Modeling iron release from cast iron pipes in an urban water distribution system caused by source water switch

Significant iron release from cast iron pipes in water distribution systems (WDSs), which usually occurs during the source water switch period, is a great concern of water utilities because of the potential occurrence of “red water” and customer complaints. This study developed a new method which combined in-situ water stagnation experiments with mathematical models and numerical simulations to predict the iron release caused by source water switch. In-situ water stagnation experiments were conducted to determine the total iron accumulation in nine cast iron pipes in-service in Beijing when switching the local water to treated Danjiangkou Reservior water. Results showed that the difference in the concentration increment of total iron in 24 hr (ΔCI_TI,24), i.e. short-term iron release, caused by source water switch was mainly dependent on the difference in the key quality parameters (pH, hardness, nitrate, Larson Ratio and dissolved oxygen (DO)) between the two source waters. The iron release rate (R_Fe) after switch, i.e. long-term iron release, was closely related to the pipe properties as well as the DO and total residual chlorine (TRC) concentrations. Mathematical models of ΔCI_TI,24 and R_Fe were developed to quantitatively reveal the relationship between iron release and the key quality parameters. The R_Fe model could successfully combine with EPANET-MSX, a numerical simulator of water quality for WDSs to extend the iron release modeling from pipe level to network level. The new method is applicable to predicting iron release during source water switch, thus facilitating water utilities to take preventive actions to avoid “red water”.     

不确定节点水量下水质监测点优化选址方法

针对供水管网水质监测点的优化选址问题,提出污染源位置识别准确度的概念,以水质监测点探测到的不同污染事件的时段区间冗余度最小化,和污染事件探测概率最大化为优化目标,结合一个案例管网,采用非支配排序遗传算法计算节点用水量变化条件下的监测点优化选址方案,算例结果显示节点用水量的不确定性不显著影响监测点的污染事件探测能力和可能性节点识别能力,但使监测点的污染源位置识别准确度降低.     

实验室信息管理系统在环境监测站中的应用——以西安市环境监测站为例

根据环境监测站以往的业务特点和存在的问题,引入了基于监测站特色的实验室信息管理系统。笔者重点介绍了西安环境监测站实验室信息管理系统的工作流程和系统组块,反映出系统灵活、严谨的运行特点,以及全面的系统应用功能。此外,描述了本站LIMS快速、高效的运行状况、常见弊端和LIMS实施的局限性。为今后同行业监测站LIMS的建设、实施和应用提供范本和应用经验和建议,促进了环境监测行业的信息化、现代化管理。     

“5.12”汶川地震诱发滑坡特征参数统计分析

2008年5月12日四川省汶川县发生了Ms 8.0级大地震,震后遥感影像解译与调查结果表明,在约48 700km2的区域内,地震诱发了不少于48000处的滑坡灾害。基于GIS空间分析方法,分别使用滑坡面积与滑坡数量这两个统计参数,对滑坡的地层岩性、坡度、滑向、高程、所在烈度区、上下盘位置和与发震断裂的距离等共7个参数进行了统计分析。统计结果表明,汶川地震滑坡多发育在(1)砂岩、粉砂岩、千枚岩与灰岩地层中;(2)坡度为30°～50°,尤其是35°～45°范围内;(3)沿着垂直于发震断裂SEE方向运动;(4)高程为800～2000m,尤其是1000～1600m范围内;(5)Ⅷ～Ⅺ烈度区范围内;(6)发震断裂的上盘:(7)距离发震断裂40km,尤其是10km的区域内。     

供应链食品安全管理自适应系统的结构设计

食品供应链是食品安全监管体系的重要组成部分和载体。本文探讨了自适应系统理论在供应链食品质量安全管理方面应用的可能性;针对目前的食品安全问题,依照自适应原理,设计了食品安全的自适应系统,该系统含有两套自适应的子系统,即低成本常规食品安全管理系统和高成本食品安全突发事件控制预测系统;两套子系统所采用的规则集不同,但可相互通讯,共享跟踪系统及其所采集的数据。整个系统最终输出的是安全供应渠道,与供应链决策系统中的成本、需求方向、生产计划等一起构成决定食品原材料供应来源的因素。系统以人工神经网络为自适应系统的主体,判断安全的食品供应结点并预测突发性食品安全问题;同时,提出了实现上述功能的一种可能的系统结构,以期有效实现食品安全的动态反应和控制,为完善我国食品质量安全管理提供新的思路。     

论环境监察工作制度修订的必要性

随着环境监察形势的不断变化,环境监察现有工作制度难以有效应对日新月异的环境保护新形势;环境监察工作体制、机制以及执法理念的更新换代,未来的环境监察工作制度需要进一步完善,才能更好地为国家环境保护工作保驾护航。     

Implementing an effective conduct of operations and operational discipline program

This paper introduces the concepts of conduct of operations (COO) and operational discipline (OD), the attributes of effective COO/OD systems, and the steps an organization might take to improve its COO/OD programs. In general, the COO program encompasses the management systems developed to encourage performance of all tasks in a consistent, appropriate manner. OD is the deliberate and structured execution of the COO management systems by personnel throughout the organization. By introducing a framework and tools for describing, evaluating, and improving COO/OD, this paper provides guidance that can be used by companies to improve process safety performance.     

One-year survey of opportunistic premise plumbing pathogens and free-living amoebae in the tap-water of one northern city of China

In this study, qPCR was used to quantify opportunistic premise plumbing pathogens (OPPPs) and free-living amoebae in 11 tap water samples collected over four seasons from a city in northern China. Results demonstrated that the average numbers of gene copies of Legionella spp. and Mycobacterium spp. were significantly higher than those of Aeromonas spp. (p?<?0.05). Legionella spp. and Mycobacterium spp. were 100% (44/44) positively detected while P. aeruginosa and Aeromonas spp. were 79.54% (35/44) and 77.27% (34/44) positively detected. Legionella pneumophila was only detected in 4 samples (4/44), demonstrating its occasional occurrence. No Mycobacterium avium or Naegleria fowleri was detected in any of the samples. The average gene copy numbers of target OPPPs were the highest in summer, suggesting seasonal prevalence of OPPPs. Average gene copy numbers of OPPPs in the taps of low-use-frequency were higher than in taps of high-use-frequency, but the difference was not significant for some OPPPs (p?>?0.05). Moderate negative correlations between the chlorine concentration and the gene copy numbers of OPPPs were observed by Spearman analysis (r_s ranged from ? 0.311 to ? 0.710, p?<?0.05). However, no significant correlations existed between OPPPs and AOC, BDOC, or turbidity. Moderate positive correlations were observed between the target microorganisms, especially for Acanthamoeba spp., through Spearman analysis (p?<?0.05). Based on our studies, it is proposed that disinfectant concentration, season, taps with different-use frequency, OPPP species, and potential microbial correlations should be considered for control of OPPPs in tap water.     

Dynamics of dust explosions suppression by means of extinguishing powder in various industrial conditions

In industrial conditions, there are different kinds of installations endangered by an explosion of dust–gas mixtures. In order to prevent them from any consequences of potential explosions, active protection systems which use extinguishing powders, as the suppressing material, are more and more widely applied. It often happens that the industrial installations are additionally endangered by an action of mechanical vibrations. In the above-mentioned conditions, the extinguishing powder tends to aggregate, making the process of dispersing it in the protected areas more difficult.

The results of research into optimization of the shape, number of igniters and miniaturization of the explosive charge mass are presented. In case of occurrence of the mechanical vibrations in the installations that cause aggregation of the suppressing powder, the best solution was modification of the perforated combustion chamber located inside the extinguisher. As a result of that, a certain amount of gases generated in the course of combustion of the main charge is directed over the membrane, where the gases crash a layer of aggregated powder. Thus, the process of pushing the powder out from a container towards the dispersing head improves considerably and consequently increases the efficiency of the explosion-suppressing process.     

CONFLICT AND COOPERATION OVER INTERNATIONAL FRESHWATER RESOURCES: INDICATORS OF BASINS AT RISR1

ABSTRACT: In this paper we seek to identify historical indicators of international freshwater conflict and cooperation and to create a framework to identify and evaluate international river basins at potential risk for future conflict. We derived biophysical, socioeco‐nomic, and geopolitical variables at multiple spatial and temporal scales from GIS datasets of international basins and associated countries, and we tested these variables against a database of historical incidents of international water related cooperation and conflict from 1948 to 1999. International relations over freshwater resources were overwhelmingly cooperative and covered a wide range of issues, including water quantity, water quality, joint management, and hydropower. Conflictive relations tended to center on quantity and infrastructure. No single indicator—including climate, water stress, government type, and dependence on water for agriculture or energy—explained conflict/cooperation over water. Even indicators showing a significant correlation with water conflict, such as high population density, low per capita GDP, and overall unfriendly international relations, explained only a small percentage of data variability. The most promising sets of indicators for water conflict were those associated with rapid or extreme physical or institutional change within a basin (e.g., large dams or internationalization of a basin) and the key role of institutional mechanisms, such as freshwater treaties, in mitigating such conflict.