The importance of temperature in assessing iron pipe corrosion in water distribution systems

Temperature is expected to play a significant role in the corrosion of iron pipes in drinking water distribution systems. Temperature impacts many parameters that are critical to pipe corrosion including biological activity, physical properties of the solution, thermodynamic and physical properties of corrosion scale, and chemical rates. Moreover, variations in temperature and temperature gradients may give rise to new corrosion phenomena worthy of consideration by water treatment personnel.     

Comparison of mesophilic and thermophilic anaerobic digestions of thermal hydrolysis pretreated swine manure: Process performance, microbial communities and energy balance

Anaerobic digestion (AD) of swine manure (SM) commonly shows low biogas output and unsatisfactory economic performance. In this study, thermophilic AD (TAD, 50 ± 1 °C) was combined with thermal hydrolysis pretreatment (THP, 170 °C/10 bar), to investigate its potential for maximizing biogas yield, securing successful digestion and microbial diversity, as well as improving energy balance. Four lab-scale continuously stirred tank reactors were operated for 300 days and compared with each other, i.e., reactor 1 (raw SM fed in mesophilic AD: RSM-MAD), reactor 2 (THP-treated SM fed in MAD: TSM-MAD), reactor 3 (RSM-TAD), and reactor 4 (TSM-TAD). The results showed that THP was efficient to increase methane production of SM, TSM-TAD mode led to the highest methane yield (129.8 ± 40.5 mL-CH₄/g-VS/day) among the tests (p < 0.05). Although TAD was more likely to induce free ammonia (> 700 mg/L) or volatile fatty acids (> 6000 mg/L) accumulation compared with MAD in start-up phase, TSM-TAD treatment mode behaved a sustainable digestion process in a long-term operation. For TSM-TAD scenario, higher Shannon–Weaver (3.873) and lower Simpson index (0.061) indicated this mode ensured and enlarged the diversity of bacteria communities. Phylum Bathyarchaeota was dominant (59.3%−90.0%) in archaea community, followed by Euryarchaeota in the four reactors. RSM-MAD treatment mode achieved the highest energy output (4.65 GJ/day), TSM-TAD was less effective (−17.38 GJ/day) due to increased energy demands. Thus improving the energetic efficiency of THP units is recommended for the development of TSM-TAD treatment mode.     

石墨炉原子吸收分光光度法测地面水中的铍

介绍了用石墨炉原子吸收分光光度计测定地面水中的铍的方法的建立     

循环流化床锅炉床温控制方法

就目前电厂循环流化床锅炉运行中存在的床温波动问题，讨论了导致床温波动的因素，并针对性地提出了控制床温的一些措施。     

DENSITY CURRENT INTRUSIONS IN AN ICE-COVERED URBAN LAKE1

ABSTRACT: Evidence is presented that snowmelt runoff from an urban watershed can produce density current intrusions (underflows) in a lake. Several episodes of density current intrusions are documented. Water temperatures and salinities measured near the bottom of a 10 m deep Minneapolis lake during the late winter warming periods in 1989, 1990, 1991, and 1995 show significant rapid changes which are correlated with observed higher air temperatures and snowmelt runoff. The snowmelt runoff entering this particular lake (Ryan Lake) has increased electrical conductivity, salinity, and density. The source of the salinity is the salt spread on urban streets in the winter. Heating of littoral waters in spring may also contribute to the occurrence of the sinking flows, but is clearly not the only cause.     

中国科学技术协会五届二次全委会明年在京召开我会两名代表参加全会活动

中国科学技术协会五届二次全委会明年在京召开我会两名代表参加全会活动中国科协第五届全国委员会第二次会议将于１９９７年２月２２日至２４日在北京召开。我会副理事长、中国科协全国委员会委员程映雪教授作为正式代表，我会副秘书长、“中国安全科学学报”主编徐德蜀高...     

平衡调温调湿方式中变流量冷冻水系统设计

通过对变流量冷冻水系统的分析指出，在运用平衡调温调湿方式的空调系统中，应用变流量冷冻水系统可以较大地节约能源和投资；并提出了实现这种应用的方法。     

结构面分布特征对隧道围岩变形影响的数值模拟分析

结构面对隧道围岩变形及稳定性起着决定性作用。运用三维离散元方法(3DEC)研究结构面分布特征,重点是结构面线密度1/λ、强度和倾角对隧道围岩变形的影响,总结了结构面分布与围岩变形特征的关系。结果表明,在结构面强度较低的情况下,结构面线密度对隧道变形的影响较大,其影响可分为两种情况:①λ≤0.2时,围岩的弯曲变形大于沿结构面的剪切变形,属于应力型大变形;②0.2<λ≤0.4时,沿结构面的剪切变形大于围岩的弯曲变形,属于结构型大变形。结构面倾角主要影响围岩大变形发生的位置。将数值模拟结果与国内工程实例实测变形资料相对比,发现一致性较好。本研究结果对隧道支护结构的设计以及施工设计具有借鉴意义与指导作用。     

温度及外加碳源对生物脱氮除磷过程的影响

针对污水处理厂普遍面临的进水碳源不足及冬季低温时出水氮磷不能稳定达标的问题,研究了温度(21、15和10℃)和外加碳源(乙酸)对活性污泥缺氧条件下反硝化及释磷过程的影响。结果表明,在缺氧条件下投加乙酸,释磷与反硝化反应可同时进行,且乙酸投量的增加仅延长快速碳源反硝化阶段及缺氧释磷阶段的反应时间;温度降低为15℃和10℃时,快速碳源反硝化阶段反硝化速率及缺氧释磷速率较21℃分别降低了约29.2%、42.2%和26.1%、32.3%。当硝态氮目标去除量与磷酸盐目标释放量之比超过5时,乙酸的最优投量以满足反硝化要求为准,计算得出21、15和10℃时常州某城镇污水处理厂乙酸最优投加量计算值约为30、39和46 mg/L。     

pH和温度对2,2’,4,4’-四溴联苯醚在土壤中吸附和解吸行为的影响研究

研究了pH和温度对2,2’,4,4’-四溴联苯醚(BDE-47)在土壤中的吸附和解吸行为的影响。结果表明,pH和温度都可以影响BDE-47在受试土壤中的吸附和解吸行为。pH升高或降低均会使土壤对BDE-47的吸附能力提高,且在碱性环境中提高的程度更大;酸性或碱性条件下BDE-47在土壤中的解吸滞后性显著增强。温度降低后,土壤对BDE-47的吸附能力提高,5℃时的单点分配系数(Kd,表征土壤对BDE-47的吸附能力)是25℃时的1.03~1.67倍;温度由25℃降低到5℃后,BDE-47在土壤中的解吸滞后性增强。