膜生物反应器技术在环境激素废水处理中的应用

本文主要介绍膜生物反应器技术在环境激素废水处理研究中的应用现状。     

Facilitating biodiversity conservation through partnerships to achieve transformative outcomes

Conservation biology is a mission-driven discipline that must navigate a new relationship between conservation and science. Because conservation is a social and political as well as an ecological project, conservation biologists must practice interdisciplinarity and collaboration. In a comparative study of 7 cases (Jaguars in the Chaco, Grevy's zebra in Kenya, Beekeeping in Tanzania, Andean cats in Argentina, Jaguars in Mexico, Lobster fishing, and Black bears in Mexico), we examined motivations for collaboration in conservation, who can collaborate in conservation, and how conservation professionals can work well together. In 5 case studies, successful conservation outcomes were prioritized over livelihood benefits. In the other 2 cases, livelihoods were prioritized. All case studies employed participatory approaches. There were multiple external actors, including local and Indigenous communities, nongovernmental organizations, agencies, regional and national governments, and international organizations, which enhanced conservation and wider sustainability outcomes. Key collaboration aspects considered across the case studies were time (mismatch between relationship building and project schedules), trust required for meaningful partnerships, tools employed, and transformative potential for people, nature, and the discipline of conservation biology. We developed guidelines for successful collaboration, including long-term commitment, knowledge integration, multiscalar and plural approaches, cultivation of trust, appropriate engagement, evaluation, supporting students, and efforts for transformation.     

Derivative spectrophotometric method for copper determination

A simple, sensitive and selective method by solvent extraction-first derivative spectrophotometry is described for the determination of microamounts of copper in water by means of its reaction and extraction at pH 8.0 with 3-(4-phenyl-2-pyridinyl-5-phenyl-1,2,4-triazine) (PPT) and picrate (2,4,6-trinitro-phenol) into 1,2-dichloroethane. Copper was thus determined in the range 7.5–350 ng/ml with a detection limits (3) of 2.3 ng/ml. The relative standard deviations were in all instances less than 2.0%. The proposed method was successfully applied for the determination of copper in several kinds of water.     

Respirometric Monitoring for the Determination of Effective Height and Reaction Rate Constant in Up-Flow Autotrophic Denitrification Reactor Packed with Sulfur

A novel technology for the removal of nitrogen from wastewater, autotrophic denitrification process with sulfur particle, has been developed. A respirometer was employed for the monitoring of nitrogen gas produced in the reactor. It was found that the autotrophic denitrification studied by gas production rate and nitrate depletion rate followed a first order reaction from the relationship. The reaction rate constant based on effective volume, k_N was ranged from 2.67 to 3.07 h^–1. The effective height was around 23.8 and 50% of the total height for 11.8 and 5.9 h of packed bed contact time, respectively. It was assumed that the reaction rate constants were similar in each experimental condition, PBCT = 11.9 and 5.9 h because there was little gradient of biomass concentration within 50% of the total height. The respirometry was found to be a simple and fast way to monitor the denitrification process. The method was especially useful for the determination of kinetic parameters.     

亚铁催化声化学降解罗丹明B

比较了不同金属离子对罗丹明B的声化学降解作用，发现超声时加入Fe^2＋反应速率常数为单独超声波降解时的1．6倍，反应在前5h内符合假一级动力学。研究了亚铁离子强化声化学对罗丹明B的降解作用，考察了Fe^2＋用量，溶液初始pH值，曝气，反应温度和超声功率等因素对脱色速率的影响。研究表明，酸性条件有利于染料的脱色；有曝气时的声化学脱色速率常数是单独超声时的6倍；声化学反应的活化能较低，反应在低温就可以进行；超声功率的改变对脱色速率的影响不大。UV-VIS扫描图谱显示，染料在225nm和256nm处的紫外吸收明显降低，初步探讨了罗丹明B的降解机理。     

Formation and cytotoxicity of a new disinfection by-product (DBP) phenazine by chloramination of water containing diphenylamine

Disinfection by-products (DBPs) in drinking water have caused worldwide concern due to their potential carcinogenic effects. The formation of phenazine from diphenylamine (DPhA) chloramination was studied and its cytotoxicities for two human cancer cells were also investigated. Phenazine was detected synchronously with the consumption of DPhA by chloramination, which further confirmed that the new DBP phenazine can be produced along with N-nitrosodiphenylamine (NDPhA) from DPhA chloramination. The formation of phenazine had a maximum molar yield with solution pH increasing from 5.0 to 9.0, with phenazine as the main product for DPhA chloramination at lower pH, but higher pH favored the formation of NDPhA. Thus, solution pH is the key factor in controlling the formation of phenazine and NDPhA. Both the initial DPhA and chloramine concentrations did not show a significant effect on the molar yields of phenazine, although increasing the chloramine concentration could speed up the reaction rate of DPhA with chloramines. The cytotoxicity assays showed that phenazine had significant cell-specific toxicity towards T24 (bladder cancer cell lines) and HepG2 (hepatic tumor cell lines) cells with IC50 values of 0.50 and 2.04 mmol/L, respectively, and T24 cells being more sensitive to phenazine than HepG2 cells. The IC50 values of phenazine, DPhA, and NDPhA for T24 cells were of the same order of magnitude and the cytotoxicity of phenazine for T24 cells was slightly lower than that of NDPhA (IC50, 0.16 mmol/L), suggesting that phenazine in drinking water may have an adverse effect on human health.     

Integrating decay, storage, kinetic selection, and filamentous backbone factors in a bacterial competition model.

Filamentous bulking in activated sludge systems occurs when filamentous organisms outgrow floc-forming bacteria and interfere with sludge settling. The competition between filaments and floc formers has been described previously using the kinetic selection and filamentous backbone theories. We hypothesized that differences in decay rates and storage abilities also affect this competition. We tested this hypothesis by integrating these four factors into a substrate-utilization model to predict and explain coexistence in a completely mixed reactor. In addition, filamentous and nonfilamentous sludges were developed in laboratory-scale reactors and analyzed to determine decay rates. The modeling results showed coexistence of the two organism types, and sensitivity analysis showed that the kinetic parameters, storage rate constants, and backbone coefficient had the greatest effect on the simulation results. Monte Carlo simulation showed the effect of storage, and the ranges of dilution rates wherein one group outcompeted the other were delineated.     

双变截面SCR脱硝系统导流板优化设计

根据某电厂1 000 MW塔式锅炉脱硝系统催化剂首层速度偏差较大的问题,建立了基于CFD仿真分析技术的三维SCR脱硝系统数学模型,对该系统双变截面烟道处的导流板布置方式进行研究,以优化催化剂首层的速度分布。通过对比不同结构导流板下的结果,提出将原始SCR系统的双变截面烟道拆分为X方向和Z方向2个变截面烟道的改造方案。在此结构下重新进行优化设计,改造后系统内的回流区和低速区消除,流场均匀性显著提升,取得了积极的效果。为实际电厂优化调试,解决类似工程问题提供了参考数据。     

微涡旋絮凝-逆流气浮-纳滤集成工艺去除水中腐殖酸的动态运行特征

通过微涡旋絮凝逆流气浮-纳滤集成工艺的动态试验研究,确定其运行周期为72 h,能很好地去除水中腐殖酸有机物,但不同纳滤膜组成的集成工艺处理效果不同.采用PACl絮凝剂处理水样2时,以流程1运行的含TQ56-36FC型纳滤膜的集成工艺出水的高锰酸盐指数为0.45 mg/L,UV254nm在0.003 3左右波动,且有95%以上的脱盐率.以流程2运行的含M-N1812A型纳滤膜的集成工艺处理3种水样时的膜清水的高锰酸盐指数在0.75 mg/L左右波动,UV254nm大都远小于0.007 5,有时甚至为0.水样1和水样3的UV254nm平均值为0.005 4,水样2的最低,平均值为0.003 3,脱盐率只有6%～10%.以PACl为絮凝剂时,集成系统有较强的适应原水水质变化的能力.预处理中活性炭柱的存在提高了M-N1812A型纳滤膜清水样的水质,但并没有延长膜的使用周期.这也表明膜的污染更重要的是来自无机物的污染.