Effect of illumination on the hydrogen-production capability of anaerobic activated sludge

To investigate the influence of illumination on the fermentative hydrogen production system, the hydrogen production efficiencies of two kinds of anaerobic activated sludge (floc and granule) from an anaerobic baffled reactor were detected under visible light, dark and light-dark, respectively. The 10 mL floc sludge or granular sludge was respectively inoculated to 100 mL diluted molasses (chemical oxygen demand of 8000 mg·L^-1) in a 250 mL serum bottle, and cultured for 24 h at 37°C under different illumination conditions. The results showed that the floc was more sensitive to illumination than the granule. A hydrogen yield of 19.8 mL was obtained in the dark with a specific hydrogen production rate of 3.52 mol·kg^-1MLVSS·d^-1 (floc), which was the highest among the three illumination conditions. Under dark condition, the hydrogen yield of floc sludge reached the highest with the specific hydrogen production rate of 3.52 mol·kg^-1MLVSS·d^-1, and under light-dark, light, the specific hydrogen production rate was 3.11 and 2.21 mol·kg^-1MLVSS·d^-1, respectively. The results demonstrated that the illumination may affect the dehydrogenase activity of sludge as well as the activity of hydrogen-producing acetogens and then impact hydrogen production capacity.     

生物炭对土壤中阿特拉津吸附特征的影响

为探究生物炭对土壤中阿特拉津的吸附特征及影响因素,采用批处理实验研究了灭菌(T1)、5％秸秆生物炭+灭菌(T2)、未灭菌(T3)和5％秸秆生物炭+未灭菌(T4)条件下对土壤中阿特拉津吸附特征及土壤理化性质的影响.结果表明,在最初0-12 h内,不同处理下阿特拉津吸附量均随时间的延长而快速增加,而在12-96 h内增加较...     

Cultivation of aerobic granular sludge in a conventional,continuous flow,completely mixed activated sludge system

Aerobic granules were formed in a conventional, continuous flow, completely mixed activated sludge system (CMAS). The reactor was inoculated with seed sludge containing few filaments and fed with synthetic municipal wastewater. The settling time of the sludge and the average dissolved oxygen (DO) of the reactor were 2 h and 4.2 mg·L^-1, respectively. The reactor was agitated by a stirrer, with a speed of 250 r·min^-1, to ensure good mixing．The granular sludge had good settleability, and the sludge volume index (SVI) was between 50 and 90 mL·g^-1. The laser particle analyzer showed the diameter of the granules to be between 0.18 and 1.25 mm. A scanning electron microscope (SEM) investigation revealed the predominance of sphere-like and rod-like bacteria, and only few filaments grew in the granules. The microbial community structure of the granules was also analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Sequencing analysis indicated the dominant species were α, β, and γ-Proteobacteria, Bacteroidetes, and Firmicutes. The data from the study suggested that aerobic granules could form, if provided with sufficient number of filaments and high shear force. It was also observed that a high height-to-diameter ratio of the reactor and short settling time were not essential for the formation of aerobic granular sludge.     

十溴联苯醚(BDE-209)对土壤跳虫的急、慢性毒性效应

为揭示溴代阻燃剂对土壤生态系统的潜在危害,采用回避实验和繁殖实验评价了十溴联苯醚(BDE-209)对2种土壤跳虫Folsomia candida和Folsomia fimetaria的急/慢性毒性。48h的急性回避实验中,BDE-209对F.candida和F.fimetaria产生毒性效应的EC_(50)值分别为1.27和0.79mg·kg~(-1),LOEC值均小于0.5mg·kg~(-1)。慢性繁殖实验中,BDE-209对F.candida和F.fimetaria繁殖毒性的EC_(50)值分别为0.81和0.56mg·kg~(-1),LOEC值分别为<0.25和<0.5mg·kg~(-1)。研究表明,土壤BDE-209污染对跳虫的繁殖和环境行为有显著影响,且在较低暴露浓度下(0.25mg·kg~(-1))即对跳虫繁殖产生抑制效应;有性生殖的F.fimetaria比孤雌生殖的F.candida对BDE-209污染的毒性响应更为敏感。     

Abatement of sulfide generation in sewage by glutaraldehyde supplementation and the impact on the activated sludge accordingly

Hydrogen sulfide emission in sewer systems is associated with toxicity, corrosion, odour nuisance and high costs treatment. In this study, a novel method to inhibit sulfide generation from sewage by means of glutaraldehyde supplementation has been suggested and evaluated under anaerobic conditions. Different concentrations of glutaraldehyde at 10, 15, 20, 30 and 40 mg·L^-1 have been investigated. Besides, the possible impacts of glutaraldehyde supplementation on an activated sludge system and an appraisal of the economic aspects are presented as well. As observed from the experimental results, a dosage of 20 mg·L^-1 glutaraldehyde resulted in a significant decrease of the sulfide production by 70%–80% in the simulated sewage. Moreover, the impacts of additional glutaraldehyde at 20 mg·L^-1 on activated sludge, in terms of chemical oxygen demand removal and oxygen uptake rates, were negligible. From an economical point of view, the cost of the commercial glutaraldehyde products required in the operation, which was calculated on the basis of activated sulfide removal avoidance, was around €3.7–4.6 S·kg^-1. Therefore it is suggested that glutaraldehyde supplementation is a feasible technique to abate the sulfide problems in sewer systems. Yet further research is required to elucidate the optimum “booster” dosage and the dosing frequency in situ accordingly.     

Zn和Cd胁迫作用对长梗白菜形态和生理性能的生态毒理影响

本文以不同Cd、Zn浓度胁迫下的长梗白菜为研究对象,采用盆栽实验,分析了Cd和Zn胁迫下长梗白菜形态参数(重量、长度、表面积、叶的分形维数)、生理性能的影响以及从土壤中提取Cd和Zn的能力.结果 表明,Cd、Zn胁迫对长梗白菜的生长具有"低促高抑"效应,且共同胁迫对生长的影响大于单一胁迫.在0.6 mg·kg-1 Cd...     

Identification of cadmium-induced genes in maize seedlings by suppression subtractive hybridization

A maize variety, Huatian-1, had an unusually low translocation rate of cadmium (Cd) (59.6 mg·kg^-1 in the roots and 0.093 mg·kg^-1 in the grain) compared to 24 other varieties while being grown in soils with 16.50 mg·kg^-1 Cd. This indicates that this particular species may have special mechanisms that affect the absorption and translocation pattern of Cd. In this paper, the technique of suppression subtractive hybridization (SSH) was used to isolate and identify Cd-induced genes from Huatian-1 hydroponically ?exposed? to? 0.1 mM ?CdCl₂ ?for? 1 h,? 12 h, 24 h, and 48 h. We found a total of 15 differentially expressed genes in the four groups; 2, 3, 4, and 6 genes were from the groups of 1 h, 12 h, 24 h, and 48 h treatment, respectively. Phospholipase PLDb1 mRNA, adenosine triphosphate (ATP) phosphoribosyl transferase 2, and Sp17 were turned on in the maize in response to Cd stress, and it might provide new clues to explain the mechanism of maize tolerance to Cd.     

低碳氮比废水好氧颗粒污泥系统稳定性及微生物种群多样性研究

低碳氮比(C/N)废水处理是含氮废水处理中的难题之一.本实验在C/N为4:1和2:1(COD和NH₄⁺-N浓度分别为400 mg·L^-1和100 mg·L^-1,400 mg·L^-1和200 mg·L^-1)条件下,考察好氧颗粒污泥系统对低碳氮比废水的处理效果、长期运行稳定性,研究C/N对好氧颗粒微生物结构变化的影响.研究结果表明,在C/N为4:1的废水中接种活性污泥培养好氧颗粒污泥,形成的颗粒沉降性能良好,MLSS为4.94 g·L^-1,SVI30为40 mL·g^-1,COD去除率90%以上,氨氮去除率接近100%.降低碳氮比,即C/N为2:1后,好氧颗粒的物理及硝化性能无明显变化,MLSS为11.38 g·L^-1,SVI₃₀/SVI₅维持在1左右,COD去除率大于85%,氨氮去除率98%.碳氮比降低使颗粒微生物多样性减少,其中陶厄氏菌受影响较小,而硝化功能菌出现更替:噬氢菌、食酸菌、里德拜特氏菌消失,鞘氨醇单胞菌、束缚杆菌等成为优势菌种.实验表明,该低碳氮比条件下好氧颗粒污泥系统能够稳定运行,且具有优良的处理性能.     

Continuous biohydrogen production from diluted molasses in an anaerobic contact reactor

An anaerobic contact reactor (ACR) system comprising a continuous flow stirred tank reactor (CSTR) with settler to decouple the hydraulic retention time (HRT) from solids retention time (SRT) was developed for fermentative hydrogen production from diluted molasses by mixed microbial cultures. The ACR was operated at various volumetric loading rates (VLRs) of 20–44 kgCOD·m^-3·d^-1 with constant HRT of 6 h under mesophilic conditions of 35°C. The SRT was maintained at about 46–50 h in the system. At the initial VLR of 20 kgCOD·m^-3·d^-1, the hydrogen production rate dropped from 22.6 to 1.58 L·d^-1 as the hydrogen was consumed by the hydrogentrophic methanogen. After increasing the VLR to 28 kgCOD·m^-3·d^-1 and discharging the sludge for 6 consecutive times, the hydrogentrophic methanogens were eliminated, and the hydrogen content reached 36.4%. As the VLR was increased to 44 kgCOD·m^-3·d^-1, the hydrogen production rate and hydrogen yield increased to 42.1 L·d^-1 and 1.40 mol H₂·molglucose-consumed^-1, respectively. The results showed that a stable ethanol-type fermentation that favored hydrogen production in the reactor was thus established with the sludge loading rate (SLR) of 2.0–2.5 kgCOD·kgMLVSS^-1·d^-1. It was found that the ethanol increased more than other liquid fermentation products, and the ethanol/acetic acid (mol/mol) ratio increased from 1.27 to 2.45 when the VLR increased from 28 to 44 kgCOD·m^-3·d^-1, whereas the hydrogen composition decreased from 40.4% to 36.4%. The results suggested that the anaerobic contact reactor was a promising bioprocess for fermentative hydrogen production.     

Effects of shear force on formation and properties of anoxic granular sludge in SBR

This paper reports the effects of shear force on anoxic granular sludge in sequencing batch reactors （SBR）. The study was carried out in two SBRs （SBR1 and SBR2） in which sodium acetate （200mg COD·L^-1） was used as the sole substrate and sodium nitrate （40 mgNO3-N·L^-1） was employed as the electron acceptor. The preliminary objective of this study was to cultivate anoxic granules in the SBR in order to investigate the effects of shear force on the formation of anoxic granular sludge and to compare the properties of anoxic sludge in the SBR. This study reports new results for the values of average velocity gradient, a measure of the applied shear force, which was varied in the two SBRs （3.79 s^-1 and 9.76 s^-1 for SBR1 and SBR2 respectively）. The important findings of this research highlight the dual effects of shear force on anoxic granules. A low shear force can produce large anoxic granules with high activity and poor settling ability, whereas higher shear forces produce smaller granules with better settling ability and lower activity. The results of this study show that the anoxic granulation is closely related to the strength of the shear force. For high shear force, this research demonstrated that： 1） granules with smaller diameters, high density and good settling ability were formed in the reactor, and 2） granular sludge formed faster than it did in the low shear force reactor （41days versus 76 days）. Once a steady-state has been achieved, the nitrate and COD removal rates were found to be 98% and 80%, respectively. For low shear force, such as was applied in SBR1, this research demonstrated that： 1） the activity of anoxic granular sludge in low shear force was higher than that in high shear force, 2） higher amount of soluble microbial products （SMPs） were produced, and 3） large pores were observed inside the larger granules,which are beneficial for nitrogen gas diffusion. Electron microscopic examination of the anoxic granules in both reactors showed that the morphology of the granules was ellipsoidal with a clear outline. Coccus and rod-shaped bacteria were wrapped by filamentous bacteria on the surface of granule.     

Transport of Sewage Sludge in a Mixed Water Column

Sewage sludge from four publicly-owned treatment works was sampled and characterized in terms of parameters affecting transport at the 106-mile deep ocean disposal site as part of the US Environmental Protection Agency's site monitoring programme. Samples from treatment plants in Passaic Valley, Rahway, and Elizabeth, New Jersey and New York City were characterized in terms of dynamic size distribution, suspended solids and density. the transport characteristics of sludge particles were measured using a 2 metre computer-interfaced laboratory settling column. Experiments were conducted at constant salinity (35 ppt) while varying hydrodynamic mixing, sludge type and concentration using a modified factorial experimental design. Hydrodynamic power dissipation was varied so that the vertical dispersion and rms fluid shear rate ranged between 0-6 cm²S^-1 and 0-30s^-1 respectively. Results indicate that at least 80% of suspended sludge particles will eventually settle under mixed conditions. the average settling velocities ranged between 0.05-4.05 × 10^-3 cm ^s-1. Shear rates above 15 s^-1 inhibited sludge settling due to aggregate breakup and boundary effects, but at a lower shear rate, differential settling and fluid shear were the dominant transport mechanisms. Sludge dilution (1/500-1/5000) had a limited effect on the settling rate. Results from this study can be used to calibrate particle transport models to determine the fate of sludge disposed at an ocean disposal site.     

硝酸钙投加频次对污泥生物调理效果的影响

在接种了反硝化菌的剩余污泥中投加硝酸钙药剂,利用反硝化菌消耗NO3-进行反硝化作用去除污泥中易生物降解的有机物,利用Ca2＋的中和、架桥作用,改善污泥的脱水性能.固定NO;总投加浓度为100 mg?g-1 TS,在6d的时间内,按1次、2次、3次、6次的投加频次向污泥中投加硝酸钙.结果表明,1次投加对污泥脱水性能的提升...     

Technical measures to achieve a cleaner production mode for recycled paper mills

China’s paper production reached 79.8 ×10⁶ t in 2008 and ranked number one in the world. Because of its high consumption of water, energy and materials and its serious pollution, the present processes are not likely to be sustainable. An alternative, the closed Water Loop-Papermaking Integration (WLPI) method, is put forward in this paper. The WLPI method can be realized in a recycled paper mill by adding technologies and using recycled water. Many industrial case studies have shown that a large quantity of water, energy and materials can be saved, and the quantity of waste sludge and wastewater discharge was minimized by using the WLPI method. The design of the water reuse system, control of calcium hardness, water recycling and minimal waste sludge are discussed. Anaerobic technology plays an important role in the WLPI method to lower cost, energy use and waste. In the brown paper and coated white board production, zero-effluent discharge can be realized. Fresh water consumption is only 1–2 m³·t^-1. For the paper mills with deinking and bleaching processes, about 10 m³·t^-1 of fresh water and a similar amount of effluent discharge are needed. Power saving using anaerobic technology is 70% when recycled water is used in comparison with the conventional activated sludge process. Waste sludge can be decreased to about 5% of the initial process due to reuse of the waste sludge and the lower bio-sludge production of the anaerobic process.     

通过式固相萃取/超高效液相色谱-串联质谱法测定蔬菜中18种农药残留

建立了超高效液相色谱-串联质谱(UPLC-MS;MS)快速测定蔬菜中18种农药残留的方法.样品经乙腈提取后,经Oasis PRiME HLB固相萃取柱净化,采用ACQUITY UPLC HSS T3 C18(50 mm×2.1 mm,1.8μm)色谱柱进行分离,以0.1%甲酸水溶液和乙腈作为流动相进行梯度洗脱.采用电喷雾电离源、正离子模式下以多反应监测(MRM)进行定性和定量分析.结果表明,18种农药在0.5—50μg·L^-1范围内线性关系良好(r2>0.995),方法最低检出限为0.4—1.5μg·kg^-1,最低定量限为1.4—5.0μg·kg^-1.在韭菜、芹菜、番茄、白菜基质中,5、10、50μg·kg^-1添加水平下的加标回收率为60.2%—126.9%,相对标准偏差(RSD)为0.4%—21.6%(n=3).     

Fermentative hydrogen production from beet sugar factory wastewater treatment in a continuous stirred tank reactor using anaerobic mixed consortia

A low pH, ethanol-type fermentation process was evaluated for wastewater treatment and bio-hydrogen production from acidic beet sugar factory wastewater in a continuous stirred tank reactor (CSTR) with an effective volume of 9.6 L by anaerobic mixed cultures in this present study. After inoculating with aerobic activated sludge and operating at organic loading rate (OLR) of 12 kgCOD?m^-3·d^-1, HRT of 8h, and temperature of 35°C for 28 days, the CSTR achieved stable ethanol-type fermentation. When OLR was further increased to 18 kgCOD?m^-3·d^-1 on the 53rd day, ethanol-type fermentation dominant microflora was enhanced. The liquid fermentation products, including volatile fatty acids (VFAs) and ethanol, stabilized at 1493 mg·L^-1 in the bioreactor. Effluent pH, oxidation-reduction potential (ORP), and alkalinity ranged at 4.1–4.5, -250–(-290) mV, and 230–260 mgCaCO₃?L^-1. The specific hydrogen production rate of anaerobic activated sludge was 0.1 L?gMLVSS^-1·d^-1 and the COD removal efficiency was 45%. The experimental results showed that the CSTR system had good operation stability and microbial activity, which led to high substrate conversion rate and hydrogen production ability.     

三苯基锡对大鼠肥胖发生的影响

三苯基锡(triphenyltin,TPT)和三丁基锡(tributyltin,TBT)在环境中经常同时存在,针对TBT对肥胖发生的影响已有较多研究,但TPT能否诱导肥胖的发生尚不明晰.本研究用环境水平的TPT(0.5、5和50 μg·kg-1)对青春期Sprague Dawley大鼠进行灌胃处理54 d后,测量大鼠体...     

蚯蚓粪复配硼钼调理剂对土壤改良和茄子生长的影响作用

土壤质量决定着农产品的质量和农业生产的可持续发展,然而土壤退化成为农业生产的重要限制因素之一,施用土壤调理剂有利于减缓土壤退化的速度.该研究配制土壤调理剂,即蚯蚓粪?草菇渣?蛭石=6?3?1、钼酸钠50 g·kg?1、硼酸13.3 g·kg?1,并设5个不同的处理CK、QY-T1、QY-T2、QY-T3、QY-T4,研...     

施氮与凋落物去除影响下中亚热带阔叶林土壤氮素矿化潜势和硝化潜势研究

氮沉降影响土壤氮循环,而凋落物是土壤有机氮的主要来源,因此,为了探讨氮沉降和凋落物是否去除作用下,亚热带森林土壤潜在的氮素矿化与硝化作用,选择已进行8年模拟氮沉降试验的亚热带罗浮栲(Castanopsis fabri)常绿阔叶林土壤为研究对象,野外样地氮添加设置3个水平:对照(CK,0 kg·hm?2·a?1)、低氮(...     

上海市公园绿地常见落叶树木叶片汞浓度时空特征及环境意义

植物叶片汞浓度与大气气态单质汞(GEM/Hg0)浓度的线性关系表明叶片汞浓度大小可用于指示植物生长区内GEM浓度的高低水平.通过分析上海市绿地公园(25座)中常见落叶树木樱花、水杉、法桐叶片汞浓度的时空变化特征,探究区域内GEM含量水平及分布特征.2017年5-10月对7座公园中这3种树木叶汞浓度进行连续监测,结果显示...     

不同恢复年限刺槐林土壤碳、氮、磷含量及其生态化学计量特征

地处西秦岭山地的甘肃天水吕二沟小流域土壤侵蚀问题严重,上世纪五六十年代开始,当地政府在研究区实施了多年的生态恢复措施以保持水土,但目前尚未有植被恢复对土壤生态计量特征的系统调查.分析不同林龄人工林土壤碳、氮、磷含量及其生态化学计量特征可在一定程度上揭示土壤养分的限制情况.选取黄土丘陵沟壑区不同生长年限(5、20、40、...