Optimization of ozonation within biological treatment for a tannery wastewater

Bu çalışmada, biyolojik arıtma sırasında ozon ile kimyasal oksidasyon prosesi için optimum ozonlama noktasının belirlenmesi araştırılmıştır. OTH profillerinin elde edilmesine dayalı respirometrik ölçümler yardımıyla - çalışmaya konu edilen fiziko-kimyasal ön arıtmaya tabi tutulmuş - deri endüstrisi atıksuyu numunesindeki (A Numunesi’ndeki) KOİ bileşenleri belirlenmiştir. Respirometrik analizler aracılığıyla biyolojik arıtma sırasındaki reaksiyon sürelerine bağlı olarak B, C ve D numuneleri tanımlanmıştır. Ozonlama deneyleri başlangıç anı (A Numunesi), kolay ayrışabilen KOİ bileşeninin tümüyle giderildiği an (B Numunesi), başlangıçtaki yavaş ayrışan çözünmüş KOİ bileşeninin yarı yarıya giderildiği an (C Numunesi), geriye sadece çözünmüş inert KOİ bileşeninin kaldığı an (D Numunesi) için yürütülmüştür. Ozonlama deneyleri sonucunda, farklı oksidasyon ürünlerinin oluşumuna bağlı olarak değişik arıtma verimleri elde edilmiştir. Kolay ayrışabilir nitelikli organik maddenin biyolojik arıtmada giderilmesinin ardından ozonlama prosesinin (ara ozonlama prosesinin) uygulanması, tüm numuneler içerisinde mg/l cinsinden KOİ giderimi bazında en iyi sonuçları vermiştir. Ön ve son ozonlama prosesleriyle karşılaştırıldığında; kolay ayrışabilir nitelikli organik maddenin biyolojik arıtmada giderilmesinin ardından 40 mg/dak’lık optimum ozon akısında uygulanan ozonlama prosesi, biyolojik arıtmaya söz konusu prosesin entegrasyonu açısından en uygun seçenek olarak belirmiştir. KOİ fraksiyonları arasındaki dönüşüm mekanizmalarından hangisinin baskın olduğunu daha iyi algılayabilmek için ozon ile kimyasal oksidasyon prosesine tabi tutulmuş numunelerde respirometrik analizlerin de yapılması önerilmektedir. Anahtar Kelimeler: Biyolojik arıtma, deri endüstrisi atıksuyu, KOİ fraksiyonasyonu, ozonlama, respirometrik ölçümler.Industrial wastewaters contain various organic compounds each in a different oxidation state. Due to this varying organic content, every industrial effluent has a unique fingerprint in terms of COD fractions. Biological processes are usually prescribed for treating the industrial effluents with considerably high COD content, mainly composed of soluble biodegradable fraction, as they have economic advantages over chemical oxidation. Some industrial effluents, i.e. tannery wastewaters on the other hand, may contain considerable amounts of biorefractory organics; so that applying biological treatment alone may not yield adequate COD removal efficiencies to meet the discharge standards. Such cases necessitate the usage of an advanced chemical oxidation method i.e. ozonation along with biological treatment. In a combined biological and ozone treatment, pre-ozonation is executed to enhance the biodegradability by producing more oxidized and soluble organic compounds. Post-ozonation, alternatively, is used as a complementary treatment step to achieve additional reductions in terms of organic matter and to provide a polishing effect on the biological treatment effluent. Ozone can also be applied within biotreatment as an in-mid treatment step where easily biodegradable COD can be removed by the first biological treatment and the inert COD is converted to biodegradable forms by the following ozonation process to ease the further biological treatment. In a combined treatment scheme comprising biological treatment and chemical oxidation with ozone, the assessment of the optimum location of ozonation depends on the treatment efficiency, appropriateness and economical feasibility analysis of the integrated system. Thus, the objective of this study is to investigate the suitability of ozone application before / within / after biological treatment. In this framework, a chemically settled tannery effluent characterized by a large amount of organic matter with different biodegradability is selected as a strong wastewater that requires an additional treatment step before /within / after biological oxidation. The investigated sample taken from the tannery wastewater treatment plant located in Rehau, Germany, is subjected to ozonation experiments in order to choose the optimal treatment scheme for ozonation within biological treatment. Conventional characterization performed on the chemical settling effluent reflects a strong wastewater character with a total COD content of 2020 mg/l, almost entirely soluble in nature. Respirometric evaluation of chemically pre-treated wastewater sample indicates that 46% of the total COD is rapidly hydrolysable COD. The slowly hydrolysable COD component amounts only to 3% of the total COD since the chemical treatment almost completely removes the particulate organic matter. Consequently, the total COD includes a total biodegradable COD fraction of 81%, while the remaining 19% is classified as initial inert COD portion which only composes of soluble compounds. The required reaction periods to obtain different COD fractions are also determined from OUR profiles. After respirometric measurements, the chemical settling effluent (Sample A) and the biologically treated wastewater (Sample D, containing only soluble inert COD portion as the remaining soluble fraction) are subjected to ozonation experiments. Ozonation is also conducted on two different phases in biological treatment; namely in a phase where the readily biodegradable COD is completely depleted (Sample B), and in another point where the rapidly hydrolysable COD is at half of its initial concentration (Sample C). In order to obtain the samples of B, C and D, a lab-scale fill and draw reactor operated at an F/M ratio of 0.2 g COD / g VSS, fed with Sample A, is used. During the course of ozonation studies, the sequence of biological treatment and ozonation depicts different COD removal efficiencies, as the performance of ozonation step is strongly dependent on the extent of biological oxidation. A value of 40 mg O3/min is determined as the optimum ozone flow-rate because the total COD reduction of biologically pre-treated samples cannot be significantly improved beyond that level. Total COD abatement rate constants of biologically pre-treated samples are by far bigger than those obtained for pre-ozonation process. Compared to pre- and post-ozonation processes, the best integrated process is the application of ozone at a stage of biological treatment where readily biodegradable substrate is entirely consumed; as this treatment scheme leads to the highest decreases in COD concentrations among other integration alternatives. Respirometric evaluation of the ozonated wastewater samples is recommended to highlight the conversions between COD components. Keywords: Biological treatment, tannery wastewater, COD fractionation, ozonation, respirometry

Ozonation application in activated sludge systems for a textile mill effluent

The study investigates the effect of partial ozonation of textile wastewater, both at the inlet (pre-ozonation) and the outlet (post-ozonation) of biological treatment, for the optimization of COD and color removals, both typical polluting parameters associated with the textile industry. Pre-ozonation provides at optimum contact time of 15 minutes 85% color removal, but only 19% COD reduction. Removal of the soluble inert COD fraction remains at 7%, indicating selective preference of ozone for simpler compounds. Post-ozonation is much more effective on the breakdown of refractory organic compounds and on color removal efficiency. Ozonation after biological treatment results in almost complete color removal and a 14% soluble inert COD reduction. The polishing effect of post-ozonation also proves quite attractive from an economical standpoint, involving approximately 50% of the ozone utilization at the same ozone flux rate and contact time, yet providing a lower soluble residual COD level

Wastewater reuse for the minimization of fresh water demand in coastal areas—selected cases from the textile finishing ındustry

Availability of water to the industry often becomes prohibitive, both in terms of quality and cost, in coastal areas. This study takes the textile industry and evaluates the prerequisites of water recovery and reuse. In this context, a large spectrum are studied for their water, the general quality of wastewater generated, quality and treatability of reuse wastewater streams, and expected changes in the overall effluent quality after segregation of the recovery wastewater portion

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

In plant control applications and their effect on treatability of a textile mill wastewater

Water minimization and exploration of the potential for wastewater recovery and reuse are priority issues of industrial wastewater management. They are extremely significant for the textile industry commonly characterized with a high water demand. The study presents a detailed in-plant control survey for a wool finishing plant. A comprehensive process profile and wastewater characterization indicate that process water consumption can be reduced by 34%, and 23% of the wastewater volume can be recovered for reuse. Treatability of reusable wastewater fraction and the effect of in-plant control applications on effluent treatability were also investigated

Effect of chemical treatment on soluble residual COD in textile wastewaters

The effect of chemical treatment on the magnitude of soluble residual COD in the biological treatment effluent is investigated for knit fabric finishing wastewater. Bentonite is selected for its potential to remove soluble COD together with color and particulate components. Chemical treatment using bentonite, when applied prior to biological treatment removes around 40% of the biodegradable as well as soluble inert COD initially present in the wastewater. As a chemical post-treatment, it acts as a polishing step, removing particulate matter and a minor portion of around 20% of the remaining soluble COD. These findings suggest chemical pre-treatment as a better alternative for the optimization of soluble COD removal

Investigation of chemical treatment processes effect on the size distribution of olive oil mill wastewater

Bu deneysel çalışmada bir zeytinyağı karasuyu örneği (KOİ: 155000 mg/L; TOK: 40000; Toplam fenol (T-Fenol): 4100 mg/L) kimyasal arıtma yöntemlerinden çöktürme, koagülasyon, elektrokoagülasyon ve Fenton prosesi ile arıtmaya tabi tutulduktan sonra içeriğinde meydana gelen değişim, dane boyut dağılımı (DBD) analizi uygulanarak incelenmiştir. Bu kapsamda ham ve arıtılmış karasu örnekleri filtrasyon/ultrafiltrasyon temelli fiziksel ayırma prosedürü kullanılarak 1600, 450, 220, 13, 8, 5, 3, 2 ve 1 nm gözenek boyutlu filtrelerden geçirilmiştir. DBD analizlerinden elde edilen sonuçlara göre ham karasu örneğinde KOİ, TOK, BOİ5 ve renk (absorbans) parametrelerini oluşturan bileşenlerin daha çok partiküler boyut aralığında (>1600 nm; toplam KOİ’nin %54’ü, TOK’un %43’ü, BOİ5’in %43’ü ve rengin %57’si), T-Fenol parametresini oluşturan bileşenlerin ise kolloidal boyut aralığında (2 nm-1600 nm; %54) dağıldığı gözlenmiştir. Çalışılan arıtma proseslerinden en yüksek giderim, faz transferi ile giderim mekanizmasına dayanan koagülasyon ve çöktürme proseslerinden elde edilmiş (%55-60 KOİ, %45-48 TOK ve %32 T-Fenol), öte yandan Fenton prosesinin karasuyun organik madde giderimi için yeterli olmadığı tespit edilmiştir. Arıtma prosesleri sonrasında gerçekleşen giderimlerin KOİ-TOK parametreleri için büyük oranda partiküler boyut aralığında, T-Fenol için partiküler ve kolloidal aralıklarda dağıldığı bulunmuştur.In this experimental study, an olive oil mill wastewater (OOMW, COD:155000 mg/L; TOC:40000; Total phenol(TPh): 4100 mg/L) was subjected to different chemical treatment processes such as precipitation, coagulation, electrocoagulation and Fenton’s reagent. After the treatment processes, the change in the organic content of OOMW was investigated by applying particle size distribution (PSD) analysis. In this concept, sequential filtration/ultrafiltration procedure was followed by employing different molecular weight cut-off membranes including 1600, 450, 220, 13, 8, 5, 3, 2 and 1 nm for raw and treated OOMW samples. Accordingly, the PSD results for raw OOMW, the components of COD, TOC, BOD5 and color (absorbance) parameters were mostly in the particle fractions (>1600 nm; 54% of COD, 43% of TOC, 43% of BOD5 and 57% of color), while TPh parameter was distributed in the colloidal fractions (2 nm-1600 nm;54%). Among the treatment processes, the highest removals were obtained from coagulation and precipitation processes (55-60% COD, 45-48% TOC and 32% TPh) that based on the phase transfer removal mechanism. Otherwise, the obtained reductions by Fenton’s reagent was poor. The major removals were observed in particulate fractions for COD-TOC where the main TPh removal was observed both in particulate and colloidal fractions after treatment processes

Feasibility analysis of in-plant control for water minimization and wastewater reuse in a wool finishing textile mill

This study evaluates the feasibility of water minimization and wastewater reuse for a wool finishing textile mill. The evaluation process is based upon a detailed analysis on water use, process profile and wastewater characterization, indicating a potential for 34% reduction in water consumption and for 23% of wastewater recovery for reuse. Wastewater reuse requires treatment and results in a remaining wastewater stream with stronger character and consequently more costly to treat. The feasibility includes technical considerations for appropriate treatment alternatives and related cost factors for water consumption, treatment for reuse and for discharge either to sewer or to receiving media

A scientific approach to wastewater recovery and reuse in the textile industry

Wastewater recovery and reuse in industries requires all the basic steps of quality management. It should involve a comprehensive in plant survey of processes with wastewater generation, identification of recoverable streams, and treatment requirements for reuse. It should equally undertake evaluation of wastewater quality remaining after segregation of the recovered portion, with specific emphasis on technological implications of appropriate treatment and compliance with effluent limitations. In this study, all these factors were experimentally assessed and evaluated for a knit fabric processing textile plant

ASSESSMENT OF FACTORS AFFECTING ENGRAFTMENT AFTER AUTOLOGOUS STEM CELL TRANSPLANTATION

Aim: The aim of this study was to identify factors that may be related to the development of engraftment following peripheral stem cell infusion after myeloablation. Material and Method: The data of 121 patients who underwent autologous hematopoietic stem cell transplantation were retrospectively reviewed. Of the patients, 39 (32%) had multiple myeloma (MM), 34 (28%) had non-Hodgkin lymphoma (NHL), 33 (27%) had Hodgkin lymphoma (HL), 9 (8%) had acute leukemia and 6 (5%) had solid tumor. BEAM (carmustine, etoposide, arabinoside-C, melphalan), high doses of ICE (ifosfamide, carboplatin, etoposide), ME (melphalan plus etoposide), BuCy (busulfan and cyclophosphamide), and melphalan were used as preparation regimes. The mean age was 41.3 years with a median of 43 years (range 16-71 years). To identify factors that may be relevant in the development of engraftment following stem cell infusion, preparation regime, type of growth factor, total CD34+ cell count, and neutropenic fever occurrence were evaluated. Results: Neutrophil > 500/mu l and plt > 20,000/mu l levels were achieved at 10,1 +/- 2,3 and 11,5 +/- 3,9 days, respectively. Patients age, gender, diagnosis, radiotherapy before transplantation, and G-CSF administration had no significant effect on engraftment time. It was found that platelet engraftment was more rapid in patients who underwent ICE than in those who underwent the BEAM preparation regime; in addition, it was found that neutrophil engraftment was more rapid in patients who underwent ICE than in those who underwent the melphalan preparation regime. No direct correlation was demonstrated between CD34+ cell count and engraftment, while the engraftment was found to be more rapid in higher CD34+ cell counts. Discussion: Further studies are needed to identify the optimal peripheral stem cell transplantation protocol to improve bone marrow regeneration; to accelerate hematopoietic regeneration after myeloablative therapy; and to determine factors influencing engraftment