Erzincan Atıksu Arıtma Tesisi için yaşam döngüsü analizi
Life cycle assessment of Erzincan Wastewater Treatment plant
Yazar: FATMA SUDE TANDIROĞLU
Danışman: PROF. DR. ÖZLEM KARAHAN ÖZGÜN
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Çevre Mühendisliği Ana Bilim Dalı / Çevre Bilimleri, Mühendisliği ve Yönetimi Bilim Dalı
Derece: Yüksek Lisans, 2023
Konu: Çevre Mühendisliği = Environmental Engineering

Özet:
Son yıllarda küresel ısınma, iklim değişikliği ve kuraklık su kaynaklarına erişimi zor hale getirmişir. Artan nüfusa bağlı olarak, tüketim fazlalığı her şey de olduğu gibi su kullanımında da artışa sebep olmuştur. Canlılar yaşamın en temel parçası olan suyu bilinçsizce kullanarak israf etmeye başlamışlardır. Tüm bunlar suyun tekrar kullanılabilmesi, arıtımının sağlanarak daha az zararlı hale gelmesi gibi ihtiyaçları ortaya çıkarmıştır. Bu bağlamda sürdürülebilirlik çalışmalarının hız kazanması ile atıksu arıtma tesisleri de günden güne önem kazanmıştır.
Bu çalışmada Erzincan ili evsel atıksularını arıtan, atıksu arıtma tesisine ait çevresel etkilerin yaşam döngüsü analizi metoduyla araştırılması esas alınmıştır. Erzincan atıksu arıtma tesisi, evsel nitelikli atıksuların toplanılıp arıtıldıktan sonra Karasu Nehri'ne deşarj edilmesine kadar ki sürecin yönetilmesinden sorumludur. Endüstriyel atıksuların karışmadığı atıksu arıtma tesisine yaşam döngüsü yaklaşımının uygulanabilmesi için fonksiyonel birim ve sistem sınırları belirlenmiştir. 
Tesise ait envanter analizinden sonra tüm veriler 1 m3 fonksiyonel birim cinsinden normalize edilmiştir. Sistem sınırları tesisteki her bir arıtma ünitesi olarak belirlenmiştir. Arıtma üniteleri sırasıyla kaba ızgara, giriş pompa istasyonu, ince ızgara, havalandırmalı kum ve yağ tutucu, son çöktürme havuzu, geri devir binası, çamur yoğunlaştırıcı, çamur susuzlaştırıcı, çamur depolama sahası ve çıkış pompa istasyonudur. Ayrıca sistem sınırlarına tesiste mevcutta olmayan ama uygulandığı varsayılan solar kurutma yaklaşımı da dahil edilmiştir. Kimyasal maddenin ithal edildiği ülkeden, EAAT'ye gelene kadar ki süreç de sistem sınırları içerisindedir. Kaba ızgara, ince ızgara, kum ve yağ tutucu ünitelerinden çıkan atıkların bertarafı da sistem sınırları içerisindedir. 
Yaşam döngüsü analizinin yapılabilmesi için bu çalışmada GaBi 9.8.1.68 yazılımından faydalanılmıştır. CML 2001 metodu kullanılarak, ünitelere ait girdi ve çıktılar sistem sınırları kapsamında GaBi üzerinde oluşturulmuştur. GaBi girdi ve çıktı değerlerine ait normalizasyonu yaparak etki kategorilerine göre sonuçları listelemiştir.
CML 2001 metodu kapsamında GaBi üzerinde listelenen etki kategorileri Küresel Isınma Potansiyeli (KIP), Asidifikasyon Potansiyeli (AP), Ötrofikasyon Potansiyeli (ÖP), Ozon Tabakası İncelme Potansiyeli (OTİP), Abiyotik Element Tüketim Potansiyeli (AETP), Abiyotik Fosil Tüketim Potansiyeli (AFTP), Tatlı Su Ekotoksisite Potansiyeli (TSEP), İnsan Toksisite Potansiyeli (İTP), Sucul Ekotoksisite Potansiyeli (SEP), Fotokimyasal Ozon Oluşum Potansiyeli (FOOP), Karasal Ekotoksisite Potansiyeli (KEP) olarak belirtilmiştir.
Yaşam döngüsü analizi çalışması yapılan atıksu arıtma tesisi için, literatür değerleri kıyaslaması sonucunda EAAT için elde edilen GaBi sonuçlarının uyumlu olduğu görülmüştür. KIP, AETP, AFTP, TSEP, SEP etki kategorileri için en yüksek etki kaynağı elektriktir ve en yüksek katkı havalandırma havuzu, giriş pompa istasyonu ve çıkış pompa istasyonundan kaynaklanmaktadır. AP, İTP, FOOP için en yüksek katkı havalandırma havuzu, çamur susuzlaştırıcı ve giriş pompa istasyonundan kaynaklanmaktadır. ÖP, KEP için en yüksek katkı havalandırma havuzu, çamur deposu ve giriş pompa istasyonundan kaynaklanmaktadır. OTİP için en yüksek etki kaynağı kullanılan katyonik polielektrolit kimyasalıdır. OTİP için en yüksek katkı ise çamur susuzlaştırıcı, havalandırma havuzu ve giriş pompa istasyonundan kaynaklanmaktadır. 
Elde edilen sonuçlar doğrultusunda elektrik tüketimi, çevresel etkiler içerisinde en yüksek etki kaynağıdır. Erzincan atıksu arıtma tesisinde kullanılan elektrik enerjisi şehir şebekesinden çekilmektedir. Bu çalışmada TEİAŞ elektrik verileri referans alınmıştır. Elektrik kaynağı olarak yenilenebilir enerji kaynakları kullanılırsa çevresel etkilerin daha az seviyelere ineceği düşünülmektedir.   
Kullanılan kimyasal malzemenin tesise taşınması sırasında ortaya çıkan çevresel etkiler de bu çalışmada ele alınmıştır. Katyonik polielektrolit madde ABD, İtalya, ispanya, Çin, Fransa olmak üzere 5 farklı ülkeden ithal edilecek şekilde yaşam döngüsü analizi etkileri hesaplanmıştır. Tesiste mevcutta bulunmayan ancak yapılması düşünülen solar çamur kurutma yaklaşımının yaşam döngüsü analizi de hesaplanmıştır. Bu ünite sayesinde, arıtma çamuru miktarının %33,3 azalacağı tespit edilmiştir. Giriş ve çıkış pompaları elektrik tüketiminde büyük rol oynar. Pompa verimlerinin arttırılmasıyla da çevresel etkilerde düşüş olacağı düşünülmektedir.
Küçük ölçekli bir yerleşim yeri olan Erzincan iline ait evsel nitelikli atıksuların arıtıldığı bu atıksu arıtma tesisi için yaşam döngüsü analizi çalışması yapılmış ve elde edilen sonuçlar literatür değerleri ile karşılaştırılmıştır. Literatür değerleri ile benzerlik ve farklılıklar değerlendirilip yorumlanmıştır.

Abstract:
In recent years, global warming, climate change and drought have made access to water resources difficult. Due to the increasing population, the excess of consumption has caused an increase in water use as well as everything else. Waste water has reached very high levels because living beings use water, which is the most basic part of life, unconsciously. All of these have revealed needs such as the reuse of water, ensuring its treatment and making it less harmful. In this context, wastewater treatment plants have gained importance day by day with the acceleration of sustainability studies.
In this study, it is based on the investigation of the environmental effects of the wastewater treatment plant that treats the municipal wastewater of Erzincan province by the method of life cycle analysis. Erzincan wastewater treatment plant is responsible for managing the process of domestic qualified wastewater until it is collected, treated and discharged into the Karasu River. Industrial quality wastewater is not mixed into the collection line of this treatment plant. Functional unit and system boundary have been determined in order to apply a life cycle analysis approach to the wastewater treatment plant.  
After the inventory analysis of the treatment plant, all the data were normalized in terms of 1 m3 functional units. The system boundaries are determined as each treatment unit in the facility. The treatment units are coarse screen, inlet pumping station, fine screen, grit chamber, aeration tank, final sedimentation tank, return sludge station, sludge thickening tank, sludge dewatering tank, sludge landfill and outlet pumping station respectively. In addition, the solar drying approach, which is not available at the facility but is assumed to be applied, is also included in the system boundaries. The process from the country where the chemical substance is imported to the EAAT until it arrives is also within the boundaries of the system. The disposal of wastes from coarse screen, fine screen, grit chamber units is also within the boundaries of the system.
CML 2001 method that are listed on GaBi within the scope of the impact categories Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP), Ozone Layer Depletion Potential (ODP), Abiotic Depletion Potential (ADP for elements), Abiotic Depletion Potential (ADP for Fossil), Freshwater Aquatic Ecotoxicity Potential (FAEP), Human Toxicity Potential (HTP), Marine Aquatic Ecotoxicity Potential (MAEP), Photochemical Ozone Creation Potential (POCP), Terrestic Ecotoxicity Potential (TETP) as is stated.
The electrical energy consumed for 1 m3 of treated wastewater was obtained as 0.374 kWh. The electrical energy inventories were obtained from the energy form specified separately for each equipment. The average of electricity consumption according to the months in 2021 is based on. The aeration tank takes over 66.7% of the electricity consumption. 9.61% of the electricity consumption is caused by the inlet pumping station and 9.34% is caused by the outlet pumping station. The total electrical energy consumed in this plant is in accordance with the electricity consumption information of wastewater treatment plants in the literature. The basis of the differences revealed in the literature are factors such as the characterization of the inlet wastewater, the geography where the treatment plant is located, the treatment technology applied at the facility.
The GWP value of Erzincan wastewater treatment plant was obtained as 2.36 x 10-1 kg CO2-Equivalent. The highest source of effect for GWP is electricity, and the aeration tank, inlet pumping station, outlet pumping station units account for 91.86% of this source of effect.
The AP value of the Erzincan wastewater treatment plant was obtained as 10.27 x 10-4 kg SO2-Equivalent. The highest source of effect for AP is electricity, and the aeration tank, inlet pumping station, outlet pumping station units account for 64.94% of this source of effect. The second highest source of effect is the cationic polyelectrolyte substance. The sludge dewatering unit accounts for 29.65% of this source of effect.
The EP value of the Erzincan wastewater treatment plant was obtained as 9.65 x 10-3 kg PO4-Equivalent. The highest source of effect for EP is electricity, and the aeration tank, inlet pumping station, outlet pumping station, grit chamber account for 62.88% of this source of effect. The second highest impact source is the waste sludge stored in the sludge landfill. The sludge landfill accounts for 19.4% of this impact source.
The ODP value of Erzincan wastewater treatment plant was obtained as 3,46 x 10-10 kg R11-Equivalent. The highest source of influence for ODP is electricity. Aeration tank, inlet pumping station, outlet pumping station, return sludge pump account for 54.3% of this source of effect. The second highest source of effect is cationic polyelectrolyte, and the sludge dewatering unit alone accounts for 39.32% of this source of effect.
The ADP for elements value of the Erzincan wastewater treatment plant was obtained as 1.04 x 10-8 kg Sb-Equivalent. The source of the highest impact for ADP for elements is electricity. The aeration tank, inlet pumping station, outlet pumping station account for 78.9% of this source of effect. The second highest source of effect is cationic polyelectrolyte, and the sludge dewatering unit alone accounts for 10.47% of this source of effect.
The ADP for fossil value of the Erzincan wastewater treatment plant was obtained as 0.97 MJ-Equivalent. The source of the highest effect for ADP for fossil is electricity. The aeration tank, inlet pumping station, outlet pumping station account for 85.64% of this source of effect. The second highest source of effect is cationic polyelectrolyte, and the sludge dewatering unit alone accounts for 10.96% of this source of effect.
The FAEP value of Erzincan wastewater treatment plant was obtained as 2.60 x 10-3 kg DCB-Equivalent. The highest source of effect for FAEP is electricity, and the aeration tank, inlet pumping station, outlet pumping station account for 91.74% of this source of effect. The second highest impact source is the waste sludge stored in the sludge landfill. The sludge landfill accounts for 7.65% of this impact source.
The HTP value of Erzincan wastewater treatment plant was obtained as 1.64 kg DCB-Equivalent. The highest impact source for HTP is electricity, and the aeration tank, inlet pumping station, outlet pumping station account for 68.82% of this impact source. The second highest source of effect is cationic polyelectrolyte, and the sludge dewatering unit alone accounts for 18.34% of this source of effect.
The MAEP value of the Erzincan wastewater treatment plant was obtained as 617 kg DCB-Equivalent. The highest source of effect for MAEP is electricity, and the aeration tank, inlet pumping station, outlet pumping station account for 70.12% of this source of effect. The second highest source of impact is thought to be the waste oil entering the sludge thickening unit. The sludge thickening unit alone accounts for 27.91% of this source of effect.
The POCP value of Erzincan wastewater treatment plant was obtained as 7.48 x 10-5 kg Ethane-Equivalent. The highest source of effect for POCP is electricity, and the aeration tank, inlet pumping station, outlet pumping station account for 72.67% of this source of effect. The second highest source of effect is cationic polyelectrolyte, and the sludge dewatering unit alone accounts for 24.8% of this source of effect.
The TETP value of the Erzincan wastewater treatment plant was obtained as 1.07 x 10-2 kg DCB-Equivalent. The highest source of effect for the TETP is electricity, and the aeration tank, inlet pumping station, outlet pumping station account for 72.79% of this source of effect. The second highest impact source is the waste sludge stored in the sludge landfill. The sludge landfill alone accounts for 23.42% of this impact source.
For the wastewater treatment plant where the life cycle analysis study was carried out, it was found that the GaBi results obtained for the EAAT were compatible as a result of the literature value comparison. For the GWP, ADP for Elements, ADP for Fossils, FAEP, MAEP impact categories, the highest impact source is electricity, and the highest contribution is due to the aeration tank, inlet pumping station and outlet pumping station. The highest contribution for AP, HTP, POCP is due to the aeration tank, sludge dewatering tank and inlet pumping station. The highest contribution for EP and TETP is due to the aeration tank, sludge landfill and inlet pumping station. The source of the highest effect for ODP is the cationic polyelectrolyte chemical used for treatment. The highest contribution for ODP is due to the sludge dewatering tank, aeration tank and inlet pumping station.
According to the results obtained, electricity consumption is the highest source of impact among environmental impacts. The electrical energy used in the Erzincan wastewater treatment plant is supplied from the city grid mix. In this study, TEIAŞ electrical data were taken as a reference. It is thought that if renewable energy sources are used as electricity sources, the environmental impacts will decrease to lesser levels. 
The environmental effects that occur during the transportation of the chemical material used to the plant were also considered in this study. Cationic polyelectrolyte substance will be imported from 5 different countries, including USA, Italy, Spain, China, France, the life cycle analysis effects were calculated. The life cycle analysis of the solar sludge drying approach, which is not available at the plant but is being considered to be performed, has also been calculated. Thanks to this unit, it has been determined that the amount of sewage sludge will be reduced by 33.3%. Inlet and outlet pumps play a big role in electricity consumption. It is thought that there will also be a decrease in environmental impacts by increasing pump efficiencies.
A life cycle analysis study was conducted for this wastewater treatment plant, where domestic wastewater belonging to the province of Erzincan, which is a small-scale settlement, is treated, and the results obtained were compared with the literature values. Similarities and differences with the literature values were evaluated and interpreted.