This study aims to provide the latest understanding of cutting-edge technologies that enable wastewater organic carbon diversion and recovery through the enhancement of sludge production and blending, digestibility, dewaterability, and dewatered cake odor emission control. A comprehensive literature review showed that iron-based coagulants tend to show less negative impact than aluminum-based coagulants. This can be attributed to the reduction of ferric to ferrous ions in the course of anaerobic digestion (AD), which leads to a suite of changes in protein bioavailability, alkalinity, and hydrogen sulfide levels, and in turn the sludge dewaterability and odor potential. In terms of the roles of thermal hydrolysis pretreatment (THP), the mechanism review indicated that the improvement of sludge dewaterability and anaerobic digestibility as a result of THP was because of the destruction of extracellular polymeric substances and increase of hydrolysis rate. However, THP also brings side effects such as high free residual ammonia and recalcitrant dissolved organic nitrogen (rDON) in the effluent. Besides, a comprehensive understanding of the formation of the odorous compounds in the sludge treatment processes indicated that sulfurous and nitrogenous compounds are usually regarded as the major odor-causing substances. A Pilot THP-AD study indicated that adding aluminum to produce primary sludge can improve overall plant sludge digestibility, dewaterability, and well as the rDON reduction. Moreover, results from a pilot THP-AD and biochemical methane potential (BMP) test study indicated that adding a secondary thermal hydrolysis after a primary thermal hydrolysis-AD system can still create new BMP. Finally, a pilot study was conducted to evaluate the effect of aeration in the sludge holding tank on biosolids odor emission. The two rounds of bench-scale aeration studies indicated that aerating the sludge in holding tanks reduced peak emission concentrations of sulfurous odorous compounds. Further full-scale validation confirmed that aeration can be used by utilities as a simple means for biosolids odor control. / Doctor of Philosophy / Public wastewater treatment annually consumed 3-4% energy production and contributed 1% greenhouse gas emission in the U.S. Meanwhile, the chemical energy contained in wastewater was estimated to be 9.3 times the energy it takes to treat it. Therefore, harvesting wastewater energy is proposed as a viable means for achieving energy and carbon neutral wastewater treatment. The approach to sending wastewater energy as much as possible to anaerobic digesters in which microorganisms help harvest useful energy in the form of flammable methane was evaluated in this study. From literature, we learned that chemicals used for upstream wastewater energy capture and nutrient removal may make the downstream energy recovery difficult. While, thermal hydrolysis pretreatment, an industrial-scale pressure cooker, can be used to improve the ease of microbial bioenergy harvesting by making organics more biodegradable. However, thermal hydrolysis may also bring side effect in terms of recalcitrant organic formation. Also, in the course of energy recovery, the production and emission of nuisance odor may occur but can be controlled. Building on this existing knowledge, this study evaluated the pros and cons of the approach to using chemicals to capture and recover energy from wastewater. The results showed that the extents of energy recovery and savings was greater than the compromised solids reduction from the process. Moreover, results from a biochemical methane potential test study indicated that adding a secondary thermal hydrolysis can recover even more chemical energy from wastewater. In the end, a pilot study was conducted to develop a simple and economical approach to mitigating the odor emission issue during sludge handling. Results showed that pumping air into the sludge holding tank can substantially reduce peak odor emission. This approach was later verified in a full-scale test and recommended to utilities as a simple means for biosolids odor control.

Two different sludge pretreatments were investigated in an attempt to improve the management and performance of processes for the co-digestion of biosolids with fats, oils, and grease (FOG). The mechanisms of long chain fatty acids (LCFA) degradation in thermal hydrolysis pretreatment and the influence of pH on LCFA degradation in two-phase co-digestion systems were studied. LCFA thermal hydrolysis was investigated at different temperatures (90-250 °C) and reaction times (30 minutes and 8 hours). Approximately 1% of saturated fatty acids were degraded to shorter chain fatty acids at 140 and 160 °C (8-hr thermal hydrolysis). Only 1% or less of unsaturated fatty acids were degraded from 90 to 160 °C (8-hr thermal hydrolysis). Little degradation (< 1%) of both saturated and unsaturated LCFAs was observed at a 30-min reaction time. Both groups of LCFAs were stable up to 250 °C (30-min hydrolysis). The use of chemical-thermal treatments was also investigated. Only unsaturated LCFAs, C18:1 and C18:2, were degraded when thermally hydrolyzed with hydrogen peroxide coupled with activated carbon or copper sulfate. Semi-continuous, acid-phase digesters (APDs) under different pH conditions were studied in order to understand the effects of pH on FOG degradation. Increases in soluble chemical oxygen demand (SCOD) were observed in all APDs. However, the APDs with pH adjustment appeared to perform better than the controls in terms of solubilizing organic compounds. Approximately 38% and 29% of total COD (TCOD) was solubilized, and maximum volatile fatty acid (VFA) concentrations of 10,700 and 7,500 mg/L TCOD were achieved at pH 6 and 7, respectively; It is useful to note that the feed sludge had a VFA concentration of 2,700 mg/L COD. Higher pH (6.0-7.0) showed less accumulation of LCFA materials and more soluble LCFAs in the APDs. This indicates that the lower pH in the APDs was most likely the cause of precipitation and accumulation of LCFAs due to saturation of unsaturated LCFAs. / Master of Science

The increased demand for advanced sludge stabilization in wastewater treatment facilities over the past decade has led to the implementation of various pretreatment techniques prior to anaerobic digestion. In an attempt to reduce sludge volumes and improve sludge conditioning properties, the use of thermal hydrolysis process before anaerobic digestion has been adopted with an increase in solids destruction, COD removal, and methane gas. In this study, the evaluation of thermal hydrolysis process as a viable pretreatment strategy to anaerobic digestion has been conducted in order to assess its capacity for solids solubilization. Solubilization experiments were conducted at temperatures ranging from 130 to 170℃ and reaction times between 10 and 60 min. Anaerobic biogas production by thermally pre-treated sludge was carried out through a mesophilic anaerobic digester. The results showed that solids solubilization increased with increases in temperature and time, while temperatures above 160℃ for 30 min strongly affected the sludge characteristics. Ammonia production via deamination by thermal hydrolysis was less significant than protein solubilization at a temperature of 170℃. Both protein and carbohydrate solubilization were more dependent on temperature than reaction time. The enhancement of the biogas production was achieved with increases in temperature as pretreatment of 170℃ yielded 20% more biogas than at 130℃. However, it seems the enhancement was linked to the initial biodegradability of the sludge. / Master of Science

The increased demand for advanced techniques in anaerobic digestion over the last few years has led to the employment of various pre-treatment methods prior to anaerobic digestion to increase gas production. These pre-treatment methods alter the physical and chemical properties of sludge in order to make it more readily degradable by anaerobic digestion. The thermal hydrolysis process has been used in several treatment plants around the world, but none currently operate in the US. Thermal hydrolysis causes cell walls to rupture under the effect of high temperature and high pressure and results in highly solubilized product which is readily biodegradable. The performance of the process was evaluated for a treatment plant located in Dallas, TX. The performance assessment was based on various characteristics including pH, solids removal, COD removal and gas production. The study was conducted in two phases to investigate the effect of change in mesophilic temperature (37°C and 42°C) and the effect of solids retention time (SRT) (15 days and 20 days). Thermally hydrolyzed combined (1:1) primary and waste activated sludge was fed to a Thermal Hydrolysis (TH) anaerobic digester and its performance was compared to a conventional mesophilic anaerobic digester receiving non pre-treated sludge. The thermal hydrolysis pre-treatment was found to be more effective as compared to the conventional anaerobic digester. The efficiency of the process varied slightly with increase in temperature but the change in SRT was seen to have a greater impact on the digester's performance. The pre-treatment technique was observed to deliver the best results at a 20 day SRT. / Master of Science

Waste activated sludge (WAS) pretreatment technologies are typically evaluated in terms of the associated improvement in biogas and sludge production during digestion and post-digestion dewaterability. However, WAS properties, and hence the impact of pretreatment on WAS properties, are dependent upon the raw wastewater composition and configuration of the wastewater treatment plant (WWTP). A generally accepted means of characterizing and comparing all pretreatment processes does not exist. The motivation for this project was to evaluate the impact of pretreatment on WAS properties in terms of changes in COD fractionation. The first objective of this study was to fractionate the COD of the WAS before and after pretreatment to show how pretreatment may increase the rate and extent of aerobic digestion. The second objective was to develop a COD-based stoichiometric pretreatment model that may be integrated into WWTP simulations. A bench-scale biological reactor (BR) with a solids retention time (SRT) of 5 days was started up with WAS from the Waterloo WWTP. The BR was fed daily with a completely biodegradable synthetic substrate so that the BR WAS contained only biomass and decay products after 3 SRTs of operation. In the first phase of the study, an aerobic digester (AD) with a SRT of 10 d was fed daily with BR WAS. The BR-AD system was operated at steady state for one month. A range of physical and biochemical properties were regularly measured in each process stream. Offline respirometric tests were regularly conducted to determine the aerobic degradability and fractionate the COD of the BR and AD WAS. The oxygen uptake rate (OUR) associated with the daily addition of BR WAS to the AD was determined as an additional measurement of the aerobic degradability of the BR WAS. In the second phase of the study, the BR WAS was pretreated prior to being fed daily to the AD. High pressure thermal hydrolysis (HPTH) pretreatment was selected for this project since it is one of the most popular and promising pretreatment techniques. A sealed volume of BR WAS was heated to 150°C at 3 bars for 30 minutes. The same physical, biochemical and biological tests used to characterize the process streams in Phase 1 were employed to characterize those in Phase 2. The Phase 2 system was operated for two months at steady-state. The results of several independent tests showed that the COD of the BR WAS was comprised of storage products (XSTO) in addition to active heterotrophs (Zbh) and decay products (Ze). However, it was shown that the AD WAS only contained Zbh and Ze as XSTO was depleted in the AD. HPTH pretreatment did not reduce the TCOD concentration of the WAS however it did solubilize 56 ± 7% of COD, 49% ± 11% of organic nitrogen, 56 ± 10% of VSS and did not solubilize ISS. Furthermore, pretreatment did not generate soluble non-biodegradable COD. These findings were consistent with prior research on HPTH WAS pretreatment. Pretreatment increased the rate at which the BR WAS was aerobically degraded. The offline respirometric tests showed that the pretreated BR WAS contained a substantial amount of readily biodegradable COD (Sbsc). However, pretreatment did not increase the extent of biodegradation. The results of several independent tests showed that the non-biodegradable COD component of the BR WAS, i.e. Ze, was not converted to biodegradable COD by pretreatment. A COD-based stoichiometric pretreatment model was developed for the dose of HPTH pretreatment employed in this study. When this model was integrated into BioWin®, it was able to accurately simulate both the steady state performance of the overall system employed in this study as well as dynamic respirometry results. The experimental results showed that the TCOD of the BR WAS consisted of 51% Zbh, 12% Ze and 37% XSTO and the pretreated BR WAS consisted of 12% Ze and a negligible amount of Zbh. The pretreatment model verified these fractions and predicted that the pretreated BR WAS also contained 54% Sbsc and 32% slowly biodegradable COD (Xsp). The approach described in this study may be followed to determine the impacts of pretreatment on Zbh, Ze and XSTO when other doses of HPTH pretreatment and other pretreatment techniques are employed.

Waste activated sludge (WAS) pretreatment technologies are typically evaluated in terms of the associated improvement in biogas and sludge production during digestion and post-digestion dewaterability. However, WAS properties, and hence the impact of pretreatment on WAS properties, are dependent upon the raw wastewater composition and configuration of the wastewater treatment plant (WWTP). A generally accepted means of characterizing and comparing all pretreatment processes does not exist. The motivation for this project was to evaluate the impact of pretreatment on WAS properties in terms of changes in COD fractionation. The first objective of this study was to fractionate the COD of the WAS before and after pretreatment to show how pretreatment may increase the rate and extent of aerobic digestion. The second objective was to develop a COD-based stoichiometric pretreatment model that may be integrated into WWTP simulations. A bench-scale biological reactor (BR) with a solids retention time (SRT) of 5 days was started up with WAS from the Waterloo WWTP. The BR was fed daily with a completely biodegradable synthetic substrate so that the BR WAS contained only biomass and decay products after 3 SRTs of operation. In the first phase of the study, an aerobic digester (AD) with a SRT of 10 d was fed daily with BR WAS. The BR-AD system was operated at steady state for one month. A range of physical and biochemical properties were regularly measured in each process stream. Offline respirometric tests were regularly conducted to determine the aerobic degradability and fractionate the COD of the BR and AD WAS. The oxygen uptake rate (OUR) associated with the daily addition of BR WAS to the AD was determined as an additional measurement of the aerobic degradability of the BR WAS. In the second phase of the study, the BR WAS was pretreated prior to being fed daily to the AD. High pressure thermal hydrolysis (HPTH) pretreatment was selected for this project since it is one of the most popular and promising pretreatment techniques. A sealed volume of BR WAS was heated to 150°C at 3 bars for 30 minutes. The same physical, biochemical and biological tests used to characterize the process streams in Phase 1 were employed to characterize those in Phase 2. The Phase 2 system was operated for two months at steady-state. The results of several independent tests showed that the COD of the BR WAS was comprised of storage products (XSTO) in addition to active heterotrophs (Zbh) and decay products (Ze). However, it was shown that the AD WAS only contained Zbh and Ze as XSTO was depleted in the AD. HPTH pretreatment did not reduce the TCOD concentration of the WAS however it did solubilize 56 ± 7% of COD, 49% ± 11% of organic nitrogen, 56 ± 10% of VSS and did not solubilize ISS. Furthermore, pretreatment did not generate soluble non-biodegradable COD. These findings were consistent with prior research on HPTH WAS pretreatment. Pretreatment increased the rate at which the BR WAS was aerobically degraded. The offline respirometric tests showed that the pretreated BR WAS contained a substantial amount of readily biodegradable COD (Sbsc). However, pretreatment did not increase the extent of biodegradation. The results of several independent tests showed that the non-biodegradable COD component of the BR WAS, i.e. Ze, was not converted to biodegradable COD by pretreatment. A COD-based stoichiometric pretreatment model was developed for the dose of HPTH pretreatment employed in this study. When this model was integrated into BioWin®, it was able to accurately simulate both the steady state performance of the overall system employed in this study as well as dynamic respirometry results. The experimental results showed that the TCOD of the BR WAS consisted of 51% Zbh, 12% Ze and 37% XSTO and the pretreated BR WAS consisted of 12% Ze and a negligible amount of Zbh. The pretreatment model verified these fractions and predicted that the pretreated BR WAS also contained 54% Sbsc and 32% slowly biodegradable COD (Xsp). The approach described in this study may be followed to determine the impacts of pretreatment on Zbh, Ze and XSTO when other doses of HPTH pretreatment and other pretreatment techniques are employed.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第17542号 / 工博第3701号 / 新制||工||1563(附属図書館) / 30308 / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 高岡 昌輝, 教授 田中 宏明, 教授 米田 稔 / 学位規則第4条第1項該当

Orientador: Rosiane Lopes da Cunha / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-14T13:41:45Z (GMT). No. of bitstreams: 1 Santana_RejanedeCastro_M.pdf: 21285325 bytes, checksum: 4874213be2305b454285b0b5beaae98b (MD5) Previous issue date: 2009 / Resumo: O colágeno é uma proteína de origem animal de grande disponibilidade no Brasil e com aplicações nas indústrias de alimentos, farmacêutica e cosmética na forma de gelatina. Com o intuito de entender e melhorar as propriedades emulsificantes de ingredientes à base de colágeno extraído do couro bovino, as propriedades físico-químicas da fibra de colágeno foram inicialmente avaliadas e modificadas através da hidrólise parcial em temperaturas de 50 à 85°C por períodos de 20 e 60 minutos. O processo de hidrólise aumentou a solubilidade do colágeno de 2,9 % (m/m) para 33,0 % (m/m) e produziu frações de menor massa molar, que chegaram a alcançar 37 kDa no hidrolisado a 85°C/60min. A temperatura de desnaturação do colágeno encontrou-se em torno de 64°C, sendo que os tratamentos a 65°C e 85°C foram capazes de desnaturar totalmente a fibra de colágeno. Já as propriedades emulsificantes do colágeno foram avaliadas através da estabilidade, microestrutura e reologia de emulsões simples óleo/água (O/A) estabilizadas por colágeno, verificando a influência do pH, tipo de ingrediente (pó e fibra de colágeno), concentração de proteína, hidrólise térmica do colágeno, conteúdo de proteína solúvel e processo de homogeneização. A estabilidade estérica e eletrostática das macro-emulsões aumentou com a concentração de proteína e com a redução do pH, respectivamente, sendo obtidas macro-emulsões estáveis, sem separação de fases, em sistemas ajustados para pH 3,5 e estabilizados por 0,5% (m/m) de fibra de colágeno não hidrolisada ou 3,0% (m/m) de pó de colágeno. Já as macro-emulsões estabilizadas por 0,5% (m/m) de fibra de colágeno parcialmente hidrolisado apresentaram separação de fases, sendo que parte da proteína solúvel produzida na hidrólise se deslocou para a fase aquosa, indicando que o processo de hidrólise diminuiu a capacidade da proteína de se ligar ao óleo. A hidrólise reduziu o conteúdo de proteína insolúvel responsável pela estabilização estérica, além de deslocar o ponto isoelétrico do hidrolisado de 8,8 para uma faixa de 7,4 a 4,5, diminuindo a capacidade de estabilização eletrostática do colágeno. As micro-emulsões homogeneizadas a altas pressões apresentaram-se mais estáveis, com gotas de menor polidispersão e diâmetro médio superficial entre 0,98 a 5,13 mm, cerca de seis vezes menor que aquelas observadas nas macro-emulsões. A viscosidade e elasticidade das micro-emulsões estabilizadas por colágeno hidrolisado diminuíram com o aumento da hidrólise do colágeno e da pressão de homogeneização, já que tais processos romperam a fibra de colágeno e a gota, deixando as micro-emulsões menos estruturadas. De maneira geral, foi possível a produção de emulsões ácidas estáveis a partir do colágeno, seja através da homogeneização em Ultra-Turrax ou em altas pressões, cada processo originando emulsões com estruturas e propriedades reológicas características / Abstract: Collagen is a protein derived from animal source with high availability in Brazil and some applications in food, cosmetics and pharmaceutical industries. To understand and improve the emulsifying properties of the collagen derived from bovine hide, the physicochemical characteristics of collagen fibers was initially determined and modified through thermal hydrolysis at temperatures ranging from 50 to 85°C for periods of 20 and 60 minutes. The hydrolysis process increased the protein solubility from 2.9% (w/w) to 33.0% (w/w) and the amount of molecules of low molecular mass, led to values until 37 kDa for the hydrolisates at 85°C/60min. It was verified that hydrolysis at 65°C and 85°C denaturated the collagen fiber, once the denaturation temperature of collagen fibers is around 64°C. Emulsifying properties of collagen was also studied on the the effects of the pH, type of ingredient, protein concentration, thermal hydrolysis of the collagen, soluble protein content and emulsification process. The stability, microstructure and rheology of oil-in-water emulsions stabilized by collagen were evaluated. The results showed that the steric and electrostatic stability of macroemulsions increased with the protein concentration and the reduction of pH, respectively, promoting the formation of stable macro-emulsions, without phase separation, at pH 3.5 and stabilized by 0.5% (w/w) collagen fibers or 3.0% (w/w) collagen powder. However, the macro-emulsions stabilized by 0.5% (w/w) hydrolysed collagen fiber showed phase separation. Part of the soluble protein produced in hydrolysis migrated to the aqueous phase, indicating that the hydrolysis process reduced the interaction between protein and oil. The hydrolysis decreased the insoluble protein content responsible by the structural stability of the emulsions and changed the isoelectric point of the collagen from 8.8 to a range of 7.4 to 4.5, decreasing the capacity of electrostatic stabilization of collagen. The micro-emulsions emulsyfied by highpressure was composed by droplets with low dispersion and small mean diameter (between 0.98 and 5.13 mm), six times lower than those observed values in the macroemulsions. The increase of the pressure and the hydrolysis process in the microemulsion stabilised by hydrolyzed collagen leds to a reduction in the viscosity and elasticity of the micro-emulsion stabilised by hydrolyzed collagen, probably attributed to the break of the droplets and collagen fiber in the valve pressure. Finally, it can be estimated the production of acid emulsions stabilizated by collagen, high pressure, being theirs structure and rheological properties differents / Mestrado / Mestre em Engenharia de Alimentos

Landfill leachates and thermal hydrolysis pretreated anaerobic digestion centrate can quench UV light at publicly owned treatment works (POTWs). Increased eutrophication, has led to tightening of nutrient discharge limits in some regions of the country. Biologically recalcitrant organic nitrogen, adds to effluent nitrogen making it difficult to meet these requirements. The study aimed at characterizing landfill leachate and centrate fractions to develop an understanding that might help design on-site treatment methods. Leachates varying in on-site treatment and ages were fractionated on basis of hydrophobic nature. Humic substances were the major UV light quenching fractions. Majority of the humic substances were > 1 kDa molecular weight cut off (MWCO) indicating that membrane treatment might be effective for UV quenching substances removal. UV absorbing substances were found to be more bio-refractory than organic carbon. Significant decrease in humic substances with long term landfilling indicated that age was important in determining the potential for leachates to impact the UV disinfection. Organic nitrogen was observed to be hydrophilic in nature (mostly < 1 kDa). Proteins which are easily biodegradable contributed around one-third of the organic nitrogen. For thermal hydrolysis centrate, the optimum treatment depended on particle size and hydrophobic nature. Biological treatment was observed to be more effective for the removal of organic matter and UV254 quenching substances for fractions < 300 kDa. Biological treatment had little impact on organic nitrogen. Coagulation-flocculation is an effective treatment for higher molecular weight (MW) fractions whereas a membrane bioreactor would be more suitable for smaller MW fractions. / Master of Science

Anaerobic digestion has been the preferred method for reducing and stabilizing waste sludge from biological wastewater treatment for over a century; however, as sludge volumes and disposal costs increase, there has been a desire to develop various methods for reducing the volume of sludge to be treated, improving the performance of the digesters, and increasing the energy value of the sludge. To this end, there have been numerous pretreatment and side-stream systems studied and developed over the past several decades with the overall goal of reducing the volume of biosolids to be disposed of in landfills or by land application. These technologies can be broken into four large groups: mechanical, thermal, chemical and biological, although there is often overlap between groups. This research approached the evaluations of these technologies through several methods in the hopes of developing effective tools for predicting the performance of each technology. Batch digestion studies mimicking several of these treatment methods and extensive analytical work on samples from full-scale installations were conducted to determine the effectiveness of each technology. From these studies a simple batch digestion methodology was developed to analyze the effectiveness of the Cannibal solids reduction process on wastewater streams that have never been exposed to it. Batch digestion of sludges pretreated with ozone, mechanical shear and sonication provided insight into the effectiveness of each technology. Extensive analytical work on samples collected from full-scale installations of thermal hydrolysis, mechanical shear and the Cannibal process provided some insight into the workings of each process and potential leads as to how to further characterize and evaluate each process. / Master of Science