一种新型生物反应器为不同的微生物群落的高密度栽培
Summary
A novel reactor design, coined a high density bioreactor (HDBR), is presented for the cultivation and study of high density microbial communities. Here, the HDBR is successfully applied in a photobioreactor (PBR) configuration for the study of nitrogen metabolism by a mixed high density algal community.
Abstract
A novel reactor design, coined a high density bioreactor (HDBR), is presented for the cultivation and study of high density microbial communities. Past studies have evaluated the performance of the reactor for the removal of COD1 and nitrogen species2-4 by heterotrophic and chemoautotrophic bacteria, respectively. The HDBR design eliminates the requirement for external flocculation/sedimentation processes while still yielding effluent containing low suspended solids. In this study, the HDBR is applied as a photobioreactor (PBR) in order to characterize the nitrogen removal characteristics of an algae-based photosynthetic microbial community. As previously reported for this HDBR design, a stable biomass zone was established with a clear delineation between the biologically active portion of the reactor and the recycling reactor fluid, which resulted in a low suspended solid effluent. The algal community in the HDBR was observed to remove 18.4% of total nitrogen species in the influent. Varying NH4+ and NO3– concentrations in the feed did not have an effect on NH4+ removal (n=44, p=0.993 and n=44, p=0.610 respectively) while NH4+ feed concentration was found to be negatively related with NO3– removal (n=44, p=0.000) and NO3– feed concentration was found to be positively correlated with NO3– removal (n=44, p=0.000). Consistent removal of NH4+, combined with the accumulation of oxidized nitrogen species at high NH4+ fluxes indicates the presence of ammonia- and nitrite-oxidizing bacteria within the microbial community.
Introduction
城市废水通常治疗活性污泥法中，以减少悬浮固体（SS），生物需氧量（BOD），有机和无机氮和磷含量5,6。活性污泥处理，二次处理废水的装置，工作需要在一个曝气池填充有传入的废水和再循环的异养微生物的混合液的有机碳的氧化（通常称为活性污泥）5-7。该混合液，然后进入一个相当大的澄清器（沉淀池）其中污泥沉降更容易收集，要么被布置或再循环回到曝气池，而澄清，处理后的废水可以继续三级处理或消毒被释放到前受纳水体5-7。在辅助净化器的处理过的废水和固体（污泥）的高效分离为一个是正确功能所必需tewater处理系统，因为任何活性污泥不断超越澄清会增加废水5-8 BOD和SS。
对于二级处理的废水，其减少或消除需要大澄清罐，包括附装生长（生物膜）的反应器，膜生物反应器（MBR）的，与颗粒污泥的反应器有许多替代生物过程存在。在生物膜反应器中，形成生物膜，其中土壤微生物天然骨料和附上作为层在固体表面上，允许生物量保留和积累，而不需要一个澄清槽。生物膜反应器可分为三种类型：填充床反应器，流化床反应器，和生物转盘。填充床反应器，诸如滴滤器和生物塔，利用一个固定的固体生长表面5,6。流化床反应器（快堆）依赖于微生物的附着于颗粒，如砂，粒状活性炭（GAC），或玻璃珠，其通过高向上流速9,10保持悬浮状态。旋转生物反应器依赖于形成在安装于旋转轴媒体允许生物膜的生物膜被交替地暴露于空气和液体被治疗5,6。膜生物反应器使用的膜过滤单元，无论是在生物反应器（浸没配置）或经由再循环（侧流配置）5,11外部。该膜用于实现生物质和固体颗粒从处理后的液体11,12良好的分离。颗粒污泥反应器是上流式反应器中，速度13微生物极为致密，沉降颗粒的形成发生时，他们暴露在高肤浅的空气向上流动。
作为另一替代活性污泥法，一种新型的上流式反应器系统，现在被称为高密度生物反应器（卧床），为designeD和通过销售和Shieh（2006）建研究COD去除率由活性污泥从在低F / M条件合成废物流是已知会引起的沉降污泥差形成（即，膨胀污泥）1,7,14。所利用的卧床系统改性流化床反应器中，通常由一个上流式反应器和一个外部再循环罐的。流化床反应器一般操作与再循环流的流速足够高以保持生物膜生长基质悬浮但足够低以使生物膜覆盖的衬底被保留。不像流化床反应器中，卧床描述在销售和Shieh（2006）中使用相对低的循环物流的流速其中，随着外部通气，防止了反应器1内形成的生物量区的中断。随后的研究证明了这一点反应堆设计的能力，使用硝化/反硝化细菌3,4成功治疗了一系列的氮通量。在所有的螺栓IES的卧床内的稳定，生物质致密区的形成不再需要外部絮凝/沉淀工艺1-4。
正如我们在这里报告，使用卧床的生长致密培养物也已在光生物反应器（PBR）配置为藻类的培养试验。我们讨论的好处和这种新颖的反应器系统的藻类培养缺点及其潜在用于克服大的障碍与生物质收获（即，良好的固-液分离15,16）相关联的藻类生物燃料的商业化。以下协议描述了安装，启动，来自样品，并保持与藻类感兴趣的微生物群落的卧床所需的步骤。在异养和硝化/反硝化文化的启动和运行方案的变化也将被提及。最后，一般的优点，缺点，以及这种新型反应器设计未知数将突出显示。
Protocol
Representative Results
Discussion
本节将首先解决可能的操作问题，以及使用不同的微生物群落所需要的协议变化的讨论。这种反应器设计的优点将讨论的，包括以管理控制氧通量的和在反应器内形成的高密度的絮凝物的能力。目前的挑战和调查可能的途径也将被提及。
协议的细微差别和变化
HDBRs种植不同类型的文化中的操作需要运营协议的微小变化，这取决于被调查的物种。充分的混合和…
Disclosures
The authors have nothing to disclose.
Acknowledgements
The authors would like to acknowledge Aspen Walker at the University of Pennsylvania for her assistance in reactor maintenance and sample collection.
Materials
| Aeration stone | Alita | AS-3015C | |
| Aerator | Top Fin | Air-1000 | |
| Ammonium chloride | Sigma Aldrich | A9434 | |
| Anion analysis column | Shodex | IC SI-52 4E | |
| Beaker (600 mL) | Corning Pyrex | 1000-600 | Used as mixing vessel (MV). Addition of hose barbs at the bottom and 500 mL levels. Outside diameter of hose barbs 3/8". |
| Calcium chloride | Sigma Aldrich | C5670 | |
| Cation analysis column | Shodex | IC YS-50 | |
| Cobalt chloride hexahydrate | Sigma Aldrich | C8661 | |
| Copper chloride | Sigma Aldrich | 222011 | |
| Ferric chloride | Sigma Aldrich | 157740 | |
| Filter (vacuum) | Fisherbrand | 09-719-2E | 0.45 um membrane filter, MCE, 47 mm diameter |
| Graduated cylinder (1000 mL) | Corning Pyrex | 3025-1L | Used as reactor vessel (R). Addition of hose barbs at bottom, 500 mL, and 1 L levels. Outside diameter of hose barbs 3/8". |
| HPLC/IC | Shimadzu | Prominence | |
| Magnesium sulfate | Sigma Aldrich | M2643 | |
| Masterflex L/S variable speed drive | Masterflex | 07553-50 | Drive for recycle and feed pumps (2 needed) |
| Nickel chloride hexahydrate | Sigma Aldrich | N6136 | |
| Potassium nitrate | Sigma Aldrich | P8291 | |
| (Monobasic) Potassium phosphate | Sigma Aldrich | P5655 | |
| Pump head | Masterflex | 07018-20 | Recycle pump head |
| Pump head | Masterflex | 07013-20 | Feed pump head |
| Pump tubing | Masterflex | 6404-18 | Recycle pump tubing |
| Pump tubing | Masterflex | 6404-13 | Feed pump tubing |
| Sodium bicarbonate | Sigma Aldrich | S5761 | |
| Zinc sulfate heptahydrate | Sigma Aldrich | Z0251 |
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