The releasing characteristics of phosphorus, nitrogen compounds, organics, and some metal cations during thermal treatment of excess sludge were investigated. It was found that during heating not only phosphorus, but ...
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The releasing characteristics of phosphorus, nitrogen compounds, organics, and some metal cations during thermal treatment of excess sludge were investigated. It was found that during heating not only phosphorus, but also nitrogen compounds, organics, and some metal cations could be released in abundance. The maximum orthophosphate （ortho-P） release of about 90 mg/L in concentration was observed at 50℃ in 1 h. Except for volatile fatty acids （VFAs）, comparatively little total nitrogen （TN）, total organic carbon （TOC）, and metal cations were released at the same time. Such results might favor further process of phosphorus recovery. VFAs were considerably released only at 50℃. Acetic, butyric, and propionic acid were the most abundant components in turn and their releasing profiles exhibited good linear relationship with time （R2 = 0.9977, 0.9624, and 0.8908, respectively）. The concentrations of Mg^2＋ and K^＋ increased with time and temperature during thermal treatment, but Ca^2＋ decreased. The release of Mg^2＋ and K^＋ agreed well with TP release （R^2 = 0.9892 and 0.9476, respectively）. Temperature in the experimental range had very little impact on the linear relationships, especially of Mg^2＋. Moreover, the parameter of mixed liquor suspended solids （MLSS） was found to be an important factor for thermal sludge treatment as the released ortho-P and total phosphorus （TP） at 50℃ increased more than one-fold when MLSS was increased from 4000 to 8000 mg/L.
Taking two typical rivers in high mountains and steep gorge areas as example,this paper analyzes the spetiotemporal variability of the eco-hydrological characteristics and the driving forces leading to ***,based on th...
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Taking two typical rivers in high mountains and steep gorge areas as example,this paper analyzes the spetiotemporal variability of the eco-hydrological characteristics and the driving forces leading to ***,based on the species-environmental data processing,this paper adopts canonical correspondence analysis(CCA)method to identify the environmental factors influencing the distribu- tion of river bank ***,this study uses the ecological diversity Index to represent the spatiotemporel variability of ecological ***,this paper uses the multiple correlation method to analyze the relationship between the hydrological factors and meteorological factors,and to identify the key factors leading to the hydrological regime *** last,based on the analysis of basin water quality data,this paper analyzes the regularity of spatiotemporal variability and its driving *** the systematic analysis on the outcome,we could get that the spatiotemporel distribution of eco-hydrological characteristics shows the regular changes from the upstream to downstream(from the north to the south),and the spatiotemporal variability of eco-hydrological characteristics is typical from the east to the ***,aspect and water distribution are the primary natural driving forces leading to the spatiotemporel variability of eco-hydrological characteristics;and exploitation and op- eration of hydroelectric power station,construction of road on the river bank,and basin land utilization are the main human driving forces.
Agricultural activity is one of the most important sources of aerosol *** understand the mass distribu-tion and sources of aerosol particles and their inorganic water-soluble ions in a suburb farmland of Beijing,parti...
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Agricultural activity is one of the most important sources of aerosol *** understand the mass distribu-tion and sources of aerosol particles and their inorganic water-soluble ions in a suburb farmland of Beijing,particle samples were collected using a microorifice uniform deposit impactor(MOUDI)in the summer of 2004 in a suburb vege-table *** distribution of the particles and their inor-ganic water-soluble ions in the diameter range of 0.18-18 mm were *** dominant fine particle ions were SO_(4)^(2−),NO^(3−),and NH_(4)^(+).The association of day-to-day variation of the concentration of these ions with temperature,humidity,and solar radiation suggested that they are formed by the reac-tion of NH_(3) released from the vegetable field with the acid species produced from photochemical *** particle K+is likely from vegetation emission and biomass *** particles like Ca^(2+),Mg^(2+),NO_(3)^(−),and SO_(4)^(2−)are sug-gested to come from the mechanical process by which the soil particle entered the atmosphere,and from the reaction of the acid species at the surface of the soil *** results show that fertilizer and soil are important factors determining the aerosol particle over agricultural fields,and vegetable fields in suburban Beijing contribute significantly to the aerosol particle.
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