Filtre edilebilme sayısı ile filtrasyon optimum dozunun araştırılması

Abstract

ÖZET Bu çalışmada, filtrasyonda kullanılan optimum pıhtılaştırıcı dozu ile kavanoz deneyinde bulunan op timum doz arasındaki ilgi araştırılmıştır. Bu maksat la derin yatak kum filtrasyonu için bir filtre edile bilme sayısı formülü geliştirilmiştir. Kurulan bir pi lot tesiste farklı dozda katyonik polielektrolit ile pıhtılaştırılmış killi su, bulanıklığının giderilmesi için hızlı derin yatak filtrasyonuna tabi tutulmuştur. Türetilen formülle, filtre edilebilme sayısının aldığı değerler incelenerek optimum doz bulunmuş ve kavanoz deneyi ile tesbit edilen optimum dozla mukayese edil miştir. Birinci bölümde filtre çeşitleri, filtrasyon değişkenleri, filtrasyon mekanizmaları, filtrasyonda kütle korunumu ve kinetik denklemleri, filtre katsayı sı (impediment modulu), yük kaybı modelleri, filtre e- dilebilme sayısı ile ilgili bilgiler özetlenmiş ve ça lışmanın gayesi belirtilmiştir. İkinci bölümde Mohanka'nın teklif ettiği yük kaybı denklemi ile Saatçi ve Oulman'm verdikleri lo jistik denklem (filtre çıkış suyu konsantrasyon değişi mine ait) den hareketle yeni bir filtre edilebilme sa yısı formülü çıkarılmıştır»II Üçüncü bölümde deneysel çalxşmalarda kullanıla malzemeler, metod, deney düzeni, deneylerin yapılışı a çıklanmış ve deney sonuçları grafik halinde verilmişti Dördüncü bölümde teklif edilen filtre edilebil me sayısı formülü diğerleri ile karşılaştırılmış ve de ney sonuçları yorumlanarak tartışılmıştır. Ayrıca, for mül literatürdeki bir çalışmaya uygulanarak alınan so nuçlar değerlendirilmiştir. Beşinci bölümde elde edilen sonuçlar belirtil miştir. Kavanoz ve filtrasyon deneyi ölçüm değerleri Ek.l ve Ek. 2 de ; bir hesaplama örneği Ek. 3 de veril miştir.. '.

Ill SUMMARY The relationship between optimum coagulant dose in filtration and the optimum dose found in jar test is investigated in this work. For this reason, an equation for filtrability number which can be used in deep bed filtration is derived. In a pilot plant, different doses of cationic polyelectrolytes and coagulated clay suspen sion were subjected to direct filtration in order to remove turbidity. Using this derived equation the values of filtrability numbers were investigated to see the effects of parameters such as coagulant dose, the way to add the coagulant and filtration rate on filter per formance. The filtration optimum dose calculated with the derived equation was compared with the optimum dose found with the jar test. Also, using the results of a filtration experiment from the literature, the dependance of filtrability number and filter coefficients on a coa gulant dose and filtration rate were investigated and discussed. In the first section, kinds of filter, the relation among filtration variables such as filtration rate, grain size of media, depth of filter and the quality of effluent and head loss, coagulation, the removal mecha nisms, mass balance, kinetic and filter coefficient (im-IV pediment modulu) equations, head loss models, filtrability indices are briefly summarized and the aim of this re search is explained. In the second section, a filtrability number which can be used in deep bed filtration is derived, For this reason, using simultanous solution of the equation of Mohanka and Ives about the change in hydraulic gradient with specific deposit, i = i + K a o where, i and i are hydraulic gradients at the start and after t time, K is a coefficient, a is apecific deposit and _ the logit line equation of Saatçi and tOulman on effluent concentration, f C/C° ^ Logit (C/Co) = m(1 _ C/CJ = «+<Jt - k F L a =i - £ş = k c x o where, C and C are concentrations of influent and effluent, o ' t is filtration time, a and 0 are logit line coefficients, k is attachment coefficient, F is filter capacity, v is filtration rate and L is filter depth the following equation of filtrability number is derived, rs - -i- - -1^2_ _J_ ln aVnı+e^) K P H`Ho 2[l+e(a+^1V In the third section, the materials used through 3ut the experiments, the procedure of experiments are explained and the experimental results are given with jraphs. A mixer with six pedals, a suspension of 45 FTU 'Formazin Turbidity Unit) prepared with kaolinite clay.nd a coagulant of either cationic (Cat Floe Tl, Cat loc T) or anionic (Decapol, NaCMC, LT2 5, LT29) poly- lectrolytes are used for jar tests. It is found that nly cationic polymers were efficient in removal of urbidity o An aparatus which consists of a suspension pre- aration container, a constant level container which rovides a usable pressure of 4.5 meter, a filter column f 4 cm diameter and 25 cm length and a piezometer panel as used for filtration experiments. Polymer solution as dosed with a pump, The filter media was composed of 3 cm of sand with two different grain sizes, 0.355-.425 mm in one group of experiments and 0.85-1.00 mm i the other group of experiments» Only cationic polymers `at Floe Tl, Cat Floe T) were used in all four groups f experiments. Influent and effluent turbidity (C, C) id head loss were measured periodically in the experi- ?nts where polymer dose, filtration rate, filter media, )lymer kind and polymer addition point were changed. ıe measurements of turbidity, flow rate and head loss ire made with DR 2 Hach Spectrophotometer, rotameterVI and piezometer respectively. The change of turbidity with clay concentration of suspension was studied and the- relation between them is given as a linear equation. Both jar and filtration experiment results are given in Appendix 1 and 2. The change of supernatant residual turbidity with polymer dose is given as a graph in the jar tests. Filtration test results which consists of the changes of effluent to influent con centration ratio (C/C ) and head loss with time are given as separate graphs for each test group. In the forth section, the dimension of filtrability -3 number was found as ML and a comparxson was made with the other filtrability indices available in the litera ture. The breakthrough curves between the minimum point and either a constant C/C value or a constant filtra- o tion time were subjected to regression analyses of Saat çi and Oulman's logit equation and a and 0 coefficients were found. Head loss results were subjected to regres sion analyses in the form of H = H + e,t and the ini- o tial head loss and the head loss t time were calculated. Arithmetic averages of influent turbidity were taken and corresponding clay concentrations were calculated from the above mentioned calibration equation o Using these values filtrability numbers and filter coefficients such as deposition rate k F, attachment ? i o ' coefficient k and filter capacity F were calculated i oVII and the results are tabulated whilst the changes due to polymer dose and filtration rate are given as graphs. The effects of changes of filtration rate and the polymer concentration used in treating the filter bed on the changes in the filtrability number and filter coefficients are investigated in the light of Byeseda and Sylvester's test results. The results make up the fifth section. They are shortly as follows: (1) The proposed filtrability number equation is valid in uniform sized media and in laminar flow condition. It can be used in the inves tigation of the effects of optimum coagulant dose and other parameters of filtration. (2) The optimum coagulant doses calculated through filtrability number equation are smaller than the value found with jar test. (3) When the filter bed is treated with polymer solution, the filter capacity increases with the used polymer concentration, but it decreases when flocculated water is filtered» (4) The application of polymer with influent causes surface removal» (5) The rise in filtration rate causes deterioration of the filtrability»