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scott2080铁杆木虫 (著名写手)
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【求助完毕】30 金币求修改一段英文，非常感谢！
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我投了篇文章 三番五次的修改都说英文不行： would be great if you could revise the English of your paper with the help of a native speaker or proficient colleague (the language and spelling needs improvement) 晕菜啊，麻烦大家看看我写的introduction 到底有多少错误，谢谢了。 请大家不要顶贴 实实在在帮我看看问题 Sequencing batch reactors were operated at organic loading rates (OLRs) of 0.5, 1.5 and 4.5 kg COD m-3 d-1 and substrate COD/N/P ratios of 100/5/1 and 100/5/0, respectively. The granules’ first appearance time, maturation time, biological morphology, settleability and organic matter removal efficiency for wastewater were used to as indicators to evaluate the granulation. Through the experiment, granules failed successfully to be cultivated under the OLR of 0.5 kg COD m-3 d-1 for the absence of filamentous bacteria during the full cultivation periods. Aerobic granules were not detected on Day 38, operating at an OLR of 1.5 kg COD m-3 d-1 and substrate COD/N/P ratio of 100/5/1. A certain amount of filamentous bacteria were found within the clear borderline of an apparent mature granular sludge. It did a stable process with SVI between 60-80 mL g-1 and COD removal efficiency of about 96%. Under an OLR of 4.5 kg COD m-3 d-1 and COD/N/P ratio of 100/5/1, aerobic granules were initially observed on Day 25; but the settleability of these granules began to deteriorate within 10 days after their maturation time. Similar phenomenon also occurred under OLR of 4.5 kg COD m-3 d-1 and COD/N/P ratio of 100/5/0, however a more numerous filamentous bacteria with smaller diameter were found interlacing with one and other for its excessive growth due to the higher OLR and absence of phosphor. Results showed that a certain quantity filamentous bacteria acted as the framework of granules is the most crucial step to achieve a quick and stable granulation. the higher of OLR and phosphor absence would be more likely to favor the growth of filamentous bacteria so as to promote the granulation by the strongly hydraulic shear force, but serious sludge bulking would be more likely to occur so as to result in biomass washout and decrease of COD removal efficiency. INTRODUCTION Aerobic granulation is a recently described phenomenon and currently under active investigation in wastewater biological treatment. It is generally accepted that aerobic granular sludge is a compact microbial aggregate formed via the self-immobilization of different microorganisms, and shares different features compared with conventional activated sludge floc. Granules were found to have the advantages of great settleability, high mechanical strength, balanced microbial community, high bio-activity, great stability and protection from toxic shock. So far most studies mainly focused on the mechanism of formation, structure of the microbial population and physic-chemical characteristics of aerobic granules, operation and application of granules reactors and so on. The previous research showed that aerobic granules were be incubated from anaerobic granular sludge indirectly[1] and cultivated by being seeded with aerobic sludge floc, and the following factors were considered important to the aerobic granulation, e.g., organic loading rate[2][3], sedimentation time[4][5], hydraulic retention time[6], oxygen concentrations[7][8], substrate compositions[9][10], hydraulic shearing force[11][12][13], periodical starvation[14], exchange ratio in SBR[5], cellular polysaccharides[15], pH, Alkalinity, and so on. To date, little information is available on effects of organic loading rates (OLRs) and substrate COD/N/P ratios on the granular granulation. Therefore, this study attempts to cultivate granules in the SBRs by being seeded with floc sludge under the different OLRs and substrate COD/N/P ratios, The first appearance time , maturation time, biological morphology, settleability, and organic matter removal efficiency of granules for wastewater were used to as indicators to evaluate the granulation. It was expected that these results would be helpful for the development of quick startup and stable running of granules bioreactor. [ Last edited by qingshaojun0823 on 2009-11-16 at 23:27 ] |
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scott2080(金币+1):谢谢参与
scott2080(金币+20,VIP+0):非常感谢 ！ 8-7 20:06
linghanyuan(金币+1,VIP+0):鼓励新虫 8-7 20:12
scott2080(金币+1):谢谢参与
scott2080(金币+20,VIP+0):非常感谢 ！ 8-7 20:06
linghanyuan(金币+1,VIP+0):鼓励新虫 8-7 20:12
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We have operated sequencing batch reactors at organic loading rates (OLRs) of 0.5, 1.5 and 4.5 kg COD m-3 d-1 and substrate COD/N/P ratios of 100/5/1 and 100/5/0, respectively. The granules’ first appearance time, maturation time, biological morphology, settleability, and organic matter removal efficiency for wastewater were employed as indicators to evaluate the granulation. Granules failed to be cultivated under the OLR of 0.5 kg COD m-3 d-1 in the absence of filamentous bacteria during the full cultivation period. Aerobic granules operated at an OLR of 1.5 kg COD m-3 d-1 and substrate COD/N/P ratio of 100/5/1, remain not detected on Day 38. A fair amount of filamentous bacteria were found within the clear borderline of an apparent mature granular sludge that accounts for a steady process with SVI between 60-80 mL g-1 and COD removal efficiency of about 96%. Under an OLR of 4.5 kg COD m-3 d-1 and COD/N/P ratio of 100/5/1, aerobic granules were initially observed on Day 25. The settleability of these granules began to deteriorate within 10 days after their maturation time. Similar phenomenon occurred under OLR of 4.5 kg COD m-3 d-1 and COD/N/P ratio of 100/5/0. Numerous filamentous bacteria with smaller diameter were found interlacing with one and another for the excessive growth owing to higher OLR and absence of phosphor. Our results demonstarte that a certain quantity filamentous bacteria act as the framework of granules, which is the most crucial step to achieve a quick and stable granulation. The higher the OLR and phosphor absence, the more likely the growth of filamentous bacteria is favored associated with promoting the granulation by strongly hydraulic shear force. Serious sludge bulking would be more likely to occur resulting in biomass washout and the decrease of COD removal efficiency. INTRODUCTION Aerobic granulation is a newly described phenomenon and currently under active investigation in wastewater biological treatment. The general concensus is that aerobic granular sludge is a compact microbial aggregate formed via the self-immobilization of different microorganisms, and shares different features compared with conventional activated sludge floc. Granules have the advantage of great settleability, high mechanical strength, balanced microbial community, high bio-activity, great stability, and protection from toxic shock. So far most studies mainly focused on the mechanism of formation, structure of the microbial population, physical-chemical characteristics of aerobic granules, operation and application of granules reactors and so on. Previous research indicated that aerobic granules were to be incubated from anaerobic granular sludge indirectly [1] and cultivated by being seeded with aerobic sludge floc. The following factors were considered important to the aerobic granulation, e.g., organic loading rate [2][3], sedimentation time [4][5], hydraulic retention time [6], oxygen concentrations [7][8], substrate compositions [9][10], hydraulic shearing force [11][12][13], periodical starvation[14], exchange ratio in SBR[5], cellular polysaccharides [15], pH, Alkalinity. To date, little information is available on effects of organic loading rates (OLRs) and substrate COD/N/P ratios on the granular granulation. The presnet study attempts to cultivate granules in the SBRs by being seeded with floc sludge under the different OLRs and substrate COD/N/P ratios. The first appearance time, maturation time, biological morphology, settleability, and organic matter removal efficiency of granules for wastewater are used to as indicators to evaluate the granulation. Our results are useful for the development of quick startup and stable running of granules bioreactor. |
6楼2009-08-07 19:50:34
