In China,over 1.43×10^(7)tons of dewatered sewage sludge,with 80%water content,were generated from wastewater treatment plants in 2007.About 60%of the COD removed during the wastewater treatment process becomes c...In China,over 1.43×10^(7)tons of dewatered sewage sludge,with 80%water content,were generated from wastewater treatment plants in 2007.About 60%of the COD removed during the wastewater treatment process becomes concentrated as sludge.Traditional disposal methods used by municipal solid waste treatment facilities,such as landfills,composting,or incineration,are unsuitable for sludge disposal because of its high water content.Disposal of sludge has therefore become a major focus of current environmental protection policies.The present status of sludge treatment and disposal methodology is introduced in this paper.Decreasing the energy consumption of sludge dewatering from 80%to 50%has been a key issue for safe and economic sludge disposal.In an analysis of sludge water distribution,thermal drying and hydrothermal conditioning processes are compared.Although thermal drying could result in an almost dry sludge,the energy consumption needed for this process is extremely high.In comparison,hydrothermal technology could achieve dewatered sewage sludge with a 50%–60%water content,which is suitable for composting,incineration,or landfill.The energy consumption of hydrothermal technology is lower than that required for thermal drying.展开更多
Current use of enrichment and processing technologies of ores requires the introduction of closed circuits of water treatment. A decrease in technological properties is caused by accumulations of ion-molecular compone...Current use of enrichment and processing technologies of ores requires the introduction of closed circuits of water treatment. A decrease in technological properties is caused by accumulations of ion-molecular components in the circulating water. The objective of the simulation is to determine the maximum allowable concentrations of ions and molecules as well as the choice of conditions for deposition or adsorption.First of all, our examinations decrease the concentration of copper ions and fatty acids in the circulating water. By pre-mixing water with the highest concentration of these ions, a reduction of copper ion and fatty acid concentrations in the recycled water occurs. The results do not only ensure the achievement of the maximum permitted concentration(MPC) of copper and iron, significantly reducing the amount of oxidized copper, they also make it possible to use the united sewage as current water for the flotation process. Mixing and adding filtrate of tailings, discharges of urban wastewater treatment and effluent of ash pit of thermal power stations(TPS) to recycled water causes an increase in the capacity of the enrichment plant by 15–17%.展开更多
基金the National High Technology Research and Development Program of China(Grant No.2006AA06Z384).
文摘In China,over 1.43×10^(7)tons of dewatered sewage sludge,with 80%water content,were generated from wastewater treatment plants in 2007.About 60%of the COD removed during the wastewater treatment process becomes concentrated as sludge.Traditional disposal methods used by municipal solid waste treatment facilities,such as landfills,composting,or incineration,are unsuitable for sludge disposal because of its high water content.Disposal of sludge has therefore become a major focus of current environmental protection policies.The present status of sludge treatment and disposal methodology is introduced in this paper.Decreasing the energy consumption of sludge dewatering from 80%to 50%has been a key issue for safe and economic sludge disposal.In an analysis of sludge water distribution,thermal drying and hydrothermal conditioning processes are compared.Although thermal drying could result in an almost dry sludge,the energy consumption needed for this process is extremely high.In comparison,hydrothermal technology could achieve dewatered sewage sludge with a 50%–60%water content,which is suitable for composting,incineration,or landfill.The energy consumption of hydrothermal technology is lower than that required for thermal drying.
文摘Current use of enrichment and processing technologies of ores requires the introduction of closed circuits of water treatment. A decrease in technological properties is caused by accumulations of ion-molecular components in the circulating water. The objective of the simulation is to determine the maximum allowable concentrations of ions and molecules as well as the choice of conditions for deposition or adsorption.First of all, our examinations decrease the concentration of copper ions and fatty acids in the circulating water. By pre-mixing water with the highest concentration of these ions, a reduction of copper ion and fatty acid concentrations in the recycled water occurs. The results do not only ensure the achievement of the maximum permitted concentration(MPC) of copper and iron, significantly reducing the amount of oxidized copper, they also make it possible to use the united sewage as current water for the flotation process. Mixing and adding filtrate of tailings, discharges of urban wastewater treatment and effluent of ash pit of thermal power stations(TPS) to recycled water causes an increase in the capacity of the enrichment plant by 15–17%.
