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
Aeration is an important factor affecting the biological aeration filter.With a set of experiment device specially designed for the purpose,and the particle image velocimetry technique,the velocity field of the gas-li...Aeration is an important factor affecting the biological aeration filter.With a set of experiment device specially designed for the purpose,and the particle image velocimetry technique,the velocity field of the gas-liquid two-phase flow is studied under different conditions.The various simulated aeration states were actually applied to the experimental device of sewage treatment,and the results of the numerical simulation were verified.The final experimental results indicate that the most efficient state occurs when the ratio of water in aeration tank h / w =1,the diameter of capillary tubes d=0.6mm and the velocity of bubbles v=0.3m/s.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.
基金supported by the National Natural Science Foundation of China (Grant No. 50679071)the China Postdoctoral Science Foundation (Grant No. 20070410378)
文摘Aeration is an important factor affecting the biological aeration filter.With a set of experiment device specially designed for the purpose,and the particle image velocimetry technique,the velocity field of the gas-liquid two-phase flow is studied under different conditions.The various simulated aeration states were actually applied to the experimental device of sewage treatment,and the results of the numerical simulation were verified.The final experimental results indicate that the most efficient state occurs when the ratio of water in aeration tank h / w =1,the diameter of capillary tubes d=0.6mm and the velocity of bubbles v=0.3m/s.
