乙酸/丙酸作为EBPR碳源的动力学模型研究(Ⅰ) ——模型的建立

以活性污泥ASM2模型为基础,采用混合短链脂肪酸(SCFAs)作为基准物质,建立了增强生物除磷系统中聚磷菌和(PAO)的厌氧/好氧动力学模型.模型的显著特点是厌氧代谢过程中的糖原水解、聚羟基烷酸合成、以及聚磷水解速率由SCFAs的速率方程表示,并考虑了厌氧维持对动力学和计量学的影响.模型建立了过程计量学系数矩阵,包括3个溶解性组分、4个颗粒性组分,同时考虑了pH对代谢动力学的影响.最后,在PAO模型的基础上,建立了GAO的动力学模型,该模型包含7个过程,磷的浓度仅对其好氧生长有影响.     

无排泥条件下的膜-生物反应器系统处理焦化废水可行性研究

小试规模浸没式厌氧/缺氧/好氧-膜-生物反应器(A1/A2/O-MBR)系统用于处理实际焦化废水,在无排泥条件下连续运行160 d.考察了长期运行条件下系统对不同污染物的去除性能,并通过亲疏水组分分离和三维荧光光谱法,对进出水焦化废水中溶解性有机物(DOMs)特征进行分析.结果表明,A1/A2/O-MBR系统能稳定去除88.0%±1.6%的COD,99.9%的挥发酚,99.4%±0.2%的浊度和98.3%±1.9%的NH4+-N,相应的平均出水浓度分别为249 mg/L±44 mg/L、0.18 mg/L±0.05 mg/L、1.0NTU±0.2 NTU和4.1 mg/L±4.3 mg/L;最大TN去除率可达到74.9%.在系统160 d运行过程中,MLVSS/MLSS维持在90.2%±1.0%,没有出现无机物的积累;污泥的表观产率(MLVSS/COD)逐渐降低并最终稳定在0.035 kg/kg.在焦化废水DOMs的疏水酸性、疏水中性、疏水碱性和亲水物4种组分中,疏水酸性物是进出水中最主要的溶解性有机碳(DOC)和色度组分,分别占进出水总DOC的70%和67%,总色度的75%和76%.三维荧光光谱分析表明腐殖质类物质是系统出水中残留的主要难降解有机物和致色物质.     

Kinetic analysis of waste activated sludge hydrolysis and short-chain fatty acids production at pH 10

The accumulation of short-chain fatty acids (SCFAs), a preferred carbon source for enhanced biological phosphorus removal microbes, was significantly improved when waste activated sludge (WAS) was fermented at pH 10. The kinetics of WAS hydrolysis and SCFAs production at pH 10 were investigated. It was observed that during WAS anaerobic fermentation at pH 10 the accumulation of SCFAs was limited by the hydrolysis process, and both the hydrolysis of WAS particulate COD and the accumulation of SCFAs followed first-order kinetics. The hydrolysis and SCFAs accumulation rate constants increased with a increasing of temperature from 10 to 35℃, which could be described by the Arrhenius equation. The kinetic data further indicated that SCFAs production at pH 10 was a biological process. Compared with the experiment of pH uncontrolled (blank test), both the rate constants of WAS hydrolysis and SCFAs accumulation at 20℃ were significantly improved when WAS was fermented at pH 10.     

低分子量有机酸对红壤中硫丹释放动力学的影响

采用自行设计的动力学试验装置及平衡振荡试验,系统研究了3种低分子量有机酸(草酸、酒石酸和柠檬酸)和水对红壤中α-硫丹(-αendosulfan,αES)的动力学释放行为.结果表明,10 mmol/L的酒石酸和柠檬酸可使αES的释放百分率相对于水和草酸提高7~18个百分点,其中尤以酒石酸的效果最为明显,但水和草酸对αES的释放能力却不存在显著差异(p>0.05),αES的释放存在明显的快速和慢速释放期,特别在前200 mL释放较快;水和草酸对αES的释放动力学数据可由双常数方程和抛物线扩散方程较好描述,并不是代表简单表面扩散的表观一级动力学方程,而酒石酸和柠檬酸则更倾向于Elovich方程(R2>0.99,p<0.000 1),说明对这类立体结构较复杂的有机氯农药来说,影响其在水相中释放的主导因素已不是简单的颗粒表面扩散机制,还可能涉及到土壤颗粒内部的向外扩散机制、颗粒表面的活化与去活化作用、土壤颗粒表面的溶解及对包被在土壤矿物表面的固有有机质结构干扰造成的表面点位能量分布的不均匀等多种机制,使释放动力学的机制更进一步复杂化.     

C/N对污泥厌氧发酵产酸类型及代谢途径的影响

研究了污泥的初始C/N对污泥发酵产酸类型的影响及产酸代谢途径.初始C/N在12时,形成的是乙酸型发酵类型;当初始C/N在56左右,可实现丙酸型发酵类型;而当C/N处于156时,则形成丁酸型发酵.不同发酵产酸类型的形成是由优势产酸菌群的改变导致的.末端限制性片段长度多态性分析(T-RFLP)微生物种群的结果表明,构成乙酸型发酵类型的主要优势菌群为消化链球菌属;而丙酸型发酵类型中的优势菌群则为丙酸杆菌属;梭菌属则是丁酸型发酵类型中的优势产酸功能菌.有机酸代谢途径中关键酶活性检测结果表明,在低C/N条件下,乙酸的累积主要是通过氨基酸之间的Stickland反应形成,而随着C/N值的增大,导致丙酸和丁酸累积的主要代谢途径转变为糖酵解的丙酮酸途径.     

Source profiles of particulate organic matters emitted from cereal straw burnings

Cereal straw is one of the most abundant biomass burned in China but its contribution to fine particulates is not adequately understood. In this study, three main kinds of cereal straws were collected from five grain producing areas in China. Fine particulate matters （PMzs） from the cereal straws subjected to control burnings, both under smoldering and flaming status, were sampled by using a custom made dilution chamber and sampling system in the laboratory. Element carbon （EC） and organic carbon （OC） was analyzed. 141 compounds of organic matters were measured by gas chromatography-mass spectrum （GC-MS）. Source profiles of particulate organic matters emitted from cereal straw burnings were obtained. The results indicated that organic matters contribute a large fraction in fine particulate matters. Levoglucosan had the highest contributions with averagely 4.5% in mass of fine particulates and can be considered as the tracer of biomass burnings. Methyloxylated phenols from lignin degradation also had high concentrations in PM2.5, and contained approximately equal amounts of guaiacyl and syringyl compounds. 13-Sitostrol also made up relatively a large fraction of PMz5 compared with the other sterols （0.18%-0.63% of the total fine particle mass）. Normal alkanes, PAHs, fatty acids, as well as normal alkanols had relatively lower concentrations compared with the compounds mentioned above. Carbon preference index （CPI） of normal alkanes and alkanoic acids showed characteristics of biogenic fuel burnings. Burning status significantly influenced the formations of EC and PAHs. The differences between the emission profiles of straw and wood combustions were displayed by the fingerprint compounds, which may be used to identify the contributions between wood and straw burnings in source apportionment researches.     

Isolates identification and characteristics of microorganisms in biotrickling filter and biofilter system treating H2S and NH3

A combination system of biotrickling filter （BTF） and biofilter （BF）, adopting surfactant-modified clinoptilolite and surfactant- modified wood chip as the media respectively, was applied to treat H2S and NH3 simultaneously. The identification and sole carbon sources utilization patterns of isolates in the combination system were studied by Biolog system. The isolates were identified as Bacillus sphaericus, Geobacillus themoglucosidasius （55℃） and Micrococcus luteus （ATCC 9341） in BTF, and Aspergillus sydowii （Bainier ＆ Sartory） Thom＆ Church in BE Among 95 substrate classes supplied by Biolog system, the carboxylic acids and methyl esters had the highest utilization extent for the four species, followed by the amino acids and peptides. The descending sequence of carbon sources utilization capability of isolates was A. sydowii （52.6%）, M. luteus （39.5%）, B. sphaericus （21.6%）, and G. thermoglucosidasius （17.7%）.     

Phospholipid fatty acid patterns of microbial communities in paddy soil under different fertilizer treatments

The microbial communities under irrigated rice cropping with different fertilizer treatments, including control （CK）, PK, NK, NP, NPK fertilization, were investigated using phospholipid fatty acid （PLFA） profile method. The results of this study revealed that the fertilizer practice had an impact on the community structure of specific microbial groups. The principal components analysis （PCA） showed that proportion of the actinomycete PLFAs （10Me 18：0 and 10Me 16：0） were the lowest in the PK treatment and the highest in the NPK treatment, which means that soil nitrogen status affected the diversity of actinomycetes, whereas nitrogen cycling was related to the actinomycets. Under CK treatment, the ratio of Gram-positive to Gram-negative bacteria was lower compared with that in fertilizer addition treatments, indicating that fertilizer application stimulated Gram-positive bacterial population in paddy soil. The fatty acid 18：2to6,9, which is considered to be predominantly of fungal origin, was at low level in all the treatments. The ratio of cyl9：0 to 18：1 to7, which has been proposed as an indicator of stress conditions, decreased in PK treatment. Changes of soil microbial community under different fertilizer treatments of paddy soil were detected in this study; however, the causes that lead to changes in the microbial community still needs further study.     

麦秸对两相厌氧废水处理工艺产酸相的影响

采用间歇试验的方法对不同pH条件下,两相厌氧工艺处理含麦秸的低浓度废水的产酸相进行了研究.分别考察了酸性、中性和碱性条件对有麦秸反应器和无麦秸反应器中的COD、氨氮、VFA变化的影响.试验结果表明:在三种pH条件下,除第一周期外有麦秸反应器的出水pH始终要低于无麦秸反应器的出水pH,并且酸性条件下的出水pH值最低.介于...     

Temporal and spatial variations of low-molecular-weight organic acids in Dianchi Lake, China

Low-molecular-weight organic acids (LMWOAs) in eutrophic lake water of Dianchi, Southwestern China Plateau were investigated diurnally and vertically using ion chromatography. Two profiles (P1 and P2) were studied due to the difference of hydrochemical features. Lactic, formic, pyruvic and oxalic acid were detected as major components at P1 and P2 which were on average 7.98 and 6.53 mol/L, respectively, corresponding to their proportions of 2.68% and 2.48% relative to DOC. Pyruvic acid was regarded as the uppermost species at P1 and P2, reaching up to 3.82 and 3.35 mol/L and accounting for 47.9% and 51.3%, respectively, in individual TOA. Although humus were of biogenetic production at both sites, the significant negative correlation between diurnal variations of TOAs, fluorescence intensity (FI) of protein-like components and humic-like components at P1 indicated LMWOAs were greatly originated from bacterioplankton excretion and degradation. However, correlations between diurnal variations of humic-like FI and physicochemical parameters demonstrated algal origination of LMWOAs at P2. Although content of humus was high, TOA at P2 was 1.45 mol/L lower than that at P1, due to the co-influence of more intense photo-oxidation and aggregation at P2. Therefore, TOAs exhibited quite opposite diurnal variation trends of increasing-decreasing and decreasing-increasing at P1 and P2, respectively. Except for impact of solar radiation, bacterial decomposition and assimilation rendered shifts of maximal LMWOAs along water column at P1. Covering with massive algae, UV rays penetrated shallower depth that LMWOAs assembled in surface layer water before 18:00 at P2 and represented decreasing profiles.