Fakültatif stabilizasyon havuzlarında biyolojik verime etkiyen faktörlerin araştırılması

Abstract

0 Z E T Ev ve sanayi kullanılmış sularının ihtiva ettiği orga nik maddeler tasfiye edilmeden döküldükleri çevrede fizikseiL, kimsayal ve biyolojik değişikliğe sebep olduğundan ekolojik denge bozulmakta ve çevre kirlenmektedir. Kullanılmış suların tasfiyesinde, klasik metodlar yanında inşa ve işletme kolay lığı ve düşük enerji maliyetleri dolayısıyla özellikle kır yerleşmelerinde stabilizasyon havuzları tercihan kullanil- maktâdır. Bu havuzlar topraktan yapılan basit yapılardır. Kullanılmış sular bu havuzlara doğrudan verildiğinden, biyo lojik madde giderimi yanında çökelme havuzu olarak da vazife görmektedirler. Stabilizasyon havuzlarında oksijen ihtiyacı yüzeysel havalanma ve algler tarafından fotosentezle üreti len oksijenle sağlanmaktadır. Üretilen çözünmüş oksijen aero bik bakteriler tarafından organik maddenin stabilizasyonunda` kullanılmaktadır. Reaksiyon sonucu ortaya çıkan C0_ ve diğer ürünlerden alglerin hücre sentezinde istifade edilmektedir. Tabana çökelen organik maddeler ise anaerobik bakteriler ta rafından parçalanarak CH,, H2S ve diğer ürünlere dönüşmekte dir.'..''-' ^ Bu çalışmada, besin maddesi tüketimini veren, güneş radyasyonu ile -alg teşekkülü ve oksijen üretimi arasındaki bağıntılar ve dispersiyonlu akım modelleri incelendikten sonra fakültatif stabilizasyon havuzunu temsil eden bir mo del yardımıyla laboratuarda deneyler yapılmış ye su kalitesi ile ilgili çeşitli parametreler ölçülmüştür. Elde edilen de ney sonuçları değişik istatistik metodlarla değerlendiril miş ve biyolojik verimi ifade eden b ağıntılar elde edilmiş tir.II Çalışmanın son kısmında dispers iyonlu akım modelleri ile belirlenen dispersiyon sayıları yardımıyla Wehner-Wilhem denkleminden, ölçülen biyolojik verilere tekabül eden K. t de-: ğerleri bulunmuş ve t bekleme müddetleri bilindiğinden K re- aksiyon katsayıları ayrı ayrı tayin edilmiştir. Daha sonra hesaplanan K reaksiyon katsayılarının hangi parametrelerin etkisi altında olduğu araştırılmış ve reaksiyon katsayısını veren genel bir bağıntı çık-arılmıştır.

Ill INVESTIGATION OS FACTORS EFFECTING BIOLOGICAL EFFICIENCY IN FACULTATIVE STABILIZATION PONDS S U M,.M`. A R Y Discharge of domestic and industrial wastewater to open surface water bodies without treatment causes environ mental pollution. Treatment of wastewater by means of treatment plants will bring an additional financial load to municipa lities and industries. In Turkey wastewater can also be treated by stabilization ponds, which can easily be cons tructed and operated mostly in rural areas, besides the con ventional treatment plants which is complex and require high energy in operation..Stabilizations ponds are opened in land with a water thickness öf 1-2 m to which water is directly conveyed. Suspenden particles in wastewater are led to settle in the pond and accumulate at the bottom. For the aerobic decom position of the organics by bacteria, required oxygen is supplied by surface aeration and by the photosynthesis reaction of algae which results oxygen as a product in stabilization ponds. Products» resulted in aerobic stabi lization, are used in the cell synthesis of algae. Stabilization, ponds can be classified as aerobic, anaerobic and facultative with respect to the nature ofIV the biological activity. Aerobic ponds are constructed for the growth of algae by the dissolved organics, complately treating water aerobically and to reduce the microorganisms, algae and nutrients like nitrogen and phosphorous. İn facultative ponds organics which settle to the bottom of the pond decompose anaerob ically here. These ponds are applied in treating the domestic and industrial wastewaters. For the treatment of industrial wastewater» which contains high organic matter, anaerobic ponds have been used.. ; Many relationships have been given for the substrate utilization in stabilization ponds ;, Some of these equations are ampirical^ and semi ampirical based on experiments; and some are mathematical expressions depending on reactor theory. Also, some investigators developed models of nitrogen and phosphorus based ön nutrient cycles. Some other researchers expressed different relationships for the calculation of reaction coefficient in dispersed flow models. Studies related to above mentioned cases and the characteristics öf the different relationships for the calculation öf reaction coefficient in dispersed flow models. Studies related to above mentioned cases and the characteristics of the different stabilization ponds have been given in the first chapter. In the second chapter^^the relationships between the algae growth and oxygen production with the useful solarenergy have been given. Calculations related to the required surface area for biochemical reactions and the mean radiation have been illustrated. Also, in this chapter equation jgiving the relationship between the light intensity penetrating through the pond depth and algae concentration was given. In the third chapter equations expressing BOD,- removal efficiency for piston, complately mixed and dispersed flow conditions have been given. An equation covering the dimen sions of pondr hydraulic detention time, and kinematic vis cosity of the fluid in the calculation of dispersion coeffi^ cient which is necessary for the.use of Wehner-Wiihelm equation for dispersed flow conditions, has been presented. lit the fourth chapter, reactions related to the bacteria and algae in stabilization ponds and. their optimum conditions have been illustrated. The facultative pond which is suitable for these conditions has been presented» and laboratory models have been made at different scales of this pönd. Models were supplied with domestic water at different flow-rates from the same feeding tank. Different parameters, defined in this chapter, were measured with previously set intervals at these models, which were running at different detention times.VI In the fifth chapter the results of the parameters, measured at the analyzed models in the fourth chapter, have been given. The range of change of this parameters have been eştaslished with the extrem values determined. Com- parision of the parameters with the values in the literature have been done and range of changes have been interpreted. In the sixth chapter, measured parameters and cal culated biological efficiency values have been given. Due to the surface areas, of the ponds and the flow rates of the feeded wastewater, loading values öf pond have been determined. Measured parameters and calculated parameters have been arranged as a matrix. Paired correlations of interparameters have been determined for each model by regression analysis. Parameters affecting the ponds have been obtained by statistical methods using the analysis method of factor with main component. Also, in this chapter the relationship expressing. The biological, efficiency have been developed by multiple regression analysis, and its computer program has been established. Biological effi ciency was determined for the winter, summer and whole year data separately. Also another computer program was developed to calculate the theoretical.- cf-f iciency J>y the use.of regression coefficients, and to calculate the variance, standart error between the theoretical and observed effi ciencies..VII In the design of dispersed flow model ponds, d dis persion coefficient and K, BOD- removal rate constant are the required parameters. K.t values were obtained from the graphs giving the Wehner-Wilhem relationship solution which depends on the determined pond efficiencies and measured dispersion coefficient in the pond. These K.t values were divided by hydraulic detention times and K reaction coeffi- -ciens were obtained. Reaction coefficients defined for each group of measured parameters formed a column in the para meters matrix. Reaction coefficient was expressed as the exponential function of the other parameters. This expres sion was arranged and a general relationship was obtained to yield the reaction rate constant for different parameters. It was determined that this expression satisfied^ the effi- ciencies obtained by the measured parameters on the models. Besides, it also satisfied the values in the literature for the suitable parameters as a special case*