Salinity exchange between seawater/brackish water and domestic wastewater through electrodialysis for potable water

● Present a general concept called “salinity exchange”. ● Salts transferred from seawater to treated wastewater until completely switch. ● Process demonstrated using a laboratory-scale electrodialysis system. ● High-quality desalinated water obtained at ~1 mL/min consuming < 1 kWh/m ³ energy. Two-thirds of the world’s population has limited access to potable water. As we continue to use up our freshwater resources, new and improved techniques for potable water production are warranted. Here, we present a general concept called “salinity exchange” that transfers salts from seawater or brackish water to treated wastewater until their salinity values approximately switch, thus producing wastewater with an increased salinity for discharge and desalinated seawater as the potable water source. We have demonstrated this process using electrodialysis. Salinity exchange has been successfully achieved between influents of different salinities under various operating conditions. Laboratory-scale salinity exchange electrodialysis (SEE) systems can produce high-quality desalinated water at ~1 mL/min with an energy consumption less than 1 kWh/m³. SEE has also been operated using real water, and the challenges of its implementation at a larger scale are evaluated.     

Enhancement of extracellular Cr(VI) reduction for anammox recovery using hydrazine: performance,pathways, and mechanism

● N₂H₄ addition enhanced and recovered anammox performance under Cr(VI) stress. ● N₂H₄ accelerated electron transfer of Cr(VI) reduction for detoxification. ● N₂H₄ enhanced anammox metabolism for activity recovery from Cr(VI) inhibition. ● Extracellular Cr(VI) reduction to less toxic Cr(III) was the dominant mechanism. The hexavalent chromium (Cr(VI)) would frequently impose inhibition to anaerobic ammonium oxidation (anammox) process, hindering the efficiency of nitrogen removal in wastewater treatment. Hydrazine (N₂H₄), which is an intermediate product of anammox, participates in intracellular metabolism and extracellular Cr(VI) reduction. However, the roles of N₂H₄-induced intracellular metabolism and extracellular reduction in nitrogen removal under Cr(VI) stress remain unclear. The addition of 3.67 mg/L of N₂H₄ increased the anammox activity by 17%. As an intermediate, N₂H₄ enhanced anammox metabolism by increasing the heme c content and electron transfer system activity. As a reductant, N₂H₄ accelerated the reduction of c-Cyts-mediated extracellular Cr(VI) to the less toxic Cr(III). Extracellular Cr(III) accounts for 74% of the total Cr in a Cr(VI)-stressed anammox consortia. These findings highlight that N₂H₄-induced extracellular Cr(VI) reduction is the dominant mechanism for the survival of anammox consortia. We also found that N₂H₄ increased the production of extracellular polymeric substances to sequester excessive Cr(VI) and produced Cr(III). Taken together, the study findings suggest a potential strategy for enhancing nitrogen removal from ammonium-rich wastewater contaminated with Cr(VI).     

一种海水透明度测量新方法的研究与实现

随着海洋光学探测技术的不断发展,传统的海水透明度测量方法已无法满足当前对海洋环境参数全方位、多角度、动态实时测量的要求.文章依据海水透明度的光度学定义,提出了一种测量海水透明度的新方法,并基于常用的光学器件及测量仪器,设计了一套海水透明度的实时测量装置,介绍了测量装置的安装调节方法.理论分析和实验均表明,该测量装置可以有效实时测量海水透明度.     

CDM项目温室气体减排成本的不确定性分析

以清洁发展机制(CDM)为背景,针对计算温室气体排放量和减排成本中存在的不确定性进行了MonteCarlo模拟研究,分析了不确定性变量是如何影响决策变量的.结论是:各类碳排放因子、碳排放量、碳减排成本、减排收益是相互关联而存在连锁影响的,其中的发电碳排放因子和煤炭开采释放的甲烷排放系数是主要的.这为进一步计算或估计存在的风险,从而为参与CDM谈判决策提供重要的决策参考.     

贵州七星洞石笋文石-方解石序列记录的气候变化

文石-方解石型石笋的矿物相变化可能与气候环境变化存在联系,但中国季风区有关此类石笋的古气候研究比较匮乏.本文对七星洞一个文石-方解石型石笋开展了岩石学鉴定和氧、碳同位素组成分析,发现其文石层的出现与δ18O值、δ13C值的显著偏正存在联系,通过对文石形成的可能机制和δ18O、δ13C值变化的一般规律进行综合分析,验证了...     

Levels,congener profile and inventory of polychlorinated biphenyls in sediment from the Songhua River in the vicinity of cement plant,China: a case study

This study investigated the contamination levels, homologue, and congener profiles and evaluated the residue inventory of polychlorinated biphenyls (PCBs) in sediment of the Songhua River in the vicinity of cement plant. The total concentration of detected 35 PCB congeners ranged from 1.12 to 2.19 ng/g dry weight (dw) in sediment, with a mean value of 1.56 ng/g dw, and the concentration of PCBs decreased in the following order: the downstream?>?cement plant?>?upstream. The results of total organic carbon (TOC)-normalized PCB concentrations indicate that the sediments have low potential ecological risk in this area. The study results on homologue and congener of PCBs show that the emissions from cement production could be the major sources of PCBs in sediment, and the low-chlorinated PCBs will be exchanged among air, water, and sediment with increasing temperature during summer and flow to downstream with water during the wet season. The spatial density and total burden of PCBs in the surface sediments were 17.2 ng/cm² and 1.2 kg, respectively. To our knowledge, this study is the first to explore the pollution characteristics of unintentionally produced PCB emissions from cement industry by means of monitoring sediment samples.     

2000~2013年鄱阳湖流域蒸散量时空变化

蒸散是陆地表面水分循环的重要过程,是研究流域水资源、水循环等领域的重要参数。以鄱阳湖流域为研究对象,利用鄱阳湖流域5个主要子流域水文控制站监测流量资料和气象站监测降水资料,根据水量平衡原理计算各子流域年度蒸散,验证MODIS蒸散数据产品（ET_MOD）,并分析2000~2013年鄱阳湖流域蒸散时空变化状况和土地利用变化对蒸散量的影响。研究结果表明：（1）ET_MOD具有较高的精度,年蒸散量的平均误差为165.9 mm,平均相对误差为9.78%;（2）2000~2013年鄱阳湖流域的年蒸散变化范围875.4~912.2 mm;鄱阳湖流域总蒸散量呈先增加后减少的“几”字形季节变化特征;（3）从蒸散量与地形特征的关系看,鄱阳湖平原区蒸散量低,周边的山地丘陵区较高;各子流域的蒸散量表现为：赣江流域 > 抚河流域 > 信江流域 > 修水流域 > 饶河流域;（4）土地利用方式对蒸散量有显著的影响,各土地利用类型的平均蒸散量表现为：林地 > 农田 > 草地 > 未利用地。     

改良剂对湿地土壤团聚体及抗悬浮能力的影响试验

以巢湖十五里河河口湿地土壤为研究对象,选用PAM(J)、PAM+生物炭(SJ)和PAM+泥炭(NJ)为土壤结构改良剂,研究改良剂对淹水条件下培养后土壤水稳性团聚体数量、土壤抗悬浮能力和土壤磷释放的影响。结果表明,四种处理(CK、NJ、J和SJ)0.25 mm水稳性团聚体含量大小顺序为:J(58.73±0.57%)SJ(48.27±3.58%)NJ(34.47±2.02%)CK(2.31±0.15%)。在室内风浪扰动模拟实验中,扰动后上覆水体悬浮物浓度(SS)和水体磷浓度的大小顺序均是:CKNJJSJ,且CK显著大于NJ、J和SJ。添加PAM(J)、PAM+生物炭(SJ)和PAM+泥炭(NJ)不仅能显著提高0.25 mm研究区湿地土壤水稳性团聚体的含量,也能显著增强风浪扰动下淹水土壤的抗悬浮能力,进而显著降低淹水后土壤磷释放能力,其中以添加PAM+生物炭组合提升淹水后湿地土壤抗悬浮和降低磷释放能力的效果最佳。     

TEV、UT、UHF技术在开关柜局部放电检测中的应用

针对10kV开关柜局部放电问题,为排除干扰,准确判断开关柜局部放电类型和放电点位置,提出采用暂态地电位(transient earth voltage, TEV)、超声波(ultrasonic test, UT)、特高频(ultra high frequency, UHF)技术进行联合检测的方法,并在现场实测工作中进行了应用和验证。结果表明:该联合方法对开关柜设备缺陷的检测与定位非常有效,提高了开关柜局部放电检测的准确性和有效性。