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911.
Enhanced sludge solubilization by microbubble ozonation 总被引:7,自引:0,他引:7
A microbubble ozonation process for enhancing sludge solubilization was proposed and its performance was evaluated in comparison to a conventional ozone bubble contactor. Microbubbles are defined as bubbles with diameters less than several tens of micrometers. Previous studies have demonstrated that microbubbles could accelerate the formation of hydroxyl radicals and hence improve the ozonation of dyestuff wastewater. The results of this study showed that microbubble ozonation was effective in increasing ozone utilization and improving sludge solubilization. For a contact time of 80 min, an ozone utilization efficiency of more than 99% was obtained using the microbubble system, while it gradually decreased from 94% to 72% for the bubble contactor. The rate of microbial inactivation was obviously faster in the microbubble system. At an ozone dose of 0.02 g O3 g−1 TSS, about 80% of microorganisms were inactivated in the microbubble system, compared with about 50% inactivation for the bubble contactor. Compared to the bubble contactor, more than two times of COD and total nitrogen, and eight times of total phosphorus content were released from the sludge into the supernatant by using the microbubble system at the same ozone dosage. The application of microbubble technology in ozonation processes may provide an effective and low cost approach for sludge reduction. 相似文献
912.
Factors influencing arsenic accumulation by Pteris vittata: a comparative field study at two sites 总被引:1,自引:0,他引:1
This study compared the factors influencing arsenic (As) accumulation by Pteris vittata at two sites, one containing As along with Au mineralization and the other containing Hg/Tl mineralization. The soils above these two sites contained high As concentrations (26.8-2955 mg kg(-1)). Although the As concentration, pH, soil cation exchange capacity and plant biomass differed significantly between the two sites, no differences were observed in the As concentrations in the fronds and roots, or the translocation factors, of P. vittata, suggesting that this species has consistent As hyperaccumulation properties in the field. The As concentration in the fronds was positively related to phosphorus (P) and potassium (K), but negatively related to calcium (Ca), at one site. This suggested that P, K and Ca influenced As accumulation by P. vittata in the field. 相似文献
913.
Toxicity and bioaccumulation of copper in three green microalgal species 总被引:13,自引:0,他引:13
The effective concentrations of copper on the inhibition of the growth of Scenedesmus obliquus, Chlorella pyrenoidosa and Closterium lunula at 96 h (96 h EC50) were determined to be 50, 68 and 200 microg/l, respectively. The low initial bioaccumulation of Cu by C. lunula was found to be responsible for its tolerance to Cu. The amount of Cu accumulated by all three microalgae reached the maximum value and decreased quickly after the peak followed by a slow decrease over the next 6 d. Bioaccumulation of Cu by C. lunula was directly proportional to the initial Cu concentration. After reaching the first peak after 1 d, the bioconcentration factor of Cu by microalgae declined to its minimum value during the exponential growth phase but increased in the stationary growth phase again. This indicates that desorption of Cu from microalgae was higher during the exponential growth phase but lower in the stationary growth phase. Smaller microalgae with low 96 h EC50 values are more efficient in removing Cu from wastewater. 相似文献
914.
使用40 kHz超声(US)脱色氯甲烷(包括CCl4、CHCl3和CH2Cl2)与偶氮染料(包括甲基橙与铬黑T)混合模拟废水,考察了氯甲烷初始浓度对偶氮染料超声脱色和TOC去除的影响.结果表明:偶氮染料的单独超声脱色速率很慢;而在CCl4与CHCl3存在时超声能使偶氮染料短时间内脱色至无色,但对其TOC的超声去除促进作... 相似文献
915.
916.
采用强电离介质阻挡放电方法制取高浓度氧活性粒子(O+2、O3)并注入气体外排烟道中,实现O+2、O3氧化NO转化成资源酸(HNO3)的等离子化学反应。描述强电离放电的氧活性粒子产生器,讨论烟道中O+2、O3氧化NO成HNO3等离子体反应机制,分析回收酸液的NO-2、NO-3离子种类及浓度。考察强电离放电等离子体源的输入功率、水体积百分比、气体温度、气体流速对NOx氧化率的影响。氧化率为97.2%的最佳实验条件是:O+2浓度为1.38×1010个/cm3,O3浓度为210 mg/L,烟气温度为65℃,H2O体积浓度为5.6%,停留时间为0.94 s。 相似文献
917.
918.
919.
隐孢子虫是常见的球状寄生虫。接触含有隐孢子虫卵囊的水体可致隐孢子虫病,主要的临床表现为腹泻,严重者可致死。游泳池是主要的传播场所。采用容积为5 500 L的游泳池,进行隐孢子虫卵囊替代物的修复模拟实验,研究在游泳池条件下絮凝沙滤技术对直径为4.5μm隐孢子虫卵囊替代物的去除效果。实验结果表明,氯化铝剂量为0.1 mg/L,沙滤料高度为30 cm,内循环流速为11.5 L/min,对隐孢子虫卵囊替代物去除率在90%以上。该技术对浊度具有较好的处理效果,当进水浊度降低且接近于出水浊度时,系统进入稳定运行阶段,对虫卵囊替代物去除率可以达到96%。 相似文献
920.