Application of Activated Carbon Treatment for Pharmaceutical Removal in Municipal Wastewater
Abstract
Many pharmaceuticals are found in municipal wastewater effluents due to their persistence in the human body as well as in conventional wastewater treatment processes. This discharge to the environment can lead to adverse effects in aquatic species, such as feminization of male fish. During the past decade, these findings have spawned investigations and research into suitable treatment technologies that could severely limit the discharge. Adsorption onto activated carbon has been identified as one of the two main technologies for implementation of (future) full-scale treatment. Recent research has put a closer focus on adsorption with powdered activated carbon (PAC) than on granular activated carbon (GAC). Studies where both methods are compared in parallel operation are thus still scarce and such evaluation in pilot-scale was therefore a primary objective of this thesis. Furthermore, recirculation of PAC can be used to optimize the treatment regarding the carbon consumption. Such a setup was evaluated as a separate treatment stage to comply with Swedish wastewater convention. Additionally, variation of a set of process parameters was evaluated. During successive operation at three different wastewater treatment plants an overall pharmaceutical removal of 95% could consistently be achieved with both methods. Furthermore, treatment with GAC was sensitive to a degraded effluent quality, which severely reduced the hydraulic capacity. Both treatment methods showed efficient removal of previously highlighted substances, such as carbamazepine and diclofenac, however in general a lower adsorption capacity was observed for GAC. By varying the input of process parameters, such as the continuously added dose or the contact time, during PAC treatment, a responsive change of the pharmaceutical removal could be achieved. The work in this thesis contributes some valuable field experience towards wider application of these treatment technologies in full-scale.
Application of Activated Carbon Treatment for Pharmaceutical Removal in Municipal Wastewater
Abstract
Many pharmaceuticals are found in municipal wastewater effluents due to their persistence in the human body as well as in conventional wastewater treatment processes. This discharge to the environment can lead to adverse effects in aquatic species, such as feminization of male fish. During the past decade, these findings have spawned investigations and research into suitable treatment technologies that could severely limit the discharge. Adsorption onto activated carbon has been identified as one of the two main technologies for implementation of (future) full-scale treatment. Recent research has put a closer focus on adsorption with powdered activated carbon (PAC) than on granular activated carbon (GAC). Studies where both methods are compared in parallel operation are thus still scarce and such evaluation in pilot-scale was therefore a primary objective of this thesis. Furthermore, recirculation of PAC can be used to optimize the treatment regarding the carbon consumption. Such a setup was evaluated as a separate treatment stage to comply with Swedish wastewater convention. Additionally, variation of a set of process parameters was evaluated. During successive operation at three different wastewater treatment plants an overall pharmaceutical removal of 95% could consistently be achieved with both methods. Furthermore, treatment with GAC was sensitive to a degraded effluent quality, which severely reduced the hydraulic capacity. Both treatment methods showed efficient removal of previously highlighted substances, such as carbamazepine and diclofenac, however in general a lower adsorption capacity was observed for GAC. By varying the input of process parameters, such as the continuously added dose or the contact time, during PAC treatment, a responsive change of the pharmaceutical removal could be achieved. The work in this thesis contributes some valuable field experience towards wider application of these treatment technologies in full-scale.
AOP Performance at Wastewater Treatment Plants: Recent Developments
ABSTRACT:
Advanced Oxidation Processes (AOPs) are chemical treatment techniques used to remove contaminants from water and wastewater using hydroxyl radical reactions. AOPs are efficient methods for removing organic contamination not degradable by means of biological processes. AOPs are a set of treatment processes involving the production of very reactive oxygen species (hydroxyl radicals (OH) able to destroy a wide range of organic compounds). This paper examines selected recent studies involving AOP’s application for wastewater treatment. Discussions of selected reviews and summaries of results from recent reports in the technical literature are provided below. Brief descriptions of the most popular AOPs are also provided. In addition, nano zero-valent iron systems (nZVI) for degrading organic contaminants are briefly examined. Performance data is provided where available or relevant. Of particular interest are treatments for emerging contaminants. Multiple studies involving remediation of wastewater contaminated by emerging contaminants by AOP’s and nZVI systems are reviewed.
AOP Performance at Wastewater Treatment Plants: Recent Developments
ABSTRACT:
Advanced Oxidation Processes (AOPs) are chemical treatment techniques used to remove contaminants from water and wastewater using hydroxyl radical reactions. AOPs are efficient methods for removing organic contamination not degradable by means of biological processes. AOPs are a set of treatment processes involving the production of very reactive oxygen species (hydroxyl radicals (OH) able to destroy a wide range of organic compounds). This paper examines selected recent studies involving AOP’s application for wastewater treatment. Discussions of selected reviews and summaries of results from recent reports in the technical literature are provided below. Brief descriptions of the most popular AOPs are also provided. In addition, nano zero-valent iron systems (nZVI) for degrading organic contaminants are briefly examined. Performance data is provided where available or relevant. Of particular interest are treatments for emerging contaminants. Multiple studies involving remediation of wastewater contaminated by emerging contaminants by AOP’s and nZVI systems are reviewed.
Anaerobic Digestion
INTRODUCTION
In the anaerobic treatment the organic matter is decomposed into biogas, methane (CH4) and carbon dioxide (CO2), process in which a different oxygen molecule acts as a terminal electron acceptor. Methane production occurs in different natural environments, such as swamps, lakes, rivers and sea sediments, as well as in the digestive organs of ruminant animals, where the redox potential is around -300mV. It is estimated that anaerobic digestion with methane formation is responsible for the complete mineralization of 5 to 10% of all the organic matter available on the earth.
Anaerobic digestion represents an accurately balanced ecological system, where different populations of microorganisms present specialized functions, and the breakdown of organic compounds is usually considered a two stage process. In the first stage, a group of facultative and anaerobic bacteria converts, by hydrolysis and
fermentation, the complex organic compounds (proteins, carbohydrates and fats) into simpler organic compounds, mainly volatile fatty acids (VFA), as well as carbon dioxide and hydrogen gases. In the second stage, the organic acids and hydrogen are converted into methane and carbon dioxide. This conversion is performed by a special group of microorganisms, namely methanogens, which are strictly anaerobic. These microorganisms have two main functions, produce methane which enables the removal of organic carbon and they keep the hydrogen (H2) partial pressure low enough to allow conditions in the medium for fermenting and acid producing bacteria to produce soluble compounds such as acetic acid.
Anaerobic Digestion
INTRODUCTION
In the anaerobic treatment the organic matter is decomposed into biogas, methane (CH4) and carbon dioxide (CO2), process in which a different oxygen molecule acts as a terminal electron acceptor. Methane production occurs in different natural environments, such as swamps, lakes, rivers and sea sediments, as well as in the digestive organs of ruminant animals, where the redox potential is around -300mV. It is estimated that anaerobic digestion with methane formation is responsible for the complete mineralization of 5 to 10% of all the organic matter available on the earth.
Anaerobic digestion represents an accurately balanced ecological system, where different populations of microorganisms present specialized functions, and the breakdown of organic compounds is usually considered a two stage process. In the first stage, a group of facultative and anaerobic bacteria converts, by hydrolysis and
fermentation, the complex organic compounds (proteins, carbohydrates and fats) into simpler organic compounds, mainly volatile fatty acids (VFA), as well as carbon dioxide and hydrogen gases. In the second stage, the organic acids and hydrogen are converted into methane and carbon dioxide. This conversion is performed by a special group of microorganisms, namely methanogens, which are strictly anaerobic. These microorganisms have two main functions, produce methane which enables the removal of organic carbon and they keep the hydrogen (H2) partial pressure low enough to allow conditions in the medium for fermenting and acid producing bacteria to produce soluble compounds such as acetic acid.
Anaerobic Digestion of Primary Sewage Effluent
SUMMARY
A hybrid system comprised an up-flow packed bed anaerobic reactor and a down-flow trickling-filter reactor connected in series was shown to effectively treat primary clarifier effluent. When a clarifier and sand filter were added to the system, the effluent water quality achieved values of BOD5 and TSS that were below the EPA’s water discharge limits of 30 mg/l and equivalent to highly efficient activated sludge systems. Best results were achieved at a hydraulic retention time of seven hours and with interna recycle applied to both the anaerobic and aerobic reactors. A scale-up evaluation of the system to treat three million gallons per day indicated total land use of approximately 0.6 acre, which is on the same scale currently used at the host wastewater treatment facility to treat primary clarifier effluent using activated sludge technology. An energy balanced showed that the tested system would utilize 48% of the energy currently used to operate the activated sludge system.
Anaerobic Digestion of Primary Sewage Effluent
SUMMARY
A hybrid system comprised an up-flow packed bed anaerobic reactor and a down-flow trickling-filter reactor connected in series was shown to effectively treat primary clarifier effluent. When a clarifier and sand filter were added to the system, the effluent water quality achieved values of BOD5 and TSS that were below the EPA’s water discharge limits of 30 mg/l and equivalent to highly efficient activated sludge systems. Best results were achieved at a hydraulic retention time of seven hours and with interna recycle applied to both the anaerobic and aerobic reactors. A scale-up evaluation of the system to treat three million gallons per day indicated total land use of approximately 0.6 acre, which is on the same scale currently used at the host wastewater treatment facility to treat primary clarifier effluent using activated sludge technology. An energy balanced showed that the tested system would utilize 48% of the energy currently used to operate the activated sludge system.
