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901.
Effect of wastewater composition on the calcium carbonate precipitation in upflow anaerobic sludge blanket reactors 总被引:1,自引:0,他引:1
Shucheng Yang Yanling He Yonghong Liu Charles Chou Pengxiang Zhang Dongqi Wang 《Frontiers of Environmental Science & Engineering in China》2010,4(2):142-149
Calcium carbonate often precipitates in anaerobic reactors treating wastewater with high calcium content. The aim of this
paper is to study the effect of wastewater composition on calcium carbonate precipitation in upflow anaerobic sludge blanket
(UASB) reactors. Two laboratory-scale UASB reactors were operated with calcium-containing influents using acetate and carbohydrate
as substrate, respectively. There was an obvious accumulation of inorganic precipitate observed in the biogranules. Observations
via scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) showed that the acclimated biogranules in
the two reactors differed in microstructure. Calcium carbonate was found to have precipitated on the surface of acetate-degrading
biogranules, but precipitated at the core of the carbohydrate-degrading biogranules. The results indicated that substrates
had significant influence on the location of calcium carbonate precipitation in anaerobic granular sludge, which was expected
due to the different methanogens distribution and pH gradient within the granular sludge degrading various substrates. Moreover,
the location of calcium carbonate precipitation substantially affected the specific methanogenic activity (SMA) of the granular
sludge. The SMA of the acetate-degrading biogranules dropped from $
1.96 gCOD_{CH_4 } \cdot gVSS^{ - 1} \cdot d^{ - 1}
$
1.96 gCOD_{CH_4 } \cdot gVSS^{ - 1} \cdot d^{ - 1}
to $
0.61 gCOD_{CH_4 } \cdot gVSS^{ - 1} \cdot d^{ - 1}
$
0.61 gCOD_{CH_4 } \cdot gVSS^{ - 1} \cdot d^{ - 1}
after 180-d of operation in the reactor. However, the SMA of the carbohydrate-degrading biogranules was not adversely affected
by calcium carbonate precipitation. 相似文献
902.
903.
针对丙烯腈污水处理场存在的问题,提出采用UASB—SBR组合工艺处理丙烯腈废水的新工艺,并进行试验和讨论,获得了试验基础数据,为该厂丙烯腈污水处理装置技术改造提供技术支持。 相似文献
904.
Heavy metals in rice and garden vegetables and their potential health risks to
inhabitants in the vicinity of an industrial zone in Jiangsu, China 总被引:10,自引:0,他引:10
Contamination of soil and agricultural products by heavy metals resulting from rapid industrial development has caused major concern. In this study, we investigated heavy metal (Cu, Zn, Pb, Cr, Hg and Cd) concentrations in rice and garden vegetables, as well as in cultivated soils, in a rural-industrial developed region in southern Jiangsu, China, and estimated the potential health risks of metals to the inhabitants via consumption of locally produced rice and garden vegetables. A questionnaire-based survey on dietary consumption rates of foodstuffs showed that rice and vegetables accounted for 64% of total foodstuffs consumed, and over 60% of rice and vegetables were grown in the local region. Average concentrations of Cr, Cu, Zn, Cd, Hg and Pb were 0.75, 2.64, 12.00, 0.014, 0.006 and 0.054 mg/kg dw (dry weight) in rice and were 0.67, 1.18, 4.34, 0.011, 0.002 and 0.058 mg/kg fw (fresh weight) in garden vegetables, respectively. These values were all below the maximum allowable concentration in food in China except for Cr in vegetables. Leafy vegetables had higher metal concentrations than solanaceae vegetables. Average daily intake of Cr, Cu, Zn, Cd, Hg and Pb through the consumption of rice and garden vegetables were 5.66, 16.90, 74.21, 0.10, 0.04 and 0.43 μg/(kg·day), respectively. Although Hazard Quotient values of individual metals were all lower than 1, when all six metal intakes via self-planted rice and garden vegetables were combined, the Hazard Index value was close to 1. Potential health risks from exposure to heavy metals in self-planted rice and garden vegetables need more attention. 相似文献
905.
906.
通过单因素试验研究了强化生物絮凝+生物接触氧化组合式一体化工艺对城市污水悬浮物SS、化学需氧量COD、氨氮NH3-N、总氮TN、总磷TP的去除效能和机理。试验结果表明:在组合工艺的较优运行条件下,装置对SS、COD、NH3-N、TN、TP的平均去除率分别为88.7%、89.3%、87.9%、73.4%、58.8%。组合工艺对污染物的总体去除效果良好,且稳定可靠,其中生物絮凝吸附段对总磷的去除率为32.4%,生物接触氧化段对总磷的去除率为39.1%,并对装置的除磷效果进行了分析。 相似文献
907.
从水质变化过程、水体空间维度和边界条件三个方面简要回顾了水环境模拟的研究与发展进程。介绍了目前国内外广泛应用的综合性水质模型软件:QUAL2E/2K、CE-QUAL-RIV1、MIKE11、CE-QUAL-W2、MIKE21、Delft3D、WASP、EFDC、BASINS、WARMF、SMS的特点和适用范围,重点讨论了EFDC和WASP集成应用于复杂水环境模拟的优势。对复杂水环境模拟的发展趋势进行了展望。 相似文献
908.
909.
910.
Granulation of filamentous microorganisms in a sequencing batch reactor
with saline wastewater 总被引:1,自引:0,他引:1
Proliferation of filamentous microorganisms frequently leads to operational failure for activate sludge systems. In this study, it was found that filamentous microorganisms could grow in compact granular structure with 5% sodium chloride in the substrate. In the early period of experiment, coccoid and rode-like bacteria predominated in the yellowish-brown granules, and later the white and the black granules were developed by filamentous microorganisms. The filamentous granules exhibited low porosity and fas... 相似文献