A system dynamics urban water management model for Macau, China

Urban water resources have been facing significant pressure from population growth, urbanization, and climate change. A system dynamics urban water management model was proposed to simulate the dynamic interactions between urban water demands and society, economy, climate, and water conservation. The residents'' water conservation willingness was incorporated in the model and water-saving effects were quantified. The simulation results for Macau showed that population size was the main driving force for urban water demand. The change of temperature and precipitation has obvious effects on the landscape water demand. The water demand output is sensitive to the change in population, per capita demand, and temperature. Increased precipitation will reduce urban water demand and increased economic growth will increase water demand. By implementing integrated water conservation measures and improved water conservation willingness, water demand could be reduced by 17.5%.     

外置双U型静钻根植工法能源桩换热性能研究∗

为探究外置双U型静钻根植工法能源桩换热性能,通过现场热响应试验,利用热源理论初步分析其岩土综合导热系数,建立三维传热数值模型并进行验证。利用三维传热数值模型分析换热管间距及其导热系数、换热液流速和桩周水泥土导热系数等因素对该新型桩换热性能的影响。分析结果表明,试桩区域岩土综合导热系数为1.64W(m·K)-1。提高换热管间距、换热管导热系数、换热液流速和桩周水泥土导热系数均能提高能源桩的换热性能,但当换热管间距大于0.25 m,换热液流速达到紊流态,换热管和桩周水泥土导热系数高于岩土综合导热系数后,提高上述参数对能源桩换热性能的提高贡献不大。     

曝气生物流化池生物强化处理高氨氮制革废水研究

以曝气生物流化池(ABFT)I艺为核心,通过投加高效菌酶添加剂(简称菌荆)的方法对高氨氮制革废水进行生物强化处理研究.结果表明,在菌剂投加量为0.4 kg/m3,总水力停留时间为32 h(其中生化处理段水力停留时间为29 h)条件下,菌剂投加10 d后氨氮的去除率可达80.2%,25 d后系统即可稳定运行;出水氨氮平均为4.8 mg/L,去除率为98.8%;出水COD平均为137 mg/L,去除率为76.4%.无机碳化合物和生长因子对硝化反应有促进作用,使氨氮的去除率提高约6.6%.该结果显示了ABFT工艺在处理高氨氮制革废水上具有明显优势.     

不同回流比对无植物垂直流人工湿地除氮效果的影响

通过内碳源前置反硝化脱氮工艺试验,比较了不同回流比对垂直流人工湿地除氮效果的影响。试验结果表明,TN去除率随着回流比增加而增加,NH⁺₄-N去除率则随着回流比的增加先降低后增加的趋势,两者去除率之和以回流比200％为最高,以回流比150％次之,以回流比100％为最低。从TN的去除率来看,回流比150％略高于回流比200％。     

Enhanced degradable yard waste collection bag behavior in a field-scale composting environment

The degradation of four formulations of yard waste-filled collection bags was evaluated in a field-scale test of 15.5- or 31-m-long windrows at a community yard waste composting site. Variables of bag contents, bag chemical composition, and length of exposure were evaluated. Chemical compositions of the bags included (1) low-density polyethylene (LDPE) + 6% cornstarch + 2 levels of prooxidant, (2) LDPE + 9% cornstarch + prooxidants, and (3) LDPE without cornstarch but with photooxidation enhancers. Results showed that all products weakened and/or disintegrated to some extent. However, the bags with 6% starch disintegrated too slowly to allow timely processing of the compost. The bags with 9% starch and other additives to promote multiple degradation mechanisms degraded at the fastest rate of those evaluated here. The photodegradable bags with solar exposure during composting disintegrated rapidly, but when turned to expose new surfaces to light, further strength losses occurred slowly.Paper presented at the Biodegradable Materials and Packaging Conference, September 22–23, 1993, Natick, Massachusetts.     

锌冶炼烟气制酸废水中汞的测定

采用冷原子吸收光度法测定经石灰乳和铁盐处理后的锌冶炼烟气制酸废水中汞的浓度时,可按废水中汞浓度与其pH的关系,从试样pH的高低大致估计其汞浓度范围,由此确定其稀释倍数和取样量。试样用KBrO3-KBr消解法消解,用直接法稀释,这样可以减少操作步骤、缩短测定周期、减少样品中汞的损失、提高监测结果的可靠性和准确性,同时可减少人力、物力浪费,降低监测成本。     

Reduced combustion mechanism for C1–C4 hydrocarbons and its application in computational fluid dynamics flare modeling

Emissions from flares constitute unburned hydrocarbons, carbon monoxide (CO), soot, and other partially burned and altered hydrocarbons along with carbon dioxide (CO₂) and water. Soot or visible smoke is of particular concern for flare operators/regulatory agencies. The goal of the study is to develop a computational fluid dynamics (CFD) model capable of predicting flare combustion efficiency (CE) and soot emission. Since detailed combustion mechanisms are too complicated for (CFD) application, a 50-species reduced mechanism, LU 3.0.1, was developed. LU 3.0.1 is capable of handling C₄ hydrocarbons and soot precursor species (C₂H₂, C₂H₄, C₆H₆). The new reduced mechanism LU 3.0.1 was first validated against experimental performance indicators: laminar flame speed, adiabatic flame temperature, and ignition delay. Further, CFD simulations using LU 3.0.1 were run to predict soot emission and CE of air-assisted flare tests conducted in 2010 in Tulsa, Oklahoma, using ANSYS Fluent software. Results of non-premixed probability density function (PDF) model and eddy dissipation concept (EDC) model are discussed. It is also noteworthy that when used in conjunction with the EDC turbulence-chemistry model, LU 3.0.1 can reasonably predict volatile organic compound (VOC) emissions as well.

Implications: A reduced combustion mechanism containing 50 C₁–C₄ species and soot precursors has been developed and validated against experimental data. The combustion mechanism is then employed in the computational fluid dynamics (CFD) of modeling of soot emission and combustion efficiency (CE) of controlled flares for which experimental soot and CE data are available. The validated CFD modeling tools are useful for oil, gas, and chemical industries to comply with U.S. Environmental Protection Agency’s (EPA) mandate to achieve smokeless flaring with a high CE.     

用Co3O4催化剂光催化氧化活性染料

以沉淀一热解法制备了纳米级Co3O4催化剂,并用X射线衍射仪、红外光谱仪对Co3O4催化剂进行了表征。以300W高压汞灯为光源,研究了Co3O4催化剂对不同活性染料的光催化氧化活性。实验结果表明：在活性染料质量浓度为20mg／L、250mL染料溶液中Co3O4催化剂加入量为150mg、反应2h的条件下,Co3O4催化剂对B—GFF黑、B—RN蓝、K—NR艳蓝3种活性染料溶液的脱色率分别为95％,87％,77％;适当加入酸或碱有利于提高处理效率,反应后染料溶液的pH为7．12～8．37,染料溶液初始pH为10．00时的脱色率最高为100％;Co3O4催化剂具有一定的再利用价值。     

嘉兴市内河河网污染治理方案的比较分析

从宏观的角度出发,采用经简化后的箱子模型和混合单元系列模型,估算了嘉兴市内河河网区域水系的环境容量;分析了分散处理和集中处理两个治理方案在不同的截污率、降雨径流、外围来水等因素下对内河河网的治理效果和水质改善情况以及水质治理目标的可达性。1河网水质模型1．1箱子模型把河网当作一个大的混合均匀的水箱,根据守恒原理得到以下关系式：＿＿＿＿＿＿d（VC）o。。ci。－o。。to＋co。一kVC一一一一一（）、。。v;。、O。t～l“～P—”～dt对流输入输出降雨降解储存量变化率式中：C一系统混合均匀后的物质浓度;C;。一人…     

Air pollution perception in ten countries during the COVID-19 pandemic

As largely documented in the literature, the stark restrictions enforced worldwide in 2020 to curb the COVID-19 pandemic also curtailed the production of air pollutants to some extent. This study investigates the perception of the air pollution as assessed by individuals located in ten countries: Australia, Brazil, China, Ghana, India, Iran, Italy, Norway, South Africa and the USA. The perceptions towards air quality were evaluated by employing an online survey administered in May 2020. Participants (N = 9394) in the ten countries expressed their opinions according to a Likert-scale response. A reduction in pollutant concentration was clearly perceived, albeit to a different extent, by all populations. The survey participants located in India and Italy perceived the largest drop in the air pollution concentration; conversely, the smallest variation was perceived among Chinese and Norwegian respondents. Among all the demographic indicators considered, only gender proved to be statistically significant.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01574-2.