The key role of inoculated sludge in fast start-up of sequencing batch reactor for the domestication of aerobic granular sludge

Two types of inoculated sludges, granular sludge that had been stored at-20°C and activated sludge, were investigated for the domestication of aerobic granular sludges(AGSs in sequencing batch reactors(SBRs). The results showed that using the stored granular sludge as inoculation sludge could effectively shorten the domestication time of AGS and yielded mature granular sludge after 22 days of operation. The AGS domesticated by stored granular sludge had better biomass and sedimentation properties; its MLSS and SVI reached8.55 g/L and 35.27 mL/g, respectively. The removal efficiencies for chemical oxygen demand(COD), ammonium nitrogen(NH_4~+-N) and total phosphorus(TP) reached 90.76%, 97.39% and 96.40%, respectively. By contrast, 54 days were needed to obtain mature granules using activated sludge. The microbial community structure was probed by using scanning electron microscopy(SEM) and high-throughput sequencing. The results showed that the diversity of the microbial community in mature granules was reduced when stored granular sludge rather than activated sludge was employed as inoculation sludge, and the dominant microbes were changed. The dominant species in mature granules domesticated using stored granular sludge were Zoogloea, Acidovorax and Tolumonas at the genus classification level, while the dominant species were Zoogloea and TM7-genera in granules developed from activated sludge.     

从实现安全生产谈加强运行班组安全建设的重要性

分析了近年来因运行班组人员操作不当引发事故的原因,主要归结于日常安全管理工作和应急处置不当。提出在日常安全管理方面,操作人员须熟知岗位风险、防止“三违行为”和做好装置开停工期间的安全管理;在应急处置方面,需熟练掌握应急操作技能,培养反应快速、清晰的应急意识等措施,不断提高班组安全能力建设,以便更有效地控制安全风险,实现安全生产。     

基于LMDZ模型的西南地区水汽来源及水汽再循环率的分析

研究基于LMDZ模型对我国西南地区9个站点的同位素数据进行空间插值,利用同位素混合模型对不同来源水汽对降水的贡献率进行时空分析。结果表明,我国西南地区外来水汽对降水的贡献率除部分站点外,均在90%以上;其次为植物蒸腾水汽,占比为0.3%～21.3%,地表蒸发水汽对降水贡献率最小,介于0.1%～8.1%之间,同时外来水汽对降水贡献率夏季大于冬季,而地表蒸发水汽和植物蒸腾水汽对降水的贡献率冬季略大于夏季。水汽再循环率呈现空间差异,四川盆地及周围山地地表蒸发水汽与植物蒸腾水汽略高于青藏高原及云贵高原一带。结合美国国家大气研究中心所提供的气象资料,采用MeteoInfo软件对我国西南地区各站点进行近10年(1998～2007)的后向轨迹追踪,并对其进行聚类分析得出四川省两站点和重庆站点在夏季近源局地蒸发水汽占比高达50%,贵阳夏季有28.95%的水汽为近源局地蒸发形成,其余站点夏季水汽来源大部分来自于阿拉伯海、孟加拉湾和印度洋水汽,还有一部分来自于西风带的水汽和东南季风带来的西太平洋的水汽,然而冬季水汽均来自于西风带水汽。     

Comparison of nickel adsorption on biochars produced from mixed softwood and Miscanthus straw

Environmental Science and Pollution Research - In order to understand the influence of feedstock type on biochar adsorption of heavy metals, the adsorption characteristics of nickel (Ni2+), copper...     

Impacts of urbanization on surface sediment quality: evidence from polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) contaminations in the Grand Canal of China

Introduction

Organic pollutants, especially synthetic organic compounds, can indicate paces of anthropogenic activities. Effects of urbanization on polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) distributions in surface sediment were conducted in urban sections of the Grand Canal, China, consisting of a four-level urbanization gradient.

Materials and methods

The four-level urbanization gradients include three countryside towns, two small-size cities, three medium-size cities, and a large-size city. Diagnostic ratio analysis and factor analysis?Cmultiple linear regression model were used for source apportionment of PAHs. Sediment quality guidelines (SQGs) of USA and Canada were employed to assess ecological risks of PAHs and PCBs in surface sediments of the Canal.

Results and discussion

Ranges of PAH and PCB concentrations in surface sediments were 0.66?C22?mg/kg and 0.5?C93???g/kg, respectively. Coal-related sources were primary PAH sources and followed by vehicular emission. Total concentration, composition, and source apportionment of PAHs exhibited urbanization gradient effects. Total PCB concentrations increased with the urbanization gradient, while total PAHs concentration in surface sediments presented an inverted U Kuznets curve with the urbanization gradient. Elevated concentrations of both PAHs and PCBs ranged at effect range low levels or interim SQG, assessed by USA and Canadian SQGs.

Conclusions

PAHs and PCBs in surface sediments of the Grand Canal showed urbanization gradient effects and low ecological risks.     

A novel nano-sized Co3O4@C catalyst derived from Co-MOF template for efficient Hg0 removal at low temperatures with outstanding SO2 resistance

Environmental Science and Pollution Research - Co3O4 is a promising Hg0 removal catalyst for industrial application. Operating temperature and low sulfur resistance are two of the main problems...     

耦合回流污泥预浓缩系统的新型氧化沟工艺强化除磷

针对传统的"厌氧+氧化沟"运行模式对低碳源污水除磷能力不佳的问题,采用耦合回流污泥预浓缩系统的新型氧化沟工艺对其强化除磷进行了中试实验研究。通过采用回流污泥预浓缩系统,调试回流污泥浓缩比,提高系统的除磷能力。研究结果表明,在控制最佳回流污泥浓缩比为55%的情况下,出水TP浓度和去除率分别为0.92 mg/L和67.5%,相比于浓缩比为100%、70%、50%和30%的工况,其去除率分别增加了24.3%、27.3%、8.2%和28.6%,强化了系统的除磷效果。另外,ORP可以预示预缺氧池内无效释磷和反硝化程度,以此作为自动调整最佳回流污泥浓缩比的控制参数。     

Effectiveness and mechanisms of hydrogen sulfide adsorption by camphor-derived biochar

The characteristics and mechanisms of hydrogen sulfide (H2S) adsorption on a biochar through pyrolysis at various temperatures (100 to 500 degrees C) were investigated. The biochar used in the current study was derived from the camphor tree (Cinnamomum camphora). The samples were ground and sieved to produceparticle sizes of 0.4 mm to 1.25 mm, 0.3 mm to 0.4 mm, and <0.3 mm. The H2S breakthrough capacity was measured using a laboratory-designed test. The surface properties of the biochar were characterized using pH and Fourier-transform infrared spectroscopy (FTIR) analysis. The results obtained demonstrate that all camphor-derived biochars were effective in H2S sorption. Certain threshold ranges ofthepyrolysis temperature and surfacepH were observed, which, when exceeded, have dramatic effects on the H2S adsorption capacity. The sorption capacity ranged from 1.2 mg/g to 121.4 mg/g. The biochar with 0.3 mm to 0.4 mm particle size possesses a maximum sorption capacity at 400 degrees C. The pH and FTIR analysis results showed that carboxylic and hydroxide radical groups were responsible for H2S sorption. These observations will be helpful in designing biochar as engineered sorbents for the removal of H2S.     

A cascade of anoxic and oxic fluidized bed biofilm reactors for treatment of synthetic municipal wastewater

In this study, a cascade of anoxic and oxic fluidized bed biofilm reactors system was carried out to treat synthetic municipal wastewater. The parameters of the influent flow rates and C/N ratios were discussed. System performance was acceptable for chemical oxygen demand (COD), ammonia, and total nitrogen removal. A decrease of ammonia and total nitrogen removal efficiencies, however, was observed when the influent flow rates increased to 5.04 and 6.12 1 h(-1). Total nitrogen removal decreased at the influent C/N ratio of 3:1. The measured ratios of COD reduction in the anoxic column to nitrogen removal through nitrification-denitrification were 3.7, 3.5, 3.3, and 3.1 g COD/g(-1) N on average when the influent C/N ratios changed from 6:1 to 3:1. The observed sludge yield (Yobs) was 0.169 g VSS g COD(-1) because of perfect denitrification in the anoxic column and the relatively long solids retention time.     

装车油气回收技术的应用分析

结合我国"十二五"节能规划及石油消费情况,针对装车环节产生的油气浓度高、流量大的特点,从安全、环保、节能、经济效益几个方面阐述了油气回收的必要性和重要性,在此基础上,结合国内外的油气排放标准,重点对四种常用的油气回收技术—冷凝法、吸附法、膜分离法、吸收法从工艺特点、尾气排放浓度、投资、能耗、占地面积等几个方面进行了分析,并介绍了这四种油气回收技术的发展、现状及研究方向,从而进一步提出了油气回收技术的适用性建议。