Balast Suyu Arıtım Sistemlerinin Seçiminde Kpı (anahtar Performans Göstergeleri) Uygulamaları

Abstract

Deniz taşımacılığı dünya ticaretinde oldukça büyük bir öneme sahiptir. Uluslararası nakliyeciliğin %90'ının gemiler ile yapıldığı günümüzde, gemilerin maksimum yük ve minimum balast ile seyir etmeleri ekonomik olarak tercih edilse de, gemilerin güvenli seyri açısından bu mümkün değildir. Gemilerin balast tanklarına alınan balast suyu ile her gün yaklaşık 7.000 canlı farklı bir ekosisteme taşınmaktadır. Bu canlıların bir kısmı balast tanklarındaki koşullara karşı dayanıklı olup, geminin sefer süresi boyunca hayatta kalabilmektedirler. Hayatta kalmayı başarabilen canlılar, kimi zaman balast suyu ile boşaltıldıkları ekosistemlerde varlıklarını sürdürüp, yerli türlerin varlığını tehdit edebilirler. Bu yabancı türler sadece ekosistemdeki canlılara zarar vermekle kalmaz, balıkçılığı etkileyerek ekonomik zararlara yol açabilirler, insan sağlığına zarar verebilirler ve sahillerde biyolojik kirliliğe neden olup deniz turizmini olumsuz yönde etkilerler. Balast tanklarındaki su ile taşınan zararlı sucul istilacı türlerin verdikleri zararların boyutlarının ciddi olduğunun farkına varılması ile, ulusal ve uluslararası düzeyde pek çok düzenleme ve çalışmalar yapılmıştır. Yapılan çalışmalar, balast tankları ile taşınan istilacı türlerin sorun olmalarını engellemek için, balast suyunun bu canlılardan arındrılmasına yönelik sistemlerin geliştirilmesini sağlamıştır. Uluslararası Denizcilik Örgütü tarafından 2004 yılında üye ülkelerin imzasına açılan Gemi Balast Suları ve Sedimenti Kontrolü ve Yönetimi Sözleşmesi yürürlüğe girdikten sonra, balast suyu arıtma sistemlerinin gemilerde kullanılması zorunlu hale gelecektir. Bu gereklilik ticari açıdan pek çok üretici firmanın balast suyu arıtma sistemi geliştirmesi ile sonuçlanmıştır. Piyasada balast suyu arıtma sistemi üreticileri arasındaki rekabet, gemi sahiplerini gemileri için en uygun olan sistemi seçme konusunda zora sokmaktadır. Çalışmada, hangi yöntemler ile balast suyu arıtılabilindiğine dair detaylı bilgi verilmiş, sonrasında ise balast suyu arıtma sistemi seçerken dikkat edilmesi gereken teknik ve ticari konulara değinilmiştir. Yeni inşa edilen gemiler için sistem seçmek problem olmasa da, Gemi Balast Suları ve Sedimenti Kontrolü ve Yönetimi Sözleşmesi yürürlüğe girdikten sonra inşa yılı eski olan pek çok gemiye balast suyu arıtma sisteminin entegre edilmesi, hem teknik hem de ticari açıdan oldukça zorlu bir süreçtir. Çalışmada detayları anlatılan Anahtar Performans Göstergeleri (KPI) yöntemi ile sistemin kullanılacağı gemilerin özelliklerine göre aynı anda pek çok sistem karşılaştırılıp, en uygun olan sistemin belirlenmesi amaçlanmıştır.

Maritime transportation has significant importance for international trade. Today, ships carry approximately 90 percent of all global trade. For commercial concerns, it is preferred to travel with maximum cargo and minimum ballast. However, as ballast water is used to provide stability and maneuverability during voyage, travelling with minimum ballast can cause safety problems on ships. In 1800's, solid materials such as sand, detritus and iron were usually loaded onboard in order to provide ballast. After use, these materials were discharged to water and could be able to used by other ships. But this technique was not only time consuming but also not effective. By technological progresses through the end of 1800's, the sea water had been used as ballast. There were not segregated ballast water tanks as it is today. The water used as ballast was stored in empty cargo tanks. The remain of the cargo such as oil, iron, etc. mixed with ballast water. The mix of these remains and water could be toxic and discharging these water to the marine environment were caused environmental and health problems. After realizing these problems, in 1980's, segregated ballast water tanks were designed and used in order to provide contamination of ballast water. However, as the ballast water became cleaner, there arrised another problems, invasive species. With ballast waters, every day more than 7.000 different marine species are transferred to different ecosystems. The size of the organisms in ballast water varies from micrometric viruses to organisms up to thirty centimeters. The ones who can survive in ballast tank conditions are discharged at other ports within ballast water. These organisms are called as "invasive species". The introduction of invasive marine species into a new environments by ships' ballast water has been stated as one of the four greatest treats to marine ecosystems. The problems due to the invaisve species can be analyzed in three main sections; impacts on ecology, impacts on economy and impacts on health. Introducing of invasive species can cause problems on native species. The most known example of invasive species effects on environment is recorded in Grate Lakes, United States. This area has been damaged by more than 180 invasive species during years. Zebra mussels, sea lamprey, alewife etc. were introduced to lakes and spreaded, competed with native species and damaged the food chain. These invasion problem also have effects on fisheries, factories n coastal areas. The zebra mussels has spreads more than 40 percent of US waters and cost more than US$ 750 million between 1989-2000. Also, it is estimated that invasive species cause US$ 138 billion per year in only USA. Moreover, if the ballast water contaminated with pathogens such as Vibrio cholerae discharged into the sea, this may cause illness and death in humans. After realizing these serious problems caused by the organisms carried in ballast water, there have been conducting national and international regulations. In 2004, the IMO introduced "International Convention for the Control and Management of Ships' Ballast Water and Sediments". With these regulations, the problems caused by ballast water have attracted attentions and the companies have started to research and develop ballast water management technologies. The Convention will enter into force 12 months after ratification by 30 States, representing 35 per cent of world merchant shipping tonnage. Once entered into force, BMW convention requires all ships to use ballast water treatment systems in order to meet Ballast Water Performance Standard (Regulation D-2). There have been introduced many different ballast water treatment methods. These methods can be mainly divided in three groups; mechanical methods, physical methods and chemical methods. The mechanical methods are filtration and cyclonic separation. With these applications, organisms bigger than 40-50 micron can be able to seperated from ballast water. As physical methods, there have been developed system that use heat treatment, ultra sound treatment, de-oxidizing, ultra viole and coagulation. Each method has its own advantages and disadvantages. In this study, these advantages and disadvantages of the methods are explained in details. There are also systems that uses oxidizing or non-oxidizing biocides. However, using there method on its own is not enough for BMW convention requires. In order to meet these requirement, usually combined systems such as mechanical + physical or mechanical + chemical are used for ballast water management. There are many companies developed new technologies and systems in order to treat ballast water. As the number of the companies and systems are a lot, shipyards and ship owners have difficulties to find the most suitable ballast water treatment system for their ship. To be able to find the suitable system, there are some factors that need to be considered by both system distributers and shipyards/ship owners. The most important point is the ship type, thus ballast capacity of the vessel. The vessels are divided into two categories in terms of their ballast capacity; high ballast dependent vessels such as bulk carriers and tankers and low ballast dependent vessels such as containerships and other vessels like chemical carriers, passenger ships, Ro/Ro etc. As the range of the ballast capacities are wide range, this can be determinant factor to choose ballast water treatment system, because many companies are powerful in certain pump capacity ranges. Also the water characteristics such as turbidity, salinity and silt content has effects on ballast water treatment. Other factors such as space, power requirement, vessel service area, health and safety requirements are investigated in details. A case study has been examined in seventh section of the study. There has been chosen two ships in order to show how to decide ballast water treatment system. Three combined systems using filtration + UV are considered for the vessels. Technical and design details are given in section 7. After comparing investment and operating costs of the system, the most suitable one is chosen for each vessel. The detailed investment and operation cost comparison is given in the related section. This part shows how a shipyard approaches choosing a ballast water treatment system for a vessel. However, once the BMW regulations enter into force, there will be many vessels that are need to be retrofitted. The system choosing period will not be that easy. In section eight, the main focus area of this study is explained. As there will be a huge work load on shipyards/system distributors to identify the most suitable system for many vessels. In this section, a model developed in Microsoft Excel to find suitable systems that can be applied to many vessels by using Key Performance Indicators (KPI). The model has two parts. In first part, there has been developed an automatic process to eliminate the unsuitable systems. The requirements set up by shipyards/ship owners are compared with the systems' data. With this process, the systems that are not meet the shipyards'/ship owners' requirements are identified. In second part, the system are compared in details. Every criterias which are stated in the study are graded from 1 to 6 and compared with each other. This process helps us to specify system points and find the most suitable system for vessel/vessels. In this study, only two vessels and three systems for each vessel are examined due to the confidentiality. Even so, the advantages of using KPI while choosing a ballast water treatment system can be easily seen from the study. In case of many system offers, in order to make better comparison, using KPI has benefits for shipyards. This study shows that KPI analyze makes system selection easy and reliable.