Chemical oxygen demand reduction in coffee wastewater through chemical flocculation and advanced oxidation processes

The removal of the natural organic matter present in coffee processing wastewater through chemical coagulation-flocculation and advanced oxidation processes （AOP） had been studied. The effectiveness of the removal of natural organic matter using commercial flocculants and UV/H202, UV/O3 and UV/H2O2/O3 processes was determined under acidic conditions. For each of these processes, different operational conditions were explored to optimize the treatment efficiency of the coffee wastewater. Coffee wastewater is characterized by a high chemical oxygen demand （COD） and low total suspended solids. The outcomes of coffee wastewater treatment using coagulation-flocculation and photodegradation processes were assessed in terms of reduction of COD, color, and turbidity. It was found that a reduction in COD of 67% could be realized when the coffee wastewater was treated by chemical coagulation-flocculation with lime and coagulant T-1. When coffee wastewater was treated by coagulation-flocculation in combination with UV/H2O2, a COD reduction of 86% was achieved, although only after prolonged UV irradiation. Of the three advanced oxidation processes considered, UV/H2O2, UV/O3 and UV/H2O2/O3, we found that the treatment with UV/H2O2/O3 was the most effective, with an efficiency of color, turbidity and further COD removal of 87%, when applied to the flocculated coffee wastewater.     

Quantification of emission variability for off-road equipment in China based on real-world measurements

• Emissions from 53 in-use diesel-fueled off-road equipment were measured. • There exists a large off-road equipment variability in emissions. • Engine operations have significant impacts on real-world tailpipe emissions. • Emission inventory development should take into account job duties and operations. The objective of this paper is to quantify the variability in emissions of off-road equipment using a portable emission measurement system. A total of 53 commonly used equipment for agriculture, base construction, paving construction, and material handling were selected. Time-based and fuel-based emissions were quantified by different duty and engine modes. Three duty modes (idling, moving, and working) were used. Ten engine modes were defined based on normalized engine revolutions-per-minute and manifold absolute pressure, respectively. Composite emission factors taking into account both duty modes and its corresponding time percentage during a typical duty cycle were estimated. Results showed that there existed a large off-road equipment variability in emissions. Depending on duty and engine modes, time-based NO emissions ranged from 3.1 to 237.9, 29.1‒1475.6, 83.2‒681.6, and 3.2‒385.2 g/h for agriculture, base construction, paving construction and material handling equipment, respectively while for fuel-based NO emissions these ranges were 5.3‒52.0, 11.7‒69.0, 4.8‒30.8, and 11.0‒54.6 g/kg, respectively. Furthermore, emission factors derived from this study exhibited a much larger variability compared to those used in NONROAD by US EPA and National Guideline for Off-road Equipment of China. This implied that localized measurements of emissions are needed for improvement of accuracy of emission inventory. Furthermore, both equipment types and operations should be considered for development of emission inventory and control strategy.     

含碳气溶胶研究进展：有机碳和元素碳

含碳气溶胶是我国大气区域性复合型污染的重要物种,对全球气候变化、辐射强迫、能见度、环境质量、人类健康等会产生重要影响.主要从含碳气溶胶来源及成因、环境影响、样品采集及测试等方面对国内外相关研究进行了评述,讨论了有机碳和元素碳研究中存在的关键和难点问题,并对其发展前景进行了展望.     

微波链路降水测量技术及应用研究进展综述

在介绍微波链路测雨方法的原理、优势的基础上,重点分析了国内外单频微波链路、双频微波链路和微波链路网反演降水的技术现状,讨论了微波链路在天气雷达衰减订正、降雨场联合重构和暴雨监测预警的应用,最后从测量精度、链路频率、测量要素、测量空间四个方面总结了微波链路大气探测技术的发展方向。     

大气甲烷碳同位素测试方法及其在雅克拉凝析气田上方大气中的应用

研制了一套与气体稳定同位素质谱仪联机在线分析大气甲烷碳同位素的制样技术,该方法具有精度较高(±0.4×10^-3)、用样量少(200mL)、耗时短(45min)和操作相对较为简便的优点.利用该系统对新疆塔里木盆地雅克拉凝析气田上方大气甲烷的碳同位素组成做了初步测试.结果表明,其大气甲烷碳同位素组成平均值为-45.0×10^-3,相对全球大气甲烷碳同位素平均值明显偏重1.2×10^-3～2.0×10^-3,显示了其甲烷主要来源为深部凝析气藏中的甲烷等气体的渗漏和扩散.并且由于白天日照强,温度高,气田渗漏和扩散到地表的甲烷部分被氧化,因此白天大气甲烷的浓度略低于夜晚,且¹³C_CH4较夜晚偏轻.     

机动车排放车载实验及模型模拟研究

研究机动车的排放特征及获得排放因子,是建立机动车排放清单和制定相应控制策略的基础,而路上的机动车排放车载测试被认为是实验室台架测试的一个重要补充.本研究利用AVL DiGas 4000 light五气分析仪,在澳门典型路段上对7辆汽油轿车样本开展了尾气排放车载实验.研究发现安装电喷加三元催化转化系统的车辆(以下称电喷车)在气态污染物排放上比旧的化油器车有显著降低,化油器车HC、CO和NO排放的体积浓度平均值分别为227×10^-6、1.57%和1477×10^-6,而电喷车则分别为33×10^-6、0.21%和131×10^-6,约是前者的1/11～1/7.但电喷车在冷启动阶段会出现高排放;对电喷车的CO和NO排放浓度做算术平均,其绝对值主要由出现频率少的高浓度值所贡献.研究进一步估算了汽油轿车的排放因子,同时利用MOBILE5模型计算了澳门2000年汽油轿车的平均排放因子,模型计算值和实验数据估算结果的比值在59%～139%之间,如果仅比较年平均排放因子,这个比值则在68%～132%之间.结果表明,车辆采用电喷加催化转化系统,对控制污染物排放的作用显著,但催化设备存在冷启动时起燃缓慢的问题;对电喷车的技术改进,减少其在行驶过程中出现高浓度的污染物排放,将能进一步大大降低平均排放水平;应用修正的MOBILE5模型计算澳门地区汽油轿车的排放因子,结果是比较可信的.     

海洋水色遥感大气校正算法研究进展

本文针对Ⅱ类水体的光谱特性和海洋现象的特点,综述了Ⅰ类水体及近岸Ⅱ类水体的主要大气校正算法,并介绍了各种算法的适应范围和优缺点.通过对水色卫星传感器的技术发展现状的介绍,详细整理了目前主要卫星的大气校正算法,概述了Ⅱ类水体水色反演算法的研究现状和发展方向.并根据我国近海的水体特点提出了水色遥感研究需要解决的关键问题.     

中国华北地区冬季大气污染物航空测量(I)—空中气态污染物污染特征研究

为掌握致酸大气污染物SO₂和NO_x的空间浓度分布,并探讨上述污染物扩散、迁移和传输规律,进而研究其在酸性降水形成过程中的作用,在“八五”期间酸性降水的研究中,针对中国华北地区城市和工业集中以及S0₂和NO_x等酸性大气污染物排放量大的特点,以石家庄及其以东地区为飞行区域,进行了华北地区冬季空中S0₂和NO_x污染特征的航空测量。通过测定发现在华北地区1.5km左右的空中存在着S0₂和NO_x高浓度污染空域,同时S0₂存在着高浓度汇集区。      

改进的大气CO2、CH4、N2O、CO在线观测FTIR系统

利用商用傅利叶变换红外光谱仪(FTIR)主机,与自动进样模块及标气模块集成,初步建立了一套可流程化、准确、高效分析大气CO2、CH4、CO和N2O的在线观测系统.测试结果表明,该商用FTIR主机具有良好的精度,但以仪器自带校正系数估算的结果绝对误差大,尤其CO的绝对误差可达38.8×10-9,无法满足在线观测要求.集成后的FTIR系统改用可溯源至国际标准的工作标气进行计算,有效降低了结果的绝对误差.动态及静态两种模式下各要素实测值与标称值的摩尔分数绝对误差为CO2≤0.11×10-6、CH4≤1.8×10-9、N2O≤0.15×10-9、CO≤0.5×10-9,能够满足大气在线观测需求.利用该FTIR集成系统进行6 d的模拟在线观测,采用动态流量模式(Flow)进样,每隔6 h穿插高、低浓度工作标气及目标气进样,用标气的标称值及系统更新的标气响应值计算样气及目标气结果.目标气CO2/CH4/N2O/CO的摩尔分数标准偏差分别为0.05×10-6、0.2×10-9、0.07×10-9、0.5×10-9,平均值与标称值之间的绝对误差分别为0.09×10-6、0.4×10-9、0.14×10-9、0.5×10-9.     

大气细粒子的快速捕集及化学成分在线分析方法研究

本文介绍了一种新型的大气细粒子快速捕集及其化学成分在线分析方法。该方法中大气细粒子与过饱和水蒸气绝热混和而增长成大粒子 ,并在气流的带动下惯性撞击到一垂直玻璃板上 ,一含有内标物的去离子水流自上而下将撞击到玻璃板上的粒子收集 ,收集液被直接输送到离子色谱、总有机碳分析仪 ,在线分析其中的化学成分。该方法每 12min可完成单个样品分析 ,每小时可连续采集分析 5个样品。离子色谱最低检测限约为 0 .0 5 μg/m3(NH+4 )到 0 .2 0 μg/m3(SO2 -4 ) ,不确定度约为 3 % ,TOC最低检测限为 5× 10 -5μg/m3,不确定度约为 3 %。真实的大气细粒子观测结果表明 ,该方法快速、简捷、灵敏度高 ,是实时监测大气中细粒子化学成分的有效工具