Ca2+添加对微生物矿化固结Cd2+的影响

微生物诱导碳酸盐沉淀(MICP)可将游离的重金属离子转化为稳定的矿化物,在修复土壤重金属污染方面具有广阔的应用前景.本研究从铜陵矿区周边土壤中筛选得到1株产脲酶且耐镉矿化菌株CZW-1,16S rDNA鉴定为芽孢杆菌(Bacillus sp.),并将其利用于添加外源Ca²⁺的矿化固结Cd²⁺实验中.通过扫描电镜(SEM)、傅立叶红外光谱(FT-IR)以及X射线衍射(XRD)对矿化产物进行表征和分析.结果表明,添加一定浓度的Ca²⁺可促进细菌的生长,其最佳浓度为20 mmol·L^-1.且Ca²⁺的添加可提高细菌的最小抑制浓度和促进脲酶活性,提高对Cd²⁺的矿化率,加钙前后的矿化率由68.93%提高到75.95%.通过对矿化物的定性分析,可知加钙前后的矿物沉淀由单一CdCO₃变为CdCO₃和CaCO₃的复合沉淀,其表面也由严密紧实变成填满了小颗粒CdCO₃的多孔状.     

高原城市污水处理厂中5种典型有机紫外防晒剂含量及其去除

有机紫外防晒剂具有内分泌干扰效应、遗传毒性和生殖毒性等多种负面生物效应,其进入环境中的一个主要途径为工业废水排放及污水处理厂出水的排放。昆明地处高原,紫外线较强,有机紫外防晒剂的使用量逐年增多,因此选择了5种典型有机紫外防晒剂:胡莫柳酯(HMS)、甲氧基肉桂酸乙基已酯(EHMC)、二苯酮-3(BP-3)、4-甲基苄亚基樟脑(4-MBC)和奥克立林(OC)作为目标物质,利用气相色谱-质谱联用技术,检测了昆明市5座城市污水处理厂进水、二级生化处理及深度处理进出水中有机紫外防晒剂的含量,分析了不同二级生化处理及深度处理工艺对目标物质去除效率的影响。结果表明,目标物质的去除主要依靠二级生化处理工艺,3种工艺都有比较好的去除效果,其中缺氧-厌氧-缺氧膜生物反应器工艺相对来说更好。此外,深度处理也能有效去除目标物质,紫外消毒去除效果更好。5种目标物质的总去除率达58.76%~94.0%,可见还有一部分的有机紫外防晒剂迁移到了环境中,具有一定的环境与健康风险。     

丝瓜络填料反硝化滤池对生活污水的净化

考察了以丝瓜络为填料的反硝化生物滤池对生活污水中TN和TP等污染负荷去除的效果。结果表明,通过间歇运行的方式,在不加碳源的条件下,水力停留时间为24 h,各污染物的去除效果较好,对NO3--N、NO2--N、NH3-N、TN、TP和COD平均去除率分别为95%、92%、30%、75%、25%和50%,出水总氮含量低于城镇污水处理厂一级A标准(GB 18918-2002)。通过扫描电镜对丝瓜络微观表面形貌进行观察,发现丝瓜络具有微米级的网状结构,反应后表面镶嵌有大量球形的微生物群落,且内部网壁变薄。     

滤袋长度对袋式除尘器内流场影响的数值模拟研究

为提高袋式除尘器处理大烟气量中超细颗粒物的能力,确保袋室内气流尽可能均匀,以某环保公司的中试装置为模型,采用CFD(computational fluid dynamics)模拟6、8和10 m 3种袋长除尘器内的三维流动。运用标准k-ε双方程模型和SIMPLE算法,依据流量分配系数、速度云图和过滤阻力等分析流场内的速度和压力分布。结果表明,袋长为10 m的袋式除尘器流量分配系数更趋近于1.0;相同过滤速度下,速度相对标准偏差的数值6 m>8 m>10 m,滤袋长度为10 m时速度分布比较均匀;虽然10 m的除尘器产生的过滤阻力最大,但在低过滤速度条件下,优势明显。因此长袋除尘器适合在较低的过滤速度下运行。袋式除尘器的数值模拟为提高其处理能力和优化设计提供依据。     

含固率和电极间距对牛粪发酵产电性能的影响

随着能源短缺和环境污染等问题的日益严重,农业废弃物资源化利用引起了广泛关注。为了从牛粪等农业生产废弃物中获取新能源,减少农业固体废物对环境的污染,研究了含固率和电极间距对牛粪发酵产电性能的影响,分析了产电过程中电压、电流、功率密度、挥发性脂肪酸VFA和COD等指标的变化规律。结果表明,含固率对牛粪发酵产电性能影响较大,电极间距影响较小。在碳氮比(C/N比)为18,含固率为1%,电极间距为2.5 cm时,产生的电压最高可达0.79 V,电流最高可达0.58 mA,功率密度幅值高达398 mW/m2,发酵产电结束后VFA增加了250%,COD去除率超过了80%。     

Perfluoroalkyl substances in the Lingang hybrid constructed wetland,Tianjin, China: occurrence,distribution characteristics,and ecological risks

Environmental Science and Pollution Research - In this study, the occurrence, spatial distribution, sources, and ecological risks of perfluoroalkyl substances (PFASs) in the surface waters of the...     

昆明市清水海水源保护区生态补偿机制探讨

就昆明市清水海水源区生态补偿机制进行探讨,以期为生态补偿机制的建立提供借鉴。生态补偿理论结合清水海水源区实际分析。补偿主体是国家、受水区的企业和居民,客体是水资源和生态环境的保护者,以及牺牲发展机会的企业和居民;补偿标准以费用分析法计算,包括水资源保护、水源林建设和管理等方面的投入;补偿方式近期以输血型和造血型补偿结合,远期逐步向生态造血型补偿转变;优先补偿效率高的污染防治措施、退耕还林和测土配方,其次为产业结构调整和水资源管理;补偿时限结合补偿取得的成效、水源区生态产业发展和生态质量状况来确定;补偿资金以政府财政为主、市场为辅。结果表明:应结合清水海的实际,确定生态补偿的主客体、方式、标准和时限,建立生态补偿的保障机制,加强对补偿资金的监管。进一步开展定量化研究,完善清水海水源区生态补偿基础研究,促进生态补偿机制的建立。     

The positive role of trade openness in industrial green total factor productivity—provincial evidence from China

Environmental Science and Pollution Research - The sustainable development of the economy is a key issue of global concern. Green total factor productivity (GTFP) combining economic growth with...     

Insight into soil nitrogen and phosphorus availability and agricultural sustainability by plant growth-promoting rhizobacteria

Environmental Science and Pollution Research - Nitrogen and phosphorus are critical for the vegetation ecosystem and two of the most insufficient nutrients in the soil. In agriculture practice,...     

Reduction in greenhouse gas emissions from sludge biodrying instead of heat drying combined with mono-incineration in China

Sludge is an important source of greenhouse gas (GHG) emissions, both in the form of direct process emissions and as a result of indirect carbon-derived energy consumption during processing. In this study, the carbon budgets of two sludge disposal processes at two well-known sludge disposal sites in China (for biodrying and heat-drying pretreatments, both followed by mono-incineration) were quantified and compared. Total GHG emissions from heat drying combined with mono-incineration was 0.1731 tCO₂e t^?1, while 0.0882 tCO₂e t^?1 was emitted from biodrying combined with mono-incineration. Based on these findings, a significant reduction (approximately 50%) in total GHG emissions was obtained by biodrying instead of heat drying prior to sludge incineration.

Implications: Sludge treatment results in direct and indirect greenhouse gas (GHG) emissions. Moisture reduction followed by incineration is commonly used to dispose of sludge in China; however, few studies have compared the effects of different drying pretreatment options on GHG emissions during such processes. Therefore, in this study, the carbon budgets of sludge incineration were analyzed and compared following different pretreatment drying technologies (biodrying and heat drying). The results indicate that biodrying combined with incineration generated approximately half of the GHG emissions compared to heat drying followed by incineration. Accordingly, biodrying may represent a more environment-friendly sludge pretreatment prior to incineration.