在有氧条件下用生物过滤系统去除NOx

针对有氧环境下用生物过滤法处理废气中的NOx效率普遍不高的现状,将优选后的好氧反硝化菌应用于生物过滤系统用来脱除模拟燃烧废气中NOx,同时设立反硝化菌活性再生系统,维持系统中微生物间的持续稳定反硝化协同性和有效微生物量.进一步研究高浓度氧环境下,环境因素对NO脱除效率的影响,以及研究模拟气体中NO在生物过滤系统中的转化机理.结果表明,该工艺系统能有效克服氧对反硝化菌活性的抑制作用,生物滤塔在不同氧浓度下皆可实现对NO的高效率脱除;甚至在氧气体积分数20%、气体停留时间为1min、最佳操作温度为40～50℃条件下,对647mg·m-3NO的脱除率可达85%以上.本实验有目的地培养得到好氧条件下特有的微生物混合体系,其以兼性反硝化菌为主,多种菌种的存在形成良好的生物协同性,有利于有氧环境下NOx好氧反硝化反应的高效稳定进行.     

几种生物脱氮新工艺的比较

目前已经发现了2种微生物脱氯新途径：一是根据好氧氨氧化菌具有反硝化能力，从而在一定条件下反硝化脱氯：二是在功能微生物的作用下，亚硝酸盐与氨离子一起厌氧氨氧化，并且发现了厌氧氨氧化菌与好氧氨氧化菌或甲烷菌能协同耦合在一种有利的微生态环境中。基于以上新途径提出了几种生物脱氟新工艺，包括了：SHARON、ANAMMOX、SHARON—ANAMMOX、CANON、OLAND、NOX工艺、需氧反氨化工艺（Aerobic deammonification）、甲烷化与厌氧氨氧化耦舍工艺。     

低强度超声对短程硝化污泥活性的影响

为提高短程硝化反硝化脱氮效率,采用低强度超声对短程硝化反应进行强化,通过对比氨氧化率和亚硝酸盐生产量,考察低强度超声对短程硝化污泥活性影响。首先,通过对超声能量的优化试验,发现低强度超声能够提升短程硝化污泥反应速率,且超声能量为43.20 kJ时氨氧化率和亚硝酸盐生成量最大;然后考察超声能量与污泥浓度的关系。结果表明:1)在相同超声能量(43.20 kJ)条件下,随着污泥质量浓度(0.34~1.03 g VSS/L)增加,能量密度降低,反应速率不断提高;2)保持污泥浓度恒定,增加超声能量,发现在43.20 kJ时短程硝化污泥活性最好,氨氧化速率比对照组提高25.42%,继续增加能量后去除速率开始下降,原因是适宜的能量会增加微生物细胞壁和细胞膜的通透性,加快基质传递和反应速率,提高微生物活性,但当所施加能量超出其所能承受范围,则会对微生物内部产生损害,降低其活性;3)考察超声能量对胞外聚合物浓度和酶活性影响,在43.20 kJ条件下,多糖、蛋白质和胞外聚合物(EPS)浓度分别提高了18.32%、26.54%和22.05%,氨单加氧酶活性增加19.82%。研究表明,由于低强度超声作用加快胞外聚合物分泌,增加生物酶活性,进而促进了短程硝化污泥反应速率。     

Evaluation of desiccant wheel and prime mover as combined cooling,heating, and power system

In this research heating, cooling and electrical demands of a residential tower are evaluated for Iran various weather conditions. For this purpose, several cities are selected as the representative of the specific weather conditions. To meet the cooling demand, desiccant cooling system plus alternative systems are applied. To analyze desiccant wheel, outlet humidity and temperature have been modeled. Also, the effect of rotational speed and regeneration temperature on entropy generation of the desiccant wheel has been studied based on the obtained results. It is deduced that the entropy generation may be increased by increasing the regeneration temperature and the rotational speed. To regenerate the desiccant wheel, to meet the electrical demand and also to provide heating load, prime mover in the form of internal combustion engine is selected. Since prime movers do not operate in the full load, their performance in the partial load has been evaluated. By taking into consideration the required regeneration heating, the number of required prime movers has been calculated based on the regeneration temperature and partial load for each city. The results show that the number of required prime movers is increased by increasing the regeneration temperature of the wheel.     

三级AO耦合工艺低温污水处理脱氮机理

采用分段进水三级AO耦合流离生化工艺处理低温废水,在温度为（10±1）℃条件下,控制HRT为8h,进水流量分配比为3：2：1,污泥回流比为50%,考察耦合工艺对低温污水中污染物的去除效果、反应器内污染物变化规律、各级氮去除规律及系统硝化反硝化性能.研究表明：耦合工艺COD及NH₄⁺-N去除效率均超过90%,TN及TP去除效率达到80%,反应器内生物膜污泥浓度在400~800mg/L之间,系统各级NH₄⁺-N去除率均超过80%,缺氧反硝化脱氮率及好氧同步硝化反硝化脱氮率分别为50.15%和26.05%.受底物浓度及功能菌群数量影响,系统第二级比硝化速率及比反硝化速率均最高.     

鄱阳湖沉积物重金属污染影响因素分析——基于STIRPAT模型

为探究人类活动对鄱阳湖沉积物重金属污染的影响,于2017年10月在鄱阳湖入口、出口及湖区布设20个采样点位,开展鄱阳湖沉积物重金属表层及垂向分布特征调查,评价其潜在生态风险.利用¹³⁷Cs和²¹⁰Pb计年法推算出鄱阳湖沉积物的平均沉积速率,并结合柱状分层样品重金属含量,得出具体年代的重金属蓄积特性.基于STIRPAT模型,通过偏最小二乘回归分析得到鄱阳湖沉积物重金属演变与总人口数量、城镇化率、实际人均GDP、绿色专利申请数、第二产业占比、第三产业占比6种社会经济指标的多元非线性模型.结果表明：（1）鄱阳湖表层沉积物重金属Cu污染最为严重且生态风险程度最高, 地累积指数为“强”或“中-强”污染范畴,单因子潜在生态风险指数平均值为47.25,属于“中等”生态风险.整个湖区的总潜在生态风险指数RI平均值为107.07,表明鄱阳湖表层沉积物重金属总体处于低生态危害水平.（2）1988~2017年总人口数量是影响鄱阳湖沉积物重金属Cd和Cu污染的最主要正向因素,其他正向因素为第二产业占比、第三产业占比、城镇化率及实际人均GDP,绿色专利申请数所反映出的区域绿色技术创新能力及环保研发投入对鄱阳湖沉积物重金属Cd、Cu污染具有负相关关系.     

The effect of dissolved oxygen concentration on long-term stability of partial nitrification process

Dissolved oxygen (DO) concentration is regarded as one of the crucial factors to influence partial nitrification process. However, achieving and keeping stable partial nitrification under different DO concentrations were widely reported. The mechanism of DO concentration influencing partial nitrification is still unclear. Therefore, in this study two same sequencing batch reactors (SBRs) cultivated same seeding sludge were built up with real-time control strategy. Different DO concentrations were controlled in SBRs to explore the effect of DO concentration on the long-term stability of partial nitrification process at room temperature. It was discovered that ammonium oxidation rate (AOR) was inhibited when DO concentration decreased from 2.5 to 0.5 mg/L. The abundance of Nitrospira increased from 10^11.5 to 10^13.7 copies/g DNA, and its relative percentage increased from 0.056% to 3.2% during 190 operational cycles, causing partial nitrification gradually turning into complete nitrification process. However, when DO was 2.5 mg/L the abundance of Nitrospira was stable and AOB was always kept at 10^10.7 copies/g DNA. High AOR was maintained, and stable partial nitrification process was kept. Ammonia oxidizing bacteria (AOB) activity was significantly higher than nitrite oxidizing bacteria (NOB) activity at DO of 2.5 mg/L, which was crucial to maintain excellent nitrite accumulation performance.     

C/N对SBR生物脱氮硝化过程微生物结构的动态影响

为揭示碳氮比（C/N）对硝化过程影响的机理本质,试验以人工模拟废水为研究对象,采用4组平行的SBR（R₀、R₅、R₁₀、R₁₅）反应器,基于16S rRNA基因-Illumina MiSeq高通量测序技术,考察了4种C/N（0、5、10、15）对硝化过程功能微生物组成和结构特征的影响.结果表明：4种C/N条件下,系统均获得了较好的去除氨氮（去除率>95%）和COD（去除率>90%）效果,TN也有不同程度的降低.此外,C/N会显著影响系统内微生物的多样性、种群结构和功能.R₀系统Chao1指数（922）、ACE指数（1232.4）、Shannon指数（6.76）和Simpson指数（0.96）均最大,故微生物多样性最丰富,而R₅的物种丰富度最低.在微生物门水平上,变形菌门（Proteobacteria）、拟杆菌门（Bacteroidetes）、蓝细菌门（Cyanobacteria）等9个相对丰度较高的门是重要的微生物门,其中变形菌门（Proteobacteria）约全部微生物的40.7%~65.2%,是4个系统中最优势的菌门.硝化过程的关键菌群亚硝化单胞菌科（Nitrosomonadaceae）及硝化螺旋菌属（Nitrospira）的相对丰度表现出随着C/N升高而急剧降低的趋势.基于LEfSe分析共获得了34组具有显著差异的微生物,从而得到了每种C/N条件下在微生物学分类水平上的菌群关键生物标记物.     

部分亚硝化-厌氧氨氧化处理磁混凝生活污水

以磁混凝预处理后的生活污水为处理对象,构建了部分亚硝化-厌氧氨氧化分体式反应器,通过曝气调控与生物强化促进部分亚硝化反应的稳定进行,并耦合厌氧氨氧化反应进行深度脱氮.近100d的运行结果表明,在生物强化和间歇曝气的控制条件下,亚硝酸盐积累率达到了89.93%;提高亚硝化反应器中曝气阶段溶解氧浓度（从0.6~0.8mg/L升高至1.0~1.2mg/L）有利于氨氮与总氮去除.该系统最高能够去除95.45%的氨氮和86.28%的总氮,实现了稳定、高效脱氮;磁混凝预处理后的生活污水在亚硝化反应器中,间歇曝气条件促进了残留的溶解性有机物为反硝化提供碳源,COD总去除率达到64.65%~74.42%,并且亚硝化反应器出水与系统最终出水的有机物组分相似,主要为难降解有机物.     

一株异养硝化-好氧反硝化菌Bacillus flexus X1-L的分离鉴定及效能研究

近年来,随着中国经济的快速发展,水体中氨氮超标问题已严重影响到人类身体健康和生态环境平衡,有效去除水体中的氨氮已成为人们研究的热点.在传统污水生物脱氮处理中,常采用微生物的硝化、反硝化作用去除污水中的氮素,从而降低对环境的污染.本文从活性污泥反应器中分离出一株异养硝化-好氧反硝化菌株,并命名为X1-L.菌体经形态学观察、生理生化测定及16S rRNA基因序列分析,确定属于芽孢杆菌属（Bacillus sp.）,Genbank登录号为MT457091,并利用MEGA7.0软件建立了相应的系统发育树.在以NH₄⁺-N为唯一氮源的条件下,菌株X1-L生长较好,COD去除率为96.4%,氨氮去除率达到99.6%,经硝化作用去除的氮有43.7%,证明菌株X1-L具有异养硝化能力.在以NO₂^--N或NO₃^--N为唯一氮源的条件下,菌株X1-L生长也较好,COD去除率分别为95.3%和96.4%,NO₂^--N和NO₃^--N去除率分别为95.5%和96.5%,经反硝化作用去除的氮分别有67.7%和68.2%,证明菌株X1-L具有好氧反硝化能力.