Gui-bai Li

Harbin Institute of Technology, Charbin, Heilongjiang Sheng, China

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Publications (34)72.06 Total impact

  • Lu Qi · Guo-hua Liu · Xiang Zheng · Gui-bai Li
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    ABSTRACT: In this study, a novel reuse of powdered activated carbon (PAC) and alum sludge (RPAS) process to reduce membrane fouling for drinking water treatment was evaluated by laboratory-scale experiments. As compared to coagulation, PAC combined with coagulation and reuse of alum sludge processes, RPAS process performed better in controlling trans-membrane pressure increase and reducing membrane resistances in both short-term and long-term periodical filtration. Removals of turbidity, DOC, UV254, BDOC and THMFP were 93.8, 37.3, 41.1, 83.0 and 57.9% on average by RPAS pretreatment, respectively. The results of fractionation of organic matters indicated that hydrophobic acids and hydrophilic matters were efficiently removed, while organic matters with the molecular weight (MW) more than 3 k Da was well removed with a removal efficiency of 50.4%, and that of MW less than 1 k Da were reduced by 32.6% by RPAS pretreatment, which could be attributed to the integration of PAC adsorption and the enhanced coagulation of alum sludge.
    Desalination and water treatment 11/2013; 53(9):1-8. DOI:10.1080/19443994.2013.865567 · 1.17 Impact Factor
  • Wen-zheng Yu · John Gregory · Gui-bai Li · Jiu-hui Qu
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    ABSTRACT: In order to discuss the effect of humic acid on improving coagulation performance at low temperature, an optical method was employed to investigate the aggregation kinetics of kaolin with and without humic acid at low temperature using a photometric dispersion analyzer (PDA). Moreover, the fractal dimension (D2) of the aggregates was obtained by photographic technique coupled with image analysis. The presence of humic acid in the water significantly increased the rate of aggregation at low temperature and caused a decrease in the number of small flocs. It was found that the optimal dosage of coagulant decreased in the presence of humic acid. In the model water with only kaolin, the fractal dimension of flocs with different dosage of alum was nearly the same when coagulation time was longer than 20 min. However, in the presence of humic acid, the fractal dimension of the flocs initially decreased, and then increased with dosage of coagulant, which suggested that median dosage of alum caused looser flocs. Comparing the flocs with and without humic acid, D2 was always lower in the presence of humic acid, which showed that the coagulation mechanisms for these two model waters were dramatically different. The residual turbidity in the model water with humic acid was significantly lower than that without humic acid, and the optimal dosage of alum was two times lower than that without humic acid. Al(OH)3–humic acid precipitates worked as polymers, which interact with charged particles by bridging flocculation, charge neutralization or other interactions.
    Chemical Engineering Journal 05/2013; 223:412–417. DOI:10.1016/j.cej.2013.03.008 · 4.32 Impact Factor
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    ABSTRACT: In order to quantify the activity of heterotrophic microorganism in membrane bioreactor (MBR) for drinking water treatment, biomass respiration potential (BRP) test and 2,3,5-triphenyl tetrazolium chloride-dehydrogenase activity (TTC-DHA) test were introduced and modified. A sludge concentration ratio of 5:1, incubation time of 2h, an incubation temperature that was close to the real operational temperature, and using a mixture of main AOC components as the substrate were adopted as the optimum parameters for determination of DHA in drinking water MBR. A remarkable consistency among BDOC removal, BRP and DHA for assessing biological performance in different MBRs was achieved. Moreover, a significant correlation between the BRP and DHA results of different MBRs was obtained. However, the TTC-DHA test was expected to be inaccurate for quantifying the biomass activity in membrane adsorption bioreactor (MABR), while the BRP test turned out to be still feasible in that case.
    Bioresource Technology 02/2013; 130C:136-143. DOI:10.1016/j.biortech.2012.11.151 · 5.04 Impact Factor
  • Lu Qi · Hong-chen Wang · Xiang Zheng · Gui-bai Li
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    ABSTRACT: Effects of natural organic matter molecular weight (MW) distribution in source water on the reversible and irreversible fouling of immersed ultrafiltration membranes of three different materials were systematically investigated using representative sources of natural waters. It was found from the bench-scale tests that the organic matters of the MW lower than 1 K and higher than 30 KDa were the main substances that induced reversible fouling regardless of the materials, and that of MW between 1 K and 5 KDa could cause reversible fouling for polyvinylidene fluoride (PVDF) and polysulfone (PS) membrane. As for the irreversible fouling, small organic molecules of the MW lower than 1 KDa were the main part due to the hydrogen bonds. In addition, the organic matters of MW between 1 K and 3 KDa can induce irreversible fouling for polyvinyl chloride and PVDF membrane. Results of long-term filtration tests showed that PVDF membrane was more vulnerable to small organic molecules due to its high electronegativity substances, and PS membrane had better resistance to organic fouling.
    Desalination and water treatment 12/2012; 50(1-3):95-101. DOI:10.1080/19443994.2012.708552 · 1.17 Impact Factor
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    ABSTRACT: In order to understand the mechanism of floc formation and growth in coagulation process, effect of zeta potential and surface characteristic of nano sized primary particles on coagulation efficiency were investigated by coagulation of humic acid with alum in this study. It was demonstrated that only 1 min rapid mixing was enough for adsorption of humic acid onto the precipitates of alum, and 15 min flocculation (slow mixing) only induced the formation and growth of flocs. The primary particle size of alum–humic flocs was near 50 nm and spherical. Mathematical model deduced from Derjaguin–Landau–Verwey–Overbeek (DLVO) theory showed that the formation of micro-flocs (or lag time) was determined by the square value of zeta potential of nano-sized primary particles and intensity of Brownian motion, which is closely related to water temperature. There was an absolute critical zeta potential, i.e. 13.5 mV in this study, determining whether two nano-sized particles could overcome the energy barrier consisted of Van der Waals force and electrical double layer repulsion force to allow floc formation to occur at a certain temperature. The Brownian motion determined whether the nano-sized primary particles (aluminum hydroxide precipitates with humic acid) had the opportunity to overcome the repulsive force and cement with each other. Low coagulation efficiency at high latitude area in winter is caused by low collision frequency, which is mainly attributed to the low intensity of Brownian motion at a low temperature. Furthermore, it was demonstrated that aggregation of micro-flocs or their clusters significantly depended on activated sites on the primary particles rather than the zeta potential of primary particles when sweep flocculation dominated the coagulation mechanism if the size of flocs was larger than some value.
    Separation and Purification Technology 10/2012; 99:44–49. DOI:10.1016/j.seppur.2012.08.017 · 3.07 Impact Factor
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    ABSTRACT: Pre-coagulation enhanced by KMnO(4) before ultrafiltration (KCUF) was compared with normal pre-coagulation by alum (CUF) in the ultrafiltration of water from the Songhua River, China. The trans-membrane pressure (TMP) with KCUF was much lower than that when alum alone was used. With KCUF a slower increment of TMP occurred, even under conditions of high river water turbidity. The results also showed that the removal of COD, UV(254) and TOC was appreciably higher after adding 0.5mg/L KMnO(4) compared with CUF. Although assimilable organic carbon (AOC) was increased by permanganate treatment, the AOC of the permeate from KCUF was nearly the same as that from CUF, showing that the cake layer on the surface of KCUF membrane could adsorb small molecules more effectively than that of CUF. This result was confirmed by the apparent molecular weight (MW) distribution measured by size exclusion chromatography (SEC). It was shown that flocs formed by KMnO(4) and alum were larger than those formed only by alum, causing higher removal of flocs and higher permeation flux. Lower NOM was found in the permeate from the KCUF systems because oxidation and adsorption of organic matter on the flocs occurred. The membrane was partly clogged by organic matter or other materials including some small flocs.
    Water Science & Technology 09/2011; 64(7):1497-502. DOI:10.2166/wst.2011.586 · 1.21 Impact Factor
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    ABSTRACT: Ultrafiltration is a promising process to produce qualified drinking water. The application of ultrafiltration for drinking water production has undergone accelerated development during the past decade. Membrane fouling may be the main obstacle for wider implementation of ultrafitration, which usually causes higher costs of energy, operation, and maintenance. Fouling is formed due to pore blocking, pore stricting and cake formation. Pretreatments (e.g. coagulation, adsorption, and pre-oxidation) can in various degrees alleviate the fouling by pre-reacting with the foulants in the feed water. However, adverse effects from the pretreatment are also claimed. Moreover, modest operation methods (e.g. running modes, rinsing modes, chemical cleaning, and air scouring) can effectively obtain the fouling reduction. In this report, fouling control in ultrafiltration technology for drinking water production is reviewed in terms of different effective pretreatments and operation methods. Specific mechanisms and future research required are also discussed based on the literature reviewed.
    Desalination 05/2011; 272(1):1-8. DOI:10.1016/j.desal.2011.01.051 · 3.96 Impact Factor
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    ABSTRACT: In this paper, a novel process of recycling alum sludge with powdered active carbon (PAC) was evaluated for drinking water treatment under various conditions. Results of this study indicated that the removal of turbidity, DOC and UV254 from simulated raw water by recycling alum sludge with PAC could reach up to 89.2%, 52.7% and 60.1%, respectively, which were better than that of recycling alum sludge alone, and it may be due to the adsorption of PAC which existed in mixed sludge. Turbidity of raw water had an important impact on the recycle of alum sludge with the PAC process, which is better to be applied in treating raw water with turbidity less than 100 NTU. In addition, the optimal pH for humic acid removal by recycling alum sludge with PAC was approximately 5. It was postulated that combination of adsorption and sweeping by hydroxide precipitates and the adsorption of PAC existing in mixed sludge played a key role in the enhancement of turbidity and organic matter removal.
    Desalination and water treatment 01/2011; 25(1-3):170-175. DOI:10.5004/dwt.2011.1603 · 1.17 Impact Factor
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    ABSTRACT: Effect of operating conditions on the fouling of immersed ultrafiltration(UF) membrane for the Suzhou Internal River was investigated with a pilot scale study. Results show that fouling could be reduced by both the continuous aeration and intermittent aeration, while the aeration intensity should be selected reasonably. Fouling could be reduced by intermittent filtration only due to the decrease of the filtration duration, but the combination of aeration and intermittent filtration could have better control of fouling. The transmembrane pressure (TMP) of UF operation could be significantly reduced by coagulation pretreatment and the combination of coagulation, aeration and backwashing could have better mitigation of membrane fouling in the real application of immersed UF.
  • Yi Wang · Yong-peng Xu · Jun Nan · Gui-bai Li
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    ABSTRACT: Meso-macropore adsorbents were prepared from biological sludge, chemical sludge and hybrid sludge of biological and chemical sludges, by chemically activating with 18.0 M H(2)SO(4) in the mass ratio of 1:3, and then pyrolyzing at 550 °C for 1 h in anoxic atmosphere. The physical and chemical characteristics of the sludge-based adsorbents were examined in terms of surface physical morphology, specific surface area and pore size distribution, aluminum and iron contents, surface functional groups and crystal structure. Furthermore, the adsorption effect of these adsorbents on the organic substances in wastewater was also investigated. The results indicated that the adsorption capacities of the sludge-based adsorbents for UV(254) were lower than that of commercial activated carbon (AC), whereas the adsorption capacities of the adsorbents prepared from hybrid sludge (HA) and chemical sludge (CA) for soluble COD(Cr) (SCOD(Cr)) were comparable or even higher than that of the commercial AC. The reasons might be that the HA and CA possessed well-developed mesopore and macropore structure, as well as abundant acidic surface functional groups. However, the lowest adsorption efficiency was observed for the biological sludge-based adsorbent, which might be due to the lowest metal content and overabundance of surface acidic functional groups in this adsorbent.
    Water Research 09/2010; 45(2):819-27. DOI:10.1016/j.watres.2010.09.008 · 5.32 Impact Factor
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    ABSTRACT: In this paper, the influences of air bubbling mode, air flow rate, air bubble size and feed water quality on the membrane fouling of immersed hollow-fiber (HF) membrane for ultrafiltration of river water were investigated. The membrane was operated in the intermittent suction mode of 9min on/1min off. The results showed that continuous air bubbling was more effective for mitigating membrane fouling than intermittent bubbling (1min on/9min off in the study) at the same air flow rates of 1.0, 2.5, 5.0, and 7.5m3/m2h, respectively. Furthermore, an optimum air flow rate was observed for immersed HF membrane system when considering the alleviating effect on membrane fouling and energy consumption simultaneously, with the optimum value determined as 5.0m3/m2h in this investigation. It was also found that the smaller the air bubble was (4dia of 3.5, 5.0, 6.5, and 8.0mm were investigated), the more effective the air bubbling would be for mitigating the membrane fouling of immersed HF membrane. However, even if air bubbling was performed, eliminating membrane foulants from the feed water before ultrafiltration was still necessary for the reduction of membrane fouling.
    Desalination 09/2010; 260(1):225-230. DOI:10.1016/j.desal.2010.04.026 · 3.96 Impact Factor
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    ABSTRACT: The effects of the concentration of dissolved total organic carbon (TOC), the TOC/Br− ratio, bromide ion levels, the chlorine to ammonia-N ratio (Cl:N), the monochloramine dose and the chlorine dose on the formation of trihalomethanes (THMs) (including chloroform, bromodichloromethane, chlorodibromomethane, and bromoform) from chlorination were investigated using aqueous humic acid (HA) solutions. The profile of the chloramine decay was also studied under various bromide ion concentrations. Monochloramine decayed in the presence of organic material and bromide ions. The percentage of chloroform and brominated THMs varied according to the TOC/Br− ratio. Total THMs (TTHMs) formation increased from 112 to 190 μg/L with the increase concentrations of bromide ions from 0.67 to 6.72 mg/L, but the chlorine-substituted THMs were replaced by bromine-substituted THMs. A strong linear correlation was obtained between the monochloramine dose and the formation of THMs for Cl:N ratios of 3:1 and 5:1. These ratios had a distinct effect on the formation of chloroform but had little impact on the formation of bromodichloromethane or chlorodibromomethane. The presence of bromide ions increased the rate of monochloramine decay. Key wordsTrihalomethanes (THMs)-Humic acid (HA)-Bromide-Monochloramine CLC numberTU991.2-X5
    Journal of Zhejiang University - Science A: Applied Physics & Engineering 08/2010; 11(8):606-612. DOI:10.1631/jzus.A1000100 · 0.61 Impact Factor
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    ABSTRACT: A computer-controlled digital camera was used to examine the formation, breakage, and regrowth of flocs formed by kaolin or the mixture of kaolin and humic acid with aluminum sulfate (alum) at different intensities of applied shear, as well as for continuous optical monitoring (Photometric Dispersion Analyzer). The computer-controlled digital camera could record the flocs size and morphology. There was full regrowth of flocs in kaolin suspension when their zeta potential was close to zero, regardless of intensity of the applied shear, which indicated a significant reversibility of the floc break-up process. However, such a process displayed a distinct irreversibility at higher alum dosage when the flocs were positively charged as the intensity of applied shear increased, though there was full reversibility of floc breakage at low applied breakage shear. Addition of humic acid weakened the reversibility of broken flocs in all cases, especially at high breakage shear. Two-dimensional fractal dimension (D(2)) of regrown flocs in kaolin suspension coagulated under condition of charge neutralization was not influenced by the applied shear except at high applied shear (400 rpm), whereas at a higher alum dosage the D(2) decreased as the applied shear increased. The D(2) was lower in the presence of humic acid. Further, the D(2) of regrown flocs with charge neutralization was higher than that with higher alum dosage, whether the model water contained humic acid or not. Without humic acid in water, the residual turbidity and particle number after breakage and regrowth were both decreased as the applied shear increased up to 250 rpm. Higher breakage shear, such as 400 rpm, gives higher residual turbidity (or residual particle number). This work gives new information and a better understanding of the regrowth of broken flocs, a subject which is of considerable practical importance in water and wastewater treatment.
    Environmental Engineering Science 06/2010; 27(6):483-492. DOI:10.1089/ees.2009.0424 · 0.93 Impact Factor
  • Jia-yu Tian · Zhong-lin Chen · Jun Nan · Heng Liang · Gui-bai Li
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    ABSTRACT: An integrative membrane coagulation adsorption bioreactor (MCABR) with simultaneous dosing of polyaluminium chloride (PACl, 10 mg/L) as the coagulant and powdered activated carbon (PAC, 8 mg/L) as the adsorbent into the bioreactor was put forward and investigated for the drinking water treatment from slightly polluted surface water. The MCABR exhibited excellent capacity for the removal of organic matter even at a low hydraulic retention time of 0.5 h. As for DOC, UV254, TOC, CODMn, THMFP, HAAFP, BDOC and AOC, the removal efficiencies by the MCABR reached to 63.2, 75.6, 68.3, 72.7, 55.3, 56.2, 67.4 and 75.5%, respectively. In the MCABR, four kinds of mechanisms, i.e. separation by the membrane, biodegradation by micro-organisms, coagulation by PACl, and adsorption by PAC jointly contributed to the removal of dissolved organic matter (DOM), with their respective contributions of 11.1, 8.3, 24.6 and 19.2% in DOC removal, and 11.4, 5.0, 38.1 and 21.1% in UV254 removal. Furthermore, scanning electronic microscopy (SEM) and confocal laser scanning microscopy (CLSM) observations showed that a sludge layer was formed on the membrane surface in the MCABR, which was demonstrated to provide additional rejection for DOM in the mixed liquor, especially for the organic molecules of 3000–300 Da.
    Journal of Membrane Science 04/2010; DOI:10.1016/j.memsci.2010.02.018 · 4.91 Impact Factor
  • Lu Qi · Heng Liang · Yi Wang · Gui-bai Li
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    ABSTRACT: Effects of PAC and alum sludge generated from water treatment process on the effluent quality and fouling of immersed UF membrane were systematically investigated with representative source of natural water and the efficiency of coagulation, PAC adsorption and RPAS to treat natural surface water prior to UF were compared. It was found that the average turbidity removal by RPAS could reach up to 80.2%, and the turbidity removal of immersed membrane UF was independent of the influent, which could be kept at 99%. Particulates were reduced after being pre-treated by different processes, and particles with sizes ranging from 0.5 to 3.5μm and larger than 13.5μm were effectively removed by RPAS. UF coupled with RPAS pre-treatment got the best removal for DOM compared to other processes with average DOC and UV254 removal 54.1% and 47.2% due to the high removal in the influent of UF. The residual alum content in the effluent of RPAS with UF was less than coagulation and bacteria were almost all removed by membrane. The membrane-fouling was mitigated by pre-treatment processes at different degrees, TMP of UF coupled with RPAS process was relatively stable in 15d of run, the adsorption of PAC and large number of Al(OH)3 complexes and precipitates for the foulant molecules might be an important mechanism.
    Desalination 11/2009; 249(1):440-444. DOI:10.1016/j.desal.2009.06.053 · 3.96 Impact Factor
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    ABSTRACT: The hybrid process of biological activated carbon (BAC) and submerged membrane bioreactor (sMBR) was evaluated for the drinking water treatment from polluted raw water, with the respective hydraulic retention time of 0.5 h. The results confirmed the synergetic effects between the BAC and the subsequent sMBR. A moderate amount of ammonium (54.5%) was decreased in the BAC; while the total removal efficiency was increased to 89.8% after the further treatment by the sMBR. In the hybrid process, adsorption of granular activated carbon (in BAC), two stages of biodegradation (in BAC and sMBR), and separation by the membrane (in sMBR) jointly contributed to the removal of organic matter. As a result, the hybrid process managed to eliminate influent DOC, UV(254), COD(Mn), TOC, BDOC and AOC by 26.3%, 29.9%, 22.8%, 27.8%, 57.2% and 49.3%, respectively. Due to the pre-treatment effect of BAC, the membrane fouling in the downstream sMBR was substantially mitigated.
    Bioresource Technology 09/2009; 100(24):6243-9. DOI:10.1016/j.biortech.2009.07.008 · 5.04 Impact Factor
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    Jun Nan · Wei-peng He · Juan-juan Song · Gui-bai Li
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    ABSTRACT: Polyaluminium chloride (PAC) synthetic water was selected as a coagulant and kaolin suspension particles as objects to be removed. Online instruments such as the turbidimeter and particle counter were employed to monitor the flocculation process online and collect test data. The aim of the experiments was to study the dynamic distribution characteristics of suspension particles in the flocculation process. The 3D flow field in the reacting vessel was also simulated at different slow stirring speeds. The experiments showed that particle collision and aggregation in the flocculation process is in compliance with the Sutherland cluster aggregation model. This study further indicated that under appropriate hydrodynamic conditions, the distribution of turbulent flow in the reactor could be improved to increase the odds of effective particle collision and restrain the breakup of formed flocs by vortex shearing force. A good flocculation effect could therefore be produced.
    Journal of Zhejiang University - Science A: Applied Physics & Engineering 09/2009; 10(9):1350-1358. DOI:10.1631/jzus.A0820652 · 0.61 Impact Factor
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    ABSTRACT: Chemical cleaning of fouled hollow-fiber polyvinyl chloride (PVC) membrane with the consecutive use of NaOH and ethanol during ultrafiltration of river water was investigated in the study. Results showed that through the chemical cleaning with 1% NaOH for 30min, a negative cleaning efficiency of -14.6% was observed for the PVC membrane. This might be due to the increase of membrane hydrophobicity, which was reflected by the increase of contact angle from 69.7 degrees to 87.6 degrees . On the other hand, the cleaning efficiency of 85.1% was obtained by the consecutive cleaning with 30min of 1% NaOH and 30min of ethanol. Individual ethanol cleaning could remove 48.5% of the irreversible resistance, indicating that NaOH cleaning also made its contribution (36.6%) to the removal of membrane foulants. Scanning electronic microscopy (SEM) and atomic force microscopy (AFM) analyses demonstrated that both NaOH and ethanol were not only able to eliminate the foulants on membrane surface, but also able to remove the in-pore fouling of the PVC membrane. The synergetic effects for removing membrane foulants were observed between the NaOH and ethanol. Furthermore, ethanol could also restore the hydrophilicity of the membrane by decreasing the contact angle from 87.6 degrees to 71.4 degrees . Considering that ethanol is easy to be used and reclaimed, the consecutive chemical cleaning by alkali and ethanol is recommended for PVC membrane in filtration of surface water.
    Water Research 09/2009; 44(1):59-68. DOI:10.1016/j.watres.2009.08.053 · 5.32 Impact Factor
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    ABSTRACT: In the article, the inactivation effect of chlorine on E. coli biofilm and the influence of chlorine oxidization on the contents of assimilable organic carbon (AOC), microbially available phosphorus (MAP) and bacterial regrowth potential (BRP) was investigated in the simulated drinking water distribution system. Results showed that chlorine resulted in more efficient reduction on suspended E. coli than did in biofilm. The inactivation effect of E. coli was influenced by chlorine concentration. Likewise, higher chlorine concentration resulted in more E. coli inactivation rate at the same CT (chlorine concentration multiply by time) value, when biofilm was oxidized by chlorine. Concentrations of AOC and MAP in bulk water increased owing to organic substance dissolved from biofilm. The AOC concentration increased from 20.78 microg/L to 120.17 microg/L, and the MAP was increased from 0.11 microg/L to 0.17 pg/L, and the Chlorine oxidization enhanced BRP concentration in the bulk water. BRP reached maximum at 1.10 x 10(7) CFU/mL when chlorine concentration was 1.0 mg/L, CT value was 100 mg x min/L.
    Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.] 06/2009; 30(5):1381-5.