An autotrophic nitrogen removal process:Short-cut nitrification combined with ANAMMOX for treating diluted effluent from an UASB reactor fed by landfill leachate

A combined process consisting of a short-cut nitrification （SN） reactor and an anaerobic ammonium oxidation upflow anaerobic sludge bed （ANAMMOX） reactor was developed to treat the diluted effluent from an upflow anaerobic sludge bed （UASB） reactor treating high ammonium municipal landfill leachate.The SN process was performed in an aerated upflow sludge bed （AUSB） reactor （working volume 3.05 L）,treating about 50% of the diluted raw wastewater.The ammonium removal efficiency and the ratio of NO 2 N to NOx-N in the effluent were both higher than 80%,at a maximum nitrogen loading rate of 1.47 kg/（m 3 ·day）.The ANAMMOX process was performed in an UASB reactor （working volume 8.5 L）,using the mix of SN reactor effluent and diluted raw wastewater at a ratio of 1：1.The ammonium and nitrite removal efficiency reached over 93% and 95%,respectively,after 70-day continuous operation,at a maximum total nitrogen loading rate of 0.91 kg/（m 3 ·day）,suggesting a successful operation of the combined process.The average nitrogen loading rate of the combined system was 0.56 kg/（m 3 ·day）,with an average total inorganic nitrogen removal efficiency 87%.The nitrogen in the effluent was mostly nitrate.The results provided important evidence for the possibility of applying SN-ANAMMOX after UASB reactor to treat municipal landfill leachate.

Identification and Metabolic Mechanism of Non-fermentative Short-cut Denitrifying Phosphorus-removing Bacteria

To investigate the characteristics and metabolic mechanism of short-cut denitrifying phospho- rus-removing bacteria （SDPB） that are capable of enhanced biological phosphorus removal （EBPR） using nitrite as an electron acceptor, an aerobic/anoxic sequencing batch reactor was operated under three phases. An SDPB-strain YC was screened after the sludge enrichment and was identified by morphological, physiological, biochemical properties and 16S rDNA gene sequence analysis. Denitrifying phosphorus-removing experiments were conducted to study anaerobic and anoxic metabolic mechanisms by analyzing the changes of chemical oxygen demand （COD）, phosphate, nitrite, poly-fl-hydroxybutyrate （PHB）, and glycogen. The results show that strain YC is a non-fermentative SDPB similar to Paracoccus denitrificans. As a kind of non-fermentative bacteria, the energy of strain YC was mainly generated from phosphorus release （96.2%） under anaerobic conditions with 0.32 mg P per mg synthesized PHB. Under anoxic conditions, strain YC accumulated 0.45 mg P per mg degraded PHB, which produced most of energy for phosphate accumulation （91.3%） and a little for glycogen synthesis （8.7%）. This metabolic mechanism of strain YC is different from that of traditional phosphorus-accumulating organisms （PAOs）. It is also found that PHB, a kind of intracellular polymer, plays a very important role in denitrifying and accumulating phosphorus by supplying sufficient energy for phosphorous accumulation and carbon sources for denitrification. Therefore, monitoring AP/APHB and ANO2 -N/APHB is more necessary than monitoring AP/ACOD, ANO2 -N/ACOD, or AP / ANO2 -N.

Effects of Short-cut Flowering Branches on Harvest Time,Yield and Quality of Guire No.82 Mango

[Objectives]To further study the technology of short-cut flowering branches for Guire No.82 Mango,adjust its harvest time,increase yield and improve fruit quality,and increase the economic benefits of mango production.[Methods]The experiment of short-cut flowering branches was carried out for Guire No.82 Mango.[Results]At the initial flowering stage and full flowering stage of the primary inflorescence,with short-cut flowering branches and corresponding cultivation techniques,Guire No.82 Mango was easy to extract regenerated inflorescences.Compared with the control group,the flowering period of the regenerated inflorescences was delayed by 30-35 d and 40-50 d,respectively;the harvest time was delayed by 30 and 40 d,respectively;the yield significantly increased by 1.63 times and 2.25 times,respectively;compared with the control group,the number of fruits with embryo increased significantly,which were 1.39 and 2.25 times of the control,respectively;there was no significant difference in the fruit quality at the harvest time.[Conclusions]Short-cut flowering branches at the initial flowering stage and full flowering stage of the primary inflorescence is an effective measure to delay the marketing time of Guire No.82 Mango.

Sludge fermentation liquid addition attained advanced nitrogen removal in low C/N ratio municipal wastewater through short-cut nitrification-denitrification and partial anammox

Biological nitrogen removal of wastewater with low COD/N ratio could be enhanced by the addition of wasted sludge fermentation liquid(SFL),but the performance is usually limited by the introducing ammonium.In this study,the process of using SFL was successfully improved by involving anammox process.Real municipal wastewater with a low C/N ratio of 2.8–3.4 was treated in a sequencing batch reactor(SBR).The SBR was operated under anaerobic-aerobic-anoxic(AOA)mode and excess SFL was added into the anoxic phase.Stable short-cut nitrification was achieved after 46d and then anammox sludge was inoculated.In the stable period,effluent total inorganic nitrogen(TIN)was less than 4.3 mg/L with removal efficiency of 92.3%.Further analysis suggests that anammox bacteria,mainly affiliated with Candidatus_Kuenenia,successfully reduced the external ammonia from the SFL and contributed approximately 28%–43%to TIN removal.Overall,this study suggests anammox could be combined with SFL addition,resulting in a stable enhanced nitrogen biological removal.

Nitrogen removal from coal gasification wastewater by activated carbon technologies combined with short-cut nitrogen removal process

A system combining granular activated carbon and powdered activated carbon technologies along with shortcut biological nitrogen removal （GAC-PACT-SBNR） was developed to enhance total nitrogen （TN） removal for anaerobically treated coal gasification wastewater with less need for external carbon resources. The TN removal efficiency in SBNR was significantly improved by introducing the effluent from the GAC process into SBNR during the anoxic stage, with removal percentage increasing from 43.8%49.6% to 68.8%-75.8%. However, the TN removal rate decreased with the progressive deterioration of GAC adsorption. After adding activated sludge to the GAG compartment, the granular carbon had a longer service-life and the demand for external carbon resources became lower. Eventually, the TN removal rate in SBNR was almost constant at approx. 43.3%, as compared to approx. 20.0% before seeding with sludge. In addition, the production of some alkalinity during the denitrification resulted in a net savings in alkalinity requirements for the nitrification reaction and refractory chemical oxygen demand （COD） degradation by autotrophic bacteria in SBNR under oxic conditions. PACT showed excellent resilience to increasing organic loadings. The microbial community analysis revealed that the PACT had a greater variety of bacterial taxons and the dominant species associated with the three compartments were in good agreement with the removal of typical pollutants. The study demonstrated that pre-adsorption by the GAC-sludge process could be a technically and economically feasible method to enhance TN removal in coal gasification wastewater （CGW）.

Validity of Amontons's law for run-in short-cut aramid fiber reinforced elastomers:The effect of epoxy coated fibers

Friction between two contacting surfaces is studied extensively.One of the k n o w n friction theories is Amontons,law which states that the friction force is proportional to the normal force.However,Amontons7 law has been found to be invalid for elastomers.In the present study,the validity of Amontons7 law for short-cut aramid fiber reinforced elastomers is studied.Two types of fillers are used to reinforce the elastomers,namely highly dispersible silica and short-cut aramid fibers.Short-cut aramid fibers with two different surface treatments are used,namely non-reactive fibers with standard oily finish(SF-fibers)and fibers treated with an epoxy coating(EF-fibers).A pin-on-disc tribometer is used to investigate the frictional behavior of the composites in sliding contact with a granite counter surface.The results show that,after the run-in phase,Amontons,law is valid for those composites that are reinforced by short-cut aramid fibers(without reinforcing filler,i.e.,silica)if the contact pressure is below a threshold value.However,once the contact pressure exceeds this threshold value,Amontons'law will be invalid.The threshold contact pressure of the composites containing EF-fibers is higher than of the composites containing SF-fibers.The composites that are reinforced by silica and short-cut aramid fibers do not follow Amontons7 law.

Production of N2O in two biologic nitrogen removal processes： a comparison between conventional and short-cut Nitrogen removal processes

The N2O production in two nitrogen removal processes treating domestic wastewater was investigated in laboratory-scale aerobic-anoxic sequencing batch reactors （SBRs）. Results showed that N2O emission happened in the aerobic phase rather than in the anoxic phase. During the aerobic phase, the nitrogen conversion to N2O gas was 27.7% and 36.8% of NH＋-N loss for conventional biologic N-removal process and short-cut biologic N-removal process. The dissolved N2O was reduced to N2 in the anoxic denitrification phase. The N2O production rate increased with the increasing of nitrite concentration and ceased when NH＋-N oxidation was terminated. Higher nitrite accumulation resulted in higher NEO emission in the short-cut nitrogen removal process. Pulse-wise addition of 20 mg NO2 -N. L- 1 gave rise to 3-fold of N2O emission in the conventional N-removal process, while little change happened with 20 mg NOS-N L-1 was added to SBR1.

短切碳纤维增强MC尼龙复合材料的制备与性能

MC尼龙是一种已得到广泛应用的重要的工程塑料,但存在尺寸稳定性较差、热稳定性不高和重载下强度欠佳等缺点。本研究采用短切碳纤维(SCF)作为改性剂,探索研究了SCF/MC尼龙复合材料的制备工艺,研究了不同的SCF含量对复合材料密度、转化率、机械性能、摩擦性能及结晶度的影响。结果表明:在0~20%SCF含量范围内,复合材料的密度及拉伸强度表现为先增大后减少;转化率和冲击强度为20%SCF复合材料最为突出;而摩擦系数、磨损量在加入SCF后呈现先减少后增加的趋势。在10%SCF含量时,材料表现出较好的摩擦性能,同时结晶温度增大到182.95℃,结晶度为35.57%。研究结果证实通过添加适当比例的SCF改性剂可以有效改善MC尼龙的性能,这为进一步开发满足某些特殊螺旋传动下的新型复合材料做了有益尝试。

短电弧车削蜂窝环重铸层影响实验研究

蜂窝密封结构是当代航空发动机的先进高效密封结构,传统加工难以满足其加工质量要求,且一般电加工效率低,因此选择短电弧车削。针对材料为GH3536的蜂窝密封环进行实验,为研究不同参数对其加工后重铸层的影响,设置单因素试验,以重铸层厚度和微观形貌作为检测指标,分析电流及电压波形图、工件表面扫描电镜图、截面金相图和表面能谱图。结果证明:重铸层厚度随电压和进给速度增加而增加,随工件和电极转速增加而减小,且表面质量有相同的趋势,多槽挡板电极可以得到更好的冲液效果,重铸层更薄且表面质量更好。因此,适当降低电压和进给速度、提高工件和电极转速,以及采用多槽挡板电极,可减少微裂纹、冲蚀凹坑、褶皱和熔滴颗粒等现象,提高工件表面质量,降低重铸层厚度。

中低温条件下城市污水短程硝化控制方法研究

短程硝化对污水处理厂的节能增效有着重要意义,而低温条件下如何实现短程硝化的启动仍是亟待研究的难题。该文以实际生活污水为研究对象,开展了中低温(8~16℃)条件下短程硝化启动方法的研究。研究结果表明,在8~16℃条件下,投加50 mg/L Fe_(2)O_(3)纳米颗粒可在10 d内使反应器出水NO_(2)^(-)-N积累率达到75%以上,而投加145 mg/g MLSS的FeCl_(3)可使NO_(2)^(-)-N积累率达到100%。分子生物学分析表明,含铁物质的投加导致反应器内活性污泥微生物群落结构发生变化,并形成以Nitrosomonas为优势氨氧化细菌(AOB)、Nitrospira为优势亚硝酸盐氧化菌(NOB)的微生物群落结构,与对照试验组相比,试验组中NOB的相对丰度平均下降68.48%。中低温条件下短程硝化形成源于含铁物质对NOB的选择抑制,PLS-PM分析结果进一步阐述了含铁物质对NO_(2)^(-)-N积累的调控途径。由此可形成以含铁物质投加为手段的中低温条件下城市污水短程硝化控制方法。

短程硫黄/硫铁矿自养反硝化脱氮性能研究

为了解决异养反硝化处理低n(C)/n(N)废水需外加有机碳源和硫黄自养反硝化硫酸盐产量较高的问题,启动了短程硫黄/硫铁矿自养反硝化反应器并探究其脱氮性能,通过批式试验考察了n(S)/n(N)、初始pH、硫铁矿和石灰石等因素对脱氮性能的影响.结果表明,短程硫黄自养反硝化总氮(TN)去除率稳定在96%以上,比完全硫黄自养反硝化的实际硫酸盐产量减少大约40%.在氮容积负荷(以NO_(2)^(-)-N计)为0.40 kg/(m^(3)·d)时,短程硫铁矿自养反硝化的TN去除率高达98%,进一步解决了以S^(0)为电子供体时硫酸盐产量较高的问题.短程硫黄自养反硝化在n(S)/n(N)=2.5、初始pH=8时脱氮效果较好;FeS_(2)+NaHCO_(3)组合脱氮效果最好;CaCO_(3)在减少出水中硫酸盐产量和碱度缓释方面具有优势.Thiobacillus是硫自养反硝化反应器的主要功能菌属,相对丰度在13.2%以上.

游离氨冲击抑制联合污泥停留时间控制实现高效短程硝化

维持活性污泥系统中氨氧化菌(AOB)活性的同时抑制亚硝酸盐氧化菌(NOB)活性是实现短程硝化的关键,为此提出了一种游离氨(FA)冲击抑制联合污泥停留时间(SRT)控制实现高效持久短程硝化的方法。虽然FA冲击抑制仅1 d就能实现短程硝化快速启动,但是仍然无法长期维持短程硝化。进一步控制SRT分别为10、20 d进行实验发现,SRT为20 d效果更佳,能够实现高效持久的短程硝化。高通量测序结果反映出FA冲击抑制联合SRT控制后,亚硝化单胞菌属(Nitrosomonas)始终占优势是高氨氧化效能的重要原因。

铁磁薄膜快速稳定的磁化动力学控制

提出了亚微米铁磁薄膜磁化动力学的快速控制方案.由于自旋轨道耦合作用,外加电场所激发的自旋极化电流通过s-d交换耦合引起铁磁层的局域磁矩发生偏转.使用量子绝热捷径技术反控制法在亚微米铁磁薄膜模型中提出了电场控制方案,实现了磁化向量方向快速反转,并对电场强度进行了最优化设计.另外,分析了铁磁薄膜形状各向同性和异性下的电场控制方案.相比于现有方法,该方案将磁化向量反转时间缩短了约一个数量级,并且具有更好的鲁棒性.

硼对受高氨氮冲击后短程硝化系统效能恢复的影响研究

通过提高进水氨氮使稳定运行的短程硝化系统受到抑制,然后向反应器中投加硼来促进短程硝化效能的恢复。通过氮转化能力、氨氧化菌活性、胞外聚合物(EPS)中蛋白质(PN)和多糖(PS)含量、污泥形态和颗粒污泥的粒径分布来对短程硝化系统的变化进行表征。结果表明,稳定运行的短程硝化系统在短时间内受到800 mg/L氨氮冲击后短程硝化效能下降,污泥稳定性减弱,且在氨氮重新恢复到200 mg/L后短期内其效能仍无法恢复;与抑制期相比,投加硼后系统在恢复期的氨氮去除率从50%上升到95%,亚硝酸盐积累率从50%上升到85%,硝酸盐积累率从50%下降到15%,反应器的比氨氮氧化速率(SAOR)从18.65 mg/(g·h)上升到38.36 mg/(g·h),比耗氧速率(SOUR)从47.68 mg/(g·h)增加到54.24 mg/(g·h),MLSS增加了32%,达到4.5 g/L,EPS中PN质量分数比抑制期增加23%,m(PN)/m(PS)增加35.96%,信号分子AI-2质量浓度也从0.021 ng/mL增加到0.124 ng/mL。该研究结果阐明了硼对受高氨氮冲击下短程硝化系统效能的恢复有促进作用。

COD/N对短程内源反硝化过程中NO和N_(2)O积累的影响

利用序批式活性污泥反应器研究不同碳氮比(COD/N)(1,3,4,6)对短程内源反硝化污染物去除性能以及NO和N_(2)O积累的影响。结果表明,化学需氧量和亚硝态氮在COD/N大于3时去除效果较好。NO的积累峰值随着COD/N的增加而先增加后降低,在COD/N为4时达到最大值0.45 mg/L。而N_(2)O则呈现先降低后增加的趋势,当COD/N为3时积累峰值最小(3.7 mg/L)。NO的积累与COD/N、厌氧时间、NO和游离亚硝酸的抑制有关。N_(2)O的积累是COD/N、NO、游离亚硝酸等共同作用的结果。

短切碳纤维对泵用SiC复合陶瓷强度与耐冲蚀性影响研究

将0.5 mm、1 mm和3 mm的短切碳纤维分别加入SiC树脂复合陶瓷中,研究不同短切碳纤维长度对SiC复合陶瓷抗折强度和耐冲蚀性能的影响。研究结果表明,添加短切碳纤维后,试样的体积密度从2.45降低至2.32 g/cm^(3),而显气孔率变化不大,维持在4%。随着添加短切碳纤维长度的增加,试样的抗折强度显著提升,从61.57 MPa增加至71.67 MPa。添加3 mm的短切碳纤维后,试样的抗折强度更加稳定,多个试样间的差距显著降低。添加不同长度短切碳纤维后,试样的常温耐冲蚀性无明显变化,一次和二次冲蚀损失体积分别维持在0.033 cm^(3)和0.045 cm^(3)左右。SiC树脂复合陶瓷浇注料的制备过程中,添加3 mm的短切碳纤维可以有效提升抗折强度,同时保持复合陶瓷优秀的耐冲蚀性能。

聚丙烯的增强改性及其阻燃性能研究

以聚丙烯为基料,以短切玻璃纤维为增强材料,以多聚磷酸铵为阻燃剂,通过熔融共混加工得到了一种复合材料。探索了不同短切玻璃纤维和多聚磷酸铵用量对复合材料力学和阻燃性能的影响。结果表明,当短切玻璃纤维用量为14质量份、多聚磷酸铵用量为20质量份时,复合材料的拉伸强度可达39.4 MPa、弯曲模量和弯曲强度可达3 512、52.7 MPa,悬臂梁冲击强度可达8.2 kJ·m^(-2),并且复合材料的极限氧指数可达29,垂直燃烧可达V-0级别,即复合材料具有良好的强度和阻燃性能。

短程硝化的影响因素及其强化方法的研究进展

短程硝化-厌氧氨氧化技术相比于传统生物脱氮技术,缩短了废水脱氮反应的步骤,是一种高效低耗、经济环保的技术,如何实现前端短程硝化成为众多学者的研究热点。文章综述了短程硝化的原理、影响因素以及短程硝化的工艺强化方法等方面的研究进展,为该类研究提供参考及工程应用前景分析。

短程硝化联合厌氧氨氧化处理老龄垃圾渗滤液研究进展

垃圾填埋是我国处理垃圾的主要方式,在此过程中会产生渗滤液。其具有水质变化大、复杂等特点,是一种高氨氮的有机废水。垃圾渗滤液传统处理法又有成本高、处理效果不佳的问题,因此需要找到应对处理方式不佳的方法。短程硝化-厌氧氨氧化(PN-A)耦合工艺具有不加碳源、污泥产量少的特点。基于传统硝化反硝化脱氮在硝化过程中需要氧气,反硝化过程又需要有机物作为碳源提供营养,会增加处理成本。为了降低处理成本,短程硝化-厌氧氨氧化(ANAMNOX)耦合工艺得到了广泛应用。从PN-A工艺的影响因素出发,并对工艺未来的研究和发展方向进行了展望。

好氧颗粒污泥处理低氨氮废水短程硝化研究

采用现有的好氧颗粒污泥,通过在序批式反应器(sequencing batch reactor,SBR)中接种颗粒污泥,基于人工模拟废水,研究好氧颗粒污泥处理低氨氮污水,实现短程硝化。结果表明,短程硝化效果受到有机物浓度、pH、氨氮浓度、排水比等因素的影响,当SBR反应器进水NH_(4)^(+)-N浓度为55mg/L左右时,NH_(4)^(+)-N去除率达到97.1%,亚硝酸盐氮积累率(Nitrite Accumulation Rate,NAR)达到95%,TN去除率达到35%以上,表明SBR反应器能够实现稳定的短程硝化效果。