Autotrophic denitrification for nitrate and nitrite removal using sulfur-limestone

In the study, both nitrate and nitrite could be removed effectively using sulfur-limestone, and the bacteria involved in sulfur-based denitrification for nitrate and nitrite removal were of the same species.     

Characterization of disinfection byproduct formation potential in 13 source waters in China

The formation potential of four trihalomethanes (THMFP) and seven haloacetic acids (HAA7FP) in 13 source waters taken from four major water basin areas in China was evaluated using the simulated distribution system (SDS) chlorination method. The specific ultraviolet absorbance (SUVA254: the ratio of UV254 to dissolved organic carbon (DOC)), which ranged between 0.9 and 5.0 L/(mg m), showed that the organic compounds in di erent source waters exhibited di erent reactivities with chlorine. The HAA7FP of source waters ranged from 20 to 448 g/L and the THMFP ranged from 29 to 259 g/L. The HAA7FP concentrations were higher than the THMFP concentrations in all but one of the samples. Therefore, the risks of haloacetic acids (HAAs) should be of concern in some source waters. TCM (chloroform) and BDCM (bromodichloromethane) were the major THM constituents, while TCAA (trichloroacetic acid) and DCAA (dichloroacetic acid) were the major HAA species. Br-THM (brominated THM species) were much higher than Br- HAA (brominated HAA species), and the formation of Br-DBP (Br-THM and Br-HAA) should be of concern when the bromide concentration is over 100 g/L.     

串联微生物燃料电池的电压反转行为

微生物燃料电池是一种处理废水同时产电的具有广阔应用前景的新型水处理技术,其串联是产生更高电压的有效方法之一,但是会产生电压反转现象降低串联微生物燃料电池的性能.文章将二极管引入串联微生物燃料电池中以考察电压反转的行为.结果表明,不同的串联微生物燃料电池中均会发生电压反转.串联正向二极管的微生物燃料电池的电压反转行为与没...     

微电解法处理焦化废水影响因素研究

采用微电解法对焦化废水进行脱氮处理,并对其影响因素进行了优化研究。实验结果表明,控制进水pH值为3．0左右,炭粉的粒径为80目,搅拌速率为170r／min,反应时间为70min,Fe／C为1：1．3和混凝pH值为9．0左右,处理效果最佳;本实验对亚硝化后的焦化污水进行微电解处理,NO2^--N的去除率可达60％以上,TN的去除率可达50％以上。结果表明,此微电解工艺对各种高含氮、高浓度难降解有机物废水处理技术可行。     

珠江口狮子洋海域表层沉积物重金属污染及其生态风险评价

采用污染指数法和生态风险指数法对珠江口狮子洋海域表层沉积物中Hg、Cu、Cd、Pb、As等污染要素进行分析和评价。结果表明:该海域的总体污染程度为低污染水平,污染程度由大到小依次为As>Cu>Pb>Hg>Cd;该海域的总体生态风险性为低,生态风险性由高到低依次为Hg>As>Cd>Cu>Pb,Hg为该海域的主要潜在生态风险因子。     

含氮废水生物处理技术研究现状及发展趋势

近年来,污水脱氮处理技术不断发展,涌现了很多新方法和手段。生物脱氮技术能耗低、易于操作、无二次污染且成本低,是一项极具发展前景的技术。本文介绍了近几年国内外该方向的研究成果,内容包括水中氮污染特征、传统生物脱氮技术与新兴生物脱氮技术,文章阐述了目前生物脱氮技术存在问题,展望了生物脱氮技术的发展趋势。     

臭氧浓度升高对冬小麦田土壤呼吸、硝化和反硝化作用的影响

为研究臭氧浓度升高对农田土壤呼吸、硝化和反硝化作用的影响,采用开顶箱(OTC)法设置3个臭氧浓度处理,分别为对照CK、T1(100 nL.L-1臭氧)和T2(150 nL.L-1臭氧).以便携式土壤CO2通量观测仪测定不同臭氧浓度处理下的冬小麦田土壤呼吸速率,并采用气压过程分离(BaPS)法测定不同处理的土壤CO2产生速率、硝化速率和反硝化速率.结果表明,在本实验阶段内,CK、T1、T2处理的土壤呼吸速率之间无显著差异(p0.05),其平均土壤呼吸速率分别为(5.36±0.72)、(5.08±0.04)、(4.94±0.18)μmol.(m2.s)-1.CK和T2处理的硝化速率和反硝化速率也均无显著差异(p0.05).不同臭氧浓度处理下的土壤呼吸速率与土壤温度的指数回归关系均达显著水平(p0.05),CK、T1和T2处理的土壤呼吸的Q10值分别为1.72、1.58和1.51.Pearson相关分析结果表明,CK处理中土壤硝化速率与反硝化速率和土壤含水量之间均存在显著相关关系(p0.05),其相关系数分别为0.828和0.890;T2处理中硝化速率与土壤含水量之间存在显著相关关系(p0.05),其相关系数为0.772.本研究表明,臭氧浓度升高未显著改变冬小麦田土壤呼吸、硝化和反硝化速率,但臭氧浓度升高显著降低了土壤呼吸的温度敏感性.     

Investigation of how pressure influences the thermal decomposition behavior of azodicarbonamide

Azodicarbonamide (ADC) is a type of azo compound with outstanding application performance, it is always used as a blowing agent in the production of foamed plastics. Based on previous studies, it has been considered harmless in its practical application process. Nevertheless, our research has overturned this standpoint and denoted the special exothermic behavior of ADC under specific use processes, especially when it was placed in a high-pressure system. In this study, a simultaneous thermogravimetric analyzer (STA) was employed to preliminarily evaluate the thermal stability of ADC under atmospheric pressure. Followed with calorimetric experiments by high-pressure differential scanning calorimetry (HP DSC), the exothermic behaviors of ADC under different initial furnace pressures were investigated. The obtained results revealed that the thermal decomposition rate of ADC linearly increases along with increasing testing pressure, which shows a highly autocatalytic characteristic. The peak power of DSC curve breathtakingly reached 73 W/g when the initial testing pressure was set at 4 MPa, and the overall decomposition heat reached 1261 J/g with the scanning rate at 4 ^°C/min. Furthermore, the decomposition mechanism, thermal hazards, and explosion potential were comprehensively evaluated in this study for the first time.     

洛阳市不同功能区道路灰尘重金属污染及潜在生态风险

以洛阳市为例,调查了工业区、商业区、居民区、城乡结合处、城市绿地和城市主干道等6个功能区道路灰尘中重金属(Cu、Zn、Pb、Cr、Cd)含量,并采用Hkanson潜在生态危害指数评价重金属污染水平及其潜在风险.结果表明,洛阳市各功能区道路灰尘重金属含量均显著高出河南省土壤重金属环境背景值,平均含量依次为Zn(1 019.75 mg.kg-1)>Cr(401.63mg.kg-1)>Cu(240.94 mg.kg-1)>Pb(176.04 mg.kg-1)>Cd(2.33 mg.kg-1).在所有功能区,Cd均是污染最重的重金属,平均污染系数Cif高达35.84,之后依次是Zn(16.32)>Cu(12.05)>Pb(7.90)>Cr(6.36).各功能区道路灰尘中的重金属含量和污染水平存在较大差异,工业区的重金属总量最高、污染最重.不同功能区灰尘重金属综合潜在生态危害指数RI依次为工业区(1 709.51)>城市绿地(1 581.50)>商业区(1 297.45)>居民区(1 111.25)>城市主干道(889.97)>城乡结合部(641.39),且均已达到很强生态危害水平.产生潜在生态危害的重金属主要是Cd,在所有功能区均超出极强生态危害水平,其潜在生态危害指数Eir平均值达1 075.16,其次是Cu(60.23)和Pb(40.77),平均达中等生态危害水平,而Zn(16.32)和Cr(12.71)则为轻微生态危害水平.减少工业污染和交通污染可能是有效降低道路灰尘中重金属污染和风险的主要措施.     

水力负荷及固相碳源对BAF+多级土壤渗滤组合工艺处理污水的影响研究

碳源的选择及曝气量的控制是影响多级土壤渗滤系统(multi-soil-laying,即MSL)脱氮效果的重要因素.试验采用BAF+MSL两段式新型组合工艺,避免了传统MSL曝气过量抑制反硝化脱氮的风险.考察了不同水力负荷下,BAF+MSL对生活污水的净化效果,并比较研究了以聚丁二酸丁二醇酯(PBS)为反硝化碳源的MSL-1及木屑为碳源的MSL-2的脱氮除磷效果.结果表明,不同水力负荷下,系统对SS平均去除率为94.08%,对COD的去除率均在80%以上,出水COD在20mg·L-1以下.水力负荷对系统BAF段硝化性能影响较小,对MSL反硝化脱氮影响较大.BAF水力负荷为0.5、1及2m·3m-·2d-1时,BAF对NH4+-N的去除率均在90%以上,对TN的平均去除率依次为26.53%、11.09%、5.71%;对应MSL段水力负荷分别为0.25、0.50及1m·3m-·2d-1时,MSL-1对TN平均去除率分别为87.39%、65.09%、45.56%,MSL-2平均去除率依次为61.51%、42.52%、31.32%.MSL-1脱氮性能明显优于MSL-2,而两者除磷效果区别较小.随着水力负荷增大,MSL对TP去除率依次降低,MSL-1对TP平均去除率最高为91.97%.