Although achieving good activated sludge settleability is a key requirement for meeting effluent ... more Although achieving good activated sludge settleability is a key requirement for meeting effluent quality criteria, wastewater treatment plants often face undesired floc structure changes. Filamentous bulking has widely been studied, however, viscous sludge formation much less investigated so far. Our main goal was to find relationship between sludge floc structure and related rheological properties, moreover, to estimate pressure loss in pipe networks through hydrodynamic modelling of the non-Newtonian flows in case of well settling (ideal-like), viscous and filamentous sludge. Severe viscous and filamentous kinds of bulking were generated separately in continuous-flow lab-scale systems initially seeded with the same reference (ideal-like) biomass and the entire evolution of viscous and filamentous bulking was monitored. The results suggested correlation between the rheological properties and the floc structure transformations, and showed the most appropriate fit for the Herschel-Bulkley model (vs. Power-law and Bingham). Validated computational fluid dynamics studies estimated the pipe pressure loss in a wide Reynolds number range for the initial well settling (reference) and the final viscous and filamentous sludge as well. A practical standard modelling protocol was developed for improving energy efficiency of sludge pumping in different floc structure scenarios.
In 1999 the existing activated sludge unit of the Southpest Wastewater Treatment Plant was supple... more In 1999 the existing activated sludge unit of the Southpest Wastewater Treatment Plant was supplemented by a two-stage biofilter system aiming for nitrification and post-denitrification. In this arrangement excess biomass of the filters is wasted through the activated sludge unit, facilitating backseeding, and recirculation of the nitrate-rich effluent of the N-filter serves for decreasing the methanol demand of the DN-filter and for saving aeration energy at the same time. The paper reports on the development of an ASM1-based mathematical model that proved to be adequate for describing the interactions in the combined system and was used to compare the efficiency of different treatment options. Full-scale results verified that backseeding may considerably improve performance. However, nitrification ability of the activated sludge unit depends on the treatment temperature and, if unexpected, can be limited by insufficient oxygen supply. The upgrading possibilities outlined may serve...
The major part of wastewater treatment plants in Hungary face carbon deficiency regarding influen... more The major part of wastewater treatment plants in Hungary face carbon deficiency regarding influent wastewater quality. However, both the decrease of bioreactor inlet organic load and the improvement of biogas production require enhanced removal efficiency in primary settlers. According to the diverse technological aspects, in order to appropriately understand, describe and determine the preclarification process, complex and thorough investigations of both hydrodynamic and biochemical parameters are crucial.
Part-time aeration is frequently applied in activated sludge systems in order to decrease treatme... more Part-time aeration is frequently applied in activated sludge systems in order to decrease treatment costs by achieving nitrification and denitrification in the same basin. However, measurements and mathematical simulations carried out at the North-Budapest Wastewater Treatment Plant (Budapest, Hungary), clearly show that especially in the increasingly characteristic shortage of readily biodegradable carbon-source, this technique may lead to high effluent nitrate and/or ammonia concentrations at decreased temperatures. This situation may be worsened when co-digestion of external wastes with high N-content increase the ammonia concentration of sludge processing return flows. In these cases, denitrification should rather be enhanced in pre-anoxic zones. Pronounced pre-denitrification leads to better usage of the influent carbon-source and to considerably less methanol demand when dosing external carbon-source proves to be necessary.
In 1999 the existing activated sludge unit of the Southpest Wastewater Treatment Plant was supple... more In 1999 the existing activated sludge unit of the Southpest Wastewater Treatment Plant was supplemented by a two-stage biofilter system aiming for nitrification and post-denitrification. In this arrangement excess biomass of the filters is wasted through the activated sludge unit, facilitating backseeding, and recirculation of the nitrate-rich effluent of the N-filter serves for decreasing the methanol demand of the DN-filter and for saving aeration energy at the same time. The paper reports on the development of an ASM1-based mathematical model that proved to be adequate for describing the interactions in the combined system and was used to compare the efficiency of different treatment options. Full-scale results verified that backseeding may considerably improve performance. However, nitrification ability of the activated sludge unit depends on the treatment temperature and, if unexpected, can be limited by insufficient oxygen supply. The upgrading possibilities outlined may serve...
In order to stop eutrophication and protect the water quality of Lake Balaton, the canalization a... more In order to stop eutrophication and protect the water quality of Lake Balaton, the canalization and wastewater treatment system was redesigned in the late 70 s. Hence, regional sewer systems leading to sub-central treatment plants were established. Long retention times and long pressure sewer section, however, combined with the high sewage temperatures created a new environmental problem: the production of odorous and corrosive compounds such as hydrogen sulphide. In the present study, a preventive procedure to control anaerobic biodegradation processes in the sewage has been developed. It is based on the metabolic advantage of nitrate reduction over sulphate consumption. In a model experiment, problems deriving from the inappropriate application of nitrate addition were discovered, e.g. decreasing effectiveness by initiating undesired attached microbial growth, and denitrification and subsequent sludge loss in the secondary clarifier. The main concern of the system-specific procedu...
An ASM1-based mathematical model was developed for the description of the combined activated slud... more An ASM1-based mathematical model was developed for the description of the combined activated sludge-biofilter system of the Southpest Wastewater Treatment Plant, Budapest, Hungary. This model includes the interactions of the activated sludge and biofilter units, i.e. the influence of both the clarified activated sludge effluent and the backwashed nitrifying and denitrifying microorganisms. Concentration profile measurements have been carried out throughout the combined system in order to track the biological processes. Optimization possibilities of the existing combined plant were investigated by mathematical simulations under the different detected operational conditions. In these studies concentration data measured on separate days and the appropriate flow rates of the preclarified influent and the recycled streams registered at the treatment plant were used. Simulation results showed that N-removal of the activated sludge unit could be highly intensified by appropriate aeration, that would facilitate the efficient growth of backwashed biomass. However, in some cases, shortage of readily biodegradable carbon source proved to be the limit of the benefits available.
In the course of our investigations we tried to find a method for the bouquet qualification of wi... more In the course of our investigations we tried to find a method for the bouquet qualification of wines by gas chromatography. For this purpose, instead of aroma research studies requiring complex equipment and laboursome precise laboratory work, we developed a method for head space analysis functioning with simple experimental instruments and being sufficiently fast for serial routine work. By the method developed, the head space of a great number of samples taken from 7 different wine-types have been successfully examined. Errors of measurement were checked by standard deviation analysis and the values obtained (3,23%) were found satisfactory. According to the above, our head space analysis may provide a satisfactory basis for elaborating a method for the instrumental bouquet qualification of wines.
Knowledge of the lVIaillard reaction looks back to more than 70 years [1]. According to this reac... more Knowledge of the lVIaillard reaction looks back to more than 70 years [1]. According to this reaction, amino acids, compounds containing amino acids, and sugars and compounds degrading into sugars interact with one another under certain conditions. A chain reaction starts, the end products of which are sparingly soluble or more or less insoluble compounds, belonging to the group of melanoides. In spite of the emphasis laid by lVIaillard on the practical importance of the reaction (particularly in biology, agricultural sciences and geology), it raised no particular interest, and was soon forgotten. It was only in the fourties to sixties of this century that the attention of the researchers in two fields centered on this reaction. Its role and importance was recognized on the one hand in humus formation [2, 3], and on the other hand, it was made responsible for the non-enzymatic browning of foodstuffs
ÐAn activated sludge treatment plant of Sandoz and Ciba±Geigy (currently Novartis) had diculty me... more ÐAn activated sludge treatment plant of Sandoz and Ciba±Geigy (currently Novartis) had diculty meeting the euent total suspended solids (TSS) permit requirement of 40 mg l À1. The plant commonly contained small, weak¯ocs with a characteristic lack of ®laments. It was hypothesized that optimization of the plant's bioreactor arrangement (i.e. the manner in which the feed was introduced into the six activated sludge basins connected in series) would lead to stronger activated sludge¯ocs with ®lamentous backbones, and that these¯ocs would provide a clearer supernatant and be less sensitive to changes in the wastewater composition. In order to optimize the bioreactor arrangement, bench-scale experiments were carried out using two model activated sludge systems operated simultaneously. A better¯oc structure and consequently lower euent TSS concentrations were achieved in the system in which the in¯uent was split between basins 1 and 2 rather than being introduced into basin 1. Furthermore, an excess sludge removal strategy of controlling the MLSS concentration proved to be more favorable than that of maintaining a stable solids retention time (SRT). Through implementation of the results in the full-scale plant, the euent TSS values were stabilized well below the permitted level.
ÐIncreasingly stringent euent nitrogen criteria require that appropriate assessments of denitri®c... more ÐIncreasingly stringent euent nitrogen criteria require that appropriate assessments of denitri®cation rates be made to facilitate the design of wastewater treatment systems. A zero-headspace reactor was used in comparative denitri®cation studies as a reference system that totally excludes oxygen. An open reactor and a reactor with a¯oating lid were also operated simultaneously to determine how oxygen input into typical laboratory reactors might in¯uence observed denitri®cation results. Preclari®ed in¯uent and activated sludge from a denitrifying domestic wastewater treatment plant were used as the carbon and biomass source, and KNO 3 was used as the nitrate source. The impact of oxygen penetration proved to be highly dependent on the denitri®cation rate. The in¯uence of the design of the experimental system was small when rapid nitrate consumption occurred, whereas oxygen penetration had a severe impact at low denitri®cation rates.
In order to reduce the pollution load of the Danube, the North-Budapest Wastewater Treatment Plan... more In order to reduce the pollution load of the Danube, the North-Budapest Wastewater Treatment Plant has been upgraded to enhanced nitrogen removal by establishing a new activated sludge treatment line and modifying the existing unit for nitrification and denitrification. As both the influent flow rate and the influent chemical oxygen demand (COD), biological oxygen demand (BOD5) and total suspended solids (TSS) concentration levels remained far below the design values, setting one fourth of the reactor volume out of operation in the Old Line, and operating the nitrification reactor of the New Line with part-time aeration proved to be possible. Analytical data as well as simulation studies supported the advantage of the intermittent-aeration process in efficient N-removal. However, the lengths of the aerated periods have to be increased with decreasing temperature, and thereby effluent total nitrogen (TN) concentration can increase due to decreasing denitrification efficiency. Potenti...
A survey has been carried out involving 55 Hungarian wastewater treatment plants in order to eval... more A survey has been carried out involving 55 Hungarian wastewater treatment plants in order to evaluate the wastewater quality, the applied technologies and the resultant problems. Characteristically the treatment temperature is very wide-ranging from less than 10 °C to higher than 26 °C. Influent quality proved to be very variable regarding both the organic matter (typical COD concentration range 600–1,200 mg l−1) and the nitrogen content (typical NH4-N concentration range 40–80 mg l−1). As a consequence, significant differences have been found in the carbon availability for denitrification from site to site. Forty two percent of the influents proved to lack an appropriate carbon source. As a consequence of carbon deficiency as well as technologies designed and/or operated with non-efficient denitrification, rising sludge in the secondary clarifiers typically occurs especially in summer. In case studies, application of intermittent aeration, low DO reactors, biofilters and anammox pr...
The purpose of the experiments was to increase the rate of activated sludge denitrification in th... more The purpose of the experiments was to increase the rate of activated sludge denitrification in the combined biological treatment system of the Southpest Wastewater Treatment Plant in order to gain savings in cost and energy and improve process efficiency. Initial profile measurements revealed excess denitrification capacity of the preclarified wastewater. As a consequence, flow of nitrification filter effluent recirculated to the anoxic activated sludge basins was increased from 23,000 m 3 d 21 to 42,288 m 3 d 21 at an average preclarified influent flow of 64,843 m 3 d 21 , Both simulation studies and microbiological investigations suggested that activated sludge nitrification, achieved despite the low SRT (2-3 days), was initiated by the backseeding from the nitrification filters and facilitated by the decreased oxygen demand of the influent organics used for denitrification. With the improved activated sludge denitrification, methanol demand could be decreased to about half of the initial value. With the increased efficiency of the activated sludge pre-denitrification, plant effluent COD levels decreased from 40-70 mg l 21 to , 30-45 mg l 21 due to the decreased likelihood of methanol overdosing in the denitrification filter
The purpose of the paper is to examine the factors that influence the deterioration of denitrific... more The purpose of the paper is to examine the factors that influence the deterioration of denitrification in open anoxic reactors. For this investigation an ASM 1-based simulation model was developed and successfully applied to fit data from batch experiments carried out in lab-scale reactor vessels (uncovered and covered) using both clarified domestic wastewater and synthetic wastewater. Applying the verified model, simulation studies were performed to investigate the effects of available denitrifiable substrate, biomass concentration, oxygen transfer rate, and temperature on deterioration of denitrification in open anoxic reactors. It has been shown that oxygen entering an anoxic reactor through the surface may not just affect denitrification metabolically, but also kinetically, due to increased dissolved oxygen (DO) concentration exerting an inhibitory effect on the denitrification rate. When the exogenous substrate concentration in the reactor vessel is high enough for a high consumption rate, the DO concentration is kept low. The higher the biomass concentration, and thereby the consumption rate of endogenous substrate, the lower the DO concentration during the low-rate denitrification phase. At low substrate removal rates, decreasing temperature will cause the DO concentration in anoxic vessels to increase. The results suggest that assuring removal of available exogenous carbon source at high rate by staging of open anoxic bioreactors may significantly improve denitrification efficiency.
ABSTRACT Im Laufe unserer Forschungen versuchten wir eine solche gaschromatographische Methode zu... more ABSTRACT Im Laufe unserer Forschungen versuchten wir eine solche gaschromatographische Methode zur Bouquetqualifizierung zu entwickeln, die die sensorische Qualifizierung von Weinen zu ersetzen bzw. auf eine objektive Weise zu ergänzen vermag. Wir entwickelten daher — ab-weichend von jener Aromaforschungsrichtung, die komplizierte Apparaturen und eine lange, präzise Versuchsarbeit benötigt — eine Methode zur Gasphasenanalyse, die nur eine einfache Versuchseinrichtung erfordert und genügend rasch ist, um als serienmäßige, für Routineuntersuchungen geeignete Methode zu dienen. Mittels der entwickelten Methode wurde die Gasphase über der Flüssigkeit von 7 Weintypen in einer großen Anzahl von Proben untersucht. Der Meßfehler wurde durch Streuungsanalyse bestimmt und der erhaltene Wert von 3,23% als genügend genau angenommen. Aus diesem Grund ist die beschriebene Methodik der Gasphasenanalyse geeignet, als Grundlage der zu entwickelnden instrumentellen Duftqualifizierungsmethode zu dienen.
The use of respirometric data for the evaluation of intrinsic biodegradation kinetic parameters f... more The use of respirometric data for the evaluation of intrinsic biodegradation kinetic parameters for single organic compounds is discussed. Emphasis is placed on the preliminary assessment of the data set to determine whether it is suitable for kinetic parameter estimation. Careful preliminary examination of the data avoids attempting parameter estimation with unacceptable data. Furthermore, the use of unbiased respirometric data
In order to decrease the organic load on the downstream domestic wastewater treatment plant, a th... more In order to decrease the organic load on the downstream domestic wastewater treatment plant, a three stage, fully aerated activated sludge system was established for the pretreatment of a vegetable processing wastewater. The results of the research verified that this design was inappropriate at the given, highly fluctuating wastewater quality. Nitrate formed through nitrification of the pea processing wastewater could not be denitrified, thus rising sludge occurred in the secondary clarifiers. On the other hand, during the corn campaign, severe deterioration of the COD (Chemical Oxygen Demand) removal efficiency, as well as the overproduction of extracellular polysaccharides leading to viscous bulking, were caused by the extremely high C/N ratio. In order to efficiently treat the wastewater of the vegetable processing industry, establishment of highly flexible systems with unaerated first stage proves to be necessary.
Although achieving good activated sludge settleability is a key requirement for meeting effluent ... more Although achieving good activated sludge settleability is a key requirement for meeting effluent quality criteria, wastewater treatment plants often face undesired floc structure changes. Filamentous bulking has widely been studied, however, viscous sludge formation much less investigated so far. Our main goal was to find relationship between sludge floc structure and related rheological properties, moreover, to estimate pressure loss in pipe networks through hydrodynamic modelling of the non-Newtonian flows in case of well settling (ideal-like), viscous and filamentous sludge. Severe viscous and filamentous kinds of bulking were generated separately in continuous-flow lab-scale systems initially seeded with the same reference (ideal-like) biomass and the entire evolution of viscous and filamentous bulking was monitored. The results suggested correlation between the rheological properties and the floc structure transformations, and showed the most appropriate fit for the Herschel-Bulkley model (vs. Power-law and Bingham). Validated computational fluid dynamics studies estimated the pipe pressure loss in a wide Reynolds number range for the initial well settling (reference) and the final viscous and filamentous sludge as well. A practical standard modelling protocol was developed for improving energy efficiency of sludge pumping in different floc structure scenarios.
In 1999 the existing activated sludge unit of the Southpest Wastewater Treatment Plant was supple... more In 1999 the existing activated sludge unit of the Southpest Wastewater Treatment Plant was supplemented by a two-stage biofilter system aiming for nitrification and post-denitrification. In this arrangement excess biomass of the filters is wasted through the activated sludge unit, facilitating backseeding, and recirculation of the nitrate-rich effluent of the N-filter serves for decreasing the methanol demand of the DN-filter and for saving aeration energy at the same time. The paper reports on the development of an ASM1-based mathematical model that proved to be adequate for describing the interactions in the combined system and was used to compare the efficiency of different treatment options. Full-scale results verified that backseeding may considerably improve performance. However, nitrification ability of the activated sludge unit depends on the treatment temperature and, if unexpected, can be limited by insufficient oxygen supply. The upgrading possibilities outlined may serve...
The major part of wastewater treatment plants in Hungary face carbon deficiency regarding influen... more The major part of wastewater treatment plants in Hungary face carbon deficiency regarding influent wastewater quality. However, both the decrease of bioreactor inlet organic load and the improvement of biogas production require enhanced removal efficiency in primary settlers. According to the diverse technological aspects, in order to appropriately understand, describe and determine the preclarification process, complex and thorough investigations of both hydrodynamic and biochemical parameters are crucial.
Part-time aeration is frequently applied in activated sludge systems in order to decrease treatme... more Part-time aeration is frequently applied in activated sludge systems in order to decrease treatment costs by achieving nitrification and denitrification in the same basin. However, measurements and mathematical simulations carried out at the North-Budapest Wastewater Treatment Plant (Budapest, Hungary), clearly show that especially in the increasingly characteristic shortage of readily biodegradable carbon-source, this technique may lead to high effluent nitrate and/or ammonia concentrations at decreased temperatures. This situation may be worsened when co-digestion of external wastes with high N-content increase the ammonia concentration of sludge processing return flows. In these cases, denitrification should rather be enhanced in pre-anoxic zones. Pronounced pre-denitrification leads to better usage of the influent carbon-source and to considerably less methanol demand when dosing external carbon-source proves to be necessary.
In 1999 the existing activated sludge unit of the Southpest Wastewater Treatment Plant was supple... more In 1999 the existing activated sludge unit of the Southpest Wastewater Treatment Plant was supplemented by a two-stage biofilter system aiming for nitrification and post-denitrification. In this arrangement excess biomass of the filters is wasted through the activated sludge unit, facilitating backseeding, and recirculation of the nitrate-rich effluent of the N-filter serves for decreasing the methanol demand of the DN-filter and for saving aeration energy at the same time. The paper reports on the development of an ASM1-based mathematical model that proved to be adequate for describing the interactions in the combined system and was used to compare the efficiency of different treatment options. Full-scale results verified that backseeding may considerably improve performance. However, nitrification ability of the activated sludge unit depends on the treatment temperature and, if unexpected, can be limited by insufficient oxygen supply. The upgrading possibilities outlined may serve...
In order to stop eutrophication and protect the water quality of Lake Balaton, the canalization a... more In order to stop eutrophication and protect the water quality of Lake Balaton, the canalization and wastewater treatment system was redesigned in the late 70 s. Hence, regional sewer systems leading to sub-central treatment plants were established. Long retention times and long pressure sewer section, however, combined with the high sewage temperatures created a new environmental problem: the production of odorous and corrosive compounds such as hydrogen sulphide. In the present study, a preventive procedure to control anaerobic biodegradation processes in the sewage has been developed. It is based on the metabolic advantage of nitrate reduction over sulphate consumption. In a model experiment, problems deriving from the inappropriate application of nitrate addition were discovered, e.g. decreasing effectiveness by initiating undesired attached microbial growth, and denitrification and subsequent sludge loss in the secondary clarifier. The main concern of the system-specific procedu...
An ASM1-based mathematical model was developed for the description of the combined activated slud... more An ASM1-based mathematical model was developed for the description of the combined activated sludge-biofilter system of the Southpest Wastewater Treatment Plant, Budapest, Hungary. This model includes the interactions of the activated sludge and biofilter units, i.e. the influence of both the clarified activated sludge effluent and the backwashed nitrifying and denitrifying microorganisms. Concentration profile measurements have been carried out throughout the combined system in order to track the biological processes. Optimization possibilities of the existing combined plant were investigated by mathematical simulations under the different detected operational conditions. In these studies concentration data measured on separate days and the appropriate flow rates of the preclarified influent and the recycled streams registered at the treatment plant were used. Simulation results showed that N-removal of the activated sludge unit could be highly intensified by appropriate aeration, that would facilitate the efficient growth of backwashed biomass. However, in some cases, shortage of readily biodegradable carbon source proved to be the limit of the benefits available.
In the course of our investigations we tried to find a method for the bouquet qualification of wi... more In the course of our investigations we tried to find a method for the bouquet qualification of wines by gas chromatography. For this purpose, instead of aroma research studies requiring complex equipment and laboursome precise laboratory work, we developed a method for head space analysis functioning with simple experimental instruments and being sufficiently fast for serial routine work. By the method developed, the head space of a great number of samples taken from 7 different wine-types have been successfully examined. Errors of measurement were checked by standard deviation analysis and the values obtained (3,23%) were found satisfactory. According to the above, our head space analysis may provide a satisfactory basis for elaborating a method for the instrumental bouquet qualification of wines.
Knowledge of the lVIaillard reaction looks back to more than 70 years [1]. According to this reac... more Knowledge of the lVIaillard reaction looks back to more than 70 years [1]. According to this reaction, amino acids, compounds containing amino acids, and sugars and compounds degrading into sugars interact with one another under certain conditions. A chain reaction starts, the end products of which are sparingly soluble or more or less insoluble compounds, belonging to the group of melanoides. In spite of the emphasis laid by lVIaillard on the practical importance of the reaction (particularly in biology, agricultural sciences and geology), it raised no particular interest, and was soon forgotten. It was only in the fourties to sixties of this century that the attention of the researchers in two fields centered on this reaction. Its role and importance was recognized on the one hand in humus formation [2, 3], and on the other hand, it was made responsible for the non-enzymatic browning of foodstuffs
ÐAn activated sludge treatment plant of Sandoz and Ciba±Geigy (currently Novartis) had diculty me... more ÐAn activated sludge treatment plant of Sandoz and Ciba±Geigy (currently Novartis) had diculty meeting the euent total suspended solids (TSS) permit requirement of 40 mg l À1. The plant commonly contained small, weak¯ocs with a characteristic lack of ®laments. It was hypothesized that optimization of the plant's bioreactor arrangement (i.e. the manner in which the feed was introduced into the six activated sludge basins connected in series) would lead to stronger activated sludge¯ocs with ®lamentous backbones, and that these¯ocs would provide a clearer supernatant and be less sensitive to changes in the wastewater composition. In order to optimize the bioreactor arrangement, bench-scale experiments were carried out using two model activated sludge systems operated simultaneously. A better¯oc structure and consequently lower euent TSS concentrations were achieved in the system in which the in¯uent was split between basins 1 and 2 rather than being introduced into basin 1. Furthermore, an excess sludge removal strategy of controlling the MLSS concentration proved to be more favorable than that of maintaining a stable solids retention time (SRT). Through implementation of the results in the full-scale plant, the euent TSS values were stabilized well below the permitted level.
ÐIncreasingly stringent euent nitrogen criteria require that appropriate assessments of denitri®c... more ÐIncreasingly stringent euent nitrogen criteria require that appropriate assessments of denitri®cation rates be made to facilitate the design of wastewater treatment systems. A zero-headspace reactor was used in comparative denitri®cation studies as a reference system that totally excludes oxygen. An open reactor and a reactor with a¯oating lid were also operated simultaneously to determine how oxygen input into typical laboratory reactors might in¯uence observed denitri®cation results. Preclari®ed in¯uent and activated sludge from a denitrifying domestic wastewater treatment plant were used as the carbon and biomass source, and KNO 3 was used as the nitrate source. The impact of oxygen penetration proved to be highly dependent on the denitri®cation rate. The in¯uence of the design of the experimental system was small when rapid nitrate consumption occurred, whereas oxygen penetration had a severe impact at low denitri®cation rates.
In order to reduce the pollution load of the Danube, the North-Budapest Wastewater Treatment Plan... more In order to reduce the pollution load of the Danube, the North-Budapest Wastewater Treatment Plant has been upgraded to enhanced nitrogen removal by establishing a new activated sludge treatment line and modifying the existing unit for nitrification and denitrification. As both the influent flow rate and the influent chemical oxygen demand (COD), biological oxygen demand (BOD5) and total suspended solids (TSS) concentration levels remained far below the design values, setting one fourth of the reactor volume out of operation in the Old Line, and operating the nitrification reactor of the New Line with part-time aeration proved to be possible. Analytical data as well as simulation studies supported the advantage of the intermittent-aeration process in efficient N-removal. However, the lengths of the aerated periods have to be increased with decreasing temperature, and thereby effluent total nitrogen (TN) concentration can increase due to decreasing denitrification efficiency. Potenti...
A survey has been carried out involving 55 Hungarian wastewater treatment plants in order to eval... more A survey has been carried out involving 55 Hungarian wastewater treatment plants in order to evaluate the wastewater quality, the applied technologies and the resultant problems. Characteristically the treatment temperature is very wide-ranging from less than 10 °C to higher than 26 °C. Influent quality proved to be very variable regarding both the organic matter (typical COD concentration range 600–1,200 mg l−1) and the nitrogen content (typical NH4-N concentration range 40–80 mg l−1). As a consequence, significant differences have been found in the carbon availability for denitrification from site to site. Forty two percent of the influents proved to lack an appropriate carbon source. As a consequence of carbon deficiency as well as technologies designed and/or operated with non-efficient denitrification, rising sludge in the secondary clarifiers typically occurs especially in summer. In case studies, application of intermittent aeration, low DO reactors, biofilters and anammox pr...
The purpose of the experiments was to increase the rate of activated sludge denitrification in th... more The purpose of the experiments was to increase the rate of activated sludge denitrification in the combined biological treatment system of the Southpest Wastewater Treatment Plant in order to gain savings in cost and energy and improve process efficiency. Initial profile measurements revealed excess denitrification capacity of the preclarified wastewater. As a consequence, flow of nitrification filter effluent recirculated to the anoxic activated sludge basins was increased from 23,000 m 3 d 21 to 42,288 m 3 d 21 at an average preclarified influent flow of 64,843 m 3 d 21 , Both simulation studies and microbiological investigations suggested that activated sludge nitrification, achieved despite the low SRT (2-3 days), was initiated by the backseeding from the nitrification filters and facilitated by the decreased oxygen demand of the influent organics used for denitrification. With the improved activated sludge denitrification, methanol demand could be decreased to about half of the initial value. With the increased efficiency of the activated sludge pre-denitrification, plant effluent COD levels decreased from 40-70 mg l 21 to , 30-45 mg l 21 due to the decreased likelihood of methanol overdosing in the denitrification filter
The purpose of the paper is to examine the factors that influence the deterioration of denitrific... more The purpose of the paper is to examine the factors that influence the deterioration of denitrification in open anoxic reactors. For this investigation an ASM 1-based simulation model was developed and successfully applied to fit data from batch experiments carried out in lab-scale reactor vessels (uncovered and covered) using both clarified domestic wastewater and synthetic wastewater. Applying the verified model, simulation studies were performed to investigate the effects of available denitrifiable substrate, biomass concentration, oxygen transfer rate, and temperature on deterioration of denitrification in open anoxic reactors. It has been shown that oxygen entering an anoxic reactor through the surface may not just affect denitrification metabolically, but also kinetically, due to increased dissolved oxygen (DO) concentration exerting an inhibitory effect on the denitrification rate. When the exogenous substrate concentration in the reactor vessel is high enough for a high consumption rate, the DO concentration is kept low. The higher the biomass concentration, and thereby the consumption rate of endogenous substrate, the lower the DO concentration during the low-rate denitrification phase. At low substrate removal rates, decreasing temperature will cause the DO concentration in anoxic vessels to increase. The results suggest that assuring removal of available exogenous carbon source at high rate by staging of open anoxic bioreactors may significantly improve denitrification efficiency.
ABSTRACT Im Laufe unserer Forschungen versuchten wir eine solche gaschromatographische Methode zu... more ABSTRACT Im Laufe unserer Forschungen versuchten wir eine solche gaschromatographische Methode zur Bouquetqualifizierung zu entwickeln, die die sensorische Qualifizierung von Weinen zu ersetzen bzw. auf eine objektive Weise zu ergänzen vermag. Wir entwickelten daher — ab-weichend von jener Aromaforschungsrichtung, die komplizierte Apparaturen und eine lange, präzise Versuchsarbeit benötigt — eine Methode zur Gasphasenanalyse, die nur eine einfache Versuchseinrichtung erfordert und genügend rasch ist, um als serienmäßige, für Routineuntersuchungen geeignete Methode zu dienen. Mittels der entwickelten Methode wurde die Gasphase über der Flüssigkeit von 7 Weintypen in einer großen Anzahl von Proben untersucht. Der Meßfehler wurde durch Streuungsanalyse bestimmt und der erhaltene Wert von 3,23% als genügend genau angenommen. Aus diesem Grund ist die beschriebene Methodik der Gasphasenanalyse geeignet, als Grundlage der zu entwickelnden instrumentellen Duftqualifizierungsmethode zu dienen.
The use of respirometric data for the evaluation of intrinsic biodegradation kinetic parameters f... more The use of respirometric data for the evaluation of intrinsic biodegradation kinetic parameters for single organic compounds is discussed. Emphasis is placed on the preliminary assessment of the data set to determine whether it is suitable for kinetic parameter estimation. Careful preliminary examination of the data avoids attempting parameter estimation with unacceptable data. Furthermore, the use of unbiased respirometric data
In order to decrease the organic load on the downstream domestic wastewater treatment plant, a th... more In order to decrease the organic load on the downstream domestic wastewater treatment plant, a three stage, fully aerated activated sludge system was established for the pretreatment of a vegetable processing wastewater. The results of the research verified that this design was inappropriate at the given, highly fluctuating wastewater quality. Nitrate formed through nitrification of the pea processing wastewater could not be denitrified, thus rising sludge occurred in the secondary clarifiers. On the other hand, during the corn campaign, severe deterioration of the COD (Chemical Oxygen Demand) removal efficiency, as well as the overproduction of extracellular polysaccharides leading to viscous bulking, were caused by the extremely high C/N ratio. In order to efficiently treat the wastewater of the vegetable processing industry, establishment of highly flexible systems with unaerated first stage proves to be necessary.
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Papers by Á. Jobbágy