Ev tipi yıkamalarda suyun tekrar kullanımı için yıkama atık suyundan renk giderme sisteminin geliştirilmesi
Development of color removal system from washing wastewater for reuse of water in domestic washing machines
Yazar: BAŞAK ARSLAN İLKİZ
Danışman: DR. ÖĞR. ÜYESİ YEŞİM BECEREN ; PROF. DR. CEVZA CANDAN
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Tekstil Mühendisliği Ana Bilim Dalı / Tekstil Mühendisliği Bilim Dalı
Derece: Doktora, 2021
Konu: Tekstil ve Tekstil Mühendisliği = Textile and Textile Engineering

Özet:
Son yıllarda temiz su kaynaklarının hızla kirlenmesi nedeniyle su geri kazanımının önemi günden güne daha da artmaktadır. Bu tez çalışması öncelikle su kaynaklarının sürdürülebilir olmasını desteklemek ve kullanılan atık suyu tekrar kullanabilmek amacıyla tetiklenmiştir. Pazarda yaygın bulunan yüksek kapasiteli ve önden yüklemeli ev tipi çamaşır makinelerinde her çevrimde yıkama ve durulama adımlarının tamamında minimum 50 L ve üzerinde su tüketimi gerçekleşmektedir. Sunulan tez çalışmasında, ozonlama yöntemi kullanılarak renkli çamaşırların yıkanmasıyla ortaya çıkan çamaşır makinesi atık sularındaki rengin giderilmesi ve rengi giderilen suyun bir sonraki yıkamada tekrar kullanılması hedeflenmiştir. Bu hedef doğrultusunda, çamaşır makinesi atık suyundaki boyarmadde konsantrasyonunu tahminleme, ozon ile renk giderme sistemine sahip makine prototipinin hazırlanması çalışmaları ve bu makinede renk giderme testleri yürütülmüştür. 
Çamaşır yıkama sonucunda oluşan atık su, gri su kategorisindedir, hanelerde evsel aktiviteler için kullanılan toplam su içerisinde yüksek bir paya sahip olup (%27) geri kazanım ve tekrar kullanım için potansiyel oluşturmaktadır. Günümüzde yaygın olarak tercih edilen pamuk içerikli tekstil ürünleri çamaşır makinelerinde sıklıkla yıkanmakta olup, bu ürünlerin renklendirilmesinde çoğunlukla reaktif boyarmaddeler kullanılmaktadır. Bu reaktif boyarmaddeler içerisinden azo ve antrakinon boyarmaddeler yaygınlık, suda yüksek çözünürlük göstermeleri, life fikse oranlarının düşük olması ve atık suda risk oluşturmaları nedeniyle tercih edilmiştir. Yıkamaya karşı renk haslığı düşük ve lekeleme konusunda problemli olarak bilinen kırmızı ve mavi renkler belirlenerek, bu renklerin elde edilmesi için azo boyarmadde sınıfından reaktif kırmızı 195 ve antrakinon boyarmadde sınıfından reaktif mavi 19 boyarmaddeleri seçilmiştir. Çalışmada yaygın kullanılan ve sık yıkama ihtiyacı bulunan örme kumaşlar tercih edilmiş ve ticari koşullarda üretilip boyanmıştır.  
Tekstil atık sularında organik kirleticilerin fazla bulunmasından dolayı, bu sulardan reaktif boyarmaddelerin giderilmesinde oksidasyon yöntemlerinden ozonlamanın ve ozon ile diğer yöntemlerin kombinasyonlarının sıklıkla tercih edildiği belirlenmiştir. Teknolojisinin olgunlaşmış olması, yan ürün açığa çıkarmaması, yerinde renk giderimini hızlı şekilde gerçekleştirebilmesinden dolayı çamaşır makinesi için ozonlama yöntemi tercih edilmiştir. 
Çamaşır makinesinde renk giderimi için yıkama çevrimindeki uygun yıkama adımının -hedef atık su çözeltisinin- belirlenmesi için yapılan deneysel çalışmada, yapılan ölçümlerde deterjan konsantrasyonu düşük olan ve yumuşatıcı içermeyen birinci durulama adımının renk giderim için daha uygun olduğuna karar verilmiştir.
Literatür araştırması sırasında renk giderimi çalışmalarında çoğunlukla konsantrasyonu bilinen yapay çözeltiler ile çalışıldığı saptanmıştır. Oysa, çamaşır makinesinde yapılan yıkamalar sonunda ortaya çıkan atık suların içeriği farklı (lif, hav, deterjan vb.) ve oldukça kaotiktir. Literatürde rastlanmaması nedeniyle tezin yenilikçi yönü olarak yapay çözeltiler yerine "evsel çamaşır makinesi atık suları" ile çalışılmıştır. Ev tipi çamaşır makinesinden kaynaklı boyarmadde içeren atık suyun renginin giderilmesi için ozonlama ile renk giderme sistemi önerisi yapılmıştır. Yaşanan en büyük zorluk, yıkama sırasında boyalı kumaşlardan elde edilen atık suların boyarmadde konsantrasyonunun bilinememesidir. Bu atık suların boyarmadde konsantrasyonunun tahmin edilmesi için iteratif bir yaklaşım geliştirilmiştir.
Boyarmadde konsantrasyonunun belirlenebilmesi için VIS spektrofotometre cihazı ile renkli atık su çözeltilerinin absorbans taraması yapılmış ve spektrumda maksimum absorbans değerini veren dalgaboyu tespit edilmiştir. Ancak, çamaşır makinesi atık suyunda yapılan ölçümlerde maksimum absorbans değeri elde edilememiştir. Boyarmadde konsantrasyonunun tahmin edilebilmesi için geliştirilen yaklaşımda, birinci adımda, saf su ile yapay olarak hazırlanan kontrol boya çözeltilerinin spektrum taramalarından maksimum absorbans değerlerinin elde edildiği dalgaboyları Reaktoset Red RFT (C.I. RR 195) için 540 nm, Reaktoset BRL Blue R Spec (C.I. RB 19) için 592 nm olarak belirlenmiştir. İkinci adımda, boya konsantrasyonları ve deterjan konsantrasyonları, sırasıyla, ana yıkama adımı için 10 –– 100 mg/L aralığında ve 4,6 g/L olarak; durulama adımı için 1 – 40 mg/L aralığında ve 0,5 g/L olarak hazırlanmış ve çözeltilerin absorbans ölçümlerinden kırmızı (RR 195) ve mavi (RB 19) boyalar için ana yıkama ve durulama kalibrasyon eğrisi denklemleri elde edilmiştir. Üçüncü adımda, renkli atık su çözeltileri tergotometer cihazında boyalı kumaşların yıkanması sonucunda elde edilmiştir. Bu çözeltiler ilgili dalgaboyunda net bir absorbans değeri vermediğinden, boyarmadde konsantrasyonunun hesaplanması için adım 2'de elde edilen kalibrasyon eğrilerine ait denklemlerin (kırmızı atık su için: A=0,0186C+0,0427, R² = 0,9997; mavi atık su için: A=0,0115C+0,0540, R² = 0,9966)  kullanılmasına karar verilmiştir. Doğrulama testlerinde, denklemlerden hesaplanan boya konsantrasyonuna en yakın konsantrasyondaki deterjanlı yapay boya çözeltilerinin spektrumları ile renkli kumaşlardan elde edilen spektrumların karakteri farklı olmasına rağmen belirlenen dalgaboyunda üst üste çakıştığı saptanmıştır.
Çamaşır makinesi ve tergotometer cihazından elde edilen atık su çözeltilerinin absorbans ve konsantrasyon değerleri arasında güçlü bir ilişki olduğu belirlenmiş ve tergotometer cihazının su ve kumaş sarfiyatını azaltmak amacıyla çamaşır makinesi yerine kullanılabileceği kanaatine varılmıştır.
Renk giderme sistemine sahip makine prototipi için, bir ozon düzeneği kurularak çalışmalara başlanmıştır. Kurulan düzenekte hava kompresörü, hava kurutucu, akış ölçer, ozon jeneratörü, ventüri, su haznesi, iki adet su pompası ve debimetre yer almaktadır. Ozon düzeneğinde yapılan deney tasarımı sonucunda renk giderme etkinliği üzerinde en etkili faktörlerin sırasıyla %22,0 ile boyarmadde*ozon jeneratörü ikili etkileşimi, %15,4 ile ozon jeneratörü*ozonlama süresi ikili etkileşimi ve %14,8 ile tek başına ozon jeneratörü olduğu saptanmıştır. 500 mg/sa kapasiteli (500-B kodlu) ozon jeneratörü ile en yüksek renk giderme oranlarına ulaşıldığından bu ozon jeneratörünün kullanılmasına karar verilmiştir. Ventüri sistemi ve geri kazanılan suyun bulunacağı depoya sahip 9 kg kapasiteli çamaşır makinesi prototipi hazırlanmıştır. Sistemin çalışma prensibi şu şekildedir: Dışarıdan hava kompresörü yardımıyla çekilen ortam havası ozon jeneratöründen geçirilerek ozon üretilmekte ve ventüri  elemanına taşınmaktadır. Pompalar yardımıyla ventüri elemanında renkli su ve ozon buluşmakta, belirli süre yapılan sirkülasyon sonrasında ozonlama yoluyla renksiz su elde edilmektedir.
Önerilen denklemler kullanılarak boya konsantrasyonları hesaplandığında, renkli kumaşların farklı tüketici koşullarında yıkanması sonucu atık su boya konsantrasyonunun 15 mg/L ile 90 mg/L arasında değişkenlik gösterdiği saptanmıştır. 
Çamaşır makinesinde ozonlama testleri iki aşamada yürütülmüştür. Birinci aşamada, çamaşır makinesinde 14 L olarak deterjanlı, 20 – 40 – 60 – 80 mg/L boya konsantrasyonuna sahip yapay çözeltiler hazırlanmış ve ozonlanmıştır.  İkinci aşamada, gerçek yıkama koşulunu temsilen ticari koşullarda üretilen kumaşların (1 kg) Beko 9 kg çamaşır makinesinde pamuklu 40 programında 52 g standart deterjan ile yıkanmasından elde edilen birinci durulama suları toplanarak ozonlanmıştır. Kırmızı ve mavi yapay boya çözeltilerinde renk giderme oranı %95 ve üzerinde gerçekleşmiştir, görsel olarak rengin tamamen giderildiği tespit edilmiştir. Renk giderimi etkinliğinin başlangıç boya konsantrasyonuna ve boyarmadde tipine bağlı olduğu belirlenmiştir. Boya konsantrasyonu arttıkça renk giderimi daha uzun sürede gerçekleşmiştir. Reaktif kırmızı 195 boyarmaddesi ile hazırlanan çözeltilerde renk gideriminin reaktif mavi boyarmadde ile hazırlanan çözeltilere göre daha uzun sürdüğü belirlenmiştir. Kırmızı ve mavi kumaşlardan elde edilen birinci durulamaya ait atık suların boya konsantrasyonu sırasıyla 35,1 mg/L ve 42,3 mg/L olarak belirlenmiştir ve kırmızı ve mavi renkli atık su çözeltilerinde %80 civarında renk giderimi sağlanmıştır. Renk giderimi mavi atık su çözeltisi için yaklaşık üç kat daha hızlıdır. Kırmızı renkli atık sularda 240 dakikada %76 oranında renk giderimi; mavi renkli atık sularda ise 70 dakikada %82 oranında renk giderimi gerçekleşmektedir. 
Ozonlama ile boyarmaddenin kromofor grubunun parçalanıp parçalanmadığının analizi için, 100 mg/L boya konsantrasyonuna sahip deterjansız çözeltiler ozonlanmış ve dondurularak kurutulmuştur. FTIR cihazı analizleri sonucunda, kırmızı çözeltilerde ozonlama etkisiyle 1540 cm-1 civarında görülen N = N bağının kırıldığı, dolayısıyla azo kromofor grubunun parçalandığı; mavi çözeltilerde ozonlama etkisiyle 1575 cm-1 civarında görülen kromofor grubu temsil eden antrakinon halkasına ait bağların kaybolduğu belirlenmiştir.
Ozon ile rengi giderilen suyun kalitesi incelendiğinde, çıkış suyu parametrelerinin giriş suyu parametrelerine göre daha iyi seviyede olduğu saptanmıştır. AKM, bulanıklık, KOİ (%54 düşüş) ve TOK (%35 düşüş) parametrelerinde ozonlama işlemi etkisiyle belirgin düşüş sağlanmıştır. Hazırlanan prototip makinede geri dönüştürülen su bir sonraki çevrimin ana yıkama adımında kullanılmıştır. 10 çevrim süresince ozonlanmış su ile yıkanan çeşitli tekstil numunelerinde herhangi bir tekstil hasarlanma etkisi görülmemiştir. Geri kazanılmış su ve şebeke suyu ile yapılan yıkamaların yıkama performansı değerleri arasında belirgin bir fark tespit edilememiştir. Çamaşır makinesi ozon ile renk giderme sisteminin enerji tüketimi, mavi kumaştan elde edilen suyu ozonlamak için pamuklu 40 programının enerji tüketiminin yaklaşık beşte biri, kırmızı kumaştan elde edilen suyu ozonlamak için pamuklu 40 programının yaklaşık üçte ikisidir. 
Ozon ile renk giderme sistemine sahip çamaşır makinelerinin yaklaşık dörtte bir oranında su tasarrufu sağlayacağı tahmin edilmektedir. 8-9-10 kg kapasiteli çamaşır makinelerinde çevrim başı yaklaşık 14 L'lik su tasarrufunun bir yılda yaklaşık 1,24 hm3'lük su tasarrufu sağlaması beklenmektedir. Çamaşır makinesi ortamında atık suyun kendi kaynağında renginin giderilmesi, geri kazanımı ve tekrar kullanımı ile sürdürülebilir yaşam desteklenebilecektir. Geliştirilen ürünün hem ticari açıdan hem çevresel açıdan başarı potansiyeli bulunmakta hem de sürdürülebilir ürün gamında kalıcı bir yer edinmesi beklenmektedir.

Abstract:
Due to the pollution of clean water resources rapidly in recent years, the importance of water recovery increases day by day. In this context, every work that can be done for the reuse of water and every step taken is very valuable. This thesis work was primarily triggered in order to support the sustainability of water resources and to reuse the wastewater. In high-capacity and front-loading domestic washing machines, which are common in the market, there is a minimum of 50 L and more water consumption in all washing and rinsing steps of each cycle. In order for consumers to know the amount of water consumed by a washing machine, it is mandatory to declare the water consumption value on the energy labels of the products. At the same time, this declaration motivates washing machine manufacturers to develop environmentally friendly products that consume less water than the competition for many years.
In the presented thesis, it is aimed to remove the color of the washing machine wastewater, which is generated by washing colored clothes using the ozonation method, and to reuse the decolorized water in the next wash cycle. In line with this goal, studies were carried out to estimate the dyestuff concentration of the washing machine wastewater, to determine the dye concentration range that can be encountered in different washing conditions, to select the ozone generator by using design of experiment method, to determine the ozone decolorization system components and to prepare the machine prototype. Then, color removal was performed in the prototype machine having ozonation system and the color removal efficiency was determined both for the synthetic dye solutions with detergent prepared in the washing machine and for the wastewater solutions obtained in the first rinse step from colored fabrics in the washing machine. During the study, the washing machine wastewater obtained from the washing of colored fabrics was compared with synthetic dye solutions. In order to evaluate the suitability for reuse of recycled wastewater by decolorization, the quality of the non-ozonated water and the quality of the ozonated water were compared by measuring certain water quality parameters. It has been investigated whether the water, which is decolorized and recovered by ozonation, will cause any textile damage in the next cycle and its side effect on washing performance. Finally, the energy consumption was defined.
Gray water of domestic wastewater, arises as a result of domestic activities such as dishwashing, laundry and bathing and corresponds to 50-80% of the total water used in households. Laundry wastewater is in the gray water category and the rate of this wastewater is high (27%), therefore it creates a big potential for recycling and reuse.Colored textile products made of cotton, which are widely used today, are frequently washed in washing machines.

Reactive dyestuffs are mostly used in dyeing process of cotton textile products. Among these reactive dyestuffs, azo and anthraquinone dyestuffs were preferred to be used in the study because of their prevalence, high solubility in water, low fiber fixation rate and because they pose too much risk in wastewater. Azo dyes are toxic, carcinogenic and pose a significant environmental risk. On the other hand, anthroquinone dyes are resistant to chemical & biological oxidation and cause permanent damage to the molecular structures of aquatic living organisms. Red and blue colors, which are known to have low color fastness to washing and are problematic in staining. In this direction, reactive red 195 from the azo dyestuff class and reactive blue 19 from the anthraquinone dyestuff class were selected to obtain these colors. Knitted fabrics, which are widely used and needed to be washed frequently, were preferred in the study. The knitted fabrics were commercially produced, dyed under industrial conditions and made ready for experimental studies.
After deciding dyestuff and colored fabric types, suitable treatment methods that can be effective in the removal of reactive dyes from wastewater and that can be adapted to the domestic washing machine were investigated. Due to the high presence of organic pollutants in textile wastewater, chemical treatment methods and advanced oxidation processes are the most preferred methods in the treatment of these waters. With the effect of oxidation, the aromatic ring that causes the coloration in the dye molecule is broken and the dyestuff in the wastewater is removed. In the literature research, it was determined that ozonation and combinations of ozone & other methods are quite successful in the color removal of reactive dyestuffs from wastewater. Ozonation method was preferred for the washing machine because its technology is mature, it does not release by-products, and it can fastly remove color by in-situ ozone generation.
Detergent is used to clean the stains in washing machine cycles, the detergent also contributes to color release and is present in the wastewater. Therefore, the presence of detergent was taken into account throughout the study. An experimental study was conducted to determine the appropriate washing step -target wastewater solution- in the washing cycle for color removal in the washing machine. Since chemicals such as detergent and softener, other than the dyestuff in the water, will affect the ozonation efficiency, it has been decided that the first rinsing step, which has lower detergent concentration and without softener, is suitable for color removal.
During the washing of colored fabrics, more color release occurs in the first wash and the release gradually decreases. Washing tests were carried out using new fabrics each time to ensure the same test conditions. Since this increases the fabric and water consumption, preliminary studies were carried out in the tergotometer device, keeping the same liquor ratio as the washing machine on a smaller scale. Meanwhile, the correlation of color in the water obtained in the tergotometer device and in the washing machine was investigated.
In decolorization studies found in literature, it was mostly worked with synthetic dye solutions with known concentrations or with dye solutions simulating dyehouse wastewater. However, the content of the wastewater that comes out after washing of colored textiles with detergent in the washing machine is different and quite chaotic. Fiber, fluff, detergent, other chemicals etc. that make up the dyeing recipe from fabrics can be released. From this point of view, and because it is not found in the literature, the innovative aspect of the thesis has been determined. In order to remove the color
of the wastewater containing dyestuff originating from the domestic washing machine, a color removal system by ozonation was proposed for a domestic washing machine; and instead of synthetic dye solutions, "domestic washing machine wastewater" was used. The biggest difficulty experienced is that the dyestuff concentration of the wastewater obtained from colored fabrics during washing cannot be known. A study was conducted to estimate the dyestuff concentration of these wastewaters and an iterative approach has been developed. 
As analysis method, absorbance scanning of colored wastewater solutions was performed with VIS spectrophotometer device in order to determine the dyestuff concentration, and first of all, the wavelength giving the maximum absorbance value in the spectrum was determined. However, the maximum absorbance value could not be obtained in the measurements made in the washing machine wastewater. For this reason, in the approach developed for the estimation of the dyestuff concentration, water solutions were prepared in three steps and their measurements were made. These are, the synthetic control dye solutions prepared with distilled water (step 1) without detergent, the synthetic dye solutions prepared with conditioned water and detergent in the tergotometer device (step 2), and the colored wastewater solution obtained from the fabric by washing with conditioned water and detergent in the tergotometer device (step 3), respectively. The wavelengths at which the maximum absorbance values were obtained from the spectrum of the synthetic control dye solutions prepared at different concentrations were 540 nm for Reaktoset Red RFT (CI RR 195) and 592 nm for Reaktoset BRL Blue R Spec (CI RB 19) dye. Calibration curve and calibration equations of each dyestuff were defined. 
In the second step, dye concentrations and detergent concentrations are adjusted as 10 – 20 – 30 – 45 – 60 – 75 – 90 – 100 mg/L (dye) and 4.6 g/L (detergent) for the main wash step, and as 1 – 5 – 10 – 15 – 20 – 25 – 30 – 40 mg/L (dye) and 0.5 g/L (detergent) for the rinsing step, respectively. The absorbance of each solution was measured at the relevant wavelength, red (RR 195) and blue (RB 19) dyestuffs, main wash and rinse calibration curve equations were obtained. In the third step, colored wastewater solutions were obtained by washing of colored fabrics in a tergotometer device and the absorption spectra of the wastewater solutions were examined with VIS spectrophotometer. Since these solutions do not give a clear absorbance value (peak value) at the relevant wavelength, it was decided to use the equations of the calibration curves obtained in step 2 to calculate the dye concentration. In the analyzes made for verification purposes, the dye concentration of the wastewater solutions obtained from the washing of colored fabrics was calculated from the equations. It was determined that the spectra of synthetic dye solutions with detergent at the closest concentration to the calculated concentration and the spectra obtained from colored fabrics overlapped at the determined wavelength, although the characteristics were different. After that, for calculating the concentrations of wastewater solutions, it was decided to use the equations for synthetic dye solutions representing first rinsing (for red wastewater: A=0.0186C+0.0427, R² = 0.9997; for blue wastewater: A=0.0115C+ 0.0540, R² = 0.9966). 
In the next step, the absorbance values of the colored wastewater solutions obtained in the washing machine and the tergotometer device, and the calculated concentration values were compared. The correlation of these two washing devices was examined. It was determined that there is a strong relationship between absorbance and concentration values of both devices and it was concluded that the tergotometer device
can be used instead of a washing machine. Then, regression analysis was performed to investigate the effects on dye concentration in washing machine and tergotometer. According to the regression analysis, it was determined that the most effective factor in the 95% confidence interval was the washing step with 89.5%, followed by the color/dye type with 3.4% and the washing device with 1.5%.
Before the ozonation system was adapted to the washing machine, an ozone system setup was installed. The system setup includes an air compressor, air dryer, flowmeter, ozone generator, venturi injector, water storage tank, two water pumps and flowmeters. In the literature studies, it has been seen that ozone systems with diffuser elements are mostly used. In the color removal system, which is planned to be placed in the washing machine, ozone application need to be performed in the moving water environment, so it was decided to use a venturi element instead of the diffuser element. In addition, in the patent research, it was determined that the systems that are more suitable for the washing machine contain a venturi element. 
In ozone setup, reactive dyestuff type, ozone generator production capacity and ozonation duration were chosen as variable parameters and a 3-factor, full factorial experimental design (DoE) with 2 repetitions was made to examine their effects on decolorization efficiency. It was seen that all the factors examined on the color removal efficiency are effective as single factor and in interaction. The most effective factors were dyestuff*ozone generator interaction with 22.0%, ozone generator*ozonation duration interaction with 15.4%, and ozone generator alone with 14.8%. With the highest capacity ozone generator (500-B), the highest color removal rates (77.2% for the red 1st rinse water; 80.8% for the blue 1st rinse water) were achieved. According to the DoE output, it was decided to use the ozone generator 500-B (with 500 mg/h ozone generation capacity) for the washing machine.
The prototype washing machine was prepared by placing the ozone decolorization system with the venturi inside the 9 kg capacity Beko washing machine. A suitable water tank is placed inside the machine, where the color removal will be done and the recycled water will be stored. Pumps are installed to divert colored and colorless waters. A filter was used to filter the particles such as fibers in the water. The working principle of the system is as follows: The ambient air drawn from the environment with the help of the air compressor is passed through the ozone generator, and ozone is produced and transferred to the venturi element. Colored water provided with the pumps and ozone meet in the venturi element, and after a certain period of circulation, colorless water is obtained by ozonation.
Starting from the difficulty of unknown dyestuff concentration in the colored water released from the laundry, different washing conditions were created to determine the initial dyestuff concentration range, the first rinse waters were collected and absorbance measurements were taken. The dyestuff concentrations were calculated by using the proposed equations. As a result of washing colored fabrics under different consumer conditions, it was determined that the wastewater dyestuff concentration varied between 15 mg/L and 90 mg/LOzonation tests in the washing machine were carried out in two stages. In the first stage, 14 L of synthetic dye solutions of 20 – 40 – 60 – 80 mg/L dyestuff concentration with detergent were prepared in the washing machine and ozonized. In the second stage, the first rinse water obtained from washing of commercially produced colored fabrics (1 kg) to represent the actual washing condition in a Beko 9 kg washing machine in the cotton 40 program with 52 g of standard detergent was collected and ozonated. Ozonation efficiency was calculated
as decolorization percentage from the decrease in absorbance measurements at 540 nm and at 592 nm for red solutions and for blue solutions, respectively. VIS spectra of each ozonation duration were compared. In addition, the water samples taken at the end of each ozonation period were visually compared and all the findings were evaluated together.
The decolorization rate in red and blue synthetic dye solutions was ~95% and above, it was determined that the color was completely removed visually. It was found that the color removal efficiency depends on the initial dye concentration and dyestuff type. As the dye concentration increased, the color removal duration increases. The color removal duration in solutions prepared with reactive red 195 dyestuff were longer than the solutions prepared with reactive blue dyestuff. It was determined that the pH values of the solutions decreased with the effect of ozonation, while the conductivity values did not change significantly.
The dye concentration of the first rinse wastewater obtained from the red and blue fabrics was determined as 35.1 mg/L and 42.3 mg/L, respectively, and around 80% color removal was achieved in the red and blue colored wastewater solutions. It was determined that the color removal was approximately three times faster for the blue wastewater solution than for the red wastewater solution. At the end of 240 minutes ozonation of red colored wastewater ~76% of the color was removed, whereas in blue colored wastewater ~82% color removal was achieved after 70 minutes. When the red and blue fabrics were washed together, the color of the wastewater solution was removed by ~70% at the end of 150 minutes. The removal of reactive red 195 dye (Reaktoset Red RFT) in red colored wastewater and reactive blue 19 dye (Reaktoset BRL Blue R Spec) in blue colored wastewater were confirmed both by spectrometric analysis and visual evaluation. It is thought that the differences such as molecular structure and molecular weight between the red dyestuff and the blue dyestuff affect the ozonation duration.FTIR analyzes were carried out in order to analyze whether the chromophore group of the dyestuff, which is the resource of the color, is degraded in wastewater by ozonation. The difficulty encountered here is that due to the very dilute solutions, information about the change of chemical bond vibrations cannot be obtained from the FTIR spectra. Thereupon, it was decided to freeze-dry the samples with the freeze-dry method found in the literature search and analyze them in solid state in the FTIR device. The problem caused by the dilute solution was solved by preparing synthetic dye solutions with a dye concentration of 100 mg/L without detergent. As a result of FTIR analyzes, it was determined that the N = N bond, which is seen around 1540 cm-1 in red solutions, was broken by the ozonation effect, thus the azo chromophore group was degraded. Similarly, it was determined that the bonds belonging to the anthraquinone ring, which represents the chromophore group, which was seen around 1575 cm-1 in blue solutions, were lost with the ozonation effect.
When the quality of the decolorized water was examined, it was determined that the ozonated water parameters were at a better level than the inlet water parameters. A significant decrease was achieved in the parameters of TSS, turbidity, COD (54% decrease) and TOC (35% decrease) with the effect of ozonation process. However, it was determined that there was no significant difference in total aerobic microorganism analysis between inlet water and ozonated water.
The recycled water in the prototype machine was used in the main washing step of the next cycle. No textile damage effect was observed in various textile samples washed with ozonated water for 10 cycles. Similarly, no significant difference was found between the washing performance values of the washes made with recycled water, so it was concluded that reused water did not have any side effects in terms of both textile damage and washing performance.
The energy consumption of the recommended ozone decolorization system for the washing machine is about one-fifth of the cotton 40 program and about two-thirds of the cotton 40 program to ozonize the water from the blue clothes and the red clothes, respectively.
It is estimated that the washing machines with the ozone decolorization system will save about one fourth of water consumed in cotton wash cycles. Considering the sales quantities, the water saving of approximately 14 L per cycle in washing machines with a capacity of 8-9-10 kg washing machine is expected to provide a water saving of approximately 1.24 hm3 in a year. Sustainable life can be supported by removing the color of the wastewater at its source, by recycling and reuse it in the washing machine. This is seen as an important opportunity for new generation washing machines to become the world's least water consuming products. It is expected that these environmentally friendly washing machines will be preferred by environment conscious users. The product being developed has the potential to be successful both commercially and environmentally, and is expected to be an essential and lasting product within sustainable products.