Çamaşır makinesi atık suyunun arıtımı ve yeniden kullanımı için selüloz nanofibril kaplamalı nanolif membranların geliştirilmesi
Development of cellulose nanofibrile coated nanofiber membranes for the treatment and reuse of washing machine wastewater
Yazar: SEZER GENÇTÜRK
Danışman: DOÇ. DR. DERYA YÜKSEL İMER
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Çevre Mühendisliği Ana Bilim Dalı / Çevre Bilimleri, Mühendisliği ve Yönetimi Bilim Dalı
Derece: Yüksek Lisans, 2024
Konu: Çevre Mühendisliği = Environmental Engineering
Dizin: Membran teknolojileri = Membrane technologies ; Nanolif = Nanofiber ; Nanoselüloz = Nanocellulose ; Çamaşır makineleri = Washing machines

Özet:
Gündelik yaşamda ve temizlik endüstrisinde yoğun kullanılan çamaşır makineleri, evsel atıksu kirliliğinin önemli kaynakları arasında yer almaktadır. Özellikle içeriğinde bulunan deterjanlar, boyalar, ağartıcılar, mikroplastikler ve nanoplastikler ile su kaynaklarına ve su yaşamına zarar vermektedir. Bunun yanında, özellikle evsel kullanımda çamaşır makineleri çıkış sularının içerdiği kompleks bileşenler atıksu arıtma tesislerinde bazı işletme problemlerine yol açabilmektedir. Bu nedenle çamaşır makinesi atıksularının geri kazanımı ve tekrar kullanımı için malzeme ve teknolojilerin geliştirilmesi önemli bir araştırma konusudur. Bu atıksuların geleneksel arıtma yöntemleri ile merkezi arıtma sistemlerinde arıtımı yüksek enerji sarfiyatı ve işletme maliyetlerine yol açabilmektedir. Yerinde arıtım yöntemleri düşünüldüğünde geleneksel yöntemler yetersiz kalmaktadır. Son yıllarda kompozit membran sistemleri yenilikçi yaklaşımlarıyla artıma proseslerinde kullanılmaktadır. Bu noktadan hareketle, tez çalışmasında yerinde çamaşır makinesi atıksularının arıtımını ve yeniden kullanımını sağlayacak selüloz nanofibril (CNF) gibi doğal kaynaklı, biyobozunur malzemeler ile üretilmiş hibrit membranların üretimi, karakterizasyonu ve performansları araştırılmıştır. Tez kapsamında, membran üretiminde elektroeğirme tekniği kullanılarak polimer bazlı (Poliakrilonitril- PAN) destek tabaka membranları üretilmiş olup, düşük basınç altında CNF malzemesinin membran yüzeyine fiziksel kaplaması sağlanmış ve nihai olarak kompozit membran malzemesi geliştirilmiştir. Deneysel çalışmalar kapsamında, kompozit membran üretimi, karakterizasyonu, sentetik boya çözeltisi ve gerçek çamaşır makinesi atıksuyu arıtım performans testleri gerçekleştirilmiştir. Tezin önemi, literatürde kısıtlı çalışma alanına sahip olan fakat günlük hayatta çok yüksek atıksu hacimlerine ulaşabilen çamaşır makinesi atıksularının yönetiminde sürdürülebilir malzemelerinin detaylı incelenmesi, optimum çalışma şartlarının belirlenmesi ve çamaşır makinesi atıksularına özel geliştirilen deneysel bir metodoloji çerçevesinde kurgulanması ve bukonuda literatüre katkı sağlayacak sonuçlara ulaşılmasıdır.

Abstract:
Laundry washing machines, widely used in the daily life and the industrial sectors, are significant sources of domestic wastewater pollution. The detergents, dyes, bleaches, microplastics, and nanoplastics in wastewater can cause severe damage to water resources and aquatic life. Additionally, the complex components in laundry machine wastewater can place a significant burden on wastewater treatment plants, leading to serious management and financial challenges. Therefore, the recovery and reuse of laundry machine wastewater is crucial for environmental protection. While conventional treatment methods, including physicochemical processes, can be effective, they often result in high energy consumption and operating costs. In recent years, composite membrane systems have emerged as innovative approaches for wastewater treatment. Hybrid membranes constructed from natural and biodegradable materials such as cellulose nanofibers (CNF) have shown promise as a new technology for laundry wastewater treatment.
This thesis focuses on the investigation of laundry wastewater recovery using innovative composite membrane systems. Electrospinning was employed to fabricate polymer-based (polyacrylonitrile-PAN) support layer membranes, which were then coated with cellulose-based nanomaterials (CNF) as adsorbents in a low pressure cell to develop a composite membranes. Experiments were conducted to investigate the fabrication, characterization, dye removal performance, and laundry wastewater treatment performance of the composite membrane systems. The innovative side of this thesis lies in its exploration of novel membrane materials and systems for laundry wastewater recovery using high-performance, environmentally friendly, and sustainable materials under optimal conditions. This involves the development of experimental methodology using novel material compositions and methods. As a result, the study aims to develop and implement composite nanofiber membranes with high filtration capacity and durability, tailored to the potential characteristics of laundry wastewater. Cellulose Nanofiber (CNF)-coated membranes, aiming to create reinforced membranes that are feasible, cost-effective, and high-performance for applications such as on-site treatment. The hypothesis of thesis is that CNF-coated membranes enhance removal efficiency for contaminants and dyes in laundry wastewater, enabling a wide range of uses. Polyacrylonitrile (PAN), a thermoplastic polymer material, was chosen as the ideal support layer for the membrane.
During the laboratory studies, both 'electrospinning' and 'low pressurized cell (LPC)' techniques were utilized. Electrospinning, renowned for its application in nanofiber membrane production, has gained prominence as a versatile technique with significant research focus in various fields, including textiles, medical materials, and biotechnology. The LPC technique was employed to deposit varying concentrations of CNFs onto the membrane surface under constant low pressure, enabling investigation into several key parameters such as permeate flux, dye removal efficiency, and the temperature and pH dependent effects of CNFs on these performance metrics. Prior to electrospinning, a PAN solution was prepared with a concentration of 12 wt%. The electrospinning processes were conducted for 6 h at room temperature, employing positive voltages of 10 kV, feed rates set at 0.5 mL/h using a 10 mL syringe pump, a distance between the nozzle connected to the syringe pump and the roller collector set at 10-15 cm, and a rotating speed of the roller collector at 200 rpm. After the electrospinning processes, PAN membranes were allowed to rest for 24 h at room temperature.
CNFs for PAN membrane coatings were prepared by dissolving them in distilled water at various weight percentages. The prepared CNF solutions contained 5 g, 7 g, and 10 g CNF, respectively. The membranes were placed in a filtration system and throughout the 2 h test period, all water samples were evaluated for permeate flux and 1 mg/L Methylene Blue solution removal efficiency at both constant and varying pH conditions. It was found that CNF-coated membranes have high dye removal in methylene blue and it was determined that the lowest temperature of 25 °C and the pH value of dye 6.4 showed the most effective removal performance. The initial flux was observed as 30.7 L/m2h and flux at the end of the 2 hour period was observed as 27.4 L/m2h . The dye removal efficiency was found to be 98.9% at the initial time of filtration and 97.2% at the end of filtration. The treatment processes commenced with the utilization of composite membranes. The optimal working conditions for these membranes were established using synthetic wastewater, followed by their application to real wastewater from laundry machines. After examining the performance of dye removal under different variable conditions and the behavior of the layered membrane against these parameters, experiments were conducted using the optimum membrane system with real wastewater samples obtained from a laundry machine. Following flux analysis at various temperatures, tests for COD, color, pH, turbidity, and conductivity were performed on each permeate water sample. 
Based on all the results obtained from the removal studies conducted with CNF-coated nanofiber supported membranes produced within the scope of this thesis, and evaluating the potential uses of the reclaimed water, it was determined that the best option for this water is to be used in the rinsing phase of the washing cycle via a module installed inside the washing machine according to the guideline document prepared by the General Directorate of Water Management of the Ministry of Agriculture and Forestry of the Republic of Turkey in 2022, greywater, once treated and ready for use can be utilized in various areas such as hotels, schools, hospitals, residential complexes, and industries. Additionally, it can be used as irrigation water or stored in fire hydrants in some regions for firefighting purposes. Upon a general evaluatin of the expected water characterizations for these reclamation options, it was conclued that the water quality obtained in this thesis does not meet the required standards. Therefore, additional studies are needed to bring the reclaimed water to the desired levels.
For the treatment of washing machine wastewater, optimum conditions for economical, sustainable and environmentally friendly coated mambrane system were determined through dye removal results avaluated under different temperature and pH conditions. These evaluations confirmed the applicability of the membrane system. To further enchance the sustainability and applicability of the membrane system, it will be tested in pilot-scale system that can be modularly integrated into washing machines.
Overall, the 12 wt% PAN membrane fabricated with 6 hours and 7 g CNF system achieved high efficiencies in color, turbidty, and COD removal. In the results from the filtrates of the first washing wastewater: 18.2% - 50.0% COD removal efficency, 96.5% - 97.06% color removal efficiency, and 96.1% - 97.1% turbidity removal efficieny were determined. Results from the filtrates of the second washing wastewater: 31.2% - 33.4% COD removal efficency, 92.8% - 96.05% color removal efficiency, and 93.3% - 97.2% turbidity removal efficency were detected. Given these findings, CNF and cellulose-based nanomaterials exhibit significant potentioal for the treatment of washing machine wastewater.