Investigation of coagulation conditions for enhanced picophytoplankton removal in drinking water treatment
Başlık çevirisi mevcut değil.
- Tez No: 400041
- Danışmanlar: PROF. HİDEKİ HARADA, PROF. OSAMU NİSHİMURA, PROF. TATSUO OMURA
- Tez Türü: Doktora
- Konular: Çevre Mühendisliği, İnşaat Mühendisliği, Environmental Engineering, Civil Engineering
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 2012
- Dil: İngilizce
- Üniversite: Tohoku University
- Enstitü: Yurtdışı Enstitü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 134
Özet
Özet yok.
Özet (Çeviri)
Picophytoplankton (picoplanktonic cyanobacteria) is a small plankton rangingbetween 0.2 and 2 ?m in size, comprised of picocyanobacteria and eukaryoticphototrophs. The presence of picophytoplankton and its metabolites in the drinkingwater source can cause a series problems for drinking water treatment. For instance,picophytoplankton cells contributed to the turbidity of treated water and clog the filtersin the facilities. Their intracellular metabolites also contributed to the production ofundesired tastes and odors, the formation of assimilable organic carbon (AOC),disinfection byproducts (DBPs) and cyanotoxins. Therefore, picophytoplankton hasrecently become one of the most important targets in drinking water treatment.Despite the many negative effects of picophytoplankton, the removal ofpicophytoplankton from drinking water has not been well studied. Therefore, the studiesneed to be done to enhance coagulation process for effectively picophytoplanktonremoval from drinking water. In this study, the coagulation mechanisms ofpicophytoplankton and how to improve picophytoplankton with coagulation processwere discussed based on it is physical and chemical conditions, e.g. rapid mixing speed/ time, flock size distribution and zeta potential.Experiments were conducted using both raw water and artificial water samplesincluding picophytoplankton. In this study, as a first step we were investigated optimalpH conditions and the most effective coagulant type for picophytoplanton removal. ThepH experiment results showed that the removal of picophytoplankton and turbidity inthe coagulation process proceeded best between pH 5.5 and 6.5. In addition, poly silicairon (PSI) showed the best removal perfomance in comparison to poly aluminumchloride (PAC), ferric chloride (FeCl3) and aluminum chloride (Alum). In this study, wewere also tried to find the effective mechanism for picophytoplankton. The resultsshowed that floc formation and sweep coagulation were shown to be the predominantmechanisms for picophytoplankton removal. The artificial water experiments showedthat sedimentation performance of picophytoplankton was significantly dependent onfloc formation with turbid materials in the system.In this study, we were also investigated the applicability of the zeta potential tocontrol the coagulation of different algal systems. For this purpose, we comparedMicrocystis aeruginosa, Chlorella vulgaris and Synechococcus sp. These species arecommonly found in water sources and are believed to be associated with water qualityand treatment problems in water treatment plants. Zeta potential experiments showedthat the residual turbidity in the Microcystis aeruginosa system decreased 0.14 NTU asa function of the coagulant dose. The corresponding zeta potential at that point was+20.12 ± 1.3 mV with coagulant dose of 100 mg/l PACl for Microcystis aeruginosa.Moreover, high coagulant dose didn?t cause to restabilization of Microcystis aeruginosasystem. It was demonstrated that high zeta potential provides good removal forMicrocystis aeruginosa. In addition, it was observed that flocs formed in theMicrocystis aeruginosa system were larger and formed more quickly than those in othersystems.There were three different zeta potential ranges observed for Chlorella vulgaris. Thefirst range was the initial range of turbidity removal. At this range, however, very lowturbidity removal was observed; the zeta potentials were between -25.16 ± 1.1 mV and -13.49 ± 1.8 mV. The second range was the maximum removal range of turbidity whereChlorella vulgaris removal is attributed charge neutralization mechanism. The zetapotentials were between -11.4 ± 1.9 mV and +8.71 ± 2.2 mV in this range. The thirdrange was the restabilization range; at this range, residual turbidity increased to 2.28NTU again where the zeta potential values ranged between +16.87 ± 1.5 mV and +24.1± 1.2 mV. Restabilization of Chlorella vulgaris system could be explained by highcoagulant dose. This sequence of removal ranges is only observed for Chlorellavulgaris system, in contrast to other systems.There was very low turbidity removal in the Synechococcus sp. system observedwhen the zeta potential range of the system was between -5.87 ± 1.2 mV and 0 mV.However, when the zeta potential of the Synechococcus sp. system moved from thenegative side into the positive side, the turbidity removal increased. The zeta potentialvalue which provided for the maximum turbidity removal was +13.91 ± 1.1 mV withdose of 300 mg/l PACl for Synechococcus sp. system and the residual turbidity at thatpoint was 4.02 NTU. More difficulty was encountered removing turbidity from theSynechococcus sp. system than from the Microcystis aeruginosa and Chlorella vulgarissystems. This may be due to the low density and small size of the formed flocs, both ofwhich would contribute to the low sedimentation performance of the Synechococcus sp.flocs. The results showed that charge neutralization is the most effective method for theremoval of turbidity caused by Synechococcus sp. The results demonstrated that apositive zeta potential contributed to turbidity removal in each algal system. Zetapotential experiments revealed that optimal cell removal was obtained irrespective ofpH if the zeta potential was maintained between +8.71 mV and +28.2 mV.In this study, the effect of different velocity gradients and rapid mixing durations onfloc growth in the cyanobacterial system in order to improve the coagulationflocculationprocess were investigated. It was noted that the floc size of both theSynechococcus sp. and kaolin system first increased and then decreased with increasedG in the coagulation process, which demonstrated that there were three different rangesfor both Synechococcus sp. and kaolin flocs formation: the low velocity gradient range(G < 200 s-1), which was the aggregation-dominated range; the mean velocity gradientrange (G= 250 s-1 for Synechococcus sp.-PSI flocs and G=546 s-1 for kaolin-PSI flocs;G= 200 s-1 for Synechococcus sp.-PAC flocs and G=390 s-1 for kaolin-PAC flocs),where coagulation rates were maximized and breakup was minimal; and the highvelocity gradient range (G > 250 s-1 for Synechococcus sp.-PSI flocs and G > 546 s-1 forkaolin-PSI flocs; G > 200 Synechococcus sp.- PAC flocs and G > 390 s-1 for kaolin-PAC flocs), where flocs breakup was dominant. In the aggregation-dominated range,the aggregate size increased in proportion to the share rate, but resulted in smaller flocsdue to the low particle collision rates. Although breakup most likely occurred, thebreakage was considered to have relatively insignificant impact on the overall aggregatesizes. In the mean velocity gradient range, a balance between the rate of aggregationand the rate of breakage was reached; the flocs reached their maximum size. In thebreakup dominant range, collisions between the flocs produced more, but smaller flocs.In the beginning of this range, while a slight decrease was noted in the size ofSynechococcus sp. flocs, the size of the flocs in the kaolin system significantlydecreased, indicating less breakup in the Synechococcus sp. flocs in comparison tokaolin flocs. At the end of this range, the re-growth ability of Synechococcus sp. flocswas observed to be higher than the kaolin flocs.The physical parameters experiments indicated that at mean G value flocs formationwas maximized, producing the largest flocs. In addition, in contrast to previous studies,relatively high velocity gradients are suggested for the coagulation process in drinkingwater treatment. Consequently, if the above mentioned coagulation conditions areprovided during the experiments picophytoplankton removal efficiency can beincreased in drinking water treatment plants.As a result, this study showed that PSI the best coagulant type forpicophytoplankton removal and can be recommended in drinking water treatment. Inaddition, if the zeta potential of picophytoplankton system be keep over +7 mV, theoptimum picophytoplankton removal can be provided. Lastly, for picophytoplanktonsystem, the optimal rapid mixing conditions can be suggested that G value is 200 s-1 forPSI and the rapid mixing time is 90 s.
Benzer Tezler
- Bor minerallerinin elektrostatik ve elektrokinetik özellikleri
Electrostatic and electrokinetic properties of boron minerals
EMRE YAŞAR
Yüksek Lisans
Türkçe
1994
Maden Mühendisliği ve Madencilikİstanbul Teknik ÜniversitesiPROF.DR. YALÇIN KAYTAZ
- Biogas recovery during anaerobic treatment of lignocellulose-rich pollutants with high sulphate content: an investigation via innovative applications
Yüksek sülfat içerikli lignoselüloz bakımından zengin kirleticilerin havasız arıtımı sırasında biyogaz geri kazanımı: yenilikçi uygulamalarla bir araştırma
EDA YARSUR
Yüksek Lisans
İngilizce
2021
Çevre Mühendisliğiİstanbul Teknik ÜniversitesiÇevre Mühendisliği Ana Bilim Dalı
PROF. DR. ÇİĞDEM GÖMEÇ
- DGM'li gerilim dalgalarıyla beslenen asenkron motorlarda harmoniklerin etkileri
The Analysis of PWM-harmonic effects in selecting two induction motors for inverter drive systems
MUSTAFA KIYI
Yüksek Lisans
Türkçe
1992
Elektrik ve Elektronik Mühendisliğiİstanbul Teknik ÜniversitesiDOÇ. DR. A. FAİK MERGEN
- Sigortada dağıtım ve tutundurma metodları
Başlık çevirisi yok
BANU GÖNENÇ
Yüksek Lisans
Türkçe
1994
SigortacılıkMarmara ÜniversitesiSigortacılık Ana Bilim Dalı
DOÇ. DR. OSMAN GÜRBÜZ
- Akışkan yataklı kum filtreleri ile yüzeysel suların arıtımında optimum şartların araştırılması
Investigation of optimum operational parameters in surface water treatment with fluidized bed filters
MEHMET ŞÜKRÜ KIRMIZI
Yüksek Lisans
Türkçe
2010
Çevre MühendisliğiGebze Yüksek Teknoloji EnstitüsüÇevre Mühendisliği Ana Bilim Dalı
DOÇ. DR. EBUBEKİR YÜKSEL