Activated sludge processes are key technologies to treat wastewater. These biological processes produce huge amounts of waste activated sludge (WAS), now commonly called biosolids. Mechanical, thermal, and/or chemical WAS conditioning techniques have been proposed to reduce the sludge burden. The ultrasonic treatment of WAS is quite novel.The present paper reports on extensive investigations using an ultrasonic treatment of WAS, to study its potential to meet one or all of four objectives: (1) reduce WAS quantities; (2) achieve a better dewaterability; (3) provoke a release of soluble chemical oxygen demand (COD) from the biosolids, preferably transformed into biodegradable organics; and (4) possibly destroy the filamentous microorganisms responsible for sludge bulking. Although meeting these objectives would help to solve the problems cited, the energy consumption could be a considerable drawback: the paper will thus assess whether all or some objectives are met, and at what operational cost.A literature survey defines the occurring phenomena (cavitation) and the important operation parameters [such as frequency, duration, specific energy input (SE)].The experiments are carried out in a batch reactor of volume up to 2.3 L. The ultrasonic equipment consisted of a generator, a converter, and a sonotrode, supplied by Alpha Ultrasonics under the brand name of Telsonic. Three different kinds of sludge were tested, with different concentrations of dry solids (DS) between approximately 3.5 and 14 g DS/L WAS. Ultrasonic energy was introduced in a continuous manner (against possible pulsed operation). The major operational parameters studied include duration of the ultrasonic treatment and specific energy input. The applied frequency was set at 20 kHz.The release of COD from the WAS phase into the filtrate phase is a function of the specific energy input with yields of nearly 30% achievable at SE values of 30,000 kJ/kg DS. A major fraction of the COD is transformed into biodegradable organics (BOD). The reduction in DS fraction of the sludge is proportional to the COD release rates.Although the DS content is reduced, the dewaterability of the sludge is not improved. This reflects itself in increased filtration times during vacuum filtration and in increased values of the capillary suction time (CST). This more difficult dewaterability is the result of considerably reduced floc sizes, offering an extended surface area: more surface water is bound (CST increases) and the filterability decreases as a result of clogging of the cake. To reach the same dryness as for the untreated cake, the required dosage of polyelectrolyte is nearly doubled when the SE of the ultrasound treatment is increased from 7500 to 20,000 kJ/kg DS.The ultrasonic reduction of filamentous WAS organisms is not conclusive and very little effect is seen at low intensities and short treatment durations. Microscopic analysis of the WAS identified the dominant presence of Actynomyces.The rele
{"title":"Ultrasonic treatment of waste activated sludge","authors":"R. Dewil, J. Baeyens, Rebecca Goutvrind","doi":"10.1002/EP.10130","DOIUrl":"https://doi.org/10.1002/EP.10130","url":null,"abstract":"Activated sludge processes are key technologies to treat wastewater. These biological processes produce huge amounts of waste activated sludge (WAS), now commonly called biosolids. Mechanical, thermal, and/or chemical WAS conditioning techniques have been proposed to reduce the sludge burden. The ultrasonic treatment of WAS is quite novel.The present paper reports on extensive investigations using an ultrasonic treatment of WAS, to study its potential to meet one or all of four objectives: (1) reduce WAS quantities; (2) achieve a better dewaterability; (3) provoke a release of soluble chemical oxygen demand (COD) from the biosolids, preferably transformed into biodegradable organics; and (4) possibly destroy the filamentous microorganisms responsible for sludge bulking. Although meeting these objectives would help to solve the problems cited, the energy consumption could be a considerable drawback: the paper will thus assess whether all or some objectives are met, and at what operational cost.A literature survey defines the occurring phenomena (cavitation) and the important operation parameters [such as frequency, duration, specific energy input (SE)].The experiments are carried out in a batch reactor of volume up to 2.3 L. The ultrasonic equipment consisted of a generator, a converter, and a sonotrode, supplied by Alpha Ultrasonics under the brand name of Telsonic. Three different kinds of sludge were tested, with different concentrations of dry solids (DS) between approximately 3.5 and 14 g DS/L WAS. Ultrasonic energy was introduced in a continuous manner (against possible pulsed operation). The major operational parameters studied include duration of the ultrasonic treatment and specific energy input. The applied frequency was set at 20 kHz.The release of COD from the WAS phase into the filtrate phase is a function of the specific energy input with yields of nearly 30% achievable at SE values of 30,000 kJ/kg DS. A major fraction of the COD is transformed into biodegradable organics (BOD). The reduction in DS fraction of the sludge is proportional to the COD release rates.Although the DS content is reduced, the dewaterability of the sludge is not improved. This reflects itself in increased filtration times during vacuum filtration and in increased values of the capillary suction time (CST). This more difficult dewaterability is the result of considerably reduced floc sizes, offering an extended surface area: more surface water is bound (CST increases) and the filterability decreases as a result of clogging of the cake. To reach the same dryness as for the untreated cake, the required dosage of polyelectrolyte is nearly doubled when the SE of the ultrasound treatment is increased from 7500 to 20,000 kJ/kg DS.The ultrasonic reduction of filamentous WAS organisms is not conclusive and very little effect is seen at low intensities and short treatment durations. Microscopic analysis of the WAS identified the dominant presence of Actynomyces.The rele","PeriodicalId":11769,"journal":{"name":"Environmental Progress","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73256290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Environmental Protection Agency has recently proposed a reduction in mercury emissions from coal-fired power plants. There are two broad approaches under development to controlling mercury emissions from coal-fired electric utility boilers. (1) powdered activated carbon (PAC) injection; and (2) multipollutant control, in which Hg capture is enhanced in existing and new sulfur dioxide (SO{sub 2}), nitrogen oxides (NOx), and particulate matter (PM) control devices. To help inform the recent EPA rulemaking proposal, estimates of performance levels and related costs associated with the above mercury control approaches were developed. This work presents these estimates. Estimates of cost for PAC injection range from 0.003 to 3.096 mills/kWb. In general, the higher costs are associated with the plants using spray dryers and electrostatic precipitators (ESPs) or plants using hot-side ESPs, which represent a minority of power plants. Excluding these plants, cost estimates range between 0.003 and 1.903 mills/kWh. At the low end of the cost ranges, 0.003 mills/kWb, it is assumed that no additional control technologies are needed, but mercury monitoring will be necessary. In these cases, high mercury removal may be the result of the type of NOx and SO{sub 2} control measures currently used, such as combinations of selective catalyticmore » reduction and wet flue gas desulfurization or spray drier absorbers with fabric filters on bituminous coal-fired boilers. Because mercury control approaches are under development at present, cost and performance estimates are preliminary and are expected to be refined as mercury control technologies are matured to commercial status. Factors that may affect the performance of these technologies include speciation of mercury in flue gas, the characteristics of the sorbent, and the type(s) of PM, NOx, and SO, controls used.« less
{"title":"Preliminary estimates of performance and cost of mercury emission control technology applications on electric utility boilers: An update","authors":"R. Srivastava, J. Staudt, W. Jozewicz","doi":"10.1002/EP.10057","DOIUrl":"https://doi.org/10.1002/EP.10057","url":null,"abstract":"The Environmental Protection Agency has recently proposed a reduction in mercury emissions from coal-fired power plants. There are two broad approaches under development to controlling mercury emissions from coal-fired electric utility boilers. (1) powdered activated carbon (PAC) injection; and (2) multipollutant control, in which Hg capture is enhanced in existing and new sulfur dioxide (SO{sub 2}), nitrogen oxides (NOx), and particulate matter (PM) control devices. To help inform the recent EPA rulemaking proposal, estimates of performance levels and related costs associated with the above mercury control approaches were developed. This work presents these estimates. Estimates of cost for PAC injection range from 0.003 to 3.096 mills/kWb. In general, the higher costs are associated with the plants using spray dryers and electrostatic precipitators (ESPs) or plants using hot-side ESPs, which represent a minority of power plants. Excluding these plants, cost estimates range between 0.003 and 1.903 mills/kWh. At the low end of the cost ranges, 0.003 mills/kWb, it is assumed that no additional control technologies are needed, but mercury monitoring will be necessary. In these cases, high mercury removal may be the result of the type of NOx and SO{sub 2} control measures currently used, such as combinations of selective catalyticmore » reduction and wet flue gas desulfurization or spray drier absorbers with fabric filters on bituminous coal-fired boilers. Because mercury control approaches are under development at present, cost and performance estimates are preliminary and are expected to be refined as mercury control technologies are matured to commercial status. Factors that may affect the performance of these technologies include speciation of mercury in flue gas, the characteristics of the sorbent, and the type(s) of PM, NOx, and SO, controls used.« less","PeriodicalId":11769,"journal":{"name":"Environmental Progress","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79053818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chlorine is commonly added as a disinfectant to potable water before distribution and to wastewater before discharge. The chlorine residual is usually monitored to verify proper disinfectant dose and to ensure adequate pathogen kill before wastewater discharge. Measuring chlorine residual usually requires time-intensive techniques, whereas the measurement of oxidation-reduction potential (ORP) is a possible alternative method with real-time results. Experiments were conducted in which inactivation of total coliform, E. coli, and enterococci was measured with chlorine dose, and ORP was evaluated as a predictor of kill of these organisms. Raising ORP through chlorination was effective at disinfection, yet disinfection effectiveness was found to be not well predicted with ORP measurements.
{"title":"Oxidation reduction potential as a measure of disinfection effectiveness for chlorination of wastewater","authors":"J. Bergendahl, L. Stevens","doi":"10.1002/EP.10074","DOIUrl":"https://doi.org/10.1002/EP.10074","url":null,"abstract":"Chlorine is commonly added as a disinfectant to potable water before distribution and to wastewater before discharge. The chlorine residual is usually monitored to verify proper disinfectant dose and to ensure adequate pathogen kill before wastewater discharge. Measuring chlorine residual usually requires time-intensive techniques, whereas the measurement of oxidation-reduction potential (ORP) is a possible alternative method with real-time results. Experiments were conducted in which inactivation of total coliform, E. coli, and enterococci was measured with chlorine dose, and ORP was evaluated as a predictor of kill of these organisms. Raising ORP through chlorination was effective at disinfection, yet disinfection effectiveness was found to be not well predicted with ORP measurements.","PeriodicalId":11769,"journal":{"name":"Environmental Progress","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85591402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recycling and reuse of materials are among the most important pollution prevention strategies. In many cases, direct recycling/reuse of process and waste streams may not be feasible because of the intolerable levels of contaminants that can be detrimental to the process performance or can build up to unacceptable levels. Therefore, interception may be used to selectively remove pollutants from the process streams using separation devices or interceptors. In this work, we develop a systematic procedure for the simultaneous synthesis of material reuse and interception networks. A structural representation of the solution alternatives is first presented using a source-interception-sink framework. Then, a generally applicable mathematical formulation is developed. Because of the nonconvexities associated with the general mathematical program, we invoke a number of simplifying assumptions to facilitate reformulation of the problem into a linear program. The concepts of source substreams and interceptor decomposition were used to facilitate the problem reformulation. Additionally, the tasks of assessing interceptor performance and cost were transformed into presynthesis calculations that can be conducted a priori without compromising the accuracy of the models. The problem reformulation yields a linear program that can be solved globally. A case study is solved to illustrate the developed procedure.
{"title":"Simultaneous synthesis of waste interception and material reuse networks: Problem reformulation for global optimization","authors":"F. Gabriel, M. El‐Halwagi","doi":"10.1002/EP.10081","DOIUrl":"https://doi.org/10.1002/EP.10081","url":null,"abstract":"Recycling and reuse of materials are among the most important pollution prevention strategies. In many cases, direct recycling/reuse of process and waste streams may not be feasible because of the intolerable levels of contaminants that can be detrimental to the process performance or can build up to unacceptable levels. Therefore, interception may be used to selectively remove pollutants from the process streams using separation devices or interceptors. In this work, we develop a systematic procedure for the simultaneous synthesis of material reuse and interception networks. A structural representation of the solution alternatives is first presented using a source-interception-sink framework. Then, a generally applicable mathematical formulation is developed. Because of the nonconvexities associated with the general mathematical program, we invoke a number of simplifying assumptions to facilitate reformulation of the problem into a linear program. The concepts of source substreams and interceptor decomposition were used to facilitate the problem reformulation. Additionally, the tasks of assessing interceptor performance and cost were transformed into presynthesis calculations that can be conducted a priori without compromising the accuracy of the models. The problem reformulation yields a linear program that can be solved globally. A case study is solved to illustrate the developed procedure.","PeriodicalId":11769,"journal":{"name":"Environmental Progress","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77980412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
INTRODUCTION Resource management has always been a priority for mankind. From the early ages, when it was a fight for survival, humans have learned the importance of resource conservation. Today, the focus of resource management has not just stopped at the conservation of food but has evolved and entails an even larger picture. Moreover, technological advancements and growing population have added an additional burden on Mother Nature and her resources [1]. For instance, the uncontrolled chopping of trees for human use has not only resulted in loss of forests but has also increased environmental pollution. Humankind now understands the consequences of its actions and has come to terms with the fact that the resources are limited and should be preserved and conserved for future generations. This concept of sustainability, and the development stemming from it, has been applied to a variety of actions that have been the foremost consumers of resources for years. The building industry is one of the largest consumers in terms of natural resources, and one of the largest producers of pollution thereafter, which has been a cause for concern for scientists. According to the U.S. Green Building Council (USGBC), in the United States [2] buildings account for:
{"title":"A review of tools to assess the sustainability in building construction","authors":"A. Vijayan, Ashok Kumar V","doi":"10.1002/EP.10065","DOIUrl":"https://doi.org/10.1002/EP.10065","url":null,"abstract":"INTRODUCTION Resource management has always been a priority for mankind. From the early ages, when it was a fight for survival, humans have learned the importance of resource conservation. Today, the focus of resource management has not just stopped at the conservation of food but has evolved and entails an even larger picture. Moreover, technological advancements and growing population have added an additional burden on Mother Nature and her resources [1]. For instance, the uncontrolled chopping of trees for human use has not only resulted in loss of forests but has also increased environmental pollution. Humankind now understands the consequences of its actions and has come to terms with the fact that the resources are limited and should be preserved and conserved for future generations. This concept of sustainability, and the development stemming from it, has been applied to a variety of actions that have been the foremost consumers of resources for years. The building industry is one of the largest consumers in terms of natural resources, and one of the largest producers of pollution thereafter, which has been a cause for concern for scientists. According to the U.S. Green Building Council (USGBC), in the United States [2] buildings account for:","PeriodicalId":11769,"journal":{"name":"Environmental Progress","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85385704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Srivastava, W. Neuffer, D. Grano, S. Khan, J. Staudt, W. Jozewicz
A number of regulatory actions focused on reducing NOx emissions from stationary combustion sources have been taken in the United States in the last decade. These actions include the Acid Rain NOx regulations, the Ozone Transport Commission's NOx Budget Program, and the NOx SIP Call rulemakings. In addition to these regulations, the recent Interstate Air Quality Rulemaking proposal and other bills in the Congress are focusing on additional reductions of NOx. Industrial combustion sources accounted for about 18016 of NOx emissions in the United States in 2000 and constituted the second largest emitting source category within stationary sources, only behind electric utility sources. Based on these data, reduction of NOx emissions from industrial combustion sources is an important consideration in efforts undertaken to address the environmental concerns associated with NOx. This paper discusses primary and secondary NOx control technologies applicable to various major categories of industrial sources. The sources considered in this paper include large boilers, furnaces and fired heaters, combustion turbines, large IC engines, and cement kilns. For each source category considered in this paper, primary NOx controls are discussed first, followed by a discussion of secondary NOx controls.
{"title":"Controlling NOx emission from industrial sources","authors":"R. Srivastava, W. Neuffer, D. Grano, S. Khan, J. Staudt, W. Jozewicz","doi":"10.1002/EP.10063","DOIUrl":"https://doi.org/10.1002/EP.10063","url":null,"abstract":"A number of regulatory actions focused on reducing NOx emissions from stationary combustion sources have been taken in the United States in the last decade. These actions include the Acid Rain NOx regulations, the Ozone Transport Commission's NOx Budget Program, and the NOx SIP Call rulemakings. In addition to these regulations, the recent Interstate Air Quality Rulemaking proposal and other bills in the Congress are focusing on additional reductions of NOx. Industrial combustion sources accounted for about 18016 of NOx emissions in the United States in 2000 and constituted the second largest emitting source category within stationary sources, only behind electric utility sources. Based on these data, reduction of NOx emissions from industrial combustion sources is an important consideration in efforts undertaken to address the environmental concerns associated with NOx. This paper discusses primary and secondary NOx control technologies applicable to various major categories of industrial sources. The sources considered in this paper include large boilers, furnaces and fired heaters, combustion turbines, large IC engines, and cement kilns. For each source category considered in this paper, primary NOx controls are discussed first, followed by a discussion of secondary NOx controls.","PeriodicalId":11769,"journal":{"name":"Environmental Progress","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79650105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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