Kimyasal şartlandırılmış çamur ile dondurma/çözme ile şartlandırılmış çamurun su verme özelliklerinin karşılaştırılması

The objective of this study was to compare dewatering properties of chemically conditioned sludge and freeze/ thawed sludge as determined by mainly specific resistance to filtration (SRF), dry solids content of sludge cake (DS), and capillary suction time (CST) parameters. The experimental studies were carried out with mixed sludge samples taken from a municipal wastewater treatment plant in Turkey. In chemical conditioning experiments, sludge samples were conditioned with different dosages of polymer using classical jar test method. In freeze/ thaw conditioning experiments, samples were frozen at -16.5 degrees C at different freezing rates and then thawed at 21 +/- 1 degrees C at different times in order to determine the effect of thawing time on dewatering performance. 25 mg/L polymer dose and 2.71 mm/h freezing rate were found to be optimum in terms of sludge conditioning. Rapid freezing that is higher than 8.13 mm/h could not sufficiently condition the sludge and there was no significant effect of thawing time on conditioning performance. Dewatering properties of chemically conditioned sludge and freeze/thawed sludge was determined as very close to each other. While CST and SRF reductions were calculated as 76% and 75%, respectively at 25 mg/L polymer dosage, 2.71 mm/h freezing rate application caused 79% and 76% reduction in CST and SRF, respectively

Ultrasonic pre-treatment of treatment plant sludge

Bu çalışmada, bir ileri oksidasyon tekniği olan ultrasonik arıtmanın biyolojik çamurların anaerobik çürümesi öncesinde bir ön arıtma işlemi olarak kullanılabilirliği üzerine yapılan deneysel çalışmanın sonuçları verilmiştir. Çalışmada oldukça düşük ultrasonik frekans (20 kHz) uygulamasında, özgül enerji değişiminin çamur dezentegrasyonu üzerindeki etkisi incelenmiştir. Bu amaçla, 0 ile 15880 kJ/kg KM arasında değişen özgül enerji değerleri kullanılarak flok dezenteg-rasyonu açısından en uygun enerji seviyesi dezentegrasyon derecesi parametresi dikkate alınarak değerlendirilmiştir. Bunun yanı sıra, ultrasonik ön arıtma işleminin biyolojik çamurların üst suyu özellikleri, çamur katılarının çözünürlüğü ve çamurların filtrelenebilirlik özellikleri üzerine olan etkisi değerlendirilmiştir. Ultrasonik yöntemle ön arıtılan çamurların anaerobik çürüme potansiyelleri ise yürütülen biyokimyasal metan potansiyeli (BMP) testleri ile değerlendirilmiştir. En yüksek dezentegrasyon derecesi (%57.9) değeri 9690 kJ/kg KM özgül enerji uygulamasında elde edilmiş; 9690 kJ/kg KM özgül enerjinin flok dezentegrasyonu için yeterli olduğu sonucuna varılmıştır. Daha yüksek özgül enerji uygulaması dezentegrasyon derecesinin düşmesine neden olmuştur. BMP testi sonuçları ise ultrasonik ön arıtma işleminin çamurların biyolojik olarak parçalanabilirliklerini geliştirdiğini göstermiştir. 9690 kJ/kg KM özgül enerji kullanılarak ön arıtılmış çamurda ham çamura oranla %44 daha fazla metan gazı üretimi sağlamıştır. Ultrasonik ön arıtma uygulaması çamur üst suyunda kimyasal oksijen ihtiyacı (KOİ), toplam azot ve toplam fosfor konsantrasyonlarının artışına neden olmuştur. Ultrasonik ön arıtma uygulamasıyla azalan toplam katı madde ve organik katı madde içerikleri de ultrasonik ön arıtma uygulamasının çamur katılarının çözünürlüğüne neden olduğunu göstermiştir. Kapiler emme süresi (KES) testi sonuçları ile ultrasonik ön arıtma uygulamasının çamurların filtrelenebilirlik özelliklerini olumsuz etkilediği belirlenmiştir. Anahtar Kelimeler: Anaerobik parçalanabilirlik, biyolojik çamur, flok dezentegrasyonu, ultrasonik ön arıtma.Disintegration was developed as the pretreatment process of sludge to accelerate the digestion processes. Ultrasonic treatment may be a good alternative for sludge disintegration. Ultrasonic energy can be applied biological sludge to disintegrate flocs and disrupt bacterial cells? walls, and the hydrolysis can be improved, so that the rate of sludge digestion and methane production is improved1. Ultrasound treatment as sludge disintegration results in increase of chemical oxygen demand in the sludge supernatant and size reduction of sludge solids (Tiehm etal., 1997). Ultrasonic process leads to cavitation bubble formation in the liquid phase. These bubbles grow and then violently collapse when they reach a critical size. Cavitational collapse produces intense local heating and high pressure on liquid?gas interface, turbulence and high shearing phenomena in the liquid phase. Because of the extreme local conditions, OH?, HO2?, H? radicals and hydrogen peroxide can be formed. Thus, three mechanisms (hydro-chemical shear forces, thermal decomposi-tion of volatile hydrophobic substances in the sludge, and oxidizing effect of free radicals produced under the ultrasonic radiation) are responsible for the ultrasonic activated sludge disintegration (Bougrier etal., 2005; Wang etal., 2005; Riesz etal., 1985). Previous studies showed that low frequency ultrasound like 20 kHz is very effective in activated sludge disintegration, Gonze etal., 2003; Zhang etal., 2008). The effects of initial total solids content of sludge, power density, and sonication time on floc disintegration were investigated by several researchers (Chu etal., 2001; Gonze etal., 2003; Show etal., 2007; Zhang etal., 2008). Previous studies showed that low density and long duration sonication is more efficient than high density and short duration (Pham etal., 2009; Xie etal., 2009). In this work, feasibility of using an oxidative technique of ultrasonic treatment to improve anaerobic biodegradability of biological sludge was investigated. Different specific energy inputs ranged 0 to 15880 kJ/kg DS was applied to biological sludge for disintegration purpose and optimum energy input was evaluated based on disintegration degree parameter. The disintegration degree permits to evaluate the maximum level of sludge solubilization. Increase of DD is determined as the substance that can be readily used to produce methane in the anaerobic digestion (Wang et al., 2005). The disintegration degree of sonicated sludge increased with increasing specific energy in each experiment. The highest disintegration degree was achieved 9690 kJ/kg DS application; hence 9690 kJ/kgTS of supplied energy is efficient for cell lysis. Particle size of sludge is another important parameter for floc disintegration. The reduction in particle size generally allows an easier hydrolysis of solids within the sludge due to larger surface areas in relation to the particle volumes. The result is an accelerated and enhanced degradation of the organic fraction of the solid phase (Muller, 2003). Ultrasonic treatment led to change of physico-chemical characteristics of sludge. For instance, temperature increased almost linearly with increasing specific energy. In contrast, pH decreased during ultrasonic pre-treatment. The destruction of floc structure and disruption of cells results in the release of organic sludge components into the liquid phase. Thus, sludge?s supernatant characteristics were also affected the ultrasonic pre-treatment. For 9690 kJ kg-1TS, the soluble chemical oxygen demand (SCOD), dissolved organic carbon (DOC), total nitrogen (TN), total phosphorus (TP) in sludge?s supernatant increased by 340%, 860%, 716%, and 207.5%, respectively. In sludge disintegration processes organic material is transfered to the liquid phase from the solid phase. Higher solubilisation degree of volatile solids in sludge is important for the elimination of hydrolysis phase of anaerobic biodegradation further. Ultrasonic treatment induced sludge reduction due to the solubilization of total and volatile solids. The main purpose of disintegration is the elimination of hydrolysis step to accelerate the anaerobic degradation. The potential for improving anaerobic digestion through ultrasonic pre-treatment was also evaluated with biochemical methane potential (BMP) tests. BMP results obtained in this study suggest that ultrasonic pre-treatment lead to increase the anaerobic biodegradability of biological sludge. For 9690 kJ/kg TS, 44% higher methane production in pre-treated sludge was obtained comparing to the raw sludge. Protein hydrolysis was also performed successfully by ultrasonic pre-treatment even at very low ultrasonic density levels. Furthermore, CST results showed that ultrasonic pre-treatment deteriorates the filterability of biological sludge. Keywords: Anaerobic biodegradability, biological sludge, floc disintegration, ultrasonic pre-treatment

Final disposal evaluation of anaerobically stabilized municipal treatment plant sludge

Bu çalışma, anaerobik yöntemle stabilize edildikten sonra mekanik su alma işlemlerinde susuzlaştırılan kentsel nitelikli arıtma çamurlarının düzenli katı atık depolama tesislerinde bertaraf edilebilirliğinin değerlendirilmesi amacıyla yürütülmüştür. Atıkların düzenli depolama tesislerine depolanabilme kriterleri, Tehlikeli Atıkların Kontrolü Yönetmeliği (2005), EK-11 A kapsamında yer alan eluatta çözünmüş organik karbon (ÇOK) ve orijinal atıkta toplam organik karbon (TOK) parametreleri yüksek organik madde içeriğine sahip kentsel nitelikli arıtma çamurları için önem taşımaktadır. Bu çalışma kapsamında İzmir’de bulunan bir kentsel atıksu arıtma tesisinden alınan biyolojik çamurlar mezofilik sıcaklık koşullarında anaerobik olarak stabilize edilmiştir. Anaerobik çürütme çalışmaları, laboratuvar ortamında kurulan 8.5 L hacimli iki reaktörün farklı çamur alıkonma sürelerinde 30 gün süreyle işletimi ile yürütülmüştür. Anaerobik olarak çürütülen çamurların mekanik su alma işlemlerindeki performansları bir belt-press simülatörü ile tayin edilmiştir. Laboratuvar ortamında elde edilen çamur keklerinde yapılan analizler ile anaerobik çürütme sonrasında mekanik yöntemle susuzlaştırılan çamurların düzenli depolama tesislerine depolanabilirlikleri eluatta ÇOK ve orijinal atıkta TOK parametreleri dikkate alınarak değerlendirilmiştir. Sonuçlar, anaerobik yöntemle stabilize edildikten sonra mekanik olarak susuzlaştırılan çamurların kek katı madde içeriklerinin düşük olması sebebiyle mekanik su alma işlemi öncesinde şartlandırma işlemine tabi tutulması gerekliğini ortaya koymuştur. Bunun yanı sıra anaerobik yöntemle stabilize edilmiş çamur keklerinin EK-11 A’da belirtilen TOK standartları uyarınca inert atık sınıfında yer aldığı ancak ÇOK standart değerleri uyarınca tehlikeli atık sınıfında yer aldığı ve evsel katı atık düzenli depolama tesislerinde bertarafının uygun olmadığı belirlenmiştir. Anahtar Kelimeler: Anaerobik çürütme, biyolojik çamur, düzenli depolama, mekanik su alma, nihai bertaraf. The main by-product of municipal wastewater treatment of waste activated sludge (WAS) has been increasing worldwide as a result of an increase in the amount of wastewater being treated. The sludge should be processed and disposed of in accordance with the environmental health criteria for environmental reasons. The main objectives of sludge treatment and disposal are stabilization of the organic matter contained in the sludge, reduction in the volume of sludge for disposal by removing some of the water, destruction of pathogens, collection of by-products, which may be used or sold to off-set some of the costs of sludge treatment, and disposal of sludge in a safe and aesthetically acceptable manner (Scholz, 2006). For many authorities and engineers, the effective sludge management is still a big challenge since the investment and operational costs (Metcalf & Eddy, 2003). Treatment and disposal of excess sludge in a biological wastewater treatment system requires enormously high cost which has been estimated to be 50-60% of the total expense of wastewater treatment plant (Egemen et al., 2001; Yasui, 1996). Sludge stabilization is an important issue in sludge management field for effective reduction of organic matter, removal of pathogen and odor potential. For this purpose, alkaline stabilization, aerobic and anaerobic stabilization, aerobic thermophilic digestion, and composting are introduced. Among these methods, anaerobic digestion has been widely used with its many advantages. The main advantages of anaerobic digestion in comparison with other processes are; the lower energy requirement, the production of biogas and the lower production of excess sludge including efficient degradation of biodegradable particulate organic matters in sludge (Novak et al., 2003; Speece, 1996). Mechanical dewatering processes have been widely used for reduction in the volume of sludge for disposal by removing some of the water (Scholz, 2006). Mechanical dewatering processes like centrifuging, belt filter press, and filter press reduce the total volume of sludge even further so reducing the ultimate transportation cost of disposal. The resultant sludge is a solid, not a liquid, and so can be easily handled by conveyers or tractors although experience has shown that the dried sludge, known as cake, is more easily handled at solids concentrations of >20%. Its solid nature makes it suitable for many more disposal options than liquid sludge (Gray, 2005). This study was carried out for evaluation of final disposal of anaerobically stabilized sludge after mechanical dewatering in a municipal solid waste landfill area. Total organic carbon (TOC) in sludge cake and dissolved organic carbon (DOC) in eluate are important parameters for treatment plant sludge contained high organic matter in terms of Turkish Hazardous Waste Control Regulation, THWR EK- 11 A, 2005. In this study, anaerobic stabilization was applied to biological sludge samples. . The samples were taken from a municipal wastewater treatment plant located in Izmir, Turkey. Anaerobic sludge digestion studies were carried out using two 8.5 L lab-scale anaerobic reactors. The reactors were operated as semi batch system in mesophilic conditions at 37±2 oC for 30 days of operation period. Different sludge retention time of 5 days and 10 days were used in digestion study. For evaluation of anaerobic digestion performance of reactors, total solids (TS), organic matter (OM), suspended solids (SS), and volatile suspended solids (VSS) were analyzed regularly. Daily methane productions in reactor content were also measured during the operation period. The belt press simulator of crown press was used for evaluation of mechanical dewatering properties of sludge. For final disposal evaluations of dewatered sludge in a municipal solid waste landfill area, TOC parameter in sludge cake obtained from crown-press application and DOC parameter in eluate samples were analyzed regularly during the operation period. Results indicated anaerobic digestion is an effective method for sludge's solids reduction and it leads to decrease organic matter content of sludge. In contrast, anaerobic digestion has not a positive effect on increasing cake solids and some conditioning processes are required before mechanical dewatering operations. In addition, final sludge cake is classified as inert material based on the TOC parameter but it is classified as hazardous waste based on the DOC parameter according to Turkish Hazardous Waste Control Regulation, THWR EK- 11 A, 2005 and it can not be storage in a municipal solid waste landfill area for final disposal purpose. Keywords: Anaerobic digestion, biological sludge, landfilling, mechanical dewatering, final disposal

Evaluation of parameters which effect phosphorus release by using Box-Wilson experimental design method

Son yıllarda, fosfor doğal rezervlerinin hızla tükenmesi nedeniyle birçok endüstriyel sektör için ana ham madde kaynağı olan fosforun atıksu ve arıtma çamurlarından geri kazanılmasına yönelik yapılan araştırmalar önem kazanmıştır. Arıtma çamuru ve çamur küllerinden fosfor geri kazanımı için; çamur bünyesinden salınması ve sıvı ortama alınan salınmış fosforun geri kazanılması olarak iki aşamalı yöntem izlenmektedir. Atıksu ve arıtma çamuru bünyesinden fosforun salınması amacıyla çeşitli kimyasal ve ısıl işlemler kullanılmaktadır. Bu çalışmada, arıtma çamuru bünyesinde bağlı olan fosforun salınması için asidik işlem uygulanmış; bu amaçla inorganik bir asit olan nitrik asit ve organik bir asit olan oksalik asit kullanılmıştır. Fosfor salınması üzerinde karıştırma sıcaklığı, karıştırma zamanı ve asidin konsantrasyon değeri gibi parametrelerin etkileri araştırılmıştır. Sonuçların değerlendirilmesi için Box-Wilson deneysel tasarım metodu uygulanarak salınan fosfor miktarı için hesaplanan değerler ile deneysel olarak ölçülmüş değerler arasında uyum olduğu belirlenmiştir. R2 değeri nitrik asit için 0.995, oksalik asit için 0.853 olarak bulunmuştur. Değerlendirme sonuçlarına göre; fosfor salınmasında nitrik asitin oksalik aside göre daha etkili bir kimyasal olduğu belirlenmiştir. Nitrik asitle yapılan çalışmalarda, konsantrasyon ve karıştırma zamanına göre sıcaklığın fosfor salınması miktarını önemli ölçüde arttırdığı gözlenmiştir. Oksalik asitle yapılan çalışmalarda nitrik asitle yapılan çalışmalarda olduğu gibi sıcaklığın daha etkili bir parametre olduğu gözlenmiştir. En yüksek fosfor salınım miktarı, nitrik asitle çalışıldığında 100ºC karıştırma sıcaklığı, 4 M konsantrasyonda ve 97.5 dakika karıştırma süresi kullanılarak; oksalik asitle yapılan çalışmalarda ise 100ºC karıştırma sıcaklığında, 2 M konsantrasyonda ve 97.5 dakika karıştırma süresi ile elde edilebileceği belirlenmiştir. Anahtar Kelimeler: Fosfor salınması, nitrik asit, oksalik asit, Box-Wilson deneysel tasarım metodu.The usual forms of phosphorus found in aqueous solutions include the orthophosphate, polyphosphate, and organic phosphate (Metcalf & Eddy, 1991). Wastewater discharges of nitrogen and phosphorus to the environment are undesirable because these nutrients accelerate eutrophication (Lee et al., 2003). Therefore, various phosphorus removal technologies have been developed like chemical precipitation, biological phosphorus removal, ion exchange (Morse et al., 1998).Steen (1998) has pointed out that the annual global production of phosphate is around some 40 million tones of P2O5, derived from roughly 140 million tons of rock concentrate by the year 1998. In addition, World fertilizer use would reach 60-70 million t/a of phosphates by 2050. It is concluded that global phosphate resources extend, for all intents and purposes, well into the future, but that depletion of current economically exploitable reserves can be estimated at somewhere from 60 to 130 years (Steen, 1998). Phosphrus recovery from sewage sludge and sludge ash are applied at two steps. These are phosphorus release from sludge and recovery of released phosphorus from phosphrus-enriched liquid phase. In this study, nitric acid (inorganic acid) and oxalic acid (organic acid) were utilized in order to release the phosphorus fixed in the sewage sludge. The effects of parameters which determine the efficiency of mixture temperature, mixing time and acid concentration on the phosphorus release were investigated. For the analysis of the results, Box-Wilson Experimental Design Method has been used. Sludge samples taken from belt press stages of Çiğli municipal wastewater treatment plant were dried at 103ºC in oven. Chemical composition of dried sludge was determined using X-ray diffraction analysis (XRD-Rigaku). Dried sludge samples were leached with nitric acid and oxalic acid), by applying different concentrations, various mixture temperatures, and various mixing times which were adjusted to desired levels specified by the Box–Wilson Experimental Design Method. Magnetic stirrer/hot plate and electronic temperature controller with stainless steel temperature sensor were used for the leaching process. Leachate solution with different concentrations was added to the dried sludge samples and mixed for various time periods at 300 rpm. Ratio of dried sludge (g)/ solution volume (ml) was chosen as 1/50. The concentration of phosphate in the leachate was analyzed using Stannous Chloride Method; 4500-P D according to Standard Methods (APHA, 2005). All leaching stages are repeated twice for each experimental step. Box–Wilson Experimental Design Method was used to determine the effects of parameters, such as mixture temperature (X1) solution concentration (X2) and mixing time (X3) on phosphorus release from dried sludge. Solution concentration varied between 0.1- 4 M for nitric acid and 0.1-2 M for oxalic acid. In addition, mixing time was between 15-180 min and mixture temperature was in the range at 20ºC and 100ºC. The experiments consisted of six axial (A), eight factorial (F) and one centre (C) points. The centre point was repeated three times. The amount of phosphorus release was described by using response function. Statistica 5.0 software program was used to determine, the response function coefficients. The predicted values of phosphorus release amount were in accordance with the observed values. It was found that R-squared values are 0.995, and 0.853 for nitric acid, oxalic acid respectively. Results were evaluated in terms of the effects of concentration-mixing time, temperature-mixing time, and concentration-temperature on phosphorus release from the sludge. The analysis results have shown that nitric acid is more efficient as compared to oxalic acid. In experiments carried out with nitric acid, it has been observed that the increase in nitric acid concentration and mixing time do not significantly affect phosphorus release, while an increase in mixing temperature effects considerably. Experiments conducted using oxalic acid have shown that increasing mixing temperature results increasing phosphorus release, whereas concentration increase and mixing time have no significant effect. The best phosphate release amounts were accomplished, at 4 M concentration, 100ºC mixture temperature, and 97.5 min mixing time for nitric acid. In experiments with oxalic acids, the best phosphate release amounts were accomplished at 2 M concentration, 100ºC mixture temperature, and 97.5 min mixing time. Keywords: Phosphorus release, nitric acid, oxalic acid, Box-Wilson Experimental Design Method

Pre-treatment processes applied to decrease quantity and to improve dewatering properties of treatment plant sludge

Atıksu arıtma tesislerinde, arıtma işlemleri sonucunda oluşan arıtma çamurlarının anaerobik yöntemlerle stabilizasyonu; atık bünyesindeki organik madde içeriği ve patojen mikroorganizma konsantrasyonunun azaltılması amacıyla günümüzde yaygın olarak kullanılan bir yöntemdir. Anaerobik çürüme uygulamasının derecesine bağlı olarak çok faydalı bir son ürün olan ve temiz enerji kaynağı olarak nitelenen biyogaz eldesi mümkün olmaktadır. Anaerobik çürüme prosesinin oldukça yavaş bir süreç olması ve çürüme sonrasında organik maddelerin tümüyle parçalanamaması nedeniyle tam stabilizasyonun sağlanamaması ve elde edilen biyogaz miktarının az olması araştırmacıları anaerobik çürümeyi hızlandıracak ve stabilizasyon derecesini artırmayı sağlayacak yeni yöntemler geliştirmeye yöneltmiş ve çamur ön arıtımı amacıyla kullanılan bir yöntem olarak çamur dezentegrasyonu geliştirilmiştir. Dezentegrasyon işleminde, çamura uygulanan gerilmeler sayesinde çamur flok yapısı bozulmakta, mikroorganizma hücre duvarları parçalanmakta, hücre içeriğindeki organik çamur bileşenleri sıvı faza geçmektedir. Dezentegrasyon sonucunda, çamur katılarının organik madde içeriği en aza inmekte, dolayısıyla daha düşük miktarda ve daha stabil bir çamur eldesi mümkün olmaktadır. Organik maddenin yüksek derecede parçalanması klasik anaerobik çürüme işlemine göre daha fazla biyogaz üretimine olanak sağlamaktadır. Bu çalışmada anaerobik arıtma öncesinde çamura bir ön arıtma işlemi olarak uygulanan dezentegrasyon işleminin mekanizması ve amaçları özetlendikten sonra dezentegrasyon yöntemleri hakkında bilgi verilmiştir. Anahtar Kelimeler: Çamur, anaerobik çürüme, dezentegrasyon.The main by-product of municipal wastewater treatment of waste activated sludge (WAS) has been increasing worldwide as a result of an increase in the amount of wastewater being treated. Treatment and disposal of excess sludge in a biological wastewater treatment system has enormously high cost which has been estimated to be 50?60% of the total expense of wastewater treatment plant (Egemen et. al., 2001). Anaerobic digestion is a common process for stabilization of treatment plant sludges. Compared with other processes, its advantages are less energy required, a better stabilized product, and usable gas. Anaerobic digestion process is achieved through several stages: hydrolysis, acidogenesis, methanogenesis. For waste activated sludge degradation, the rate-limiting stage is the hydrolysis. Biogas considered as the clean energy source is produced in the anaerobic digestion process depending on the stabilization degree. Anaerobic digestion is a slow process, which results in a long residence time and the requirement of a large tank volume. In order to improve hydrolysis and anaerobic digestion performance disintegration was developed as the pretreatment process of sludge to accelerate the anaerobic digestion and to increase degree of stabilization (Bougrier et. al.,2005) . Disintegration process results in an improvement of velocity and degree of degradation. To increase of stabilization degree of sludge with disintegration process provides less sludge production, more stable sludge and more biogas production comparing the classical anaerobic digestion. Sewage sludge disintegration can be defined as the destruction of sludge by external forces. The forces can be of physical, chemical or biological nature. As a result of the disintegration process is numerous changes of sludge properties (Müller et. al., 2004). Disintegration cause disruption of microbial cells in the sludge, thereby destroying the cell walls (Vranitzky et. al., 2005). The destruction of floc structure and disruption of cells results in the release of organic sludge components into the liquid phase. These components exist in a dissolved phase, e.g. components of intracellular water, or can be liquefied. Particle size or colloidal components may still be present within the solution because they cannot be separated from the liquid phase. Their minute particle size and only a slight difference in density of particle and surrounding water are the cause. But components are easily biodegradable on the other hand. Since they are already liquefied or offer a large surface in comparison their volume, the hydrolyzing process is simple. Released carbon compounds after disintegration are easily accessible and can be digested much faster in later biological process than sludge in a particular phase. The results are shorter degradation times and higher degrees of degradation during the aerobic and anaerobic stabilization. Besides, these compounds can further be used for carbon limited process steps within the wastewater treatment such as denitrification or the biologically enhanced phosphorus elimination. After disintegration, the liquid phase has to be cleaned from the released nitrogen and phosphorus compounds before leaving the treatment plant. If this happens by returning the water into the WAS-process, additional capacities have to be taken into account. Disintegration within the sludge pre-treatment has advantages in combination with selective recyling processes due to the increased nitrogen and phosphorus concentrations (Müller et. al., 2004). In recent years, for the purpose of waste activated sludge (WAS) minimization and more biogas production than classical anaerobic digestion, several disintegration methods have been investigated. The methods can be classified as following topics; - Chemical disintegration (Ozone treatment, Alkaline treatment, Fenton process etc.) - Mechanical disintegration (Stirred ball-mill, High-pressure homogenizer, Ultrasonic Homogenizers, Lysatcentrifuge, Jet Smash Technique, The High Performance Pulse Technique etc.) - Thermal disintegration - Biological disintegration (High temperature sludge stabilization with thermophilic bacteria, Enzymatic lysis). In this study, the mechanisms and objectives of disintegration process was summarized and then disintegration methods were evaluated. Keywords: Sludge, anaerobic digestion, disintegration