高铁酸钾预处理强化污泥破解及厌氧产酸

在序批式污泥厌氧反应器中探究了高铁酸钾对污泥破解及厌氧产酸的影响。实验结果表明高铁酸钾对污泥具有较强的破解性,当高铁酸钾的质量浓度由0 mg/L增加至16 mg/L时,溶解性COD与总COD的比值由6.2%升至35.6%。同时污泥液相中溶解性蛋白质的质量浓度由561 mg/L增加至1 365 mg/L。高铁酸钾的浓度与挥发性悬浮固体(VSS)的减量具有一定的线性关系。当高铁酸钾的质量浓度为8 mg/L时,污泥厌氧产挥发性脂肪酸最大,并且最大值为895 mg/L,其浓度是空白组2.56倍。     

Short-term impact of olive mill wastewater (OMWW) applications on the physico-chemical and microbiological soil properties of an olive grove in Argentina

The purpose of this work was to investigate the effects of spreading olive oil mill wastewater (OMWW) on soil biochemical parameters and olive production in an organically managed olive orchard. The experiment was carried out with three different doses of OMWW (80, 160 and 500 m³ ha^?1) and a control (untreated soil). Three samplings were done at 10, 30 and 90 days after the administration of the byproduct. OMWW application differentially modified the biochemical properties of the soil analyzed. Organic matter, organic carbon, total nitrogen and extractable phosphorus soil contents increased proportionally with each increasing dose. The values of these parameters decreased gradually with time. Total microbial activity was altered and the OMWW 500 m³ ha^?1 treatment proved to be the most active when compared with the other applied doses. OMWW agricultural application also modified the structure of soil microbial communities, particularly affecting Gram positive and negative bacteria, while fungal biomass did not show consistent changes. Although there was a salinity increase in the treated soil, especially at the highest dose, the productive parameters analyzed (fruit and oil tree^?1) were not affected. In light of the obtained results, we consider that low dose of OMWW could be considered an alternative farming practice for semiarid regions.     

Effects of a gradually increased load of fish waste silage in co-digestion with cow manure on methane production

This study examined the effects of an increased load of nitrogen-rich organic material on anaerobic digestion and methane production. Co-digestion of fish waste silage (FWS) and cow manure (CM) was studied in two parallel laboratory-scale (8 L effective volume) semi-continuous stirred tank reactors (designated R1 and R2). A reactor fed with CM only (R0) was used as control. The reactors were operated in the mesophilic range (37 °C) with a hydraulic retention time of 30 days, and the entire experiment lasted for 450 days. The rate of organic loading was raised by increasing the content of FWS in the feed stock. During the experiment, the amount (volume%) of FWS was increased stepwise in the following order: 3% – 6% – 13% – 16%, and 19%. Measurements of methane production, and analysis of volatile fatty acids, ammonium and pH in the effluents were carried out. The highest methane production from co-digestion of FWS and CM was 0.400 L CH4 gVS^?1, obtained during the period with loading of 16% FWS in R2. Compared to anaerobic digestion of CM only, the methane production was increased by 100% at most, when FWS was added to the feed stock. The biogas processes failed in R1 and R2 during the periods, with loadings of 16% and 19% FWS, respectively. In both reactors, the biogas processes failed due to overloading and accumulation of ammonia and volatile fatty acids.     

Effects of bulking agent addition on odorous compounds emissions during composting of OFMSW

The effects of rice straw addition level on odorous compounds emissions in a pilot-scale organic fraction of municipal solid waste (OFMSW) composting plant were investigated. The cumulative odorous compounds emissions occurred in a descending order of 40.22, 28.71 and 27.83 mg/dry kg of OFMSW for piles with rice straw addition level at ratio of 1:10, 2:10 and 3:10 (mixing ratio of rice straw to OFMSW on a wet basis), respectively. The mixing ratio of rice straw to OFMSW had a statistically significant effect on the reduction of malodorous sulfur compounds emissions, which had no statistically significant effect on the reduction of VFAs, alcohols, aldehydes, ketones, aromatics and ammonia emissions during composting, respectively. The cumulative emissions of malodorous sulfur compounds from piles with the increasing rice straw addition level were 1.17, 1.08 and 0.88 mg/dry kg of OFMSW, respectively. The optimal mixing ratio of rice straw to OFMSW was 1:5. Using this addition level, the cumulative malodorous sulfur compounds emissions based on the organic matter degradation were the lowest during composting of OFMSW.     

Essential versus potentially toxic dietary substances: a seasonal comparison of essential fatty acids and methyl mercury concentrations in the planktonic food web

We investigated seasonal variability of essential fatty acids (EFA) and methyl mercury (MeHg) concentrations in four size categories of planktonic organisms in two coastal lakes. MeHg concentrations increased significantly with increasing plankton size and were independent of plankton taxonomy. However, total EFA increased from seston to mesozooplankton, but decreased in the cladoceran-dominated macrozooplankton size-class. Analysis of EFA patterns revealed that linoleic, alpha-linolenic, arachidonic, and eicosapentaenoic acids increased with increasing zooplankton size, but docosahexaenoic acid (DHA) in the cladoceran-dominated macrozooplankton was generally lower than in seston. This consistent pattern demonstrates that cladocerans, although bioaccumulating MeHg, convey less DHA than similar-sized copepods to their consumers. It is thus evident that fish consuming cladocerans have restricted access to DHA, yet unrestricted dietary access to MeHg. Thus, the structure of planktonic food webs clearly affects the composition of EFA and regulates dietary supply of these essential nutrients, while MeHg bioaccumulates with increasing zooplankton size.     

郑州市PM2.5中有机酸的污染特征、来源解析及二次生成

大气颗粒物中的有机酸广泛参与大气中的各种物理化学反应,对二次有机气溶胶和霾的形成贡献极大,因此分析颗粒物中有机酸的浓度分布特征、评估其污染来源、探究其二次生成,对深入研究有机气溶胶及其二次转化具有重要意义.在郑州市不同季节采集大气细颗粒物（PM_2.5）样品,识别并定量二元酸类、脂肪酸类和树脂酸类有机酸共30种,探究其浓度分布特征、季节变化、来源贡献及二次生成.定量的二元酸类以丙二酸（di-C₃）和琥珀酸（di-C₄）含量最为丰富,并且表现出明显的季节变化特征：夏季 > 秋季 > 冬季 > 春季;脂肪酸类表现出明显的双峰优势,以棕榈酸和硬脂酸（C₁₈）最为丰富,季节变化特征为冬季最高,春季最低.利用主成分分析结合多元线性回归（MLR）方法对郑州市PM_2.5中的有机酸进行来源解析,结果表明,35%的有机酸来自于燃烧源和交通源,24%来自于烹饪源、23%来自于二次生成以及17%来自于天然源.利用标记物种的比值（如di-C₃ /di-C₄、F/M和C_18：1 /C₁₈）探究有机气溶胶二次形成及其老化过程.结果表明,夏季光化学反应剧烈,有机气溶胶老化或二次生产比例较高,冬季光化学反应较弱,有机气溶胶老化程度较低.采用相关性分析与MLR相结合的方法,量化了气相氧化和液相氧化对二元酸形成的相对贡献,气相氧化在采样过程中起主导作用,占比为58%,特别是夏季,占总二次转化的61%.     

微氧水解酸化工艺处理高浓度抗生素废水

试验研究了高浓度难生物降解抗生素废水微氧水解酸化效果.结果表明,微氧环境提高了兼性水解酸化菌的生理代谢功能,曝气搅拌改善了水力条件,在最短HRT为10h ,最大OLR为20kg/(m³·d)条件下,酸化率为58.64%,出水VFA为4825mg/L ,极大地改善了废水的生物降解性能,BOD₅/COD升高了17%左右,为后续好氧生物处理提供了良好的基质准备.在进水水质波动较大的情况下,出水水质相对稳定,出水COD和SS浓度分别为7000～8000mg/L和150～300mg/L ,COD和SS去除率分别为15%～30%和90%～95%.出水VFA的变化滞后于酸化率的变化,酸化率能更好地表征水解酸化系统的效果.反应器底部的污泥床层是VFA生成的主要反应区,随着OLR的升高,达到稳定VFA浓度的反应器高度逐渐增加.填料区功能主要在于截留出水中的SS.污泥以粒径为0.5～1.0mm之间的小颗粒污泥和絮状污泥为主.     

Sucrose-derived catalytic biodiesel synthesis from low cost palm fatty acid distillate

The current homogeneous acid catalyst for biodiesel product however, would lead to formation of many undesirable by-products that make the post treatment of the biodiesel to be difficult and costly. Thus, sucrose-derived solid acid catalyst was developed in the present study which aims to improve the esterification process and reduce the generation of waste. The physicochemical properties of the synthesized catalysts were studied by various techniques such as, BET surface area, X-ray diffraction (XRD), temperature programmed desorption of NH₃ (TPD-NH₃), scanning electron microscopy (SEM). Response surface methodology (RSM) with central composite design (CCD) is used to determine the optimum parameters for the catalytic reaction. The experimental results showed that the catalyst exhibited good catalytic activity in the transesterification of PFAD, providing maximum biodiesel yield of 94% at optimum parameters. The better catalytic activity of the aforementioned catalyst in the biodiesel reaction could be attributed to the presence of optimal number of catalytically active acid site density on its surface.     

微藻脂肪酸在中国近海缺氧海水-沉积物界面中的降解模拟研究

通过一系列培养实验,模拟了有机物在中国近海季节性缺氧环境沉积物-海水界面的降解过程.以中国近海典型的赤潮藻中肋骨条藻(Skeletonema costatum)为研究对象,对中肋骨条藻中的几种典型脂类生物标志物在不同程度缺氧海水-沉积物界面中的降解行为进行追踪.通过分析测定不同培养时间获取的不同含氧体系(氧饱和度100%、50%,25%和0%)中中肋骨条藻4种主要脂肪酸[14:0、16:0、16:1(7)、20:5]的含量,结果表明,在前2~3周4种脂肪酸迅速减少,之后则变化很慢甚至几乎不变.在不同含氧体系中4种脂肪酸的降解存在很大差异,14:0、16:1(7)、20:5经过两个月的培养,在4种不同含氧体系中几乎降解完全,而16:0在4种体系中剩余25%~35%.根据multi-G模型对4种脂肪酸降解进行定量描述,结果表明,每种化合物可以分为降解较快和较慢的部分,各化合物的平均降解速率常数k av范围在0.079~0.84 d-1,14:0与16:1(7)的降解在25%含氧体系中最快,在降解最快的体系中,14:0的k av是最慢体系(含氧50%)的2.3倍,16:1(7)的k av是最慢体系(含氧100%)的1.7倍;16:0的最快降解速率出现在无氧体系中(0.17 d-1),是最慢体系[50%含氧体系(0.079 d-1)]的2.1倍;20:5的降解速率常数则与含氧量呈正相关.结果表明,影响中国近海缺氧海区沉积物-海水界面中中肋骨条藻中脂肪酸降解的因素除了含氧量之外,有机化合物本身的结构和性质以及环境中微生物作用等对其降解也存在着很大影响.     

A novel online analyzer for accurate and rapid measurement of volatile fatty acids in anaerobic wastewater treatment

Volatile fatty acids (VFAs), which are largely generated during the anaerobic acidification process, are considered to be reliable indicators of the stable process operation. However, the common methods for monitoring VFAs are offline, and they are typically manual requiring time-consuming, costly and complex instruments. This study aims to develop a novel online analyzer for automatic measuring VFAs, which was based on the 5-pH point titration, embedded with a proportional-integral-derivative (PID) feedback control system. The results show that it can achieve accurate and rapid monitoring of VFAs ranging between 0-400 mg/L (<9 min/sample) but simultaneously faces the problems of overtitration and interference of complex characteristics of wastewater. In order to improve its accuracy and stability, the effects of three general coefficients (K_I, K_P, and K_D) of PID on the titration were investigated, and the optimal values of K_I, K_P, and K_D were found to be 1.5, 1.0, and -1.0~0.5, respectively. Besides, the initial titration speed was set at 0.06 mL/min, equal to the minimum speed of the peristaltic pump, and the dichotomy approach was integrated into the PID feedback controller. Owing to the above improvements, the relative mean deviation and standard deviation of measuring VFAs in both synthetic and real wastewaters were mostly lower than 5.0% and 5.0 mg/L, proving the online analyzer is rapid, accurate and reliable.