Küçük yerleşimler için uygun atıksu arıtma sistemlerinin Türkiye açısından değerlendirilmesi

Abstract

ÖZET Türkiye'deki küçük yerleşimlerin atıksu toplama ve uzaklaştırma problemlerinin çözümünde bilimsel esaslara dayalı öneriler geliştirmek ve bu önerilerin maliyetlerini hesaplamak bu çalışmanın ana amacı olmuştur. Bu amaç doğrultusunda önce literatür taranmış, mevcut uygulamalar değerlendirilerek, çözümler üretilmeye gayret edilmiştir. 1. Bölümde çalışmanın anlam ve önemi ile amaç ve kapsamı vurgulanmıştır. 2. Bölümde küçük yerleşimlerin atıksulannm uzaklaştırılmasında karşılaşılan problemler, tekil ve merkezi arıtma sistemlerinin birbiriyle karşılaştırılması ve Türkiye'de konu ile ilgili yatırım yapan kuruluşların faaliyetleri hakkında bilgi verilmiştir. 3. bölümde konu ile ilgili literatür taranarak küçük yerleşimlerden, ticari işletmelerden ve kamu kuruluşlarından kaynaklanan atıksularm miktar ve özellikleri kapsamlı bir şekilde derlenmiştir. 4. Bölümde küçük yerleşimlere uygulanabilecek arıtma prosesleri tek tek ana hatlarıyla tanıtılmış, arıtma mekanizmaları ve boyutlandırma kriterleri hakkında bilgi verilmiştir. 4. Bölümde ayrıca küçük yerleşimlerde uygulanabilecek atıksu toplama sistemleri incelenmiştir. 5. bölümde Türkiye'nin coğrafi, sosyal ve ekonomik durumu incelenerek değişik bölgeler için uygun küçük arıtma sistemleri önerilmiştir. Seçilen sistemlerin keşfi yapılarak nüfus ve debiye bağlı olarak toplam ilk yatırım ve işletme-bakım maliyetleriyle, 1 m3 atıksuyun arıtma maliyeti hesaplanmıştır. Ayrıca önerilen sistemler için nüfus-maliyet, debi-birim maliyet ve karşılaştırma grafikleri çizilmiştir. Yapılan değerlendirmeler sonucu 500'den küçük nüfuslar için stabilizasyon havuzunun, daha büyük debiler için uzun havalandırmalı aktif çamurun daha ekonomik olduğu sonucuna varılmıştır. Türkiye'deki küçük yerleşimlerin atıksu toplama ve uzaklaştırma sistemlerinin toplam ilk yatırım maliyeti yaklaşık 1,5 milyar $, 30 yıllık hizmet süresi için işletme ve bakım maliyeti yaklaşık 0,5 milyar $ bulunmuştur. 6. Bölümde bu çalışmada ulaşılan sonuçlar özetlenmiştir. XII

SUMMARY THE INVESTIGATION OF APPROPRIATE WASTEWATER TECHNOLOGY FOR SMALL COMMUNITIES IN TURKEY The pollution problems have been realised firstly in large cities because of the amount of impurities is higher in the regions having relatively high population. So the first studies have almost been focused on removing the wastewaters of large cities. However, since people started to want to live in a cleaner environment due to effects like increases in the amount of pollution and higher life standarts, it has caused starting of studies for removal of wastewater in small regions as well as big cities. This trend has already been experienced in developed countries. Studies on this subject in countries like Turkey were limited to removing of holiday sites' wastewater only. The purpose of this study is to determine mainly wastewater collection and removal problems of small comminities, to examine studies of related institutions in Turkey and to find out features and changing frequency of the amount of these wastewaters and to promote the wastewater collection and removal systems that could be applied in small comminities for Turkey according to regions and to evaluate them from the economic point of view by calculating costs of these systems. In the frame of the abovementioned purpose; In the first chapter, the meaning and importance and importance and purpose and concept of this study has been discussed. In chapter 2, some information has been given about the problems arising in removal of wastewaters in the small comminities and comparison of the single and central wastewater removal systems and activities of establishments making investments for this system in Turkey. In chapter 3, some information has been collected about the amount and features of the wastewater that has been disposed from the small cities, trade establishments and public facilities by examining literature related to the subject. In chapter 4, all wastewater treatment processes that could be used in small comminities has been basically promoted and some information has been given about the treatment mechanisms and their design criteria. In addition. Also the wastewater coolection systems have been evaluated that could be used in small cities. In chapter 5, small wastewater treatment systems have been suggested for different regions after examining the social, geographycal and economical conditions of Turkey. Costs for removing 1 cubic meter of wastewater with first investment and operating and maintenance and total first investment as subject to the population and flow, have been calculated after value estimation off the chosen systems. In addition, XUlfor the suggested comparison have been produced. As a result of the evaluations, it was found that stsbilization pond was better for the cities having a population less than 500 while the extended aerated lagoon was more economical for bigger flows. In Mediterranean and Aegean coastal areas, if we consider the climate, all wastewater treatment technologies can be applied. Especially biological treatment must be applied because of the recreational facilities. Packet systems are the most suitable technology for the coastal areas. This packet system can maintain the nutrient removal when it is needed. The internal parts of this region which is effected by Meditterranean climate is suitable for agriculture. Because of this characteristic, natuaral land treatment systems after biological treatment can be applied. The coastal areas which are effected by Blacksea climate are so rainy that land treatment systems can not be useful. At this region, the location of the houses is untidy. When we consider these, septic tank is the most suitable system. However, when it's very rainy septic tank can be inadequate. Then we can choose another system: After collecting the wastewater, biological process (for example long aerated active sludge) can be applied. The internal parts of the country which are effected by step climate, both social and the economical situation is worse than the other regions. At these areas location of the houses is untidy. When we consider these disadvanteges we can recommand 2 different systems: The location where the population is less than 250, we can apply land treatment systems after septic tank. As a land teratment we can use the wastewater by watering in order to aid drought. We can apply aerated lagoon, stabilization ponds or long aerated active sludge processes where the population is higher than 250 and the location of the houses are close together. When we calculate the cost of these systems the following criterias are considered: The construction costs are determined by the basis of unit cost. 25 % of the total cost is taken for transportation costs. 10 % of the total cost is taken for unknown costs. To calculate the energy costs, unit electric price is taken 0,055 $/kw.h. The service period of mechanical equipments is considered as 30 years. The interest rate is considered as 12 % for to calculate the present value of the energy cost. The operating and maintanence cost (exept energy cost) is neglected. Land prices are not included in the costs. XIVThe capital cost in Turkey for wastewater collection and treatment systems of small communities was predicted as 1.500.000.000 US$ and operating and meintenance costs for a service period of 30 years was predicted as 500.000.000 US$. At the following graphics comparison of total and unit cost of the chosen, wastewater treatment systems are shown. 35000 30000 ^ 25000 2 20000 § 15000 10000 5000 0 Comparison of costs 200 400 600 Population 800 ?Stabilization Pond ? Facultative Stab. Pond Aerated Lagoon -*- Extended Aerated Lagoon -*- Packet System 0,08 Comparison of unit costs 100 200 300 Flow (m /day) ?Aerated Lagoon. Extended Aerated Lagoon Aerobic Stabilization Pond. Facultative Stab. Pond Figure 1. Comparison of costs and unit costs XVIn chapter 6 the results of this study have been summarised. The following results were reached in this study in which the wastewater collection and treatment systems that could be applied to the small communities in Turkey have been observed and evaluated: 1. There are more problems in collection and treatment of wastewater of the small communities than big cities. First of all, these problems should be defined and a wastewater policy should be established in small communities. 2. The wastewater characteristics and water amounts consumed by each person in small communities are quite different than big cities. The first step in establishing the wastewater policy will be determination of wastewater characteristics and amounts in Turkey according to the touristic areas, holiday sites and rural areas. The systems that could be used in collection and treatment of wastewater in small communities has been evaluated in this study and different suggestions have been offered as subject to the local conditions. To accept this study as a beginning and to search the applicable technologies in more detailed way by taking the local conditions into consideration, will be of greater benefit to Turkey. 4. The biggest obstacle in making the sub-construction investments is financial. For making the wastewater collection and treatment investments in small communities, at least determining the investment priorities, the costs view of the subject should be known as well. The costs of the systems being suggested in this study have been calculated separately as subject to the population and amount of wastewater per unit and have been presented in graphs. By using these graphs, it is possible to calculate costs of any removal choice depending on the population and the unit cost per cubic meter of wastewater. It will secure benefits to compare the estimated costs and the actual costs and to carry out the necessary improvements between the two. 5. In the studied systems, it was found that the most expensive choice was packet systerms, and the most economical one for populations under 500 was stabilization ponds while it was aerated lagoons for populations over 500. The necessary value for removing 1 m3 of wastewater is less than 0,1 $. It is possible to estimate this value as 0,1 $ in consideration of wastewater collection facilities. However, flow-unit cost graphs show that unit cost decreases exponentially as depending on flow. The unit cost of 0.07 $/m3 for 25 m3/day (250 people) decreases to 0.01 8 $/m for 200 m3/day (2000 people) in extended aerated lagoon. 6. When it is accepted that the wastewater system would be in service for 30 years and capital cost and operating and maintenance cost per 1 cubic meter of wastewater would be 0,1 $/m3, total cost of wastewater collection and treatment systems in small communities of Turkey was calculated as approximately 2.000.000.000 $ consisting of 1.500.000.000 $ as capital cost and 500.000.000 $ as operating and maintenance costs. This value does not include the land prices. XVIThe cost of the systems evaluated for the cities having a population of 50-2000 people has been estimated as 1150-40000 $ excluding the land price. It is possible to meet these values for the people living in these small communities with a good organization. XVll