Alternating nitrogen feeding strategy induced aerobic granulation: Influencing conditions and mechanism

Effective cultivation of stable aerobic granular sludge (AGS) is a crucial step in the successful application of this technology, and the formation of AGS could be facilitated by some environmental stress conditions. Four identical sequencing batch reactors (SBRs) were established to investigate the aerobic granulation process under the same alternating ammonia nitrogen feeding strategy superimposed with different environmental conditions (inorganic carbon source, temperature, N/COD). Although various superimposed conditions induced a significant difference in the size, settling velocity, mechanic strength of AGS, mature aerobic granules could be successfully obtained in all four reactors after 70 days' operation, indicating the alternating ammonia nitrogen feeding strategy was the most critical factor for AGS formation. Based on the results of redundancy analysis, the presence of an inorganic carbon source could facilitate the cultivation of AGS with nitrification function, while the moderate temperature and fluctuant N/COD might benefit the cultivation of more stable AGS. In addition, superimposed stress conditions could result in the difference in the microbial population between four reactors, but the population diversity and abundance of microorganisms were not the determinants of AGS formation. This study provided an effective method for the cultivation of AGS by using alternating ammonia nitrogen feeding strategy.     

The formation kinetics and control of biofilms by three dominant fungi species isolated from groundwater

Filamentous fungi can enter drinking water supply systems in various ways, and exist in suspended or sessile states which threatens the health of individuals by posing a high risk of invasive infections. In this study, the biofilms formation kinetics of the three genera of fungal spores, Aspergillus niger (A. niger), Penicillium polonicum (P. polonicum) and Trichoderma harzianum (T. harzianum) isolated from the groundwater were reported, as well as the effects of water quality parameters were evaluated. In addition, the efficiency of low- concentrations of chlorine-based disinfectants (chlorine, chlorine dioxide and chloramine) on controlling the formation of fungal biofilms was assessed. The results showed that the biofilms formation of the three genera of fungi could be divided into the following four phases: induction, exponential, stationary and sloughing off. The optimum conditions for fungal biofilms formation were found to be neutral or weakly acidic at 28 °C with rich nutrition. In fact, A. niger, P. polonicum, and T. harzianum were not observed to form mature biofilms in actual groundwater within 120 hr. Carbon was found to have the maximum effect on the fungal biofilms formation in actual groundwater, followed by nitrogen and phosphorus. The resistance of fungal species to disinfectants during the formation of biofilms decreased in the order: A. niger > T. harzianum > P. polonicum. Chlorine dioxide was observed to control the biofilms formation with maximum efficiency, followed by chlorine and chloramine. Consequently, the results of this study will provide a beneficial understanding for the formation and control of fungal biofilms.     

Triazine and metolachlor herbicide residues in farm areas of the Lower Fraser valley, British Columbia, Canada

Crop soils, ditch sediments and water flowing from several Lower Fraser River (LFR) farm areas of British Columbia, Canada, to salmon tributary streams of that river were sampled in 2004-2005 to quantify for residues of triazine [atrazine, desethylatrazine (a transformation product of atrazine), propazine, and simazine] and metolachlor (a chloroacetamide) herbicides. Average concentrations [microg kg-1 dry weight (d.w.)] of triazine (10,110) and metolachlor (8,910) herbicides detected in crop soils at the start (May 2004, 2005) of the growing season were about 17 and 6 times, respectively, higher than those found for both herbicide groups during (June-Sept, 2004, 2005) the growing season. In contrast, mean concentrations (microg L-1) of triazines (0.092) and metolachlor (0.014) in permanent ditches adjacent to farms were about 7 and 28 times, respectively, lower at the start than during the growing season. Both herbicide groups in ditch sediments were detected only during the growing season at concentrations averaging about 315 microg kg-1 d.w. The risk potential of these herbicides for non-target aquatic organisms inhabiting permanent farm ditches contiguous to tributary streams of the LFR during the growing season is evaluated and discussed.     

基于关键产品把控的舰船装备环境适应性设计对策分析方法

综合考虑舰船装备系统的复杂性和海洋环境的严酷性,提出了一种基于关键产品把控的舰船装备环境适应性设计对策分析方法.该方法在分析装备环境适应性设计基本要求的基础上,提出了按产品层次逐级进行环境适应性分析,根据其对上一级产品或整个装备系统功能的影响,层层剥离出环境适应性关键产品,通过识别环境适应性薄弱环节,消除环境适应性风险...     

缺氧—好氧—催化臭氧氧化工艺处理石化厂含盐废水

采用缺氧—好氧—催化臭氧氧化工艺处理某石化厂的含盐废水。实验结果表明：在进水COD为200~350 mg/L的条件下,经生化处理后的出水COD稳定在50~60 mg/L,COD去除率稳定在75%左右;在臭氧投加量为4.5 g/L、V（催化剂Ⅱ）∶V（废水）=1.5∶1的条件下,进行连续催化臭氧氧化后出水COD稳定在20 mg/L以下,COD去除率大于70%,满足DB 61/224—2011《黄河流域（陕西段）污水综合排放标准》。表征结果显示,催化剂表面含有铜元素,比表面积为250.815 m²/g,吸水率为60.9%,经过滤可去除废水中残留的催化剂。     

油田采出水膜法处理技术应用研究进展

对采出水膜法处理技术中的微滤、超滤、纳滤、反渗透膜以及集成技术的应用进行研究,分析成本,总结各技术的特点。超滤、微滤主要处理的是水中的油类以及悬浮物和细菌,纳滤对二价离子的脱除率较高,反渗透技术可以有效降低采出水矿化度。在实际采出水处理中,可综合运用膜技术和生物法达到更好的处理效果。     

CEMS比对监测结果反映的若干问题探讨

文章以固定污染源比对监测的结果作为参考依据,针对其反映的低浓度颗粒物采样测量、比对监测考核指标的不完善以及火电厂湿法脱硫装置未安装GGH时颗粒物浓度的测定等方面存在相关问题进行了归纳和探讨。     

关于生态资产核算方法探讨

生态资产的价值核算是可持续发展的重要组成部分。采用文献检索和对比分析法,探讨了生态资产价值构成的五分型、四分型、二分型3种分类形式,介绍了当前国内外普遍运用的几种核算方法,包括直接(实际)市场法、替代市场法、假想(模拟)市场法、空间-能值分析法和遥感模型测算方法,并对这些方法的适用范围和优缺点进行了分析比较,在此基础上,对生态资产的核算方法做了一些讨论及展望。     

Monitoring of non-point source pollutants load from a mixed forest land use

The aim of this study was to determine the unit load of NPS (non-point source) pollutants including organic variables such as BOD (biochemical oxygen demand),COD (chemical oxygen demand) and DOC (dissolved organic carbon),nitrogen and phosphorus constituents,and suspended solids (SS) and their event mean concentration (EMC) of runoff flows from a water-shed of mixed forest land use by intensive field experiments.Field monitoring for continuous measurements of rainfall,flow,and water quality was conducted over 12 storm events during 2008–2009 using automated and manual sampling methods.The EMCs of individual runoff event were estimated for each water quality constituent based on the flow rate and concentration data of runoff discharge.The average EMCs of BOD,COD,DOC,SS,TN (total nitrogen),NH 4+ -N,NO 3- -N,TP (total phosphorus),PO 43- -P from the mixed forest land were 1.794,3.498,1.462,10.269,0.862,0.044,0.634,0.034,and 0.005 mg/L,respectively.The annual unit loads of BOD,COD,DOC,SS,TN,NH 4+ -N,NO 3- -N,TP and PO 43--P were estimated as 66.9,133.2,55.5,429.8,36.5,1.6,26.9,1.3 and 0.1 kg/(ha·yr),respectively.In addition,affecting parameters on the EMCs were investigated by statistic analysis of the field data.As a result,significant correlations with precipitation,rainfall intensity,and total runoff flows were found in most constituents.     

春季桑沟湾海域贝类养殖对海水中营养盐的影响研究

根据2011年春季对桑沟湾海域8个监测点的营养盐的变化特征和历史资料的研究,分析了桑沟湾水域溶解性无机氮(DIN)、总氮(TN)、活性磷酸盐(PO34-)和总磷(TP)浓度变化及它们之间的相互关系,估算了贝类养殖的排泄物对海水污染的贡献率。结果表明,溶解性无机氮的平均浓度为0.106 1 mg/L,NO3-N为主要存在形式,占溶解性无机氮平均含量的78.3%,NH3-N、NO2-N分别占溶解性无机氮平均含量的14.2%和7.5%。总氮的平均浓度为0.234 7 mg/L,溶解性无机氮浓度占总氮浓度的45.2%。活性磷酸盐的平均浓度为0.013 3 mg/L,总磷的平均浓度为0.024 78 mg/L。春季桑沟湾贝类养殖对该海域海水磷含量的贡献率比氮的贡献率大,N/P为17.63,营养水平基本属于贫营养。