Microbial community functional structure in response to micro-aerobic conditions in sulfate-reducing sulfur-producing bioreactor

Limited oxygen supply to anaerobic wastewater treatment systems had been demonstrated as an effective strategy to improve elemental sulfur(S0) recovery, coupling sulfate reduction and sulfide oxidation. However, little is known about the impact of dissolved oxygen(DO) on the microbial functional structures in these systems. We used a high throughput tool(GeoChip) to evaluate the microbial community structures in a biological desulfurization reactor under micro-aerobic conditions(DO: 0.02–0.33 mg/L). The results indicated that the microbial community functional compositions and structures were dramatically altered with elevated DO levels. The abundances of dsrA/B genes involved in sulfate reduction processes significantly decreased(p 0.05, LSD test) at relatively high DO concentration(DO: 0.33 mg/L). The abundances of sox and fccA/B genes involved in sulfur/sulfide oxidation processes significantly increased(p 0.05, LSD test) in low DO concentration conditions(DO: 0.09 mg/L) and then gradually decreased with continuously elevated DO levels. Their abundances coincided with the change of sulfate removal efficiencies and elemental sulfur(S0) conversion efficiencies in the bioreactor. In addition, the abundance of carbon degradation genes increased with the raising of DO levels, showing that the heterotrophic microorganisms(e.g., fermentative microorganisms) were thriving under micro-aerobic condition. This study provides new insights into the impacts of micro-aerobic conditions on the microbial functional structure of sulfatereducing sulfur-producing bioreactors, and revealed the potential linkage between functional microbial communities and reactor performance.     

Bamboo charcoal addition enhanced the nitrogen removal of anammox granular sludge with COD: Performance, physicochemical characteristics and microbial community

The effects of different chemical oxygen demand (COD) concentrations on the anammox granular sludge with Bamboo Charcoal (BC) addition were evaluated in UASB reactor. The results showed that the average total nitrogen (TN) removal efficiency was reduced from 85.9% to 81.4% when COD concentration was increased from 50 to 150 mg/L. However, the TN removal efficiency of BC addition reactors was dramatically 3.1%–6.4% higher than that without BC under different COD concentrations. The average diameter of granular sludge was 0.13 mm higher than that without BC. The settling velocity was increased by elevated COD concentration, while the EPS and VSS/SS were increased with BC addition. The high-throughput Miseq sequencing analyses revealed that the bacterial diversity and richness were decreased under COD addition, and the Planctomycetes related to anammox bacteria were Candidatus Brocadia and Candidatus Kuenenia. The Metagenomic sequencing indicated that the abundance of denitrification related functional genes all increased with elevated COD, while the abundance of anammox related functional genes of decreased. The functional genes related to anammox was hydrazine synthase encoding genes (hzsA, hzsB and hzsB). The average relative abundance of hzs genes in the reactor with BC addition was higher than the control at COD concentrations of 50 mg/L and 150 mg/L. The functional genes of denitrification mediated by BC were higher than those without BC throughout the operation phase. It is interesting to note that BC addition greatly enriched the related functional genes of denitrification and anammox.     

Denitrification and microbial community in MBBR using A. donax as carbon source and biofilm carriers for reverse osmosis concentrate treatment

In this study,raw Arundo donax(A.donax)pieces were applied as carbon source and biofilm carriers for denitrification in a lab-scale moving bed biofilm reactor(MBBR)for the treatment of reverse osmosis concentrate gathered from local wastewater reuse plant.At stable phase(about 60 days),efficient denitrification performance was obtained with73.2%±19.5%NO_(3-)~-N average removal and 8.10±3.45 g N/(m~3·day)NO_(3-)~-N average volumetric removal rate.Mass balance analysis showed that 4.84 g A.donax was required to remove 1 g TN.Quantitative real-time PCR analysis results showed that the copy numbers of 16S r-RNA,narG,nirS,nosZ and anammox gene of carrier biofilm and suspended activated sludge in the declination phase(BF2 and AS2)were lower than those of samples in the stable phase(BF1 and AS1),and relatively higher copy numbers of nirS and nirK genes with lower abundance of narG and nosZ genes were observed.High-throughput sequencing analysis was conducted for BF2 and AS2,and similar dominant phyla and classes with different abundance were obtained.The class Gammaproteobacteria affiliated with the phylum Proteobacteria was the most dominant microbial community in both BF2(52.6%)and AS2(41.7%).The PICRUSt prediction results indicated that 33 predictive specific genes were related to denitrification process,and the relative abundance of 18 predictive specific genes in BF2 were higher than those in AS2.     

Anammox transited from denitrification in upflow biofilm reactor

Anammox was successfully transited from heterotrophic denitrification and autotrophic denitrification in two upflow biofilm reactors, respectively. The results showed that the volumetric loading rate and nitrogen removal efficiency in the reactor transited from heterotrophic denitrification were higher than that in its counterpart. When the hydraulic retention time was 12 h or so, the total nitrogen loading rate was about 0.609 kg N/(m^3 .d), and the effluent ammonia and nitrite concentrations were less than 8.5 mg/L and 2.5 mg/L,respectively. The upflow anammox biofilm reactor was capable of keeping and accumulating the slow-growing bacteria efficiently. During operation of the reactor, the biomass color was gradually turned from brownish to red, and the ratio of ammonia consumption, nitrite consumption and nitrate production approached the theoretical one. These changes could be used as an indicator for working state of the reactor.     

Simultaneous nitrification and denitrification in step feeding biological nitrogen removal process

The simultaneous nitrification and denitrification in step-feeding biological nitrogen removal process were investigated under different influent substrate concentrations and aeration flow rates.Biological occunenee of simultaneous nitrification and denitrification was verified in the aspect of nitrogen mass balance and alkalinity.The experimental results also showed that there was a distinct linear relationship between simultaneous nitrification and denitrification and DO concentration under the conditions of low and high aeration flow rate.In each experimental run the floc sizes of activated sludge were also measured and the results showed that simultaneous nitrification and denitriflcation could occur with very small size of floc.     

Cultivation of aerobic granules for simultaneous nitrification and denitrification by seeding different inoculated sludge

Cultivation of aerobic granules for simultaneous nitrification and denitrification in two sequencing batch airlift bioreactors was studied. Conventional activated floc and anaerobic granules served as main two inoculated sludge in the systems. Morphological variations of sludge in the reactors were observed. It was found that the cultivation of aerobic granules was closely associated with the kind of inoculated sludge. Round and regular aerobic granules were prevailed in both reactors, and the physical charactedstics of the aerobic granules in terms of settling ability, specitic gravity, and ratio Of water containing were distinct wnen the inoculate sludge differe. Aerobic granules formed by seeding activated floc are more excellent in simultaneous nitrification and denitrification than that by aerobic granules formed from anaerobic granules. It was concluded that inoculated sludge plays a crucial role in the cultivation of aerobic granules for simultaneous nitrification and denitrification.     

Effect of operating parameters on sulfide biotransformation to sulfur

A laboratory-scale bioreactor with polyethylene semi-soft packing was constructed and utilized to determine the efficlency of sulfide biotransformation to sulfur under various operating parameters. Sodium sulfide dissolved in tap water was pumped into the bioreactor as sulfide for biological desulfurization. The sulfide, sulfur and sulfate-S in the effluent and the sulfide purged as gas-phase HzS were determined to investigate the effects of operating parameters, such as pH, DO, hydraulic retention time （HRT）, temperature and salinity, on the sulfide oxidation products. The activity of bacteria was highest at pH 7.8-8.2. The maximal sulfide removal load was 7.25 kg/（m^3·day）, with a 322.07 mg/L influent sulfide concentration and 4.80 mg/L DO. The increase of DO value corresponds to a decrease in the sulfur yield. The reactor had the highest sulfide removal load and sulfur yield at 2.55 mg/L DO. HRT had little effect on desulfurization efficiency when the sulfide removal load was kept constant. The most effective desulfurization temperature was 33℃. The sulfide removal load decreased from 2.85 to 0.51 kg/（m^3.day） with increasing salinity from 0.5% to 2.5% （m/m）.     

A review of diversity-stability relationship of soil microbial community: What do we not know?

The impact of decreased biodiversity on ecosystem stability, or the diversity-stability (D-S) relationship, is one of the major concerns of modern ecological studies. Studies on the D-S relationship for soil microbial communities began in 2000 when the fumigation method was developed to generate different levels of soil microbial biodiversity. The studies used various measures and levels of biodiversity, and covered several functional parameters. Due to the lack of general concepts and reliable approaches to define microbial species, studies on the D-S relationship of soil microbial communities concentrate on genetic diversity and functional diversity more than species diversity. Contradictory results were observed in various studies on D-S relationship with possible factors affecting or even changing the directions of the D-S relationship including: (1) the methods of stability measurement, (2) the techniques in microbial diversity measurement, (3) the measures and levels of diversity, (4) the type and strength of disturbance, (5) the traits of functions, and (6) the hidden treatments stemming from diversity manipulation. We argue that future studies should take diversity, species composition and interaction, and soil environmental conditions holistically into account in D-S studies to develop modeling to predict soil functional stability. We also suggest that studies should be carried out on a wider range of disturbance types and functional parameters, and efforts be shifted towards long-term field studies.     

Sulfate reduction behavior in pressure-bearing leachate saturated zone

Attention should be paid to the sulfate reduction behavior in a pressure-bearing leachate saturated zone. In this study, within the relative pressure range of 0–0.6 MPa, the ambient temperature with the highest sulfate reduction rate of 50°C was selected to explore the difference in sulfate reduction behavior in a pressure-bearing leachate saturated zone. The results showed that the sulfate reduction rate might further increase with an increase in pressure; however, owing to the effect of pressure increase, the generated hydrogen sulfide (H₂S) could not be released on time, thereby decreasing its highest concentration by approximately 85%, and the duration extended to about two times that of the atmospheric pressure. Microbial community structure and functional gene abundance analyses showed that the community distribution of sulfate-reducing bacteria was significantly affected by pressure conditions, and there was a negative correlation between disulfide reductase B (dsrB) gene abundance and H₂S release rate. Other sulfate reduction processes that do not require disulfide reductase A (dsrA) and dsrB genes may be the key pathways affecting the sulfate reduction rate in the pressure-bearing leachate saturated zone. This study improves the understanding of sulfate reduction in landfills as well as provides a theoretical basis for the operation and management of landfills.     

Molecular characterization of microbial communities in bioaerosols of a coal mine by 454 pyrosequencing and real-time PCR

Microbial diversity and abundance in bioaerosols of a coal mine were analyzed based on 454 pyrosequencing and real-time polymerase chain reaction(PCR). A total of 37,191 high quality sequences were obtained and could be classified into 531, 1730 and 448 operational taxonomic units respectively for archaea, bacteria and fungi at 97% sequence similarity. The Shannon diversity index for archaea, bacteria and fungi was respectively 4.71, 6.29 and 3.86, indicating a high diversity in coal mine bioaerosols. Crenarchaeota, Proteobacteria and Ascomycota were the dominant phyla for archaea, bacteria and fungi, respectively. The concentrations of total archaea, bacteria and fungi were 1.44 × 108, 1.02 × 108 and 9.60 × 104cells/m3, respectively.Methanotrophs observed in bioaerosols suggested possible methane oxidation in the coal mine. The identified potential pathogens to coal miners, such as Acinetobacter schindleri,Aeromonas cavernicola, Alternaria alternata, Aspergillus penicillioides, Cladosporium cladosporioides,and Penicillium brevicompactum were also observed. This was the first investigation of microbial diversity and abundance in coal mine bioaerosols. The investigation of microbial communities would be favorable in promoting the progress of methane control based on microbial technique and concern on coal miners’ health.     

废水同步脱硫脱氮关键工艺参数及微生物群落结构的研究

大量未经处理的含硫化物和硝酸盐废水的排放将带来严重的环境问题.根据以废治废原则,使用厌氧滴滤塔反应器构建的同步脱硫耦联反硝化脱氮反应(SDD)能很好的去除废水中S~(2-)和NO-x-N.其中以聚氨酯泡沫为填料的厌氧滴滤塔反应器中生物活性最强,脱氮脱硫效果最好.体系中功能菌优先将S~(2-)氧化成S0,待S~(2-)去除完全后,再进一步将S0氧化成SO_4~(2-).同时,SDD反应降解NO_3~--N的速率快于NO_2~--N.进水S/N摩尔比越大,产物中SO_4~(2-)相对含量越低.结合实际工程考虑,应控制进水S/N摩尔比在5/3~5/2之间,S~(2-)浓度控制在538 mg·L-1以下.微生物群落结构分析结果表明,Thiobacillus属在4组反应器上占绝对优势,其相对丰度均高于40%.其次相对丰度较高的Rhodanobacter、Arenimonas和Truepera属与厌氧反硝化作用密切相关.对4组反应器中微生物进行Alpha-多样性分析结果表明取得较好脱硫耦联反硝化效果的体系中物种多样性指数也较高.     

强化厌氧污泥体系同步脱硫反硝化特性研究

以硫化物为电子给体的自养反硝化厌氧体系是代替传统异养反硝化工艺处理低C/N比含氮废水的有效工艺,可以同时去除硫化物和硝酸盐.将脱氮硫杆菌菌悬液接种到厌氧污泥体系中,脱氮硫杆菌快速富集,采用5组进水比N/S比不同的反应瓶进行试验,运行15d后,测定不同时段的出水硫化物、硝酸盐、亚硝酸盐、硫酸盐浓度等指标,考察强化厌氧污泥体系去除硫化物和硝酸盐的特性,并对生化反应机制进行初步研究.结果表明,强化厌氧污泥体系运行3h后,进水中90%的硫化物被去除,硫化物的去除与进水N/S比无关,硫化物(以S计)去除速率高达20～24g·(m3·h)-1,是相关文献报道的10倍左右;运行6h后,进水中65%的硝氮被去除,硝氮的去除负荷随着进水N/S比的提高而增大,最高达到940g·(m3·h)-1,约为硫自养反硝化体系硝氮去除负荷的2倍,此时体系中亚硝氮积累,最高浓度达到93mg·L-1,进水N/S比低的条件下,6h后亚硝氮消失,进水N/S比较高时,21h后出水中未检测到亚硝氮.表明强化厌氧污泥体系停留6h后可以实现同时去除硫化物和硝酸盐,但硝酸盐首先转化为亚硝氮.与以往不同的是研究发现硫化物与生物硫粒产生多硫化合物的链式反应,是硫化物迅速转化的主要途径,此外,还原硝氮的电子给体并不来源于硫化物,可能主要来源于体系中产生的单质硫.     

有机无机氮配施对不同程度盐渍土硝化和反硝化作用的影响

以内蒙古河套灌区轻度盐渍土S₁（EC=0.62 dS·m^-1）及中度盐渍土S₂（EC=1.17 dS·m^-1）为对象,研究硝化和反硝化进程对盐渍化程度和有机无机氮配施比例的响应及其影响因素.本试验设置了6个处理,包括不施氮（CK）、单施无机氮（U₁）以及用有机氮（U₃O₁、U₁O₁、U₁O₃和O₁）替代25%、50%、75%和100%的无机氮.结果表明,盐度升高会降低土壤硝化势而提高土壤反硝化能力,同一处理S₁土壤硝化潜势较S₂土壤高出28.81%~69.67%,而反硝化能力降低17.16%~88.91%.盐度升高会降低AOB丰度及硝化贡献率,但会增加AOA丰度和硝化贡献率;盐度增加会提高土壤nirK和nirS型菌丰度,同时会增加N₂O/（N₂O+N₂）产物比,但会抑制nosZ丰度.S₁土壤,以U₁O₁处理硝化势和反硝化能力最大,较单施化肥增幅分别达到18.59%和15.87%;S₂土壤,各施肥处理之间土壤硝化势差异不显著,反硝化能力以O₁处理最大,较单施化肥提高88.26%.S₁和S₂盐渍土分别以U₁O₁及O₁处理获得较高的AOB基因丰度及硝化贡献率,且增大了nirS和nosZ基因丰度,并显著降低N₂O/（N₂O+N₂）产物比.综上,相比单施无机氮,轻度盐渍土以有机无机氮各半配施,中度盐渍土以单施有机氮更加利于土壤硝化反硝化过程进行.     

碳源对反硝化细菌的反硝化速率和群落结构的影响

为探究碳源类型在反硝化过程中对氮素转化和微生物群落组成的影响,分别建立R1（以C₆H₁₂O₆为碳源）和R2（以CH₃COONa为碳源）反应器,通过分析R1和R2反应器中反硝化过程的氮素转化情况,评价C₆H₁₂O₆和CH₃COONa对脱氮效果的影响,并运用动力学模型对R1和R2反应器中反硝化能力进行评价;同时,采用高通量测序技术表征2种碳源对反应器中微生物群落结构和多样性的影响.结果表明:①运行后期的R1、R2反应器中单位生物量的反硝化速率（以NO₃--N计,下同）分别为8.56、11.26 mg/（g·h）,R1反应器中NO₂--N累积平均值为11.34 mg/L,显著高于R2反应器（0.20 mg/L）,且R1反应器中NH₄+-N累积平均值为6.58 mg/L,是R2反应器（0.65 mg/L）的10.11倍.②反应器中NO₃--N还原过程均符合Haldane模型,其中R1、R2反应器中单位生物量的r_max（最大降解速率）分别为35.61、47.79 mg/（g·h）,表明R2反应器中的反硝化能力强于R1反应器.③微生物经过富集后,其细菌多样性和物种丰度下降,但发挥反硝化作用的微生物相对丰度逐渐增加.R1和R2反应器中共同的优势菌门有Proteobacterias、Bacteroidetes、Firmicutes和Gracilibacters,其在R1反应器中的相对丰度依次为96.14%、2.06%、0.66%和0.47%,在R2反应器中依次为79.75%、6.88%、9.47%和2.13%,优势菌门在不同运行时间的丰度表达上存在消长变化状态.研究显示,C₆H₁₂O₆和CH₃COONa在反硝化过程的氮素转化上存在明显差异,对各类优势菌群的相对丰度有明显影响.      

包埋固定化微生物的硫自养反硝化实验研究

采用升流式颗粒污泥床,外加Na<,2>S<,2>O<,3>作为电子供体,在室温下连续运行220 d,结合硫自养反硝化与固定化包埋技术进行脱氮实验,考察包埋颗粒的驯化条件、影响因素和最佳运行条件.进水负荷(以N计)维持0.22 kg/(m<'3>·d),包埋颗粒经23 d驯化成功,NO<'-><,3>-N(100 mg/...     

西藏日太阳总辐射估算模型的优化与时间尺度效应

根据2012～2014年拉萨站点的日太阳辐射观测数据,对3种日太阳总辐射估算模型(左大康、Prescoff和王炳忠等提出的估算模型)的估算结果和实际观测结果进行误差检验分析,结果表明:3种模型都通过了显著性检验,其平均绝对误差(MAE)分别为6.17 MJ/(m~2·d)、6.42 MJ/(m~2·d)和12.31 MJ/(m~2·d),均方根误差(RMSE)分别为1.60 MJ/(m~2·d)、1.65 MJ/(m~2·d)和2.78 MJ/(m~2·d),表明利用地理位置信息和日照时数的左大康估算模型对拉萨日太阳总辐射的估算效果优于Prescoff和王炳忠估算模型。利用左大康估算模型分别估算得到2015年拉萨、那曲和葛尔地区的日太阳总辐射值,并进行模型验证。通过分析拉萨1971～2015年的太阳总辐射变化和周期性特征,研究日太阳总辐射估算模型的时间尺度效应。按照11年和四季两种不同的时间尺度,利用线性回归法对日太阳总辐射估算结果和实际观测结果进行误差和相关性分析,得到经验参数a和b的值与时间尺度有一定关系。11年和四季两种时间尺度除夏季以外,其他时间拟合模型的精度均得到了提高。通过线性回归法得出45年的西藏日太阳总辐射优化估算模型,该模型估算日太阳总辐射的误差小于左大康模型,估算精度较高。     

铁矿石和生物炭添加对潜流人工湿地污水处理效果和温室气体排放及微生物群落的影响

人工湿地中基质的种类和填充方式会影响人工湿地中微生物的多样性及丰度,进而影响污水处理效果.通过在温室内构建空白-人工湿地（CW0）、铁矿石-人工湿地（CW1）、生物炭-人工湿地（CW2）和铁矿石+生物炭-人工湿地（CW3）这4组湿地,研究不同填料人工湿地系统的污水处理效果和温室气体排放及微生物群落结构的差异.结果表明,添加铁矿石或者生物炭能够提高-0.12%～1.7%的COD去除率.添加生物炭能够分别提升22.48%的NH⁺₄-N和6.82%的NO^-₃-N去除率,并分别降低83.91%的CH₄和30.81%的N₂O排放通量.添加铁矿石能够降低1.12%的NH⁺₄-N去除率,提高3.98%的NO^-₃-N去除率,并分别降低33.29%的CH₄和25.2%的N₂O排放通量.添加生物炭或者铁矿石均能够增加放线菌门（Actinobact...     

低温下磁性载体MBBR系统微生物群落特征和功能预测分析

为阐明低温下磁性载体对移动床生物膜反应器(MBBR)处理能力的影响,探究了反应器内生物膜的微生物多样性、群落结构、功能特征和氮代谢通路.结果表明,与商用载体反应器(对照组)相比,磁性载体反应器具有更高的污染物去除率,其对NH⁺₄-N和TN的平均去除率分别提高了16.2%和12.1%.Illumina高通量测序结果显示,磁性载体生物膜的微生物多样性和丰富度更高.由于不同微生物的磁化率不同,导致两种载体生物膜微生物群落结构存在显著差异.磁性载体生物膜中硝化菌属(如：Nitrosomonas、Nitrospira)和反硝化菌属(如：Sphaerotilus、Zoogloea)的相对丰度显著增多.PICRUSt2功能预测分析显示,磁性载体生物膜的整体基因功能表达水平更高,在信号传导机制和细胞内运输、分泌和囊泡运输等方面优势更明显.此外,大多数与氮代谢相关基因在磁性载体生物膜中丰度更高,如涉及硝化过程的基因amo、hao和反硝化过程基因nap、nor等,使得生物膜的低温脱氮潜力增强.以上结果从微观生物学角度更好地解释了反应器处理能力的差异,为磁性载体强...