为满足长期或永久的遥远星际载人空间任务的需要，受控生态生保系统（Controlled ecological life support system, CELSS）要求近乎 100%的物质流闭合度。近年来，包括我国在内的世界航天大国纷纷开展了若干地基 CELSS集成试验研究，其中基于生化原理的适于地基 CELSS 的废水处理工艺日益得到重视。
目前，地基 CELSS 的废水处理有待深入研究，存在亟需解决的关键科学与技术问题，例如：1）基于 CELSS对载荷和物质流闭合度的要求，亟需开发结构紧凑、低耗高效的废水处理工艺，使之在时空严格约束条件下既能最大程度地回收利用废水中的水分和氮磷养分，又能最低程度地排放副产物（如气体和剩余污泥）； 2）亟需明确基于生化原理的废水处理过程的物质流特性，揭示污染物及元素在气、液、固三相之间的分布和转化规律，从而提高整个 CELSS的物质流闭合度。因此，针对上述需求，本研究的目的就是通过系统分析地基 CELSS 废水的特性（水质和水量）及处理与利用要求，开展基于膜生物反应器（Membrane bioreactor,MBR）的组合工艺在地基 CELSS废水处理中的研究与应用。主要结论如下：
1）首次开发了以“厌氧膜生物反应器（ Anearobic membrane bioreactor,AnMBR）+好氧膜生物反应器”为核心的组合工艺。以模拟废水为对象，通过实验室研究，明确了地基 CELSS废水处理过程中主要污染物的去除转化特征和碳、氮、磷、硫等物质流特性。为中国航天员科研训练中心研制了密闭生态循环系统试验平台废水处理系统，并成功应用于“绿航星际——4人 180天受控生态生保系统集成试验”。
2）优化了 AnMBR在水解酸化条件下的微曝气操作参数，解决了表面活性剂的持续积累，保障了组合工艺的稳定运行。为严格控制生物气的产生，AnMBR被设定在水解酸化状态下运行。试验研究发现，废水中表面活性剂和有机物在AnMBR内出现持续积累，严重影响组合工艺的稳定运行。针对上述问题，开发和优化了 AnMBR的微曝气操作条件。结果表明，微曝气促进了有机物和表面活性剂大分子团的分解和微生物的活性，AnMBR内混合液表面活性剂和溶解性化学需氧量（soluble chemical oxygen demand, SCOD）浓度从 9000 mg/L和35000mg/L以上迅速降低至2000 mg/L和12000 mg/L附近，其初期降解动力学符合零级反应特征。
3）揭示了 AnMBR-MBR组合工艺处理废水过程的微生物群落特征。高通量测序分析结果表明，微曝气水解酸化条件下，AnMBR内的优势细菌属为Aquamicrobium 、 Flaviflexus 、Thiopseudomonas和Pseudomonas ,其中Thiopseudomonas为没有微曝气时不存在的细菌种群。基于KEGG数据库的功能分析表明，微曝气促进了AnMBR内细菌的环境适应性、转录和翻译、复制和修复、细胞膜运输，增强了细菌对脂肪、氨基酸、外源性物质等的代谢能力，这是表面活性剂和有机物得以迅速降解的原因所在。 MBR内的优势微生物菌纲为Alphaproteobacteria和 Betaproteobacteria。定量 PCR分析表明，所有 MBR污泥样品中的四个硝化过程关键基因（amoA、hao、nxrA和 nxrB）均在 1.2×10 copies/µg6DNA以上，这与其良好的完全硝化效果相一致。
4）明确了 AnMBR-MBR 组合工艺处理废水过程的物质流特性。在优化的系统工况下，系统产水的总有机碳（total organic carbon, TOC）、表面活性剂、氨氮（NH4+-N）和亚硝酸盐氮（NO2--N）浓度分别低于 10 mg/L、0.15 mg/L、4 mg/L和 1 mg/L，硝酸盐氮（NO3--N）浓度高于 700 mg/L，占总氮（Total nitrogen, TN）比例在 99%以上。物质流分析结果显示，废水处理系统每产出 1 L净水，需要消耗品（碳酸氢钾和膜）5.12 g；向外排放剩余污泥 4.82 mL（以干泥计为 0.037 g），排放 5.22×10-3g氨气和1.64×10-3 g甲烷，实现了时空约束条件下高水回收率、有机物高效去除、营养元素高度保留、安全经济的废水处理目标。
To meet the requirements of long-term or permanent manned missions in far away planetary space, the controlled ecological life support system (CELSS) needs almost 100% material flow closure. For the past few years, space powers all over the world including China have conducted some terristrial-based CELSS integrated experiments, in which wastewater treatment processes based on biochemical principle were paid more and more attention. At present, wastewater treatment processes for terristrial-based CELSS needs further research and there are still some key scientific and technological problems to be solved ergently, for instance: 1) Based on the requirements of CELSS for the load and closure of material flow, it is urgent to develop a wastewater treatment process featuring small foot prints, low consumption and high efficiency, so that the water and nutrients in the wastewater can be recycled to the maximum extent under the strict constraint of time and space, and the by-products such as harmful gas and excess sludge can be discharged to the lowest level; 2) It is urgent to clarify the characteristics of the material flow in processes of wastewater treatment based on biochemical principle, and to reveal the distribution and transformation of the pollutants and elements between the gas, liquid and solid phases, so as to improve the closure of the whole CELSS material flow. Thus, for the requirements above, the purpose of this study is to carry out development and application of the combined technological
process based on membrane bioreactor (MBR) in the treatment of terrestrial-based CELSS wastewater by systematically analyzing the characteristics of the wastewater amount and quality in the CELSS and the requirements of treatment and utilization.
The major conclusions are as follows:
1) The combined technological process centering on “Anearobic membrane bioreactor (AnMBR) + MBR” was developed for the first time. Synthetic wastewater was used in the laboratory investigation and characteristics of elemination and transformation of mjor pollutants and material flow of carbon, nitrigen, phosphorus and sulphur were systematically clarified. A wastewater treatment system was developed for China Astronaut Research and Training Center’s closed ecological circulatory system platform and later was successfully applied in the 4-person-180-day CELSS integrated experiment.
2) The operational parameters of microaeration for the AnMBR under the condition of hydrolysis-acidification were optimized, which solved the continuous accumulation of surfactants and ensured the stable operation of the combined process. To limit production of biogas, the AnMBR was designed to run under hydrolysis-acidification state. Accumulation of surfactants and organic compounds in the AnMBR which was a severe threat to the stability of the system having been observed, microaeration was introduced and optimized as a technique to enhance the hydrolysis-acidification process. Relative results showed that microaeration promoted the disintegration of large aggregates and the activity of microorganism. Concentrations of surfactants and SCOD in the supernatant decreasing promptly from 9000 mg/L and 35000 mg/L to 2000 mg/L and 12000 mg/L, respectively. And what’more, the degradation in the early stage followed the kinetic characteristics of zero order reaction.
3) The microbial community characteristics of the AnMBR-MBR combined process for wastewater treatment were evealed. Analysis results of high throughout sequencing showed that under the hydrolysis-acidification condition with microaeration, the predominant genuses in the AnMBR were Aquamicrobium,Flaviflexus, Thiopseudomonas and Pseudomonas. And Thiopseudomonas was not detected in the samples collected befor the introduction of microaeration. Functional analysis based on the KEGG database revealed that during the microaeration-assisted stage, microorganism in the AnMBR was strengthened in environmental adaptation, transcription and translation, replication and repair, membrane transport and metabolic activities of lipid, amino acids and xenobiotics, which was the reason why the surfactants and organic compounds got degradated quickly. For the MBR, the predominant classes were Alphaproteobacteria and Betaproteobacteria. And results of qPCR showed that for all the 5 samples, four key functional gens (amoA, hao, nxrA and nxrB) in the nitrification process were all above 1.2×10 6 copies/µg DNA, which was consistent with the excellent nitrification effect of the MBR.
4)The material flow characteristics of the AnMBR-MBR combined process for wastewater treatment were made clear. Under the optimized process parameters,the concentration of TOC, surfactants, NH4+ -N and NO2- -N of the effluent was below 10 mg/L, 0.15 mg/L, 4 mg/L and 1 mg/L, respectively. The concentration of NO3--N was above 700 mg/L, accounting for more than 99% of TN. Analysis of the material flow indicats that for producing 1 L purified effluent, the wastewater system needs 5.12g consumables including potassium bicarbonate and membrane, and it discharges 4.82 mL excess sludge (0.037 g dry sludge), 5.22×10-3 g NH3 and 1.64×10-3 g CH4. Theses results demonstrate the realization of “cost-effective and safe wastewater treatment”with high efficiencies of water recycling, degradation of organic compounds and nutrients reclamation under spatial and temporal constrains.