İstanbul arıtma çamurlarının yönetimi ve uzaklaştırılması

Abstract

Bu çalışmanın amacı İstanbul için planlanan atıksu arıtma tesislerinin verilerini kullanarak her bir arıtma kademesi için her bir atıksu arıtma tesisinde oluşacak çamur miktarım belirlemek, günümüzde dünyada uygulanan çamur arıtma proseslerini tanıtarak ve ülkelerle örnekleyerek önerilen çanur arıtma sistemlerinin dah aiyi anlaşılmasını sağlamak ve çeşitli alternatiflerin maliyet açısından karşılaştırılmalarında yararlı olacak veriler üretmektir. Yukarıdaki amaç doğrultusunda mevcut çamur arıtma prosesleri ve sistemleri tek tek tanıtılmış, miktarlarına yönelik yapılan çalışmalar karşılaştırılmış çamur üretiminin değişimleri garafiklerle gösterilmiştir. Böylece herbir atıksu arıtma sisteminde ortaya çıkacak çamurun nasıl bertaraf edebileceğine karar vermeyi kolaylaştıracak çok miktarda veri üretilmiştir. Örnek olması açısından Paşaköy tesisinden çıkacak çamurlar için bir maliyet çalışması da yapılmıştır. Evsel atıksu arıtma tesislerinden kaynaklanan arıtma çamuru için kompostlaştirma alternatifi bu çalışmada kayda değer bir alternatif olarak önerilmiştir. Kompostlar parkların oluşturulmasında, bozulmuş ve işlenmiş arazilerin yeniden bitkilendirilmesinde, sebze ve meyvelerin yetiştirilmesinde, bahçecilik ve fidancılık mahsullerinde kullanılır. Çamurlann tahsis edilmiş alanlara depolanması da kısa vadede uygulanabilecek bir çözüm olarak görülmüştür. İstanbul Büyükşehir Belediyesinin yapmış olduğu bir araştırmaya göre İstanbul Bölgesinde 118 tane taş ocağı bulunmaktadır. Bunların içinde Kartal Maden Ocağı en büyük olanıdır. Özellikle su havzalarının dışındaki alanlar ve yine özellikle kömür ocakları arıma çamurlarının depolanması için oldukça uygun alanlardır. Özellikle kömür ocaklarında taban zemini geçirimsiz olarak yapılmalıdır. Bu çamur deposu olarak kullanılması bakımından çok idealdir. Çamurlann terkedilmiş bölgelere, taş, kum ve maden ocaklarına depolanması için Katı Atıklar Kontrol Yönetmeliğine göre stabilize edilmesi gerekir. Böylece çamurun taşınması ve depolanması esnasında ve sonrasında sinek, haşere v.s. üremesi de engellenmiş olur. Çürütücü olmayan tesislerde çamur stabilizasyonu için oldukça ucuz bir malzeme olan kireç kullanılabilir. Bu durumda çamur miktarındaki artış gözardı edilmemelidir. Ayrıca çamurlann bu dolgu alanlanna taşınması kapsamlı bir planlama çerçevesinde yapılmalı; özellikle trafiğin daha yoğun olduğu bölgelerde taşımacılığın, trafiğin daha az olduğu saatlerde yapılarak trafiği minimum etkileyecek önlemler alınmalıdır.

The target of this study, is to compare the sludge amount from each wastewater treatment plant of some previous studies and is to offer some alternatives according to these data. Another target is to produce the necessary data to the evaluate the different alternatives in respect of both economical conditions and technological basis. For determining and selecting the alternatives, the pre -studying had been done. First off all, some studies done in some countries had been investigated. In the mentioned countries, subject of sludge treatment methods based on social, economic, geographic and technical features for each country are investigated. The point that the investigated countries take care while they are planning the sludge managing and not enough utilization area is provided in our country is recovering the treatment sludge. Except this, using the sludge in agricultural areas, and sanitary land filling are the other alternatives. For the target mentioned above, first the existing sludge treatment processes and systems have been explained one by one. First off all, the studies done for the treatment sludge in Istanbul are investigated one by one. The mentioned studies are master plan, sludge management study done for ISKI in 1993 and determining the treatment sludge quantity coming from the Istanbul Waste Water Treatment Plant (Master Study- 1998) The result of the comparison is that the values calculated and estimated in the master study are the most suitable values for the other studies interested in the sludge quantity. For the management strategy, the evaluation based on the in Master Plan is done. The results are shown in a table, and the graphs based on sludge quantity for one plant and also the total sludge quantity for Asia, Europe and is table are presented separately. The Istanbul Sludge Management Project conducted in 1993 has suggested that the sludge from primary sedimentation tank first be taken to gravity thickener, and that from biological treatment to floatation thickener and then passing through anaerobic digestion process and centrifugal dewatering be taken to landfill or be incinerated without passing through digestion process as to burn them with the ashes be sent to landfill for Riva, Tuzla, Küçükçekmece and Baltalimanı. For Büyükada, Heybeliada, Kınalıada, Burgazada and Terkos; gravity thickening + Aerobic digestion + centrifugal dewatering + landfill are used; for Pasaköy the sludge from primary sedimentation tank first pass through gravity thickener, and that from biological treatment first through floatation thickener and then be taken to landfill. For Tepeören it has been suggested the sludge be processed in anaerobic digestion and centrifugal dewatering stages after treated in thickener and then be sent to landfill as last stage. In the master plan study that was started in 1997 and it is still continueing floatation. This study summarized as follows: For Yenikapı, Baltalimanı, Terkos, Kilyos, Batı Marmara it has been suggested that the sludge be treated as thickening + anaerobic digestion + centrifugal dewatering + landfill. For Kadıköy + Göksu, Büyükada, Kınalıada, Burgazada and Heybeİiada gravity thickening + centrifugal dewatering + landfill ; Büyükçekmece and Pasaköy it has been suggested that sludge from primary sedimentation tank shall first go through gravity thickener, that from biological treatment through floatation thickener and then be taken to landfill; floatation thickening + anaerobic digestion + sludge drying + landfill. For Küçükçekmece and Tuzla it has been suggested as sludge from primary sedimentation tank first be treated in gravity thickener, that from biological treatment in floatation thickener, and then by passing through anaerobic digestion and centrifugal dewatering processes be sent to landfill or be incinerated without digestion process as to send the ashes to landfill. The pilot study was determined in this paper, is a master project about sludge amount from Waste Water Treatment Plant in Istanbul. In this study, sludge amount coming from treatment plant of Istanbul is compared with previous project and showed as a table. Determining of strategy of sludge treatment process for this study is based on Master Plan Study. The last study about sludge management of treatment plant in Istanbul written by Ebru Gökgöz is more available for amount sludge calculation. For that reason amount sludge was based on mentioned study. In mentioned study, after existing sludge treatment process and system had been explained one by one, the amount of sludge due to come from the primary sedimentation tank, primary sedimentation tank with chemical addition biological treatment and advanced treatment system in wastewater treatment plants has been calculated for each of the plants, the change in the production of sludge. In Istanbul catchment area results is got as follows the disposal of treatment sludge is an important issue in Istanbul Waste Water Management Policy that should be studied carefully and, 1. Through the subject of waste water treatment has been widely negotiated, the disposal of sludge subject is limited with only a few studies and investigations. It requires more studies for sludge treatment and disposal for Istanbul. 2. There are many deficiencies in the sludge treatment legal constitution. There are unclear points regarding the final disposal of treatment sludge. XI As a natural consequence of this, we haven't got sufficient amount of knowledge about the sludge disposal of existing treatment systems. 3. Composting has not offered for treatment sludge from municipal wastewater plant until now. It is the important alternative. Composts can be used for building parks, reusing degenerated areas, growing up vegetables and fruits. Composting is used in U.S. A and Scandinavia country successfully for a long time. 4. Though incineration of the sludge is an expensive alternative, it is an advantageous method for Istanbul since there remains only a little amount of matter to be sent to landfill. But either in "Sludge Management Study" conducted in 1993 or in the Master Plan still continuing, there exists no information regarding the calculation of dry solid weight and volume for the ashes and the sludge to be sent to landfill. Execution of this calculation, is an important concept for comparison of alternatives, for determining the landfill place and landfill area. 5. In the previous studies, various alternatives have been presented for sludge treatments two alternatives, so contrary to each other have been put down as follows; * Construction of sludge treatment plants next to each of the wastewater treatment plants, * Collection of sludge from Asian Side in one center, and collection of sludge from European Side in another center, and the disposal of the sludge there. Collecting the sludge in a certain center and treating them there is a very difficult thing technologically. We need more studies for evaluation and investigation of feasibility as how to execute transfer the transfer the sludge. 6. The total investment cost of sludge treatment systems suggested in Master Plan (1997) is about 235x10 USD, and the operational cost is about 70x 106 USD /year The investment cost itself is 5 trillion USD as one USD equals to 210.000 TL. Adding the operational cost on this, we reach high costs. The end of the research, a case study which including cost analyses of Paşaköy treatment sludge with two alternatives. The first alternative is building a thickening, stabilization and dewatering unit in Paşaköy and transferring to landfill. The second alternative is sludge dewatering in Paşaköy and transferring to Tuzla and then stabilizing and dewatering in Tuzla' s exist unit. And finally transferring dewatered sludge to landfill. Results shows that the first alternative is more feasible than the second one. It is important point to supply the finance and to execute the work program together with the construction of wastewater treatment plants. If we need to make an order of processes, this would be as first putting down the criteria and considering the investment timing to together with economical actuation.