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炮打总统府金虫 (小有名气)
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[求助]
求高手翻译，环境工程水处理方面！
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Processes for biological nutrient removal (BNR) typically adopt alternating anaerobic, anoxic, and aerobic zones in order to remove nitrogen and phosphorous, as well as organic compounds, from the wastewater. In these BNR processes,nitrification reaction relies on slow-growing, autotrophic bacteria that require a long solids retention time (SRT) and a relatively high oxygen concentration, while the denitrification reaction requires an organic electron donor that is not always sufficient in the influent wastewaters . Noting the benefits of shortcut biological nutrient removal (SBNR) process, many researchers have tried to obtain consistent nitrite accumulation in nitrification, which is a key prerequisite for successful SBNR . From a biological viewpoint, two distinct approaches are possible. First, the SHARON (single reactor system for high activity ammonia removal over nitrite) process employs a short (1–2days) SRT and a high reaction temperature (35 8C) in order to selectively wash out nitrite oxidizers . SHARON process is the most suitable for wastewaters already at high temperature and with little organic carbon. The second approach uses a high pH and, consequently, a high unionized ammonium concentra-tion or a low DO to slow nitrite oxidation preferentially and washout nitrite-oxidizing bacteria. The second approach is the most suitable for insufficiently buffered wastewaters at lower temperatures (<20 8C). A key operating factor for any SBNR process using either approach to eliminate nitrite oxidation is to avoid retarding ammonium oxidation toomuch. The focus of this work was on the second approach. A number of researchers have shown that a high concentration of unionized ammonia, or free ammonia (FA),inhibits nitrite oxidizers. Anthonisen et al. reported that inhibition of nitrite oxidation by FA began at 0.1–1.0 mg FA/L, while that of ammonium oxidation at 10–150 mg/L. Thus, a selective inhibition of nitrite oxidation should be achieved within a FA concentration of 1.0–10 mg/L. One challenge of the second approach is that the threshold concentration of FA seems to increase gradually with time .Villaverde et al. concluded that the nitrifica-tion–denitrification process via nitrite is not likely to be stable or feasible for long periods of time due to the acclimation of nitrite oxidizers to FA. Nitrite oxidizers may also be more sensitive to low DO (0.5 mg/L) than ammonium oxidizers, depending on SRT . Another potential pathway in shortcut denitrification is to have rapid denitrifica-tion of nitrite as soon as it is produced by the ammonium oxidizers. Simultaneous denitrification with nitrification is now well established n aerobic reactors in which the DO level is poised at a suitably low level, typically 0.5–1 mg/L. Rapid scavenging of nitrite for denitrificationaugments the benefits of FA or low DO for inhibiting nitrite oxidizers. A hybrid shortcut biological nutrient removal (HSBNR) process integrates biofilm within a suspended-growth system to maximize the hold-up and SRT of ammonium oxidizers, while operating with relatively high FA and low DO concentrations to inhibit nitrite oxidation and enhance rapid denitrification of nitrite . The HSBNR offers the potential of three selective pressures against nitrite oxidation: high FA, low DO, and rapid direct denitrification. The HSBNR also should have the advantage of a short hydraulic retention time (HRT) and small system volume, due to the accumulation of biofilm biomass along with suspended biomass. The hybrid system was tested in a batch mode to demonstrate its promise for stabilizing SBNR . This study evaluates the hybrid reactor in the continuous-flow mode, which tests the long-term performance of shortcut nitrogen removal and investigates the relative importance of factors affecting nitrite accumulation in the HSBNR reactor: concentrations of FA, DO, and direct denitrification. |
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【答案】应助回帖
★ ★ ★ ★
爱与雨下(金币+4): 2012-02-04 22:36:36
炮打总统府(金币+10, 翻译EPI+1): ★★★很有帮助 感谢交流！ 2012-02-05 13:55:26
爱与雨下(金币+4): 2012-02-04 22:36:36
炮打总统府(金币+10, 翻译EPI+1): ★★★很有帮助 感谢交流！ 2012-02-05 13:55:26
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翻译如下，仅供参考。不当之处请指正。 污水的生物脱氮除磷工艺通常采用厌氧、缺氧和好氧处理的交替进行来实现脱氮除磷和减少有机物质。在这些生物脱氮除磷工艺中，硝化反应依赖于生长缓慢的自养型细菌，而自养型细菌的培养需要较长的污泥停留时间和较高浓度的溶解氧。另一方面，反硝化反应需要有机物提供电子，而有些污水中并不含有足够浓度的有机物。 短程生物脱氮除磷工艺（SBNR）具有多种优势。而该工艺的能够实现的重要先决条件是硝化反应过程中的亚硝酸含量需要维持稳定。从生物法的角度讲，有两种可能的解决方案。一种方法是SHARON (single reactor system for high activity ammonia removal over nitrite)工艺。该工艺采用短污泥停留时间（1 – 2天）和高反应温度（35.8 C）来选择性地消灭亚硝酸盐氧化细菌。SHARON工艺对高温和机物含量低的废水特别适用。第二种方法采用提高pH值增加非离子氨浓度或者降低溶解氧的方法来减缓亚硝酸氧化过程并消灭亚硝酸盐氧化细菌。此方法适用于处理缓冲不足的低温废水（<20.8C）。对于任一种短程生物脱碳除磷工艺而言，在操作中防止亚硝酸盐氧化的关键点在于避免使氨氧化过于缓慢。 本次研究的着重点在于第二种方法。已有研究成果显示在高浓度非离子氨（或称游离氨，或FA）存在的情况下，亚硝酸盐氧化会受到抑制。Anthonisen研究组 的报告中指出游离氨浓度在达到0.1–1.0 mg /L以上时即能对亚硝酸盐氧化产生抑制作用，而在达到10-150mg/L以上时才会对氨氧化反应产生抑制作用。因此，选择性地抑制亚硝酸氧化是可以通过将游离氨的浓度范围控制在1.0–10 mg/L而实现的。 第二种方法存在的一个技术问题是游离氨浓度的阈值随时间推移会逐渐增加。Villaverde的研究成果指出，在亚硝酸盐氧化细菌对游离氨的适应过程中，通过亚硝酸盐的硝化-反硝化反应是不会长期稳定的。此外，在不同的污泥停留时间条件下，亚硝酸盐氧化细菌可能比氨氧化细菌更容易受低溶解氧浓度的影响。另一种短程反硝化反应的途径是在氨氧化细菌产生亚硝酸盐后使其即时反硝化。目前已经存在完善的技术可以在适当低浓度DO（0.5-1mg/L）的厌氧反应器中令反硝化与硝化反应同时进行。快速消耗可用于反硝化反应的亚硝酸盐能增加游离氨或低溶解氧抑制亚硝酸氧化细菌的效果。 联合性的短程生物脱氮除磷工艺（HSBNR）在悬浮污泥系统中结合了生物膜，该设置可最大化氨氧化细菌的含率和污泥停留时间，并同时采用较高的游离氨和较低的溶解氧浓度用于抑制亚硝酸盐的氧化和提高亚硝酸盐的反硝化。HSBNR可能提供三种机制用于抑制亚硝酸氧化：高游离氨、低溶解氧、快速的直接反硝化。另外，因为生物膜上生物质与悬浮生物质可以一同积累，所以HSBNR的优势还包括拥有较短的水力停留时间和较小的系统容积。联合系统在间歇模式下测试的结果显示了在稳定SBNR方面的良好前景。 此次研究评估了联合反应器在连续流条件下的处理效果。测试了其影响短程脱氮的长期效果并研究了在联合短程脱氮除磷工艺中影响亚硝酸盐累计的三种因素的相对重要性，即FA浓度、溶解氧和直接反硝化。 |
2楼2012-02-04 13:41:41
