofouling reduce membrane biofouling. 2 by measuring the flux of the virgin membrane using pure water, while Rt was determined from the flux of pure water after filtering 350 mL of microbial solution. After the Amicon cell was evacuated and the fouled membranes were gently washed with 150 ml of pure water by mixing at 100 rpm for 5 minutes using a shaker.
3 after thorough washing with 150 ml of pure water by stirring at 200 rpm for 15 min, after which the flux of pure water was re-estimated. Combined pretreatments of bacterial predation and alum coagulation to reduce biofouling of membranes & Combined pretreatments of bacterial predation and powdered activated carbon (PAC) to reduce biofouling of membranes.
RESULTS AND DISCUSSION
Investigation of Pre-treatment using Bdellovibrio-and-like-organisms (BALOs) on the dead-
- Microbial solution quality
- Filtration of microbial solution with 350ml
- Resistance-in-series model
- Discussion …
In contrast, in the case of the HP sample (an initial MOI of 200), its OD and E values alive. As mentioned above in the introduction, the 'Sieving Effect' is a key mechanism in the MF membrane system. Based on this effect, MF membrane with 0.45 µm pore size was investigated in the experiment.
On the contrary, in the case of NP cultures, they had reduced flux values compared to that of LP and HP cultures at all times. Even if OD and prey viability of LP cultures were essentially comparable to that of HP cultures, the difference in membrane filtration visualization of HP and LP cultures after 48 h suggests that an initial MOI of two conditions (LP) led to significantly higher amounts of E. In contrast, in the case of LP cultures, the total resistance values of LP cultures were similar to those of NP cultures both at 12 h and at 24 h, while its value decreased after 48 hours.
In the case of NP cultures, the main influence resulting in membrane fouling was the concentration polarization, which contained a ratio of more than 98% of the total resistance. The intrinsic membrane resistance of HP cultures, and not the biofouling resistance caused by microorganisms, was more than 50% of the total resistance. The percentage values between 24 and 48 hours were approximately 0% to 40% of the total resistance of LP cultures.
From Figure 5 and Figure 6a, in the case of MOI=200, the total number of E.coli cells was a lower value than both the NP and LP cultures throughout the time. In the case of MOI=200, the population of E. coli in addition to the initial dose or decreased over 48 hours (Figure 6a). In fact, various studies have represented that in the existence of gram-positive bacterial strains, such as Bacillus sp.
Combined pre-treatments of bacterial predation and alum coagulation to reduce membrane
- Microbial solution quality
- Microbial solution characterization before coagulation using alum
- Microbial solution characterization after coagulation using alum
- Filtration of 200ml microbial supernatant
- Resistance-in-series model
- Discussion …
The zeta potential of the LP cultures showed a low absolute value compared to that of the NP cultures. The value of SSV represented 0 when the concentration of alum was 0 and 10 ppm in both the NP and LP cultures. In addition, the SSV of the LP cultures was higher than that of the NP cultures when 100 ppm alum was used.
Specifically, the SSV of LP cultures was higher than that of NP cultures in the case of 100 ppm alum. The flux of NP and LP cultures represented a comparable trend that the flux values were proportional to the alum content. Original membrane flux for both NP and LP cultures after coagulation with (a) 0ppm, (b) 10ppm and (c) 100ppm alum.
Thus, the value of SSV represented 0 when the concentration of alum was 0 and 10 ppm in both the NP and LP cultures, as shown in Table 3. Furthermore, for LP cultures, the normalized flux of the LP cultures was significantly different when comparing 10 ppm alum with 100 ppm alum (39% and 71% respectively). However, 10 ppm alum triggered the increase in the irreversible resistance of both the NP and LP samples.
As shown in Table 3, the value of SSV showed 0 when the concentration of alum was 10 ppm in both the NP and LP cultures. Scanning electron microscopy (SEM) images of the MF membranes filtered both the NP and LP cultures after coagulation with different concentrations of alum. Since 10 ppm alum was not an adequate dose for both the NP and LP cultures, the 10 ppm alum triggered an increase in irreversible resistance for both cultures.
Combined pre-treatments of bacterial predation and powdered activated carbon (PAC) to
- Microbial solution characterization after treatment using powdered activated carbon
- Filtration of 200ml microbial solution after treatment with the PAC
- Resistance-in-series model
- Discussion …
MF membrane was performed to permeate 200 ml of NP and LP cultures after treatments with different concentrations of PAC. The flux of NP and LP cultures represented a comparable trend that flux values were proportional to PAC concentrations. Original membrane flux for both NP and LP cultures after treatment with (a) 0ppm, (b) 10ppm and (c) 100ppm of PAC.
This result indicated that 10 ppm PAC is not an appropriate PAC concentration for both NP and LP culture. In LP cultures, flux efficiency was improved compared to flux when treated with 0.10 ppm PAC. This was because the use of 100 ppm PAC removed particles from the LP cultures that caused membrane fouling.
Finally, it was found that the flow of the LP cultures was improved when 100 ppm of the PAC was used. However, for the NP cultures, the treatment with 100ppm of the PAC did not have a significant effect on the removal of viable E. Furthermore, the total resistance of the LP cultures was lower than that of the NP cultures.
For the LP cultures, the treatment with 100 ppm of PAC caused the reduction of the irreversible resistance as well as the total resistance. For the NP cultures, the reversible resistance, such as Rc, was mainly involved over all concentrations of PAC. On the other hand, the total resistance of both the NP and LP cultures was reduced in accordance with the concentration of PAC.
CONCLUSIONS
먼저 부족한 저를 지도해 주신 권영남 교수님께 감사의 말씀을 전하고 싶습니다. 그리고 논문에 많은 조언을 해주신 이창하 교수님, 이창수 교수님께도 감사드립니다. Mitchell 교수님과 Mohammed Dwidar 선생님께 감사의 말씀을 전하고 싶습니다.
내 논문의 영어 편집에 도움을 준 언어교육센터의 Deirdre Madden에게 감사의 말씀을 전하고 싶습니다. 그리고 학부 선배이자 룸메이트인 요한이 형에게 큰 도움이 됐다고 말하고 싶다. 그리고 울산에서 먼 길까지 만나서 반가웠던 동급생 요한, 승희에게도 고마운 마음을 전하고 싶습니다.
제가 고향이 아닌 울산에서의 생활에 적응하는 데는 주변 사람들이 많은 도움을 주었습니다. 직장에서 마음을 열고 내 감정을 공유했을 때 마치 IVF 마음이 집에 돌아온 것 같은 느낌이 들었습니다. 나머지 가족들에게도 감사 인사를 전하고 싶습니다.
저는 간호사 생활을 하면서 많은 어려움을 겪었습니다. 멀리서 함께 기도할 수 있어서 감사했습니다. 사랑하는 가족들에게 감사의 마음을 전하고 싶습니다.
