Evsel atıksularda inert koi oranı ve biyolojik arıtılabilirlik üzerindeki etkileri

Abstract

Bu çalışmada Yeni kapı evsel' atıksularının biyolojik arıtılabi li rli ği incelenmiştir. Birinci bölümde, atıksuların giderilmesi istenen orga nik madde içeriği açısından tanımlanmasının arıtma sis temlerinin tasarım ve işletilmesindeki önemi, çalışmanın amaç ve kapsamından bahsedilmiştir. İkinci bölümde, atıksuların fiziksel, kimyasal ve biyo lojik özelliklerinin arıtma sistemlerinin işletme ve tasarımındaki önemi, etkileri belirtilmiş; farklı bölgelere ait kentsel atıksularının giriş ve çıkış değer leri ile Istanbul1 dan kaynaklanan atıksuların değerleri karşı 1 aştın İmi ştır. Üçüncü bölümde, İstanbul evsel atıksularının Su Kirli liği Kontrolü Yönetmeliğinde verilen alıcı ortama deşarj standartlarına göre arıtma gereksinimleri belirtilmiş, subsrat ölçümünde kullanılan parametrelerin anlamı üze rinde durulmuş ve biyolojik arıtılabili rlik sonuçlarının doğru bir şekilde değerlendirilmesinde önemi olan inert çözünmüş KOI, inert parti küler KOI ve oluşan metabolik ürünleri detaylı bir şekilde anlatan modeller ile klasik model karşılaştırılarak incelenmiştir. Dördüncü bölümde, modellemeleri verilen inert çözünmüş KOI, inert partiküler KOI ve kinetik sabitlerin bulunma sında tercih edilen deneysel yaklaşımlar ve kullanılan analitik yöntemler anlatılmıştır. Beşinci bölümde, yukarıda verilen deneysel prosedür uyarınca Yenikapı evsel atıksularına ait çözünmüş inert KOI, partiküler inert KOİ ve kinetik sabitlerin sonuçları verilmişti r. Altıncı bölümde, elde edilen sonuçların bir değerlen dirilmesi yapılmış ve öneriler sunulmuştur.

Environmental problems have been dramatically increasing and efficient uses of the natural sources have been decreasing in our world due to the increasing population and industrial development. Istanbul, which is the biggest and one of the ancient cities in Turkey has many environmental problems especially water pollution because of intensive population and industrialization. It is the fact that some effective precautions should be taken in order to protect environment. The main sources of wastewater in Istanbul have been intensive population in urban areas, industrial waste and urban run off. In order to prevent the pollution mentioned above; 1) Quantitative amount of wastewater pollution load and range of it in regard to various sources should be known, 2) Wastewater should be collected by a sewerage network, afterwards it.should be treated till a certain degree maintained before collection (industrial pre-treatment ) and after collection (.Joint treatment). The wastewater should be discharged to the enviroment after an effective treatment where the treatment plant is located in the right place. It has been recently observed in the analysis which has been done by tSKt in Istanbul that BODs concentration hasn't exceeded 200-220 mg/1. However the concentration level which was found by Camp Tekser (1976) and WMT (1986) according to pollution load per unit suggested for Istanbul is greater than the one found by t ski. Therefore, it would be more rational and suitable to lower this data suggest by WMT by 1.5 factor. Pollution load and concentrations which are basically used in evaluation are as follows; xi The data given in the table above are very close to the data, which were given by Metcalf and Eddy (1979) in the medium concentration range for the municipal wastewater. In the investigation of characteristics and concentration of values similar wastewater, it has been observed that influent value of untreated municipal wastewater in California-USA is very similar to the untreated municipal wastewater in Istanbul except the parameter "Total P". The recent modifications in treatment process and removal process of Istanbul untreated municipal wastewater have shown that all of the Joint wastewater discharges need biological treatment applications. It has been foreseen that the biological treatment plants have been designed Just for the removal of carbon, also with the some extra modifications, it should have efficiently structural flexibilty to remove the nitrojen by nitrifi cation, deni trif ication system and control the phosphorus with the biological phosphorus removal. After different treatment processes in California have been inspected, by which is aimed at uses of wastewater, have been determined and the suitable treatment levels have been selected. Biological processes have been pref ered. Actived sludge proses is used most widely among the biological treatment systems and generally it is based on the biological degradation and the removal of organic matters in wastewater by microorganisms in aerobic conditions. Actived sludge processes have been used for couple of years, but continous research and analysis have indicated both the dependence of effluent concentration on influent concentration and the difference between the characteristics of inf luent-ef f İuent concentration. Xii In biological treatment systems, the microbial growth and the rate of substrate utilization are proportional to the nutrient concentration which plays a role as a rale limiting factor in the system. At the same time, the removal of these nutrients and the measurement of their concentrations are very significant since they are essential substances for the system(Ekama et al.,1986). The methods used to measure the organic content of the substrate are based on the three collective parameter» such as Biochemical Oxygen Demand(BOD), Chemical Oxygen Demand (COD)» and Total Organic Carbon (TOO. COD is prefered because of the fact that it provides an electron energy balance among three basic matters which are organic substrate, biomass and utilized oxygen. And also it is completed in a short time. One of the disadvantages is that it does not differentiate between inert and biodegradable organic matter in wastewaters. Wastewaters usually contain a very wide spectrum of organics with respect to biodegradability. Total COD measured in the influent of the actived sludge process is consisting of biologically readily degradable substrate(Sso), slowly degradable substrate(Xso), soluble inert substrate(Sio) and particular inert substrate(Xio). Total COD measured in the effluent is consisting of remaining part of the initial biologically readily degradable substrate (Ss ), inert and degradable metabolic products which are produced in the system(Sp), the initial soluble inert substrate that passes through the system in an unchanged from(Sx), particular inert products (Xp) and inert particular substrate that is removed from the system by sludge wastage (Xi). Even though the structure of metabolic products is not known completely »most of the studies indicate that the bioderadation rate of these products is lower than that of influent substrate given to system so this metabolic products are considered as inert at normal, sludge age. The purpose of this study is to examine the biological treatability of the municipal wastewater entering to the Yeni kapı Pre-treatment system. At the first stage, characterization studies are conducted on the samples - taken at different times. On these examinations, different data have been found due to the wastewater from leather industry and the contamination of sea water in the wastewater. At the second stage, for the detei - mination of the soluble inert fraction of the influent COD, the comparison method developed by Germi rl i (1990) has been used. In this method soluble wastewater and glucose which have the equal concentration have been run with seed microorganisms in different batch reactors and the COD profile with time has been studied. With the assumption that the glucose and the observed waste water will generate the same concentrations of residual Xiii microbial products and that the glucose does not contain SIo, the differences between the threshold COD values reached in the two reactors will yield to SIo level for the studied wastewater. The experimental evaluations at different times yielded the following initial inert COD values SIo=15 mg/lt, SIo=17 mg/lt Hence, it has been found that soluble inert COD is 8-10 percent of the influent soluble COD. For the determination of particular inert fraction of the influent total COD denoted as Xi. Experimental procedure is based on the fact that settleable, soluble wastewater and glucose are generated together whit seed microorganisms in different batch reactors and total substrate is followed by the time. The experimental evaluations yielded the following particular inert COD values XIo=115 mg/lt, XIo=88 mg /It For the determination of the kinetic constants, the method proposed by Dang et al.(1989) had been used. Yp value which gives the value the microbial residual products with respect to the initial soluble COD and endogenous rate constant, b, should be known in order to solve the differential equations given below according to the Runge Kutta numerical analysis method when Sso, Xo and Sp values are known.