混凝-生物接触氧化法处理城市污水的研究

采用混凝-生物接触氧化法处理生活小区废水,考察了不同混凝剂用量对COD、NH4-N、SS、TP的去除效果,同时研究了生物接触氧化法对COD、NH4-N等的去除以及耐冲击负荷能力.结果表明,随混凝剂用量的增加,COD、SS、TP的去除率随之增加,生物接触氧化法具有较高的抗冲击负荷能力,最大NH4-N去除负荷达到0.55 kg/(m3·d),最大有机去除负荷达到4.32 kg/(m3·d)     

Accumulation of butyl- and phenyltin compounds in starfish and bivalves from the coastal environment of Korea

Triphenyltin (TPT) and tributyltin (TBT) concentrations were determined in two starfish species (Asteria pectinifera and Asterias amurensis), bivalves (Crassostrea gigas or Mytilus edulis), and seawater samples from sites around the coasts of Korea. Both TPT and TBT concentrations in starfish ranged from 8 to 1560 ng/g and from <2 to 797 ng/g as Sn on a dry weight basis, respectively. TPT concentration accounted for 75.4% and 86.4% of total phenyltin concentration in A. pectinifera and A. amurensis, respectively, while monobutyltin, a degradation product of TBT, accounted for 86.3% and 57.2% of total butyltin, respectively. Triphenyltin concentrations in A. pectinifera were significantly correlated to water and bivalve TPT concentrations, which implies that dietary uptake of TPT from contaminated prey as well as direct uptake from surrounding water contribute to TPT body residues in the starfish. Starfish could be target organisms for monitoring TPT compound in the marine environment, due to their high accumulation and low degradation capacity towards TPT.     

Risk of serious injury of occupants involved in frontal crashes of cab-over-type trucks

Objectives: Truck vehicles (TVs) have a different structure and stiffness than non-TVs and are used commercially for transporting goods. This study aimed to analyze whether truck occupants have a greater risk of serious injury than those of other types of vehicles.

Methods: Crash data were obtained from the Korean In-Depth Data Analysis Study (KIDAS) for calendar years 2011–2016. Vehicles involved in frontal crash were included and classified into TVs and non-TVs (passenger cars and sports utility vehicles). We compared the demographic characteristics and serious injuries by body region between the 2 groups and analyzed factors that contributed to the serious injury severity from frontal crashes.

Results: The analysis was based on 884 occupants; 177 (20.0%) were in TVs and 707 (80.0%) were in non-TVs. Non-TVs had more frontal airbags deployments than TVs (50.9% vs. 3.4%, P <.01). TV occupants were 4.8 times more likely to have a serious lower extremity (LE) injury (adjusted odds ratio [AOR] = 4.820; 95% confidence interval [CI], 2.407–9.653) and 2.5 times to have a serious abdominal injury (AOR = 2.465; 95% CI, 1.108–5.487) compared to non-TV occupants.

Conclusions: Truck occupants had more serious LE and abdominal injuries than those of other types of vehicles in frontal crashes. Structural improvement and legislative efforts to develop safety systems are necessary to improve the safety of truck occupants.     

水中总氰化物含量测量不确定度的评定

采用异烟酸-吡唑啉酮分光光度法对水中总氰化物进行不确定度评定。充分考虑测量重复性、标准溶液的配制、标准曲线的制备等因素对测量的影响,测得总氰化物的相对合成标准不确定度为1．75×10^-2。     

核桃青皮生物炭对重金属铅、铜的吸附特性研究

采用500℃限氧裂解法将农林废弃物核桃青皮制成核桃青皮生物炭,进行了核桃青皮生物炭对铅、铜的批量吸附实验.同时,利用扫描电镜、FTIR红外等方法探讨了核桃青皮炭吸附Pb~(2+)、Cu~(2+)的特性,探究了吸附时间、溶液初始浓度、吸附温度、吸附剂投加量、溶液初始pH等因素对核桃青皮生物炭吸附Pb~(2+)、Cu~(2+)作用的影响,讨论了吸附动力学特性及吸附等温特性.结果表明:温度298.15 K、pH为3~6条件下,核桃青皮生物炭吸附Pb~(2+)和Cu~(2+)在20 min内即可达到吸附平衡,核桃青皮炭最佳投加量分别为0.8、1.5 g·L~(-1),最大吸附量分别为476.190、153.846 mg·g~(-1);吸附过程符合准二级动力学方程,等温吸附曲线符合Langmuir方程,说明其吸附过程主要是近似单分子层的化学吸附.     

Inhibition of pyrite oxidation by surface coating: a long-term field study

Pyrite and other iron sulfides are readily oxidized by dissolved oxygen in aqueous phase, producing acidity and Fe²⁺, which causes significant environmental problems. Applications of surface coating agents (Na₂SiO₃ and KH₂PO₄) were conducted at Boeun (Chungbuk, South Korea) outcrop site, and their efficiencies to inhibit the oxidation of sulfide minerals were monitored for a long-term period (449 days). The rock sample showed positive Net Acid Production Potential (NAPP = 20.23) and low Net Acid Generation pH (NAGpH = 2.42) values, suggesting that the rock sample was categorized in the potential acid-forming group. For the monitored time period (449 days), field study results showed that the application of Na₂SiO₃ effectively inhibited the pyrite oxidation as compared to KH₂PO₄. Na₂SiO₃ as a surface coating agent maintained pH 5–6 and reduced oxidation of pyrite surface up to 99.95 and 97.70 % indicated by Fe²⁺ and SO₄ ^2? release, respectively. The scanning electron microscope and energy-dispersive X-ray spectrometer analysis indicated that the morphology of rock surface was completely changed attributable to formation of iron silicate coating. The experimental results suggested that the treatment with Na₂SiO₃ was highly effective and it might be applicable on field for inhibition of iron sulfide oxidation.     

互相关算法在次声监测数据处理中的应用

次声监测数据处理技术是我国履行全面禁止核试验条约必备技术之一。重点介绍逐次多通道互相关(PMCC)算法原理、处理流程以及与之相关的数据处理系统,并利用典型次声事件进行了实验研究。结果表明PMCC在处理次声监测数据方面具有优异性能。     

Development of a Local-Scale Spatially Refined Multimedia Fate Model (LSRMFM) for Urban-Scale Risk Assessment: Model Formulation, GIS-Based Preprocessing, and Case Study

A local-scale spatially refined multimedia fate model (LSRMFM) was developed to evaluate in detail the multimedia transport of organic compounds at a spatial level. The model was derived using a combination of an advection?Cdispersion?Creaction partial differential equation, a steady-state multimedia fugacity model, and a geographical information system. The model was applied to predicting four major volatile organic compounds that are produced as emissions (benzene, toluene, xylene, and styrene) in an urban and industrial area (the 50?×?50-km area was divided into 0.5?×?0.5-km segments) in Korea. To test the accuracy of the model, the LSRMFM was used to predict the extent of dispersion and the data compared with actual measured concentrations and the results of a generic multimedia fate model (GMFM). The results indicated that the method developed herein is appropriate for predicting long-term multimedia pollution. However, the comparison study also illustrated that the developed model has some limitations (e.g., steady-state assumption) in terms of explaining all the observed concentrations, and additional verification and study (e.g., validation using a large observed data set, integration with a more accurate runoff model) would be desirable. In comparing LSRMFM and GMFM, discrepancies between the LSRMFM and GMFM outputs were found, as the result of geographical effects, even though the environmental parameters were identical. The geographical variation for LSRMFM output indicated the existence of considerable local human and ecological risks, whereas the GMFM output indicated less average risk. These results demonstrate that the model has the potential for improving the management of pollutant levels under these refined spatial conditions.     

Effects of salinity and organic matter on the partitioning of perfluoroalkyl acid (PFAs) to clay particles

The influence of salinity and organic matter on the distribution coefficient (K(d)) for perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in a brackish water-clay system was studied. The distribution coefficients (K(d)) for PFAs onto inorganic clay surfaces increased with salinity, providing evidence for electrostatic interaction for the sorption of PFAs, whereas the relationship between K(d) and organic carbon content (f(oc)) suggested that hydrophobic interaction is the primary driving force for the sorption of PFAs onto organic matter. The organic carbon normalized adsorption coefficient (K(oc)) of PFAs can be slightly overestimated due to the electrostatic interaction within uncoated inorganic surfaces. In addition, the dissolved organic matter released from coated clay particles seemed to solvate PFA molecules in solution, which contributed to a decrease in K(d). A positive relationship between K(d) and salinity was apparent, but an empirical relationship for the 'salting-out' effect was not evident. The K(d) values of PFAs are relatively small compared with those reported for persistent organic pollutants. Thus, sorption may not be a significant route of mass transfer of PFAs from water columns in estuarine environments. However, enhancement of sorption of PFAs to particulate matter at high salinity values could evoke potential risks to benthic organisms in estuarine areas.     

Denitrification and phosphorus uptake by DPAOs using nitrite as an electron acceptor by step-feed strategies

Denitrifying phosphorus accumulating organisms (DPAOs) using nitrite as an electron acceptor can reduce more energy. However, nitrite has been reported to have an inhibition on denitrifying phosphorus removal. In this study, the step-feed strategy was proposed to achieve low nitrite concentration, which can avoid or relieve nitrite inhibition. The results showed that denitrification rate, phosphorus uptake rate and the ratio of the phosphorus uptaken to nitrite denitrified (anoxic P/N ratio) increased when the nitrite concentration was 15 mg·L^-1 after step-feeding nitrite. The maximum denitrification rate and phosphorus uptake rate was 12.73 mg NO2-–N·g MLSS-1?h-1 and 18.75 mg PO43-–P·g MLSS-1?h-1, respectively. These rates were higher than that using nitrate (15 mg·L^-1) as an electron acceptor. The maximum anoxic P/N ratio was 1.55 mg PO43--P?mg NO2--N-1. When the nitrite concentration increased from 15 to 20 mg NO2--N?L-1 after addition of nitrite, the anoxic phosphorus uptake was inhibited by 64.85%, and the denitrification by DPAOs was inhibited by 61.25%. Denitrification rate by DPAOs decreased gradually when nitrite (about 20 mg·L^-1) was added in the step-feed SBR. These results indicated that the step-feed strategy can be used to achieve denitrifying phosphorus removal using nitrite as an electron acceptor, and nitrite concentration should be maintained at low level (<15 mg·L^-1 in this study).