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.
An Overview of Nanomaterials for Water and Wastewater
Introduction
Generally speaking, nanomaterials describe materials of which the structural components are sized (in at least one dimension) between 1 and 100 nm [1]. Due to the nanoscale size of nanomaterials, their properties, such as mechanical, electrical, optical, and magnetic properties, are significantly different from conventional materials. A wide range of nanomaterials have the characteristics of catalysis, adsorption, and high reactivity. In the past decades, nanomaterials have been under active research and development and have been successfully applied in many fields, such as catalysis [2], medicine [3], sensing [4], and biology [5]. In particular, the application of nanomaterials in water and wastewater treatment has drawn wide attention. Due to their small sizes and thus large specific surface areas, nanomaterials have strong adsorption capacities and reactivity. What is more, the mobility of nanomaterials in solution is high [6]. Heavy metals [7], organic
pollutants [8], inorganic anions [9], and bacteria [10] have been reported to be successfully removed by various kinds of nanomaterials. On the basis of numerous studies, nanomaterials show great promise for applications in water and wastewater treatment. At present, the most extensively studied nanomaterials for water and wastewater treatment mainly include zero-valent metal nanoparticles, metal oxides nanoparticles, carbon nanotubes (CNTs), and nanocomposite
An Overview of Nanomaterials for Water and Wastewater
Introduction
Generally speaking, nanomaterials describe materials of which the structural components are sized (in at least one dimension) between 1 and 100 nm [1]. Due to the nanoscale size of nanomaterials, their properties, such as mechanical, electrical, optical, and magnetic properties, are significantly different from conventional materials. A wide range of nanomaterials have the characteristics of catalysis, adsorption, and high reactivity. In the past decades, nanomaterials have been under active research and development and have been successfully applied in many fields, such as catalysis [2], medicine [3], sensing [4], and biology [5]. In particular, the application of nanomaterials in water and wastewater treatment has drawn wide attention. Due to their small sizes and thus large specific surface areas, nanomaterials have strong adsorption capacities and reactivity. What is more, the mobility of nanomaterials in solution is high [6]. Heavy metals [7], organic
pollutants [8], inorganic anions [9], and bacteria [10] have been reported to be successfully removed by various kinds of nanomaterials. On the basis of numerous studies, nanomaterials show great promise for applications in water and wastewater treatment. At present, the most extensively studied nanomaterials for water and wastewater treatment mainly include zero-valent metal nanoparticles, metal oxides nanoparticles, carbon nanotubes (CNTs), and nanocomposite
