Identification and modelling of aerobic hydrolysis in activated sludge systems, application of optimal experimental

Atıksularda Kimyasal Oksijen İhtiyacı (KOİ) fraksiyonlarının ve bunlara ait giderim  kinetiğinin belirlenebilmesi aktif çamur tasarımı ve işletilmesi açısından büyük önem taşımaktadır. Özellikle, yavaş ayrışan organik maddenin atıksularda yüksek miktarlarda olduğu bilinmektedir. Genelde, ayrışabilen KOİ fraksiyonlarını hızlı ve yavaş ayrışan KOİ olarak sınıflandırmak mümkündür. Ancak, atıksuyun tipi ve özelliğine bağlı olarak bu fraksiyonlar değişkenlik gösterdiği gibi çözünmüş, partiküler veya çökelebilir formlarda bulunabilmektedir. Hidroliz prosesi aktif çamur tesislerinin işletilmesinde çıkış suyu kalitesinin, fazla çamur oluşumu, oksijen ihtiyacı ve nutrient giderimi açısından büyük rol oynamaktadır. Özellikle deri, tekstil vb. endüstriyel atıksularında olduğu gibi çok yüksek miktarda yavaş ayrışan çözünmüş formdaki organik maddeye ait biyolojik giderim atıksu arıtma tesisi çıkış suyu kalitesi açısından önem taşımaktadır. Bu çalışma kapsamında, kesikli yürütülen respirometrik   deneylerin kullanılması ile çoğalma ve hidroliz kinetiğine ait sistem tanımlanması yapılmıştır. Seçilen aktif çamur modeli çoğalma, hidroliz ve ölüm olmak üzere 3 proses ve 7 parametreden oluşmaktadır. Sistemin tanımlanması, teorik ve pratik sistem tanımlama adımlarını kapsamaktadır. Teorik sistem tanımlamada, Taylor Serileri ile lineerize edilen modelden respirometrik verileri kullanarak hangi parametre gruplarının elde edilebileceği bulunmuştur. Pratik sistem tanımlamada ise gerçek veriler kullanılarak, parametre tahminleri yapılmış ve güvenilirlik aralıkları belirlenmiştir. Optimal Deney Tasarımı simülasyonlarından, deneyin başlangıç F/M (Substrat/Mikroorganizma) oranının azaltılmasının deneyin güvenilirliğini arttıracağı ancak bunun yanında parametreler arasındaki korelasyonu  da arttıracağı kanıtlanmıştır. Anahtar Kelimeler: Modelleme, hidroliz, sistem tanımlama, oksijen tüketim hızı, Optimal Deney Tasarımı.Appropriate determination of accurate COD fractionation together with degradation kinetics of organic matter has a prime importance on the design and operation of activated sludge systems. In general, regarding the total biodegradable COD, raw domestic wastewaters approximately contain readily biodegradable and slowly biodegradable substrates at fractions around 30% and 70%, respectively. On the other hand, compared to domestic wastewaters, industrial wastewaters contain much higher fraction of slowly biodegradable substrate which directly influence the effluent quality of treatment plants. In this respect, the determination  of slowly biodegradable matter as well as its degradation characteristics are crucial in terms of wastewater treatment plant design and operation. Hydrolysis process has already been known as the rate limiting step in organic carbon removal from industrial and domestic wastewaters. Considering the effluent quality, hydrolysis mechanism also plays a dominant role in delicate balance of electron donor/electron acceptor ratios in biological nutrient removal type activated sludge systems as an important carbon source. In addition to that, sludge production from activated sludge plant is also affected by the nature of slowly biodegradable matter. In parallel to the vast developments in activated sludge modeling, respirometry has always been effectively utilized as a convenient tool for influent wastewater characterization which can be regarded as a corner stone of activated sludge modeling. To date, numerious respirometric tests have been applied for gathering information on the stoichiometry and kinetics of biodegradable substrates in raw wastewaters. However, the proposed methodologies were mostly devoted to the estimation of growth associated parameters such as maximum growth rate, active fraction of biomass, heterotrophic yield and half saturation growth constant for heterotrophs etc. In this study, surface-saturation type hydrolysis kinetics was investigated based on short-term oxygen uptake rate measurements. An identifiability study were performed in order to find out best identifiable parameter groups from respirometric data with the aid of non-linear degradation model. Basically, the model has been constitued using the reactions of (i) aerobic heterotrophic growth (ii) hydrolysis of particulate matter and (iii) endogenous decay processes. Basically, the model has 7 parameters to be estimated from a single respirogram. The model identification procedure comprises the theoretical and practical identifiability studies. In theoretical identifiability study, identifiable combinations of model parameter that can be extracted from available data is studied for a certain model. Non-linear model under study was linearized with the aid of Taylor Series Expansion method. By neglecting the growth of heterotrophs under low initial F/M ratio, 6 parameter combinations were found to be theoretically identifiable from batch respirogram. On the other hand, the maximum rates governing the growth (mH) and hydrolysis (kh) were found to be individually identifiable if considerable growth of heterotrophs are taking place during the course of the experiment. From the identifiability study, it was also found that all parameters combinations include the heterotrophic yield coefficient, YH. In addition, the parameter combinations containing hydrolysis parameters always include the initial active heterotrophic biomass, XH0 as a state variable. In practical identifiability, the identifiable parameter combinations of a selected model were estimated. In this study, the information of the experiments were simulated for different initial F/M (Food/Microorganism) ratio by comparing the amount of information as well as the correlation degree among the estimated parameters. The information contents of the experiments were evaluated on the basis of Optimal Experimental Design (OED) methodology. In this regard, the effects of initial conditions on information content of experiments was evaluated via comparing the scalar functions of Fisher Information Matrix (FIM). These scalar functions were selected as the D-Criterion and E- Criterion which summarize the information volume and the correlation degree among parameters, respectively. Finally, it was found that applying lower initial F/M ratio increases the information content of the experiment, on the other hand it also increases the correlation among the estimated parameters. Keywords: Modelling, hydrolysis, identifiability, oxygen uptake rate, optimal experimental design

The characterization and biological treatability of polyamid fibre based carpet finishing waste waters

Polyamid esaslı halı işlem ve üretiminden oluşan atıksuların biyolojik arıtılabilirliğini değerlendiren bu çalışma, farklı atıksu akımları ve kompozit çıkış suyunun detaylı karakterizasyonu, kinetik tanımlaması ve respirometrik modellemesini içermektedir. Günümüze kadar yapılan endüstriyel atık sudaki çalışmaların çoğunluğu tesis dışına akan maddeleri ve genellikle de boru sonu yaklaşımını üzerinedir. Atıksuyun ortalama KOİ’si 1675 mg/l olup 1450-1900 mgKOİ/l aralığında değişmekte olup biyolojik arıtılabilirlik çalışmalarında açık renk boyama atıksuları kullanılmıştır. Organik maddenin %80-90’ı çözünmüş olmasına karşın çok az bir kısmı biyolojik olarak kolay ayrışabilen ve hemen hemen tamamı yavaş ayrışabilir formdadır. Deney sonuçlarının değerlendirilmesinde respirometrik yöntem ve aerobik sistemdeki oksijen tüketim miktarı başlıca model parametresi olarak kullanılmıştır. Respirometrik değerlendirmeler çerçevesinde yavaş ayrışan fraksiyon en iyi şekilde ikili hidroliz mekanizması ile tanımlanmaktadır. Sürekli ve tam karışımlı aktif çamur sistemleri için dizayn uygulamaları, 10 günlük çamur yaşında pek yaygın olmayan 3 günlük uzun bir hidrolik bekletme süresini tanımlamaktadır. Anahtar Kelimeler: Polyamid elyaf, halı üretimi, biyolojik ayrışabilirlik, atıksu karakterizasyonu, yavaş ayrışabilir KOİ, modelleme.Textile industry uses natural and artificial fibres and produces fabric and other textile products which contain also carpet material. So far, the majority of studies on industrial wastewaters has been conducted on plant effluents and mostly reflects an end of pipe approach. The results in the literature mainly report to what extent wastewaters are biodegradable but contain little or no information on the nature of biologically resistant compounds or COD fractions. Industrial wastewaters include a waste array of chemicals used in different steps of the manufacturing process. The impact of these chemical can best be envisaged in different wastewater streams are evaluated in terms of their individual biodegradation characteristics. Respirometric methods and the use of oxygen uptake rate in aerobic systems as a major model parameter has been a major asset in the identification of COD fractions with different biodegradation rates and in model evaluation and calibration of experimental data. These methods are especially useful in cases individual specific pollutants are hard to identify. This paper evaluates biological treatability of wastewaters generated from polyamid based carpet processing and manufacturing. It involves detailed characterization, kinetic description and respirometric modelling of different wastewater streams and the composite effluent. The average COD of the wastewater is measured as 1675 mg/l, varying in the range of 1450-1900 mg/l. Light color dying wastewaters are utilized for biological treatability due to a higher dye content associated with this process. COD fractionation indicates a 80-90 % soluble COD fraction, almost totally slowly biodegradable with a very small readily biodegradable portion. A dual hydrolysis mechanism best describes the biodegradation of the slowly soluble fraction, based on respirometric evaluations. Experimental results have been tested by a multi-component mathematical model using the endogenous decay approach and hydrolysis constants corre­sponding to the slowly biodegradable COD fractions have been evaluated using curve fitting. The very low rate coefficients characterizing the hydrolysis of the large part of the soluble COD bring interesting difficul­ties in the design of biological treatment systems. Design applications for continuous-flow activated sludge systems identify an unusually long hydraulic retention time of 3 days at a sludge age of 10 days. Respirometric analysis of the main wastewater streams provided in dept information on the biodegradation characteristics, which could be translated into the composite plant effluent and confirmed by appropriate COD mass balance. The evaluation showed that acrylic and polyamid carpet finishing wastewater was quite different from domestic sewage and other textile effluents in terms of COD fractionation and biodegradation. It could be characterized by dual hydrolysis of soluble and particulate COD components occurring at much slower rates compared to other wastewaters. The hydrolysis rate of the particulate COD was almost comparable to endogenous decay. Furthermore, in biological treatability studies, respirometry based modeling showed that the acclimated biomass exhibited similar biological response to individual wastewaters originated from each process step compared to composite sample characterizing the overall process scheme of acrylic and polyamid carpet production. On the other hand, simulation results on performance prediction and overall treatability indicate that slow hydrolysis of the major fraction of soluble COD, although rate limiting, does not pose a significant problem for effluent quality. Keywords: Polyamid fibre, carpet manufacturing, biological treatability, wastewater characterization,  slowly biodegradable COD, modelling

Evaluation of aerobic stabilization of biological treatment sludges

Ülkemizde uygulanan çevre mevzuatı gerekleri, atıksu arıtma tesislerinde oluşan çamurun arıtımını ve nihai uzaklaştırılmasını zorunlu kılmaktadır. Evsel ve endüstriyel atıksu arıtma tesislerinden kaynaklanan arıtma çamurları üzerinde yapılan analizler sonucu, bu çamurların özellikle toplam ve çözünmüş organik karbon değerlerinin yönetmelikteki değerleri sağlamadığı ve çamurların bu parametreler bakımından tehlikeli atık sınıfında değerlendirmesi gerektiğini ortaya koymaktadır. Bu çalışma kapsamında Marmara Bölgesi’nde yer alan çeşitli evsel ve endüstriyel arıtma tesisinden kaynaklanan çamurların organik madde içerikleri değerlendirilmiş ve bu çamurların stabil hale getirilmesi için aerobik stabilizasyon işlemi uygulanmıştır. Aerobik stabilizasyon reaktörlerinde, 15 gün süreyle organik madde içeriklerinin değişimi UAKM, TOK ve ÇOK parametreleri esas alınarak ve evsel çamur numuneleri için zehirlilik parametresi de dikkate alınarak incelenmiştir. Elde edilen sonuçlara göre aerobik stabilizasyon sonunda genel olarak TOK değerleri azalırken, ÇOK değerlerinde çamur numunelerine bağlı olarak artış ya da azalmalar gözlenmiştir. İncelenen evsel çamurların ikisinde de TOK konsantrasyonu %50’den daha fazla azalırken ÇOK değerlerinde artış tespit edilmiştir. Endüstriyel atıksu arıtma çamurları arasında en yüksek TOK giderimi %62 ile Nevresim Endüstrisi çamurunda gözlenmiş olup, bu endüstri ÇOK giderimde de en yüksek verimi sağlamıştır. Elde edilen bu sonuçlar ışığında, aerobik stabilizasyon işleminin uygulanma aşamasından önce her tesis için ayrıca değerlendirme yapılması gerekliliğini ortaya koymuştur. Her çamur örneği için standartların sağlanması aerobik stabilizasyon ile mümkün olamamasına rağmen, bu işlemin bazı organik maddelerin giderilmesini sağladığı aerobik stabilizasyon sonrasında evsel numunelerdeki zehirliliğin tamamen giderilmesi ile ortaya konmuştur. Anahtar Kelimeler: Çamur, stabilizasyon, aerobik, evsel- endüstriyel-tehlikeli atık.The main waste-product of the biological wastewater treatment processes is the excess sludge which needs to be disposed properly to prevent the entry of the pollutants back into the water cycle, especially after the disposal of the wasted sludge cakes into the landfill area. During the adaptation period of European Union membership of Turkey, the increase in the number of both municipal and industrial Wastewater Treatment Plant (WWTP) due to the stringent new regulations for wastewater treatment will pose more significant sludge disposal and sanitation problems in the future for Turkey. Treatment and ultimate disposal of domestic and industrial wastewater treatment plant sludges is obligated according to the regulations in Turkey. Treatment sludges categorized in three different groups namely: inert sludge, non-hazardous sludge and hazardous sludge according to the characteristics of the sludge. The total organic carbon (TOC) concentration of the sludge itself and dissolved organic carbon (DOC) concentration in the eluent of the sludge are mainly used for this classification. The higher levels of TOC and DOC values qualifies the domestic and industrial wastewater treatment sludges as hazardous sludge. The principal objective of sludge treatment is its stabilization, that is a controlled decomposition of easily degradable organic matter resulting in a significant reduction of volatile suspended solids (VSS) content, a change of an unpleasant smell into an earthy one, and an elimination of sludge putrescibility. Aerobic biological stabilization at ambient conditions has traditionally been undertaken for the stabilization of treatment sludges originated from both domestic and industrial wastewater treatment plants. In this study the characterization of the different treatment sludges originated from domestic and industrial wastewater treatment plants in Turkey was investigated and the stabilization level of these sludges was evaluated by using aerobic stabilization process. The stabilization level of sludges was evaluated by monitoring the VSS, TOC and DOC content of the sludge. Moreover, ecotoxicological assays were conducted on domestic wastewater treatment plant sludges to observe the effect of stabilization on the toxicity. Respirometric and modeling studies were also performed to assess the decrease in the organic content of the domestic wastewater treatment plant sludge during aerobic stabilization. The results of analysis conducted on the sludge itself and sludge eluent indicated that the sludges are in hazardous nature. These results suggest that the treatment sludge generated from both domestic and industrial treatment plants have to stabilized before ultimate disposal. During the course of the aerobic stabilization experiments, VSS, TOC and DOC measurements were performed at the beginning and 15 days after the beginning (at the end of the stabilization experiment) in order to monitor the extent of VSS, TOC and DOC removal. Measured TOC and DOC concentrations during the stabilization experiments of studied treatment sludges did not show a consistent trend during the 15 days of stabilization. However, the stabilization of the industrial wastewater treatment plants sludges showed a paralel stabilization to the domestic sludge. However, it is important to conduct laboratory studies prior to the application of aerobic stabilization to a treatment plant on the case basis. The acute toxicity as EC20 (%) and EC50 (%) shows the toxic value in terms of effective concentrations (%) of tested solutions that result in 20 and 50% of bioluminescence decrease. The EC20 and EC50 values were found between 0.3 and 7.3% for the studied raw domestic sludges which is in accordance with the literature data. Significant decrease in the toxicity of domestic wastewater treatment plant sludges were observed at the end of the 15 days of aerobic stabilization. The evaluation of the results obtained in this study showed that aerobic stabilization could be an alternative for stabilization of sludges originated from domestic and industrial wastewater treatment plants. However, the organic content of the sludges mainly depend on the influent wastewater characterization of wastewater treatment plant which affects the stabilization performance. Sludge stabilization results indicate higher VSS, TOC and DOC removal efficiencies for domestic wastewaters compared to the industrial sludges. Although aerobic stabilization was not successful for the compliance with the standards in each case, the removal of toxicity exerted by sludges after 15 day-stabilization suggest that at least some toxic organic material has been succesfully biodegraded during the stabilization. In order to provide appropriate municipal and industrial sludge management in Turkey, more elaborate research and engineering experience should be gained. Keywords: Sludge, stabilization, aerobic, domestic- industrial-hazardous waste

Model based process optimization of enhanced wastewater treatment plants

Avrupa Birliği’ne uyum sürecinde ele alınan atık sorunu kapsamında, alıcı ortamlara yapılacak deşarjlarda konvansiyonal parametrelerin yanısıra azot ve fosfor (besi maddesi) parametrelerinin de belli standart değerlerin altına indirilmesi gerekli hale gelmiştir. Bu nedenle, “Kentsel Atıksu Arıtımı Yönetmeliği, 2006” ile uyum sürecinde olan ülkemizde azot ve fosfor standartları mevzuatımıza dâhil edilmiştir. “Kentsel Atıksu Arıtımı Yönetmeliği, 2006” kapsamında mevcut tesislerin besi maddesi giderimine yönelik olarak geliştirilmesi, yeni kurulacak tesislerin ise besi maddesi giderecek şekilde en uygun arıtma teknolojisi kavramı çerçevesinde boyutlandırılması gereklidir. Besi maddesi giderimine yönelik en uygun arıtma teknolojisi biyolojik prosesler, bunlar arasında en ekonomik çözüm ise aktif çamur sistemleri olarak tanımlanmaktadır. Bu çalışma aktif çamur tesislerinin, Avrupa Birliği normlarında performansını sağlayabilecek optimum tasarım ve işletme süreçlerinin değerlendirilmesini amaçlamaktadır. Bu kapsamda, bir örnek olarak ele alınan İstanbul Su ve Kanalizasyon İdaresi (İSKİ) Paşaköy İleri Biyolojik Atıksu Arıtma Tesisi’nde mevcut durumda atıksu karakterizasyonu ve sistem performansı deneysel olarak belirlenmiş, elde edilen bilgiler kullanılarak sürekli kullanıma uygun olacak model-bazlı tasarım ile işletme simülasyon programları hazırlanmış ve işletme optimizasyonu çerçevesinde çıkış besi maddesi konsantrasyonlarının düşürülmesi amacıyla işletme senaryoları oluşturularak önerilerde bulunulmuştur. Yürütülen senaryo analizleri ile, havalandırma tanklarındaki çözünmüş oksijen seviyelerinin uygun ayarlanması, tesisin geri devir denitrifikasyonu prensibi yerine A2O veya UCT tipi sistem şeklinde işletilmesi ile sistem veriminin arttırılabileceği ve dolayısıyla çıkış besi maddesi konsantrasyonlarının azaltılabileceği belirlenmiştir. Anahtar Kelimeler: İleri biyolojik atıksu arıtma tesisi, atıksu karakterizasyonu, model-bazlı tasarım, işletme optimizasyonu.The Urban Wastewater Treatment Directive published in the Official Gazette No. 26047 of 08.01.2006 was adapted from the “The Council Directive (91/271/EEC)” concerning urban waste-water treatment was accepted in European Union Countries, which imposes enforcements about the collection and treatment of wastewater. This directive requires that also nitrogen and phosphorus (nutrients) to be removed together with the conventional parameters. In this context, it is very important to follow and apply the technological advances while the harmonization of legislations in Turkey with European Union Standards. Mathematical models are frequently used for the design and optimum operation of wastewater treatment systems. In order to use the activated sludge models for the process design and control, it is crucial to understand the behavior of complex biological reactions under steady and dynamic conditions. The initial step for the use of models should be, a model calibration according to the data obtained from the treatment plant and an analysis of the behavior of the treatment plant under dynamic influent and environmental conditions (Vanrolleghem et al., 2003). After the calibration of the prepared model according to the operational conditions of the treatment plant, the model can be used for the optimization of the plant, meeting the effluent quality standards, minimizing operational costs and for developing appropriate process control strategies. On the other hand the effect of changes in the process conditions on the model stability should be taken into consideration (Insel et al., 2007). The aim of this study was to evaluate the optimum design and operational criteria of advanced biological wastewater treatment plants by applying international monitoring and evaluation mechanisms that will increase the performance to norms required in the European Union. Accordingly, İSKİ Paşaköy Advanced Biological Wastewater Treatment Plant (ABWWTP) was chosen as a model plant and in the first stage on influent wastewater characterization, chemical oxygen demand (COD) fractionation and performance of the activated sludge system were experimentally determined. In the second stage, using the dimensions of the İSKİ Paşaköy ABWWTP units and the experimentally determined operational parameters, model calibration studies were conducted. On this context, theoretical parameters of model-based design and operational simulation programs applied for the plant were evaluated. In the last stage of the study, for operational optimization, according to the results obtained from the experimental and simulation studies conducted at İSKİ Paşaköy ABWWTP, operational scenarios were developed and suggestions were made. In the scenario analysis reduction of effluent phosphorus and total nitrogen concentration was aimed and the effect of (i) the aeration system control, (ii) recycle denitrification (iii) influent VFA concentration was analyzed and the effect of (iv) different system configurations was evaluated. The results of statistical data analysis of wastewater characterization studies conducted at İSKİ Paşaköy Advanced Biological Wastewater Treatment Plant aiming nitrogen and phosphorus removal revealed that due to low influent Chemical Oxygen Demand (COD), Total Kjeldahl Nitrogen (TKN), Total Phosphorus (TP) and Volatile Fatty Acids (VFA) concentrations, high efficiencies of biological phosphorus removal was not achievable. According to the scenario analysis performed for the treatment plant it has been concluded that it is possible to increase the removal efficiency of the system and achieve lower effluent total nitrogen and phosphorus concentrations by setting the dissolved oxygen levels to appropriate levels and operating the systems as an A2O or a UCT type system instead of a recycle denitrification system. It has been concluded that if the scenario analyses were applied it is not possible to meet the European Union Effluent Quality Standard of 1.0 mg/l for the phosphorus parameter. Experimental and model based studies have to be conducted for the installation of a fermentation process together with different system configurations that are required to meet the effluent quality standard by biological treatment. Keywords: Paşaköy wastewater treatment plant, wastewater characterization, model based optimization, process control

Biological treatability and modelling of denim process wastewater

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 1997Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 1997Evsel ve endüstriyel atıksular için tasarlanan biyolojik arıtma sistemleri gün geçtikçe yaygınlaşmaktadır. Biyolojik arıtma dizaynında sistemin seçimi, ilk yatıran maliyeti, projelendirme ve işletmede büyük önem taşımaktadır. Son zamanlarda yürütülen çalışmalarda aktif çamurun davranışı çok bileşenli modeller yardımıyla açıklanmaktadır. Bu çalışmada jean (kot pantolon) yıkama yapan bir tesis sırasıyla atıksu karakterizasyonu, biyolojik arıtılabilirlik ve modelleme çalışmaları kapsamında incelenmiştir. Birinci bölümde çalışmanın önemi, amaç ve kapsamı belirtilmiştir. İkinci bölümde Türkiye' de ve yurt dışında tekstil endüstrisi altkategorileri belirtilmiş ve bu alt kategorilerin atıksu kaynaklan ve genel atıksu karakterizasyonu verilmiştir. Üçüncü bölümde incelenen tesisin özellikleri ve atıksu kaynaklan incelenmiş ve tesis ile ilgili detaylı bilgiler verilmiştir. Dördüncü bölümde arıtılabilirlik bazlı atıksu karakterizasyonu, KOİ bileşenleri ve model yaklaşımının yanında proses-kinetiği de açıklanmıştır. Beşinci bölümde incelenen atıksuyun KOİ bileşenleri ve model parametrelerinin belirlenmesine yönelik yöntemler açıklanmıştır. Altıncı bölümde uygulanacak deneysel yaklaşım ve deneysel program ele alınmış ve kullanılacak düzenek açıklanmıştır. Yedinci bölümde, ilk olarak tekil ve kompozit atıksu karakterizasyonu incelenmiştir. Çalışmanın ikinci aşamasında KOI bileşenlerinin yanında modelleme çalışması ile kinetik ve stokiometrik katsayılar saptanmıştır. Sekizinci bölümde, sonuç ve öneriler sunulmuştur.Textile industry has a great importance for both industrialized and developing countries. Due to the complexity of its nature and the large variety of chemicals used in different operations, it is difficult to define a typical wastewater. Therefore, pollution based subcategorization plays an important role in pollution prevention activities concerning the textile mills. In the first part of the study, subcategorization approaches have been compared with each other and the variability of textile industry subcategories were evaluated in terms of wastewater generation and characterization. In the second part of the study, three different wastewaters originating from Denim Processing (Stone Wash) - a branch of textile industry - were evaluated with respect to the wastewater flowrate, wastewater characteristics and biological treatability. In the characterization study, experiments were "conducted on the grab samples whereas treatability studies were performed on composit samples obtained from the industry. Within the scope of the study, kinetic and stoichiometric parameters (Ph, bn, Yh) and COD fractions ( involving soluble and particulate biodegredable, Ss, Sh, Xs soluble and particulate non-biodegredable Si, Xr forms) were determined by applying lab- scale experiments to the composit wastewater samples taken from three different types of denim processes. Investigated processes have different water usages and chemical consumptions. The detailed process profiles are given in the third section. From a modelling point of view, stoichiometric parameters such as half saturation constant Ks, half saturation hydrolysis rate Kx, maximum hydrolysis coefficient, k^ which cannot be estimated by experimental procedures, were assessed by curve fitting on Oxygen Utilization Rate (OUR) profiles. Results obtained from the experiments and modelling studies are given below.. Determination of Readily Biodegredable COD, SSo The method of determination of readily biodegredable substrate (Sso) depends upon the observation of OUR profile. OUR profile may be experimentally managed to stay approximately constant during the consumption of Ss and drops to a second plateau when Ss is completely depleted. The readily biodegredable substrate concentration can be calculated from the area under the OUR curve. From the figure 1, AOi reflects the utilization rate when the maximum growth rate is sustained. The readily biodegredable substrate, Ss can be calculated from the equation, xu Sso = AOl (Vml + Vw) 1-Yh where AOi : mass of oxygen consumed by Ss Vw: volume of wastewater in the mixture (L3) Vmi: volume of mixed liquor in the mixture (L3) I I I I I I Time (minute) Figure 1 Determination of Ss with OUR profile. Determination of the endogenous respiration rate, bH The method of determining bH depends upon digesting the biomass in an aerated batch reactor and measuring OUR values, periodically. After plotting the change of OUR values with time, Dh can be calculated from the slope (Figure 2). In OUR = In [ 1.42 (I-^.Dh.Xh ] - ba-t a J3 Figure 2 Determination of bn. Determination of maximum specific growth rate, pH The maximum specific growth rate, fb can be determined by means of respirometric measurements at an appropriate F/M ratio. The method which is developed by KAPPELER and GUJER (1992), relies on seeding wastewater with a small amount of xm biomass in an aerobic reactor. From the linearized form of the expression, Ph-dh can be determined as,, OUR,, x lnOUR7=(pH-bH)t The OUR profile that belongs to Plant 1 is given in Figure 3. I 100 200 Time(miimte) 300 Figure 3 Determination of Ph-dh. The Heterotrophic Yield Coefficient, YH During the OUR assesment of the readily biodegredable substrate determination, soluble COD analysis were performed on filtrate samples. It is assumed that electron acceptor consumption was conducted on readily biodegredable substrate. In this way, YH is calculated with the use of following expression, Yh = 1- AO1 + AO2 ACOD(sol.) H h 20 40 60 Time(nsnute) Figure 4 Determination of Yh xiv . Determination of Soluble Inert COD, Si The soluble inert COD,Si is determined by the procedure proposed by GERMÎRLÎ et al,(1991). The method depends on the measurement of soluble COD of two aerobic reactors (glucose and wastewater reactor) seeded with the same amount of biomass acclimated to the glucose and wastewater mixture. After observing the soluble COD, the values reach to a plateau after a period of time. The soluble inert fraction can be calculated from the difference between the COD values of the wastewater and glucose reactors at plateau period (Figure 4). Filtrate A - Glucose Figure 5 Determination of soluble inert COD, Si. Determination of Slowly Biodegredable COD Fractions, Sho» Xso Slowly biodegredable organic fractions, Sho, Xso of total COD are determined from mass balance. This fraction can be calculated from, and Cso - Sso + Xso Sto = Sso + Sio + Sho where Cso : Total COD (mg/1) Sto : Total Soluble COD (mg/1) Sho : Rapidly Hydrolyzable COD (mg/1) Xso : Slowly Hydrolyzable COD (mg/1) Sio : Soluble Inert COD (mg/1) In the modelling approach, slowly biodegredable COD is not differentiated as rapidly and slowly biodegredable COD fractions. Stoichiometric parameters such as Ks, Kx, kj, are determined by curve fitting. Results of characterization of wastewater originated from 3 different stone wash processes are given in Table 1 and Table 2. The COD fractionation, kinetic and stoichiometric coefficients of these 3 processes are shown in Table 3 and Table 4. xv 00. «si S" °5 "Sı ü g» S VO O O o «o en o 3 f O. fî ı-ff 0* 8 4, 3.31 oo i en ov en Ov en en vo en es en es O.o vo O OV XVI Table 3 COD fractions of Wastewaters * assumed * assumed For the purpose of comparison it is necessary to mention about the domestic wastewaters. Range of kinetic and stoichiometric coefficient associated with domestic wastewaters are as follows, maximum specific growth rate pa, 2.7-6.5/day, half saturation constant Ks, 2.5-30 mg/1, half saturation hydrolysis constant Kx, 0.01-0.8 mgCOD/mgCOD, hydrolysis rate constant kh, 1-5/day. The kinetic and stoichiometric coefficients assessed in this study for denim processing wastewaters, are in accordance with the above mentioned coefficients obtained from domestic wastewaters. xvu BÖLÜM I GİRİŞ 1.1 ÇALIŞMANIN ANLAM VE ÖNEMİ Sanayi devriminden günümüze gelene kadar, endüstri dallarının hızla gelişmesi sonucu çevre kirliliği büyük boyutlara ulaşmıştır. Ülkelerin, çevre bilincinden yoksun kalkınma çabalan ve plansız endüstriyel yapılanma geri dönülmesi mümkün olmayan sonuçlar ortaya çıkarmaktadır, özellikle sanayi: bölgelerinden kaynaklanan suların toplanarak arıtılmadan su ortamına verilmesi ekolojik dengeyi bozmaktadır. Ülkemizde de endüstrilerin denetimsiz ve düzensiz faaliyet göstermeleri su kaynaklarımızı gün geçtikçe kullanılmaz hale getirmektedir. Ancak, son zamanlarda, çevre bilincinin kazanılmaya başlaması ve bununla ilgili yapılan çalışmalar, kirlenmiş su kaynaklanmızm iyileştirilmesine yönelik olumlu bir adımdır. Su kaynaklarının kirlenmesini engellemek için, evsel ve endüstriyel auksu arıtım sistemlerinin doğru olarak tasarlanması ve işletilmesi gerekmektedir. Tekstil endüstrisi teknik gelişmeleri ve iş imkanları yönünden Türkiye ekonomisinde önemli bir yer tutmaktadır. Ayrıca tekstil endüstrisi toplam endüstriyel üretimin %13 ünü oluşturmaktadır. Teknolojinin gelişmesiyle tekstil endüstrisinde su kullanımı ve aüksu karakterinin değişimi kaçınılmazdır. Bu değişime paralel olarak uygun arıtma alternatiflerinin belirlenmesinde, endüstri tanımının yanında auksu özelliklerinin bilinmesi büyük önem taşır. Eskiden beri uygulanan ampirik esaslı tasarım, biyolojik arıtma tesisinin yetersiz olması veya gerektiğinden büyük boyutlandırma durumuna neden olmaktaydı. Uygulanan bu amprik yaklaşımlar, günümüzde yerini, aktif çamurun karakterini belirten ve yüksekYüksek LisansM.Sc

Pollutant footprint analysis for wastewater management in textile dye houses processing different fabrics

BACKGROUND: This study investigated the water and pollution footprints of a dye house, which processed cotton knits, polyester (PES) knits and PES-viscose woven fabrics. Experimental evaluation was carried out for each processing sequence. Variations in wastewater flow and quality were established as a function of the production program in the plant. A model evaluation of wastewater dynamics was performed and defined specifications of an appropriate treatment scheme. RESULTS: The plant was operated with a capacity of 4300 t year−1 of fabric, which generated a wastewater flow of 403 500m3 year−1 and a COD load of 675 t year−1. The overall wastewater footprint of the plant was computed as 91m3 t−1 and the COD footprint as 160 kg t−1 of fabric. Depending on the fabric type, results indicated expected changes in wastewater flow between 600 and 1750m3 day−1 in COD load between 1470 and 2260 kg day−1 and in COD concentration between 1290 and 3400mgL−1. CONCLUSION: A model simulation structured upon COD fractionation and related process kinetics revealed partial removal of slowly biodegradable COD, coupled with high residual COD, which would by-pass treatment. Resulting biodegradation characteristics necessitated an extended aeration system, which could also enable partial breakdown of residual COD. Effluent COD could be reduced to 220–320mgL−1 with this wastewater management strategy. © 2018 Society of Chemical Industr

Optimization of nitrogen removal for alternating intermittent aeration-type activated sludge system: A new process modification

A new activated sludge process modification was proposed for intermittent aeration process to achieve more stable nitrogen removal performance. A single completely mixed reactor was divided into two compartments in series and operated in intermittent aeration mode by using activated sludge simulation model. The new configuration provided competetive advantage on nitrification as well as denitrification capacity, compared to the intermittently aerated system with a single reactor. In addition, the dissolved oxygen set-point control during air-on periods was found to be an important parameter in terms of nitrogen removal

Biodegradation kinetics of the soluble slowly biodegradable substrate in polyamide carpet finishing wastewater

BACKGROUND: Carpet manufacturing and finishing with purely synthetic fibers has received relatively little attention, compared to other textile processing types. This study evaluates the biodegradation kinetics of organic compounds generated from polyamide-based carpet manufacturing. RESULTS: Experiments were conducted on pre-washing and dyeing/softening wastewater effluents. Model evaluation of oxygen uptake rate profiles with dual hydrolysis kinetics revealed that the soluble slowly hydrolysable chemical oxygen demand (COD) was the major fraction, constituting nearly 97% of the biodegradable COD and 78% of total COD content. Degradation of the slowly hydrolysable COD fraction was characterized with a rate coefficient of 0.72 day(-1), a significant rate limiting step for substrate utilization. Model simulation of system performance indicated that an unusually long hydraulic retention time was required for an activated sludge system to reduce the effluent COD concentration. CONCLUSION: Compared to domestic wastewater, two additional hydrolysable COD fractions with different degradation kinetics were characterized. The dyeing and softening step had the highest slowly biodegradable organic matter content, with the lowest degradation rate. Simulation results showed that soluble slowly hydrolysable COD degradation did not cause any problem in terms of effluent quality. With the system operated under reduced solids retention time, the effluent COD quality was significantly influenced by the slow hydrolysis rate of soluble hydrolysable matter. (c) 2007 Society of Chemical Industry

Acute effect of benzo[a]anthracene on the biodegradation of peptone under aerobic conditions

This study investigated the acute effect of benzo[a]anthracene, a significant compound among polycyclic aromatic hydrocarbons, on the biodegradation of a synthetic organic substrate-a peptone/meat extract mixture-under aerobic conditions