数值模拟方法在二维沉淀池优化设计中的应用

简要介绍了数值方法在沉淀池悬浮物浓度计算中的应用方法 ,并尝试通过数值模拟过程建立起沉淀池沉降效率与几何尺寸间的关系 ,将其作为约束条件之一建立了一个简单的沉淀池优化设计模型。最后通过实例阐明了这种基于数值计算的优化设计模型的可行性和优势     

Feasibility of bioleaching combined with Fenton oxidation to improve sewage sludge dewaterability

A novel joint method of bioleaching with Fenton oxidation was applied to condition sewage sludge. The specific resistance to filtration(SRF) and moisture of sludge cake(MSC) were adopted to evaluate the improvement of sludge dewaterability. After 2-day bioleaching, the sludge p H dropped to about 2.5 which satisfied the acidic condition for Fenton oxidation.Meanwhile, the SRF declined from 6.45 × 1010 to 2.07 × 1010s2/g, and MSC decreased from91.42% to 87.66%. The bioleached sludge was further conditioned with Fenton oxidation. From an economical point of view, the optimal dosages of H2O2 and Fe2+were 0.12 and 0.036 mol/L,respectively, and the optimal reaction time was 60 min. Under optimal conditions, SRF,volatile solids reduction, and MSC were 3.43 × 108s2/g, 36.93%, and 79.58%, respectively. The stability and settleability of sewage sludge were both improved significantly. Besides,the results indicated that bioleaching-Fenton oxidation was more efficient in dewatering the sewage sludge than traditional Fenton oxidation. The sludge conditioning mechanisms by bioleaching-Fenton oxidation might mainly include the flocculation effects and the releases of extracellular polymeric substances–bound water and intercellular water.     

浅析生物修复技术在石油污染治理中的应用

生物修复技术是目前人们比较关注的一种新型石油污染治理技术。文章简要介绍了生物修复技术在石油污染的土壤、河流、湖泊、地下水、海洋领域的应用,阐述了该技术的研究将大力推进生物高科技的发展,对环保科技的发展具有重大意义。     

Role of secondary aerosols in haze formation in summer in the Megacity Beijing

A field experiment from 18 August to 8 September 2006 in Beijing, China, was carried out. A hazy day was defined as visibility < l0 km and RH (relative humidity) < 90%. Four haze episodes, which accounted for ~ 60% of the time during the whole campaign, were characterized by increases of SNA (sulfate, nitrate, and ammonium) and SOA (secondary organic aerosol) concentrations. The average values with standard deviation of SO₄^2 −, NO₃⁻, NH₄⁺ and SOA were 49.8 (± 31.6), 31.4 (± 22.3), 25.8 (± 16.6) and 8.9 (± 4.1) μg/m³, respectively, during the haze episodes, which were 4.3, 3.4, 4.1, and 1.7 times those in the non-haze days. The SO₄^2 −, NO₃⁻, NH₄⁺, and SOA accounted for 15.8%, 8.8%, 7.3%, and 6.0% of the total mass concentration of PM₁₀ during the non-haze days. The respective contributions of SNA species to PM₁₀ rose to about 27.2%, 15.9%, and 13.9% during the haze days, while the contributions of SOA maintained the same level with a slight decrease to about 4.9%. The observed mass concentrations of SNA and SOA increased with the increase of PM₁₀ mass concentration, however, the rate of increase of SNA was much faster than that of the SOA. The SOR (sulfur oxidation ratio) and NOR (nitrogen oxidation ratio) increased from non-haze days to hazy days, and increased with the increase of RH. High concentrations of aerosols and water vapor favored the conversion of SO₂ to SO₄^2 − and NO₂ to NO₃⁻, which accelerated the accumulation of the aerosols and resulted in the formation of haze in Beijing.     

Short-term prediction of the influent quantity time series of wastewater treatment plant based on a chaos neural network model

By predicting influent quantity, a wastewater treatment plant (WWTP) can be well controlled. The nonlinear dynamic characteristic of WWTP influent quantity time series was analyzed, with the assumption that the series was predictable. Based on this, a short-term forecasting chaos neural network model of WWTP influent quantity was built by phase space reconstruction. Reasonable forecasting results were achieved using this method. Translated from Acta Scientiae Circumstantiae, 2006, 26(3): 416–419 [译自: 环境科学学报]     

Developing chemical signatures of particulate air pollution in the Pearl River Delta region, China

PM2:5 samples were collected in a regional sampling network with three sites in Hong Kong and four sites in the adjacent inland Pearl River Delta (PRD) or Guangdong Province during four months/seasons from 2002–2003. Trans-boundary transport between Hong Kong and the inland PRD is inevitable under the influence of Asian monsoon. In summer, Hong Kong serves as the upwind site of the inland PRD while during other seasons it is under the influence of continental emissions. Previous studies have recognized the importance of using chemical signatures to differentiate local vs. regional contributions to air pollutants in Hong Kong such as the CO/NOx ratio, ratios of different VOC species. In this study, detailed chemical speciation by gas chromatography-mass spectrometry was performed with PM2:5 samples to identify new chemical signatures to distinguish aerosols in Hong Kong from those from the inland PRD. Since Hong Kong is not influenced by the continental emissions from the inland PRD during summer, comparison focused on chemical data obtained from this season for chemical signatures. The new ratios developed from the current study include LCPI/HCPI ratio of alkanes (0.39 0.02 in Hong Kong vs. 0.78 0.08 in the inland PRD), pyrene to benzo[ghi]perylene ratio (0.97 0.21 in Hong Kong compared to 0.20 0.06 in the inland PRD), and the ratio of 1,2-benzenedioic acid to 1,4-benzenedioic acid (1.8 0.1 in Hong Kong vs. 0.6 0.05 in the inland PRD). Results from this study also revealed that Hong Kong was impacted by ship emissions as reflected by substantially high V/Ni ratio (9 2) while this ratio was about 1–2 at all sites in the inland PRD, which is very close to typical ratios from residual oil combustion.     

活性炭吸附和脱附-等离子体氧化净化有机废气

根据滑动弧放电等离子体适于降解高浓度有机物废气的特性,结合活性炭吸附法,提出了吸附器的吸附浓缩和热脱附-等离子体氧化净化有机废气技术。实际运行结果表明:对于处理低浓度、大风量的有机废气,该技术与其他技术相比具有净化效率高、二次污染小和节省能耗等优点。     

Optimization of H2O2 dosage in microwave-H2O2 process for sludge pretreatment with uniform design method

A microwave-H₂O₂ process for sludge pretreatment exhibited high efficiencies of releasing organics, nitrogen, and phosphorus, but large quantities of H₂O₂ residues were detected. A uniform design method was thus employed in this study to further optimize H₂O₂ dosage by investigating effects of pH and H₂O₂ dosage on the amount of H₂O₂ residue and releases of organics, nitrogen, and phosphorus. A regression model was established with pH and H₂O₂ dosage as the independent variables, and H₂O₂ residue and releases of organics, nitrogen, and phosphorus as the dependent variables. In the optimized microwave-H₂O₂ process, the pH value of the sludge was firstly adjusted to 11.0, then the sludge was heated to 80℃ and H₂O₂ was dosed at a H₂O₂:mixed liquor suspended solids (MLSS) ratio of 0.2, and the sludge was finally heated to 100℃ by microwave irradiation. Compared to the microwave-H₂O₂ process without optimization, the H₂O₂ dosage and the utilization rate of H₂O₂ in the optimized microwave-H₂O₂ process were reduced by 80% and greatly improved by 3.87 times, respectively, when the H₂O₂:MLSS dosage ratio was decreased from 1.0 to 0.2, resulting in nearly the same release rate of soluble chemical oxygen demand in the microwave-H₂O₂ process without optimization at H₂O₂:MLSS ratio of 0.5.     

湛江市环境管理信息系统建设研究

湛江市地方环境特点和环保局职能，介绍了该市环境管理信息系统的开发目的，系统，结构设计，主要等，该系统在Ｗｉｎｄｏｗｓ９５环境下，以Ｆｏｘｐｒｏ３．０为主要支持工具，结合其他ＧＩＳ软件，模型采用ＦｏｒｔｒａｎｆｏｒＷｉｎｄｏｗｓＶｉｓｕａｌＣ＋＋４．０为编程语言，建立了全 中文界面的多媒体环境管理信息系统。     

Effects of silver nanoparticles with different dosing regimens and exposure media on artificial ecosystem

Due to the wide use of silver nanoparticles (AgNPs) in various fields, it is crucial to explore the potential negative impacts on the aquatic environment of AgNPs entering into the environment in different ways. In this study, comparative experiments were conducted to investigate the toxicological impacts of polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) with two kinds of dosing regimens, continuous and one-time pulsed dosing, in different exposure media (deionized water and XiangJiang River water). There were a number of quite different experimental results (including 100% mortality of zebrafish, decline in the activity of enzymes, and lowest number and length of adventitious roots) in the one-time pulsed dosing regimen at high PVP-AgNP concentration exposure (HOE) compared to the three other treatments. Meanwhile, we determined that the concentration of leached silver ions from PVP-AgNPs was too low to play a role in zebrafish death. Those results showed that HOE led to a range of dramatic ecosystem impacts which were more destructive than those of other treatments. Moreover, compared with the continuous dosing regimen, despite the fact that higher toxicity was observed for HOE, there was little difference in the removal of total silver from the aquatic environment for the different dosing regimens. No obvious differences in ecological impacts were observed between different water columns under low concentration exposure. Overall, this work highlighted the fact that the toxicity of AgNPs was impacted by different dosing regimens in different exposure media, which may be helpful for assessments of ecological impacts on aquatic environments.