Karışık karbon kaynağı ortamının nişasta giderim performansı ve bakteriyel kompozisyon üzerine etkisi

The microbial processes have been extensively investigated for the efficiently design and operation of the activated sludge systems. The experimental studies have often focused on the single representative carbon source, although, microorganisms have to remove wastewater which is the mixture of several different type carbon sources. Under such conditions, bacteria often utilize one carbon source preferentially and other carbon sources are consumed only, when the preferred one is exhausted. The carbon source providing the best growth rate and/or growth yield is preferred, and the successive utilization of the substrates is often represented (Monod, 1942). In the environmental engineering point of view, it is important to understand the interaction between the removal mechanisms of different carbon sources which have a different degree of complexity. Although, recent studies have mainly focused on the biodegradation kinetics of the industrially produced starch as the only pollutant in wastewater, the simultaneous use of multiple substrates, such as the co-treatment of the industrially produced wastewater with the domestic wastewater produced in the facility, can lead to differences in biodegradation kinetics of any individual organic constituent as well as in the bacterial community. The researches with bacteria and higher organisms have revealed that selective carbon source utilization is common and that glucose is the preferred carbon source by many organisms. Moreover, the presence of glucose often prevents the use of other, secondary, carbon sources (Gorke and Stülke, 2008). In a study carried out under aerobic conditions with a mixture of similar type substrates (i.e. a mixture of acetic, lactic and propionic acid), a strong decrease in the removal rates of acetic and lactic acid was observed when treated in the presence of another substrate (Dionisi et al., 2004). This strong interaction among different substrates was explained with the interconnected pathways utilized by microorganisms for the removal of these substrates. Less clear evidences are available when dealing with mixtures of different type substrates, like volatile fatty acids and carbohydrates. Carta et al. (2001) reported that there were no differences in the uptake rate of acetate and glucose under mixed substrate environment compared to single substrate environment. In addition to the substrate uptake rates, the degradation kinetics and rates of the storage compounds were also reported as the same. In another study, when starch and acetate were treated together, slightly lower rates were observed in terms of individual carbon removal of acetate and starch, as well as respective storage of PHA and glycogen compared to treatment of substrate alone (Karahan et al., 2008). The fate of slowly biodegradable carbon source was evaluated in a SBR acclimated to starch as the sole carbon source and mixture of starch and acetate. The SBRs were operated with the same organic loading rate at two different sludge ages. Acetate, which is the one of the volatile fatty acid, was used as secondary pollutant as the volatile fatty acids have been reported as the main constituents of the domestic wastewaters. Although, the carbon source was fed to the SBRs in continuous mode throughout the cycle, the production of the storage polymer, namely glycogen, was observed in all SBRs. The relatively constant storage ratios were observed in SBRs fed with different carbon sources. The COD removal efficiency of the SBRs operated at the sludge ages of 8 days was significantly affected from the presence of acetate in the environment, although the COD removal efficiencies were constant at the sludge ages of 2 days independently from the presence of the secondary substrate. The bacterial characterization studies performed with fluorescent in situ hybridization (FISH) showed the decrease in the Actinobacteria phylum which was reported as the main starch consumer when the starch removal was performed in the multiple substrate environments at the sludge ages of 8 days. On the other hand, the detection of different groups at different sludge ages indicated the importance of the sludge age for evaluating treatment performance in activated sludge systems.  Keywords: Starch; dual substrate; substrate removal kinetic; FISH, activated sludge system. Evsel atıksuların arıtımında yaygın olarak kullanılan aktif çamur sistemlerinin başlıca kirletici parametre olan karbon kaynağının giderim performansı açısından değerlendirilmesi, sistemin en uygun tasarım kriterlerinin belirlenmesi açısından büyük önem taşımaktadır. Bu konuda yürütülen çalışmalarda, evsel atıksuların içeriğini yansıtacak şekilde seçilen tek bir karbon kaynağı model substrat olarak kullanılmaktadır. Fakat farklı karbon kaynaklarının bir arada veya ayrı ayrı arıtılmaları mikrobiyal dinamikler doğrultusunda farklı giderim performansları elde edilmesine neden olabilmektedir. Bu kapsamda, çalışmanın amacı evsel atıksuların karbonhidrat içeriğini yansıtan ve hedef karbon kaynağı olarak ele alınan nişastanın, başka bir karbon kaynağı ile beraber aktif çamur sisteminde arıtılması durumunda, giderim veriminde ve bakteriyel komposizyonda oluşabilecek farklılıkların tespit edilmesidir. 2 farklı çamur yaşında işletilen sistemde, ikincil karbon kaynağı olarak evsel atıksu kompozisyonun büyük bir kısmını oluşturan uçucu yağ asitlerini temsilen asetat seçilmiş ve bu sayede farklı giderim mekanizmaları ile giderilen farklı yapıdaki karbon kaynaklarının birbirlerine etkileri araştırılmıştır. Elde edilen veriler, 8 gün çamur yaşında nişasta giderim performansının, ortamda asetatın bulunmasından etkilendiğini ancak, 2 gün çamur yaşında karışık karbon kaynağı ortamının nişasta giderim performansı bakımında önemli bir etkisi olmadığını göstermiştir. Farklı koşullarda işletilen reaktörlerde bulunan baskın türlerin Flüoresanlı yerinde hibritleşme tekniği (FISH) yöntemi ile analizi sonucunda, 8 gün çamur yaşında karışık karbon kaynağı ortamının sadece mikrobiyal aktivite üzerinde değil aynı zamanda mikrobiyal seleksiyon üzerinde de etkisi olduğunu göstermiştir. Ayrıca, deneysel sonuçlar, çamur yaşının sistem performansı ve bakteriyel kompozisyon üzerinde etkili bir parametre olduğunu ve bu nedenle aktif çamur tesislerinin tasarımında öncelikli olarak ele alınması gerektiğini ortaya koymuştur.  Anahtar Kelimeler: Nişasta; karışık karbon kaynağı; karbon kaynağı giderim kinetiği; FISH; Aktif Çamur Sistemi.&nbsp

Çift tabakalı filtreler: Türkiye şartlarına uygun bir tasarım ve değerlendirme

Silica sand is the most widely used rapid filter medium around the world. The use of dual-media filtration, however, is now widespread in developed countries. Generally anthracite coal and silica sand are used together in dual-media filters. On the other hand, large water treatment plants in Turkey (including all the older and the new plants constructed by İSKİ and DSİ) still employ single-medium sand filters. A sand/anthracite dual media filter design was evaluated as a possible upgrade of the widely used rapid sand filters in Turkey. Pilot scale direct filtration experiments were carried out using raw and synthetic waters. The raw surface water was obtained from the raw water intake at the İkitelli drinking water treatment plant of Istanbul. Two identical filters were operated in parallel in all the experiments. One filter contained the silica sand medium that is currently used by several large municipalities in Turkey, whereas the other filter contained a layer of the same sand plus an anthracite layer that replaced the topmost 40 cm of the mono-medium sand filter. The properties of the dual media filter were selected such that the currently used sand filters in Turkey can be converted to dual media filters with a minimal amount of effort. Experiments were repeated several times as follows: (i) without the use of a coagulant, (ii-iv) with 3 mg/L, 5 mg/L and 10 mg/L of alum, and (v-vi) with 5 mg/L and 10 mg/L of ferric chloride. Turbidity, particle counts, and head losses were measured and compared as functions of time. In all the experiments carried out in this work, the following were observed: (1) Whenever a coagulant was used, the filter containing sand/anthracite dual media produced effluent turbidities and particle counts similar to those obtained with the sand filter. (2) Sand/anthracite medium generated a smaller clean-bed head loss and smaller clogging head losses than those of the sand filter. Considering the experience with dual media filters over many years in other parts of the world, these findings are not surprising. These findings are significant, however, because they demonstrate the applicability of dual media filtration under unique local conditions. The following factors are important in this respect: (1) The sand medium employed in the dual media filter was the same as the currently used sand in local plants. The same sand can be continued to be used after conversion to dual media filtration. All that is necessary is to replace about 40 percent of the sand by anthracite. Furthermore, the currently used media-retaining nozzles and the underdrain system will not have to be changed. (2) The tests are unique in that, the performance of the particular combination of media sizes and depths used in this study –to the best knowledge of the authors- have not been documented in the literature. (3) Many of the studies comparing dual media filters with mono-medium filters were carried out long time ago and without particle counters, using turbidity as the sole indicator of particle removal efficiency. The use of on-line particle counters in this study allowed a better comparison of the effluent qualities achievable in single and dual media filters. It is concluded that the particular sand-anthracite dual media design selected in this study can be employed to decrease and delay filter head loss development. The use of the dual media filter design described here will allow longer filter runs while obtaining essentially the same effluent quality. Another benefit of converting to dual media filtration will be the more widespread use of direct filtration which is currently not preferred by local engineers even when faced with low turbidity raw waters. Keywords: Drinking water treatment rapid filtration, filter material, silica sand, anthracite coal, particle removal.Silika kumu, bütün dünyada en yaygın olarak kullanılan filtre malzemesi olmakla birlikte gelişmiş ülkelerde çift ve daha çok tabakalı filtrelerin kullanımı yaygınlaşmıştır. Çift malzemeli filtrelerde genellikle antrasit kömürü ve silika kumu birlikte kullanılmaktadır. Ancak Türkiye’deki mevcut büyük arıtma tesislerinde sadece silika kumu kullanımı devam ettirilmektedir. Bu çalışmada, İstanbul’un içme suyunun büyük bir bölümünü sağlayan İkitelli içme suyu arıtma tesisi girişinden temin edilen hamsu ve sentetik olarak hazırlanan sular üzerinde pilot ölçekli hızlı filtrasyon deneyleri yürütülmüştür. Çalışmalarda iki paralel filtre kullanılmıştır. Filtrelerden biri Türkiye’de yaygın olarak kullanılan silika kumunu, diğeri ise antrasit kömürü ve silika kumunu içerecek şekilde çift tabakalı olarak hazırlanmıştır. Deneyler bu iki paralel filtrenin eş zamanlı çalıştırılması ile yürütülmüş ve filtrelerin performansı zamana bağlı olarak bulanıklık, parçacık sayımı ile yük kayıpları ölçülerek mukayese edilmiştir. Çalışmanın temel hedefi değişik filtre malzemesi kombinasyonu kullanımının su kalitesi ve yük kayıplarına olan etkilerini tespit etmektir. Bu çalışmada elde edilen temel neticeler şu şekilde özetlenebilir: (i) Uygun dozajda bir yumaklaştırıcı kullanıldığı takdirde, çift tabakalı (antrasit ve kum) filtrede tek tabakalı (silika kumu) filtredekine eşdeğer çıkış suyu kalitesi elde edilmiştir. (ii) Çift tabakalı filtrede hem temiz yatak (filtrasyon başlangıcındaki) yük kayıpları hem de filtrenin tıkanmasından dolayı ortaya çıkan yük kaybı artışları tek malzemeli kum filtreninkine nazaran mühim ölçüde daha az olmuştur. Anahtar Kelimeler: İçme suyu arıtımı, hızlı filtrasyon, filtre malzemesi, silika kumu, antrasit kömürü, parçacık giderimi

Silindirik bir sıvı tankının oturma performansının belirlenmesi

Cylindrical tanks are usually used in petro-chemical industry to store water or chemical materials. When their diameters, heights are taken into account, excess stresses will be transferred to the soil that they would be built on. Therefore even if the soil is considered to have sufficient bearing capacity, under the loading conditions over a large area, there can be problems due to bearing capacity, settlements and deformations. When designing a tank, foundation engineering is an important factor to consider. In the design of these wide diameter and flexible based structures, built on the problematic soils, a need for soil improvement as it would be done for a wide area could be costly. Therefore in the geotechnical analysis for these structures, the limit and tolerable values for settlement criteria needs to be considered in terms of structural integrity performances. When wide cylindrical tank structures are built on the weak soils, the settlement performance needs to be considered along with the damages that can occur on the upper structure. Settlements can cause problems in the nearby structures and the pipe connections can be effected. Cylindrical tanks are usually built on compacted granular fill materials or ring foundations with filled granular materials in the middle. In the weak soil conditions, the appropriate soil improvement method is chosen and applied or pile foundation system is used. In this paper, a cylindrical tank constructed on a site where there could be geotechnical problems, is considered. The tank considered is 65m in diameter and has a height of 19m. The settlements that could be critical are compared with the allowable ones stated in literature. Types of settlements that a wide cylindrical tank undergo are; uniform, planar and non-planar rotation, dishing, rotation at the crust and the base of the tank, and settlement at the base of the tank. The settlement calculations done were based on Janbu's tangent modulus method developed in 1967. Uniform settlements occur where beneath the tank at every point similar settlements exist. Planar rotation occurs when there is a differential settlement between two points on the tank. Dishing occurs where differential settlements are observed between two points on the tank and the middle of the tank base settle more than expected. Under the base of the tank, if there is soil with different geotechnical properties, local settlements can occur. Due to different soil strata thickness and deformation modules at the crust of the tank non-planar deformations can happen. In the case considered here, settlement calculations are done for various points on the tank and the total settlement values changed between 32cm to 79.3cm. Therefore as the minimum values for the settlement of the structure is calculated, it is seen that uniform settlement will occur. The settlements that would occur due to dishing or rotation will make up the differential settlements. According to the settlement analysis done, dishing value of 9.6cm is calculated in the centre of the tank. The differential settlements will occur at the crust of the tank which was not within the limits suggested in literature. Settlements due to liquefaction of soil were calculated as well. With different thickness of the liquefiable layers settlement values varied in different parts of the tank. As the structure is flexible, in the case of floating roofed tank systems, due to earthquake loadings, there would be big displacements and deformations that could cause collapse of the structure or damage in the structural system. Therefore the cylindrical tanks that would be constructed in the earthquake zones, dampers can be placed in their foundations. Under the tanks that are big in diameter, differential settlements will occur. Soil improvement can be done to prevent these deformations. Stress distribution in the soil of these heavy structures attenuates at depth. Therefore site investigation needs to be done in detail and at depth. Bearing capacity can be sufficient and settlements can be within limits under static conditions. However when saturated soils are considered, under earthquake loadings, liquefaction analysis needs to be done. Excess settlements can occur due to liquefaction. Steel cylindrical tanks are usually filled with liquid. Depending on the level of fullness, the vibrating frequency of the tank changes and needs to be calculated and dampers can be used. Dynamic analysis needs to be done with considering the local soil conditions. Keywords: bearing capacity, cylindrical tanks, settlement.Geniş çaplı ve esnek taban özelliklerine sahip silindirik tank yapıların tasarımında, problemli zeminlerde iyileştirme gerekliliği ortaya çıkması durumunda, alanın genişliğine bağlı olarak ıslah maliyeti yüksek olmaktadır. Bu tip yapıların geoteknik açıdan analizinde, gerek taşıma gücü gerekse oturma kriterlerinde sınır değerler, yapısal bütünlük performansı yönünden ele alınması gerekmektedir. Tank oturmaları zeminin göçmeye karşı güvenliğine göre daha önemli ve esas tasarım koşuludur. Oturmalar aynı zamanda komşu yapıları ve boru bağlantılarını olumsuz yönde etkileyebilmektedir. Tank yapısı altında gerçekleşen oturmalara bağlı olarak üstyapı formunda deformasyonlar meydana gelmektedir. Deformasyon derecesine bağlı olarak yüzer çatılı sistemlerde, çatı sisteminin sıkışmasına ve sistemin çalışmamasına neden olabilmektedir. Zeminin sıvılaşmasına ve sıvılaşan tabaka kalınlığına bağlı olarak deformasyonlar meydana gelecektir. Yapının esnek olması nedeniyle, deprem yüklerine bağlı olarak, büyük deplasman ve deformasyonlar oluşacak yapıda yıkılma veya hasar oluşmasa dahi yapısal sistemde arızalar meydana gelebilecektir. Bu çalışma kapsamında, tank yapıları için özellikle kritik olabilen oturmalar ele alınmıştır. Literatürde silindirik tank yapıları için verilen, oturma limit değerleri ve bu değerler dikkate alınarak, siltli kil kum tabakalı bir zeminde yer alan silindirik tank yapısı için analiz yapılmıştır. Yapılan hesaplar sonucu oturmalar silindirik tankın bazı noktalarında izin verilebilecek değeri aşmaktadır. Ayrıca tank ekseni boyunca meydana gelen düzlemsel oturma, merkez noktada hesaplanan oturma ile karşılaştırılıdığında çanaklanmaya bağlı olarak oturma meydana gelmiştir. Meydana gelicek oturmaları önlemek için zemin iyileştirilmesi önerilebilinir. Anahtar Kelimeler: Silindirik tank, oturma, taşıma gücü

Galata Köprüleri ve Yeni Galata Köprüsü

Galata Bridges, being an unforgettable symbol of Istanbul, have always been one of the prevalent points of the social life in the city from Byzantine times up to today. It may be a little bit strange to start an article, written for an engineering periodical, with such an introduction but, especially the recent period Galata bridges are not only passage ways but also living structures playing important roles in the social life of the city. Considering this speciality of the Galata bridges, you cannot find any other example in the world. First of all, the New Galata Bridge has been the fourth and considering the wooden bridge of 1863, even the fifth bridge constructed in the Golden horn. Secondly, the New Galata Bridge is the third steel bridge with an opening at the middle part for marine traffic. General Manager of the General Directorate of Highways of that period had written for the New Galata Bridge; “Galata Bridge is an important piece of art in the history of bridges in various ways. Foundation conditions, opening-closing sections, abutments, arrangements in the squares have always created problems which necessitating the special technical solutions. However our Contractor, Engineer and the Administration’s engineers are successfully executing the project by solving such technical problems. When their piece of art is completed, it will be the honor of Turkish Engineering.” A protocol has been signed between the owner Istanbul Municipality and Contractor Highways 17th Division Directorate on 17.03.1982, authorizing Highways 17th Division Directorate as the responsible authority to have the New Galata Bridge and Eminönü and Karaköy Squares constructed in the name of Istanbul Municipality. All the feasibility, tender preparation, engineering and supervision services has been carried by 17th Division Directorate and his Consultant. For the preparation of Tender Documents the relevant laws as well as the specifications of General Directorate of Highways and FIDIC were taken as a basis. Tender was also opened to Alternative Proposals and another condition was imposed for the Contractors to provide foreign loans for the finance of the Project together with their proposals. Following the evaluation of the proposals the Construction Contract has been signed by the consortium established between Sezai Türkeş Feyzi Akkaya İnşaat A.Ş. and Thyssen Engineering GmgH on 27th January 1986. Although the original tender design was for a concrete pontoon type bridge structure, the winner’s alternative proposal for a pre-stressed concrete deck bridge on pile foundation with an opening type steel bascule bridge at the middle has been selected. The foreign loans brought by the consortium for the finance of the project were German Government Loans provided by German Credit Establishment KfW. In this presentation, I will try to summarize the New Galata Bridge Project with a brief history and the tender stage as well as the main structures of the bridge. The other structures such as the vehicle and pedestrian underpasses and underpass shopping areas within the scope of square arrangements, although they are the part of the tender, shall not be incorporated in this presentation. Each phases; such as design stages, construction methods of every main structure, contractual periods, subjects taken into consideration by Turkish and international media; each being a separate subject of research article, the New Galata Bridge is under public service from the acceptance date of June 1992 up to now, without inferior to the previous Galata Bridges which were the subject of many photographs taken, the articles and poems written in the history.Keywords: Galata bridges, prestressed concrete deck, pile load test, cutwater. İstanbul’un vazgeçilmez simgelerinden olan Galata Köprüleri Bizans zamanından bu yana şehrin sosyal yaşantısına da hakim olan noktalardan biridir. Bir Mühendislik dergisine yazılan bir yazıya böyle başlamak belki şaşırtıcı gelecek ama özellikle son dönem Galata Köprüleri sadece bir geçiş mekanı değil şehrin sosyal yaşantısına da katılan adeta yaşayan yapılardır. Bu yönü ile dünyada örneğine rastlamanız da pek mümkün değildir. Yeni Galata Köprüsü için dönemin Karayolları Genel Müdürü şöyle yazmıştır; “Galata Köprüsü birçok yönleriyle köprüler tarihinde önemli bir yer tutacak bir eserdir. Temel şartları, açılan kısımlar, kara ile bağlantıları, meydan düzenlemeleri hepsi çözümü gerektiren çok önemli teknik problemler ortaya çıkarmıştır. Ama, müteahhit, mühendis ve idarede görev alan mühendislerimiz bu sorunları çözerek projeyi başarı ile yürütmektedirler. Eser tamamlanınca Türk mühendisliğinin göğüs kabartıcı başarısı olacaktır.” Bu sunumda Yeni Galata Köprüsü Projesi, kısa bir tarihçeyi takiben, ihale aşaması ve ana yapıları açısından özet olarak tanıtılmaya çalışılacaktır. İhalenin parçası olan Eminönü ve Karaköy meydanlarında yapımı tamamlanan vasıta ve yaya altgeçitleri, çarşılar ve meydan düzenlemeleri bu sunuş kapsamına alınmamıştır. Öte yandan gerek projelendirme safhaları, gerek her bir yapısının inşa yöntemleri, gerek mukavelevi süreçleri ve medyaya akseden yönleri ile herbiri ayrı bir çalışma konusu olabilecek olan Yeni Galata Köprüsü Kabulünün yapıldığı Haziran 1992’den beri fotoğrafları çekilmiş, makaleleri, şiirleri yazılmış eski Galata köprülerinden hiçbir yönde aşağı kalmaksızın hizmetini sürdürmektedir. Anahtar Kelimeler: Galata Köprüleri, öngerilmeli betonarme tabliye, kazık yükleme deneyi, koruyucu mahmuz

Geoteknik bakış açısı ile özgün bir deprem hasar görebilirlik yönteminin geliştirilmesi

Earthquake damage assessment methodologies are applied mainly for two purposes; as a damage assessment methodology in urban areas and as a land use study in undeveloped areas for the purpose of city planning. Satisfactory earthquake damage assessment methodologies should incorporate the information from geological and geophysical investigations, quantitative, qualitative analyses and expert interpretations. In today's state-of-the-art, despite the existence of numerous applications in this context, there is still a need for comprehensive and quantitative methodologies to ensure that all the damage-causing phenomena are well understood and included. Regarding these studies, data collection and quality are of primary importance because once spatial database is implemented; it is rarely scrutinized for its correctness, completeness or accuracy leaving behind serious data quality issues. In Turkey devastating earthquakes, which hit Kocaeli and Düzce area in 1999 have created an increasing awareness about the damaging potential of earthquakes. In the context of earthquake preparedness efforts, microzonation projects have been prepared for various districts in Istanbul and Marmara region. In this paper, an integrated earthquake damage assessment methodology is presented to fulfill the need for standardized and quantitative approaches in this area. The approach inherently carries a soil-structure interaction concept by combining the site specific geotechnical and structural properties in a quantitative manner. The basic merit of the proposed methodology is to include all the damage making phenomenon systematically and to evaluate their effects both individually and in combination. Earthquake damage assessment analyses with respect to primary and collateral effects were conducted. The primary damage-causing effect was accepted to be ground shaking and the collateral effects were accepted as liquefaction, seismic bearing capacity degradation and landslides. At the present state of the art, existing spatial earthquake damage assessment studies acknowledge the collateral effects due to liquefaction and landslides but fail to consider those due to seismic bearing capacity degradation of shallow foundations. This consideration is important, because while liquefaction is a threat for loose and granular soils, seismic bearing capacity degradation may occur in almost all types of foundation soils.  In this paper, a damage grade was assigned for each individual event and also an integrated damage grade for their combined effects. Assigned damage grades were based on an interpretation of a probabilistic "damage-damage causing event" relationship available in the literature and applicable for the region. The damage grades given in this paper reflect a rough probabilistic evaluation but their function is to define a single decision made over a set of probabilities. The proposed methodology was also applied to Bakirkoy district in Istanbul and the results indicate the effectiveness of the approach. In order to collect the necessary geological, geotechnical data for the spatial analysis 87 borings amounting to 2011 meters were made in an area of 6.1 km2. The study was conducted by a multidisciplinary team of Istanbul University (Istanbul University Report, 2000). An extensive laboratory-testing program was conducted to determine physical and mechanical properties of soil and rock samples recovered from the boreholes. Seismic wave refraction surveys were conducted at 125 locations and electrical resistivity measurements were made at 210 points All the data related to the location of boring logs. geophysical measurement points, three dimensional topography and geology of the region were displayed via GIS maps. The analyses have shown that the district carries a considerable risk of being significantly affected by future earthquakes and therefore damage and consequent economic losses from a great magnitude earthquake centered near the district would be severe. Although it has been applied in Turkey, the proposed methodology has the basic feature of being applicable to any earthquake-prone area. The methodology developed can be extended to add the effects of any other damage making phenomena that may affect the considered region. Keywords: Earthquake damage assessment, ground shaking, liquefaction, seismic bearing capacity degradation.Gerek kentleşmiş, gerekse kentleşmeye açılacak olan bölgelerde olası bir depremin sebep olacağı zararın en aza indirilebilmesi için deprem tehdidinin boyutlarının mevcut yerel ve yapısal koşullarla birlikte oldukça gerçekçi bir seviyede tanımlanması ve alınması gereken önlemlerin buna göre belirlenmesi gerekmektedir. Deprem gibi afetlere karşı hazırlıklı olma, can ve mal kaybını en aza indirme gayretleri insani boyutları sebebiyle küresel niteliktedir. Bu makalede bu kapsamda yapılmış olan detaylı ve özgün bir çalışma tanıtılmaktadır. Şehirleşmiş alanlarda hasar görülebilirlik seviyesinin tanımlanmasına yönelik olarak ve/veya yerleşime yeni açılacak alanlar ile ilgili çalışmalara yön göstermek üzere bir deprem hasar görebilirlik yöntemi geliştirilmiştir.  Birincil hasar etkeni olarak yer sarsıntısı, ikincil etkenler olarak sıvılaşma, dinamik yükler altında taşıma gücü kaybı ve heyelan tetiklenmesi göz önüne alınmıştır. Tüm bu etkenler için performans bazlı değerlendirme yapılmıştır. Dinamik yükler altında taşıma gücü kaybına bağlı oluşabilecek oturmalar literatürde ilk kez bu çalışma kapsamında hasar görebilirlik çalışmalarına dâhil edilmiştir. Her bir hasar verici etkenin yaratacağı hasar seviyesi önemsiz hasar seviyesi-çok yüksek hasar seviyesi aralığında puanlamıştır. Bu puanların oluşturulmasında literatürde yer alan önemli veritabanları ve yayınlar kullanılmıştır. Her bir hasar puanı için elde edilen puanlar uygun bir şekilde birleştirilmiş ve böylece her bir nokta için tek bir hasar puanı elde edilmiştir. Makalenin son kısmında geliştirilmiş olan yöntem Bakırköy İlçesi için uygulanmıştır. İlçe için yapılmış olan detaylı arazi çalışmalarına dayanan analizler neticesinde farklı tipteki yapılar için yer sarsıntısı sıvılaşma, taşıma gücü ve sıvılaşmaya bağlı hasar potansiyeli ve toplam hasar görebilirlik incelenmiştir. İlçede tasarım depremi için oluşması beklenen bu hasar seviyeleri CBS ortamında haritalanmıştır. Anahtar Kelimeler: Deprem hasar görebilirlik çalışmaları, yer sarsıntısı, sıvılaşma, taşıma gücü kaybı, heyelan, toplam hasar görebilirlik

Kuzey Anadolu Fay Sistemi Güney Kolunun Geyve-Gemlik arasındaki kesiminin tektonostratigrafik evrimi

Strands of the North Anatolian Fault System (NAFS) in the Marmara Region were re-named within the content of this Ph. D. thesis. This fault system has been defined as horse-tail splitting into three strands as the Northern Strand of the North Anatolian Fault System (NAFSNS), Southern Strand of the North Anatolian Fault System (NAFSSS) and Southern-a Strand of the North Anatolian Fault System (NAFSSS-a). Lithostratigraphy, morphotectonic features, structural geology, basin models and historical earthquakes of the region were studied by this study for the Geyve-Pamukova and İznik basins located between Geyve (Sakarya), Mekece (Sakarya), İznik (Bursa) and Gemlik (Bursa) on the NAFSSS and bordered by the Armutlu-Ovacık Zone in north and the Sakarya Zone in south. Six main faults (Sarıgazi, Mekece, Dırazali, Gürle, Orhangazi, Umurbey) and three fault zones developed by the secondary segments related to the six main faults were mapped as the NAFSSS in the region. The Sarıgazi main fault in the east of the study area and in the Geyve-Pamukova basin and the Geyve Fault Zone (GFZ) were created by the secondary segments. Deposits of the Geyve-Pamukova basin were mapped based on the lithostratigraphic facies. The units from the bottom to the top of the basin were classified into four formations as Geyve (Qg), Pınarlı (Qp), Çardak (Qc) and Hocaköy (Qh). The Geyve formation was divided into Kollu pebblestone (Qgk) and Beylik clastic (Qgb) members and Çardak formation was sub-divided into Ayvalık (Qga) and Yanıkorman (Qcy) clastic members. The Kollu pebblestone member deposited at the base of the Geyve-Pamukova basin is a debris-flow deposit. The source for this member is Sakarya River and its small tributaries.Beylik clastic member of the Kollu pebblestone defines channel and set-point enviroments of the same river. The present deposition of these units in the southern edge of the basin is directly related to the deformation caused by the right lateral displacements by the Sarıgazi fault in Sakarya River. Alluvial fan Hocaköy formation overlies these basal units with uplifting of southern block by the Sarıgazi fault. The southern edge of the basin is formed by the right lateral fault. However, flood-plain sediments of the Pınarlı formation are deposited on the northern edge, where the deformation effect is less. The youngest unit is the Çardak formation located in the middle of the basin. This formation resembles to the Geyve formation. Architecture of the Iznik Basin along the NAFSSS developed when the step-over of the northwesterly striking Dirazali fault to Gurle fault triggered westerly step-over of the Gurle fault to east-westerly striking Umurbey fault due to simple dextral shear kinematics and north-nortwesterly, south-southwesterly transtensional deformation. This basin architecture was also supported by the southerly dipping, dextral oblique Orhangazi fault that is identified at the northern edge of the Iznik fault. The vertical displacement of southern edge of the basin by the right lateral faulting caused disconnections to the sea level. As a result, the İznik formation was deposited in a brackish water environment. After the sedimentation phase in the basin, the dominant right lateral oblique movement of the Gurle fault located between the Umurbey and Dırazali faults elevated the İznik formation approximately 60 m from the basin surface. Additionally, the Orhangazi fault which has the same charter as the Gurle fault controlled the İznik and Hocaköy formations located in the western section of northern edge of the basin. The slickenlines pointing out a right lateral oblique normal faulting indicate a rotation with simple shearing and transtension for the right lateral fault system. The basin was formed as lazy S shaped pull-apart basin that was created by the right lateral faulting and NNE-SSW dilatation. This neo-tectonics shows that the İznik basin is a pull-apart basin developed with a transtensional right lateral faulting. Almost all of the structural features of the right lateral simple shearing strain elipsoid were developed during the all stages of the basin opening. Keywords: Southern Strand of the North Anatolian Fault System, Tectonostratigraphy, Lazy S shaped pull-apart basin.Kuzey Anadolu Fay Sistemi güney kolu üzerinde neotektonik dönemde oluşan düzlük alanlar birbirine Mekece-İznik koridoru ile bağlanan Geyve-Pamukova ve İznik Havza’larıdır. Geyve-Pamukova Havza’sının litostratigrafisi alttan üste doğru; yanal geçişli Geyve-Pınarlı, Hocaköy ve Çardak formasyonlarını içerir. Hocaköy formasyonu güney bloktan gelen drenajın, Geyve formasyonu ise Sakarya Nehri’nin desteği ile oluşmuştur. Bunun yanında Sakarya Nehri’nin havza açılımından günümüze değin uğradığı sağ yanal atımlı deformasyon Geyve formasyonunun gelişmesinde birincil etkendir. İznik Havza’sında ise Erken Khazarian’dan günümüze alttan üste doğru İznik, Hocaköy ve Solöz formasyonları çökelmiştir. Geyve-Pamukova Havzası güney kenarındaki KD-GB doğrultulu sağ yanal atımlı Sarıgazi Fayının açılmalı dönmesi sonucunda gelişmiş gevşek S biçimli çek-ayır havza şeklinde oluşmuştur. İznik Havzası ise güney kenarındaki KD-GB doğrultulu sağ yanal atımlı Dırazali fayının, BKB-DGD doğrultulu sağ yanal oblik bir normal fay olan Gürle fayına sıçraması ile birlikte oluşmaya başlamıştır. Havzanın kuzey kenarındaki KB-GD doğrultulu sağ yanal oblik normal fay karakterli Orhangazi fayı ise havzanın Geyve-Pamukova Havzasına göre daha simetrik açılmasına destek olmuştur. İnceleme alanının bütününe hakim olan sağ yanal basit makaslamalı sistem İznik Havza’sının ise daha geniş ölçekli çek-ayır havza şeklinde açılmasını sağlamıştır. Anahtar Kelimeler: Kuzey Anadolu Fay Sistemi Güney Kolu, Tektonostratigrafi, Gevşek S biçimli çek-ayır havza.&nbsp

Lefkoşa surlariçi zeminlerinin özellikleri

Alluvial soils and overconsolidated clays constitute the most soils of Cyprus. The alluviums show relatively high apparent strength in their dry state. However, with saturation their strength decreases. The clayey parts of the alluviums have low to medium swelling potential. Overconsolidated swelling clays of Cyprus occurred as a result of the alteration of the Troodos ophiolite and the pelagic sedimentary cycles that followed in the post Createceous period. The calcium corbonate content of the clays (marls) originated from the limestones and dolomites of the Kyrenia zone. There is widespread damage to the buildings, major roads and highways all over the country which were founded on swelling clays. Clays of Cyprus can be divided into five groups. 1.Clays of Mamonia Complex, 2.Bentonitic Clays, 3.Clays of Kythrea Group, 4.Mesaoria clay zone and 5.Alluvial clays. Large parts of Nicosia is covered by man made fills, alluvial soils and swelling clays  Swelling clay problems occur continuously every year due to the soil expanding in the winter and shrinking in the summer. Nicosia is almost flat lying at about 110 - 160m above the mean sea level and is located between the Kyrenia and Troodos ranges. Several streams are flowing from south and north. The soils of Nicosia are; Man made fills, Alluviums, Mesaria Clay Zone, Kalavasos Formation and Kythrea Group. The Kythrea group is widespread in the north of Nicosia. Alternation of sandstone-siltstone-marl-claystone are widespread within the group. The group is only observed in the Turkish Republic of Northern Cyprus and its overconsolidated clays exhibits low to high swelling potential. Mesaria Clay Zone is widespread in the south of Nicosia and consists of gravel-sand-claystones. Overconsolidated Nicosia clays exhibits low to very high swelling potential. Nicosia is covered by extensive alluvial deposits of up to a thickness of 22 m. SPT, UD, and core samples taken from the boreholes are tested in the laboratory for mechanical (grading) analysis, moisture content, unit weight, specific gravity, Atterberg limits, and CaCO3 content. X-ray diffraction (XRD), Scanning Electron microprobe (SEM) and Energy Dispersive X -Ray (EDX) analysis are also conducted. The properties of Nicosia walled city soils are determined by boreholes drilled in five different locations between 2001 and 2007. The soils are man made fills, alluviums, Nicosia clays, Kalavasos Formation and Kythrea group. Man made fills and alluviums are present from the surface to between 7.20 m and 22.00 m depth. The water table is between 4.90 m and 10.00 m. There is no swelling and shrinkage within the walled city. The highest liquid limit (LL) values of the analyzed samples are present in yellowish to light grey weathered, oxidized Nicosia clay (marl). Clay and montmorillonite contests are increasing within these samples. CaCO3 contents are higher in the light coloured samples. The Liquid limit (LL) values are decreasing with the increasing amount of CaCO3. The lowest SPT N values are present in the fine grained alluvium deposits. The SPT N values of Nicosia clays ( marls) are between 33 and 75. The semi quantitative X-ray diffraction (XRD), Scanning Electron microprobe (SEM) and Energy Dispersive X -Ray (EDX) analyses indicated that the predominant clay mineral is montmorillonite (smectite), illite and chlorite or kaolinite are the other abundant clay minerals. Calcite is the major mineral of the clays (marls), quartz and feldspar are also present at high amounts. Montmorillonite (smectite) with an amount ranging between 10 and 30%. illite and chlorite or kaolinite with an amount ranging between 5 and 10%. Calcite with an amount ranging between 30 and 65% is the major mineral of the alluviums and Nicosia clays (marls). The other minerals are quartz ranging between 2 and 6%, feldspar ranging between 4 and 15 %, and dolomite ranging between 2 and 9%. EDX analysis for the Nicosia clays indicated that Si, Al, K and Mg peaks are together. Therefore predominant clay minerals are montmorillonite (smectite) and illite. The high amount of Fe %10 it could be the result of the ofiolitic Fe minerals. Despite the overconsolidation character the soils have high porosity. Keywords: Atterberg limits, montmorillonite, calcium carbonate, Nicosia clays. Kıbrıs zeminlerinin büyük bir bölümünü şişen killer, alüvyonlar ve evaporitik kayaçlar oluşturur. Kuzey KıbrısTürk Cumhuriyeti hemen hemen tamamıyle killi formasyonlar ve alüvyonlar ile kaplıdır. Kıbrıs killeri Trodos ofiyolitinin ayrışması ve Kretase sonrası pelajik tortul olarak oluşmuşlardır. Kuzey Kıbrıs (Girne) zonundaki kireçtaşı ve dolomitler ile Güney Kıbrıs zonundaki tebeşirlerin killerin oluşumunda kaynak olması ve biojenik oluşum, killi formasyonların yüksek oranda montmorillonit (smektit) ve kalsium karbonat içermelerini sağlamıştır. Mesarya zonu ve Değirmenlik grubunda bulunan aşırı konsolide killi zeminlerin kurak yarı-kurak akdeniz iklimine bağlı olarak su içeriğinin artması ile şişmesi ve azalması ile büzülmesi sonucu yapılarda hasarlar oluşmaktadır.  Düşük taşıma kapasiteli alüvyonlar çok yaygın olarak Mesarya ovasında, Lefkoşa, GaziMağusa ile doğu ve batı kıyılarda gözlenir. Alüvyonlar üzerine inşa edilen tarihi yapılarda oturmalardan veya göçmelerden büyük hasarlara rastlanmaktadır. Son on yıl içerisinde yapılarda meydana gelen hasarları önlemek ve tarihi binaların restorasyonu için Kuzey ve Güney Lefkoşa’da geoteknik incelemeler yapılmıştır. UD, SPT ve karot sondaj örnekleri alınarak laboratuvarda elek analizleri, doğal su içeriği, birim ağırlık, özgül ağırlık, Atterberg limitleri ve kalsiyum karbonat (CaCO3) miktarlarının belirlenmesi için deneyler yapılmıştır. Elektron mikroskop (SEM), yarı kantitatif (XRD) ve yarı kantitatif (EDX) element analizleri de yapılmıştır. Elde edilen değerler ışığında Lefkoşa surlariçi zeminlerinin dolgu, alüvyon, Lefkoşa killeri, Mermertepe formasyonu ve Değirmenlik grubundan oluştuğu belirlenmiştir. Dolgu ve alüvyon zeminlerin 7.20 m ile 22.00 m arasında olduğu su seviyesinin 4.90 m ile 10.00 m arasında olduğu ve su seviyesinin Lefkoşa killeri üzerinde olduğundan şişme ve büzelme meydana gelmediği tesbit edilmiştir. Lefkoşa surlariçi zeminlerinin özellikleri sunulmaktadır. Anahtar Kelimeler: Atterberg limitleri, montmorillonit, kalsiyum karbonat, Lefkoşa killeri

Geoteknik mühendisliğinde yapay sinir ağı uygulamaları ve bir örnek: Zemin profilinin tahmin edilmesi

   The use of artificial neural networks (ANN) in geotechnical engineering has gained wide application in Turkey as well as the world during the past ten years. A comprehensive literature survey has shown that applications are concentrated in basic areas such as classification, site characterization, liquefaction, hydraulic conductivity, compaction, consolidation as well as practice comprising the problems of retaining structures, settlement of foundations, pile capacity and modeling of soil behavior where the relationship among the several parameters involved is not always thoroughly understood. Several case histories are presented as examples. Latest research shows that artificial neural networks are heading towards unison with fuzzy logic and genetic algorithms and it is certainly superior to the statistical methods.The second part of the paper gives an account of research conducted into estimation of the soil profiles in the city of Adapazari, Turkey. There has been widespread damage and destruction in the city during the Mw=7.4 earthquake in 1999. The damage has largely been blamed on inferior alluvial deposits and parts of the city have been moved to the North where the soil was found to be "sound". The sediments in the city are the products of the meandering river Sakarya which also flooded the region almost biannually. The two processes have resulted in the formation of complex soil profiles and near chaotic profiles are frequent. The silty layers are possibly the source of ground failures, occasionally leading to liquefaction in the absence of sands. A comprehensive soil investigation has been carried out since 1990 by boreholes and cone penetration soundings. The authors have used the rich database available established from previous and current laboratory and field investigations. Out of this voluminous data those pertaining to depths of 2 to 7m have been used for the ANN work, as those depths have been diagnosed as the possible liquefaction zone. Data from 117 CPT sites whose coordinates were known were employed for this study. The 3236 readings of tip resistance and sleeve friction were used to establish the ANN model. The well established Robertson classification chart defines nine types of soil. It requires the normalised values of tip resistance(Qt) and and sleeve friction(Fr) a identify the soil layer. The Qt* and Fr* are further defined to form the spatial distribution by the use of equations. The training matrix even for a limited depth of 5m using the data from 90 CPTU tests came out to be of size 3236x3236, which was difficult to handle. Consequently, thirteen 1800 by 1800 matrices were established (1.60-1.98m, 2.00-2.38m, 2.40-2.78m, 2.80-3.18m, 3.20-3.58m, 3.60-3.98m, 4.00-4.38m, 4.40-4.78m, 4.80-5.18m, 5.20-5.58m, 6.00-6.38m, 6.40-6.78m, 6.80-6.98m). Data from 27 CPTU were used to form the thirteen 540 by 1800 simulation matrices and 1800 by 1800 training matrices. Analyses were carried out on the Matlab 2010a Toolbox7 NNtraintool interface. 60% of the data were employed for Training, 15% for Validation and 15% for Testing. Inspecting the results, it was found that the success rate in estimating the soil profile anywhere in the 26 km2 city area was as high as 92%. This is a surprisingly high success rate considering the highly complex and laterally variable soil profiles throughout the city.  Keywords: Geotechnical engineering, artificial neural network, artificial intelligence, soil profile, cone penetration test, site characterization.Dünyada ve Türkiye’de yapay sinir ağlarının (YSA) geoteknik mühendisliğinin pek çok alanında kullanımı son yıllarda yaygınlaşmıştır. Literatür araştırmasında; geoteknik probleminin çözümünde kullanılan YSA nın özellikle; zeminlerin sınıflandırılması, arazi karakterizasyonu, sıvılaşma, geçirimlilik ve hidrolik iletkenlik, sıkıştırma, dayanma yapıları, temellerin oturması, kazık hizmet yükünün tahmini ve zemin davranışının modellenmesi gibi karmaşık ve ilişkinin iyi anlaşılamadığı pek çok doğrusal olmayan problemlerin çözümünde başarılı ve hızlı çözümler sağladığı görülmektedir. Yapılan son çalışmalar, YSA’nın bulanık mantık ve genetik algoritma ile bütünleştiğini göstermektedir. Bu makalenin konusunu, geoteknik mühendisliğinin çeşitli dallarındaki problemlerin çözümünde YSA uygulamalarının genel bir değerlendirmesi oluşturmaktadır. Bu kapsamda YSA modellenmesi ve bu konuda yapılmış yurtdışından ve ülkemizden bazı çalışmalara örnekler verilmiştir. Makalenin ikinci bölümünde yazarlarca geliştirilen Adapazarı zeminlerinde 2-7m arası zemin profilinin CPT verileriyle analizinde yapay sinir ağının kullanımına yer verilmiştir. Koordinatları bilinen toplam 117 adet Koni Penetrasyon (CPT), verilerinden oluşturulan veri tabanı ile her 2cm. de bir alınan toplam 3236 okumayla geliştirilmiş yapay sinir ağı modeli ile rastgele seçilen lokasyonlar için yapılan tahminlerde %92 gibi oldukça yüksek bir başarı elde edilerek arazi karakterizasyonu hakkında yorum yapılabileceği görülmüştür. Anahtar Kelimeler: Geoteknik mühendisliği, yapay sinir ağları, yapay zeka, zemin profili, koni penetrasyon deneyi, arazi karakterizasyonu.&nbsp

Karma bir balast suyu arıtım sistemi ve elektrokimyasal teknoloji

The transportation of exotic species in ballast tanks is one of the most important environmental problems of the ship industry at the global levels. The technologies that will be adapted to both existing and new built ships should be developed immediately to minimize problems caused by the ballast water and sediment. There are a number of techniques taken into consideration to eliminate the organisms in ballast water. However, it is generally agreed that a single treatment method would not be sufficient to prevent the translocation these organisms. Consequently various projects which focus on the hybrid systems were initiated. These systems generally include one primary treatment and one or more secondary treatment techniques. Primary treatment is achieved by mechanical treatment such as filters. Secondary treatment may consist several physical and chemical options. Chlorine disinfection is one of the most applied techniques. The main subjects of concern about employing chlorine disinfection for ballast water organisms is the safety risk during handling and onboard storage of chlorine gas or HOCl solutions. On the other hand, electrochemically generation of disinfectants, especially oxidants as HOCl, is an emerging technique. Electrochemical generation of active chlorine on board would eliminate those unfavorable features of chlorine disinfection. This work has been prepared from the doctoral thesis which is titled as "Electrochemical Cell Application for Ballast Water Treatment" and submitted to Institute of Science and Technology of Istanbul Technical University. This study has been conducted within the project "BaWaPla - Sustainable Ballast Water Management Plant", funded by the European Union under contract number 031529, which is started at 15/11/2006 and finalized at 15/05/2010. A new hybrid ballast water treatment system has been developed within the project. This self-controlled system consists of filter systems, UV and electrochemical technologies. The electrochemical component of BaWaPla produces active substances onboard through electrolysis of seawater and eliminates the require-ment to carry or store hazardous and corrosive chemicals. A laboratory system has been prepared by Project partner LVPG GmbH, Germany and provided to Istanbul Technical University. This system is used for test assumptions and proposals for the best and optimal cell design. Employing electrolysis techniques to produce disinfectants, saline water/seawater is introduced into an electrochemical cell in the heart of the test system. Electrochemical reaction within the cell results in the production of highly effective "Hypochlorous acid rich" disinfectant. Disinfectant fluid can be affected by the design of the fluid path within the electrochemical cell, the selection of material used to produce the permeable membrane that separates the fluid paths or to direct solution past the anode and cathode (electrodes) as well as the electrical current applied to the electrodes. The choice of materials used for coating the relevant electrodes must also be considered. In this study five different electrochemical cells are assessed for BaWaPla system. The cells are supplied from FumaTech GmbH, Germany. The cells are referred as "standard cell, FTEC 100, FTEC 500, EC 100 Nr. 201, EC 100Nr. 240". The changing parameters of the cell designs are the geometry of electrodes, the dimensions of electrodes and the materials used for electrodes and their coatings. The results show that, the enlargement of electrode surface results in more chlorine figures in di-sinfectant. On the other hand, suitable electrode and coating material are essential for "reverse polarity" operation to avoid scaling of Ca2+ and Mg2+ on electrodes and clogging the membrane. Taken into consideration of these results of laboratory works, FumaTech GmbH produced new cells for BaWaPla. These cells have the electrode dimensions as FTEC 500 and the material used for electrodes and their coatings is the same as EC 100 Nr. 201. The cells have capacity of 500 L/h disinfectant production and they have the ability to be run reverse polarity so that a self cleaning process takes place. Six of these cells are employed within the land based pilot BaWaPla system at Blyth-England on August 2009. The pilot system achieved IMO (International Maritime Organi-zation) standards and it is ready for IMO approval.  Keywords: Ballast water treatment, electrochemical cell, chlorine generation.Balast tanklarında taşınan yabancı türler dünya gemi inşa endüstrisinin küresel boyuttaki en önemli çevresel problemlerinden birisidir. Bu problemin çözümüne yönelik olarak son 10-15 yılda birçok çalışma tamamlanmıştır. Bununla birlikte bu çalışmalar, kullanılan yönteme ve balast suyunda yer alan organizmalara bağlı olarak farklı sonuçlar vermektedir. Bu nedenle günümüzde gemi üzerinde balast suyu arıtımı konusunda yapılan çalışmaların çoğu birden fazla yöntemin bir arada kullanıldığı karma sistemler üzerinde yoğunlaşmaktadır. Klor gerek içme suyu dezenfeksiyonunda kullanılan en eski ve en genel yöntem olması, gerekse büyük hacimlerdeki sularda istenmeyen organizmaları gidermede de kullanılabilmesi nedeniyle balast suyu dezenfeksiyonu için önemli bir alternatif oluşturmaktadır. Ancak başta klor olmak üzere, dezenfektanların gemi üzerinde depolanması ve kullanılması gemi ve mürettebat güvenliği açısından riskler içermektedir. Diğer taraftan Cl2 gazı HOCl olmak üzere çeşitli dezenfektanların elektrokimyasal olarak üretimi gün geçtikçe önem kazanmakta ve balast suyu arıtımı için de alternatif haline gelmektedir. Bu çalışma Avrupa Birliği 6. Çerçeve Programı tarafından desteklenen 031529 kontrat numaralı araştırma projesi BaWaPla (Sustainable Ballast Water Management Plant) sonunda hayata geçirilen filtre, UV ve elektrokimyasal teknolojilerin bir arada kullanıldığı karma sistem için elektrokimyasal hücrelerin geliştirilme ve optimizasyon aşamasındaki laboratuvar çalışmalarının bir kısmını içermektedir. 3.5 yıllık Proje süresinin iki yıllık dönemde birbirinden farklı şekilde tasarlanmış 5 elektroliz hücresi farklı çalışma koşullarında test edilmiştir. Laboratuvar çalışmalarının sonuçları dikkate alınarak yeni bir hücre tasarımı gerçekleştirilmiş ve işletim parametreleri belirlenmiştir. Geliştirilen hücreler, Ağustos ve Eylül 2009’da Blyth-İngiltere’de kurulan büyük ölçekli pilot sistemde de kullanılarak test edilmiştir. Gerçekleştirilen testlerde IMO (International Maritime Organization-Uluslararası Denizcilik Örgütü) tarafından imzaya açılan “Gemilerin Balast Suları ve Sedimanının Kontrolü ve Yönetimi” sözleşmesinde yer alan deşarj standartları sağlamıştır. BaWaPla sistemi, IMO onayına hazır durumdadır. Anahtar Kelimeler: Balast suyu arıtımı, elektrokimyasal hücre, klor üretimi

Mikrobiyel yakıt hücresinde Shewanella putrefaciens tarafından organik atıklardan elektrik üretimi

A microbial fuel cell (MFC) is a bioreactor that converts chemical energy in the chemical bonds in organic compounds to electrical energy through catalytic reactions of microorganisms under anaerobic conditions. Typical two chambered MFC systems are consist of conductive anode (such as carbon cloth or carbon paper) and cathode material (with platinum), proton exchange membrane (PEM), anolyte and catholyte, external conductive wire, and digital multimeter system and computer. In a MFC, power can be generated from the oxidation of organic matter by bacteria at the anode, with reduction of oxygen at the cathode. Anodic and cathodic chambers partitioned by a PEM. A bacterium in the anode compartment transfers electrons obtained from an electron donor (e.g. glucose, acetate) to the anode electrode. This occurs either through direct contact (nanowires) or mobile electron shuttles. During electron production protons are also produced in excess. These protons migrate through the PEM into the cathode chamber. Electrons can be also transferred to the anode by electron chemical mediator. But the toxicity and instability of synthetic mediators limit their applications in MFCs. Shewanella putrefaciens is bioelectrochemically active and can form a biofilm on the anode surface and transfer electrons directly (without mediator) by conductance through the membrane. When they are used, the anode acts as the final electron acceptor in the dissimilatory respiratory chain of the microbes in the biofilm. S. putrefacience was grown on LB broth. For aerobic growth, cultures were shaken continuously on a cooling rotary shaker-incubator at 160 rpm at 25°C. For anaerobic growth, approximately 1.25 liter of anaerobically prepare (in the athmosphere controlled chamber) LB broth in glass bottle was inoculated with 12.5 mL of an aerobically grown overnight culture and incubated without agitation. After 96 h of growth, the cells will be harvested under anaerobic conditions by a continuous centrifugation system at 4800 rpm at 4°C. The cell paste will be washed three times in 50mM sodium phosphate buffer containing 0.1 M NaCl . The washed cells was re-suspended in the buffer and transferred to 100 mL capacity anode compartment of the MFC on anaerobic conditions. The two chambered microbial fuel cells (TCMFC) were constructed using two glass bottles. Each bottle's volumes were 100 mL. Each cell compartment had three ports at the top, for electrode wire, addition and sampling of solutions, and gassing. Two compartments were separated by a PEM. The anode compartment was loaded with freshly prepared bacterial suspension (suspended in 50 mM Na-phosphate buffer (pH 7.0) containing 0.1 M NaCl, vitamin, mineral solution and substrate (acetate, ethanol and propionic acid). The cathode compartment was loaded with 50 mM Na-phosphate buffer (pH 7.0) containing 0.1 M NaCl. Nitrogen and air were continuously purged through anode and cathode compartments to maintain anoxic and aerobic conditions, respectively (flow rate of nitrogen gas was approximately 15 mL per min). The microbial fuel cell was immersed in a water bath to maintain temperature (25°C). Cooler was used to supply for summer conditions and heater was used to supply for winter conditions. The air conditioner was also used to supply constant temperature. Voltage (V, volt) or current (I, amper) was measured using a multimeter with a data acquisition system. Power density (mW/m2) was calculated according to P=Current*Voltage /projected area of the anode (P= IV/A.) When the anode compartment of the microbial fuel cells were loaded with freshly prepared S. putrefaciens, potential development was measured under open circuit conditions. Before the fuel (carbon source) was added, open circuit voltage (OCV) approximately 100-200 mV were observed from the microbial fuel cell containing suspensions of S. Putrefaciens. The addition of substrate as the fuel to the cell containing S. Putrefaciens resulted in a rapid rise in OCV up to 780-840 mV. Maximum OCV observed 832 mV, 777 mV and 810 mV for 10 mM glucose centrifuged from anaerobic growth of 1250 mL, 2500 mL and 800 mL from pure culture, respectively. The addition of ethanol was OCV up to 670 mV and addition of propionic acid was OCV up to 803 mV. A membrane MFC inoculated with S.putrefaciens and the circuit was completed with a fixed load of 5000 W were used to determine the power generation as function of load. 10 mM glucose produced 4 µA current. Power density was 0.8 mW/m2. Keywords: Microbial fuel cell, electricity production, Shewanella putrefaciens, voltage, power density. Mikrobiyal yakıt hücreleri (MYH) oksijensiz ortamda elektrojen mikroorganizmaları biyokatalizör olarak kullanarak organik maddelerden elde edilen kimyasal enerjiyi doğrudan elektrik enerjisine çeviren sistemlerdir.Tipik bir MYH’si anot, katot, proton geçirgen membran ve voltaj yada akım değerlerini ölçen veri toplama cihazından oluşur.Elektrojen bakteri oksijensiz ortamda anot üzerinde biyofilm tabakası oluşturarak organik maddeleri, karbondioksit, elektron ve protona çevirir. Bu çalışmada, iki hazneli MYH ve saf kültür Shewanella putrefaciens kullanılmıştır. Bu saf kültür bakterisinin seçilmesindeki amaç, dış membran enzimlerini doğal olarak kullanma yeteneğinde olduğundan elektronlarını iletken bir anota verme kabiliyetine sahip olmasıdır. Böylece bakteri tarafından üretilen elektronları anot elektroduna iletecek dışarıdan kimyasal bir medyatör kullanma gerekliliği ortadan kalkmıştır. Bu çalışmada, MYH’de farklı organik maddelerden ve farklı miktarlarda çoğaltılan saf kültür S. putrefaciens kullanılarak açık devre voltajları ölçülmüştür. 10 mM glikoz kullanılarak 1250 mL besi maddesi içinde çoğaltılan saf kültürün santrifüjünden elde edilen devre voltajı 832 mV iken, 2500 mL saf kültür için 777 mV, 800 mL saf kültür için ise 810 mV olarak ölçülmüştür.10 mM etanol kullanılarak 1250 mL saf kültürden 670 mV, 10 mM propiyonik asit kullanılarak 1250 mL saf kültür için ise açık devre voltajı 803mV bulunmuştur. Besi maddesi olarak 10 mM glikoz kullanıldığında 5000 Ω dış direnç ile çalıştırıldığında amper değeri 4 µA ölçülmüştür. Güç yoğunluğu olarak 0.8 mA/m2bulunmuştur.  Anahtar Kelimeler: Mikrobiyal yakıt hücresi,elektrik üretimi, Shewanella putrefaciens, voltaj, güç yoğunluğu