膜生物反应器中同步硝化反硝化机制及影响因子探讨

通过膜生物反应器的连续运行,研究了DO、C/N比、F/M和pH等影响因子对膜生物反应器同步硝化反硝化的影响,并对其影响机制进行了分析。实验结果表明,DO、C/N比、F/M和pH是同步硝化反硝化效果的重要影响因子;膜生物反应器中pH值的变化在7左右,DO为0.8 mg/L,C/N比为10,F/M在0.15~0.36 kg COD/(kg MLSS.d)之间时能发生比较好的同步硝化反硝化现象。     

活性炭纤维载体生物膜法处理洗车废水研究

为了实现洗车废水的循环使用,进行了以聚丙烯腈基活性炭纤维(PAN-ACF)为生物膜载体处理洗车废水的实验研究。以LAS、COD和NH3-N等指标考察了活性炭纤维生物膜反应器对洗车废水的处理效果。结果表明:在常温下、pH=6.5~7,当进水流量在30 mL/min时,反应器达到最佳运行参数,活性炭纤维载体生物膜法对LAS、COD和NH3-N等的去除率分别达到了97%、80%和60%。出水水质完全达到《生活杂用水水质标准》(CJ/T48-99)中洗车用水主要水质指标的规定。此外,实验表明PAN-ACF作为生物膜载体具有很好的生物亲和性和再生性。     

一株氧化亚铁硫杆菌的筛选及生长条件研究

从广东省大宝山矿区尾矿中分离纯化得到一株嗜酸细菌,对其进行DNA提取和16S rRNA扩增后测序,将测序结果与国际基因数据库Genbank中已有相关菌株序列进行相似性比对后,发现该菌株与氧化亚铁硫杆菌(Acidithiobacil-lus ferrooxidans)Tf-49菌位于系统发育树的同一分支中,二者相似度高达99%以上,确定其为氧化亚铁硫杆菌并命名为DBS-8菌。另外,通过设计5因素4水平的正交实验,研究了接种量、培养温度、硫酸铵浓度、初始pH和初始亚铁浓度对该菌株生长状况的影响。结果表明适宜该菌株生长的最佳初始条件为:20%的接种量、3.0 g/L硫酸铵、9.0 g/L初始亚铁、pH=2.0和28℃培养,各初始条件对细菌生长影响的顺序为:pH初始亚铁浓度接种量温度硫酸铵浓度。     

Novel Renewable Polyols Based on Limonene for Rigid Polyurethane Foams

Novel renewable polyols based on limonene were synthesized using thiol-ene “click” chemistry. These limonene based polyols were structurally characterized using wet methods (hydroxyl number, acid value and viscosity), gel permeation chromatography and spectroscopic methods. The results indicated that high yield of polyols from limonene based materials can be obtained using thiol-ene reaction. These limonene based polyols were used successfully for preparation of rigid polyurethane foams. These foams had regular shape cells and uniform cell size distribution. Thermal studies on these foams indicated that foams were thermally stable up to 250 °C. The glass transition temperature of the foams was higher than 200 °C. These rigid polyurethane foams had high compressive strength and the highest compressive strength of 195 kPa was observed. These foams have good physical–mechanical characteristics and could be suitable for all the applications of rigid polyurethane foams such as thermal insulation of freezers, storage tanks for the chemical and food industries, and packing materials for food industries.     

Theoretical study of the impact of particulate matter gravitational settling on ambient coarse particulate matter monitoring for agricultural emissions

The particle size distributions (PSDs) of particulate matter (PM) in the downwind plume from simulated sources of a cotton gin were analyzed to determine the impact of PM settling on PM monitoring. The PSD of PM in a plume varies as a function of gravitational settling. Gravitational settling has a greater impact on the downwind PSD from sources with PSDs having larger mass median diameters (MMDs). The change in PSD is a function of the source PSD of emitted PM, wind speed, and downwind distance. Both MMD and geometric standard deviation (GSD) in the downwind plume decrease with an increase in downwind distance and source MMD. The larger the source MMD, the greater the change in the downwind MMD and GSD. Also, the greater the distance from the source to the sampler, the greater the change in the downwind MMD and GSD. Variations of the PSD in the downwind plume significantly impact PM10 sampling errors associated with the U.S. Environmental Protection Agency (EPA) PM10 samplers. For the emission sources with MMD > 10 microm, the PM10 oversampling rate increases with an increase in downwind distance caused by the decrease of GSD of the PSD in the downwind plume. Gravitational settling of particles does not help reduce the oversampling problems associated with the EPA PM10 sampler. Furthermore, oversampling rates decrease with an increase of the wind speed.     

Modified grey model for estimating traffic tunnel air quality

This study compared three forecasting models based on the mean absolute percentage errors (MAPE) of their accuracy in forecasting air pollution in a traffic tunnel: the Grey model (GM), the combination model used four sample point and five sample point prediction with GM (1,1)(GM(1,1)^4 + 5), and the modified grey model (MGM). An MGM was combined using the four points of the original sequence using the original grey prediction GM (1,1) for short-term forecasting. The proposed method cannot only enhance the prediction accuracy of the original grey model, but can also solve the jump data forecasting problem something for which the original grey model is inappropriate. The MAPE was applied to the models, and the MGM found the proposed method to be simple and efficient. The MAPE of MGM, calculated over 3 h of forecasts, were as follows: 10.12 (Upwind), 10.07 (Middle) and 7.68 (Downwind) for CO; 10.79 (Upwind), 6.05 (Middle) and 5.98 (Downwind) for NO _x , and 11.67 (Upwind), 7.32 (Middle) and 4.56 (Downwind) for NMHC. The MGM model results reveal that the combined forecasts can significantly decrease the overall forecasting error. Results of this demonstrate that MGM can accurately forecast air pollution in the Kaohsiung Chung–Cheng Tunnel.     

Odour emission characteristics of 22 recreational rivers in Nanjing

The odour emission characteristics of 22 recreational rivers in Nanjing were investigated and analysed. Eight odorous compounds (ammonia (NH₃), hydrogen sulphide (H₂S), sulphur dioxide (SO₂), carbon disulphide (CS₂), nitrobenzene (C₆H₅NO₂), aniline (C₆H₅NH₂), dimethylamine (C₂H₇N), and formaldehyde (HCHO)) were measured in odour emission samples collected using a custom-made emission flux hood chamber. The results showed that all odorants were detected in all monitoring rivers. NH₃ was the main odorant, with emission rates ranging from 4.86 to 15.13 μg/min m². The total odour emission rate of the Nan River, at 1 427.07 OU/s, was the highest of the all investigated rivers. H₂S, NH₃ and nitrobenzene were three key odour emission contributors according to their contributions to the total odour emission. A correlation analysis of the pollutants showed there was a significant positive correlation between the emission rate of NH₃ and the concentration of ammonia nitrogen (NH₄ ⁺-N) and total nitrogen (TN). The H₂S and SO₂ emission rates had a significant positive correlation with sulphides (S^2?) and available sulphur (AS) in the water and sediment. The content of TN, NH₄ ⁺-N, S^2? and AS in the water and sediment affected the concentration of H₂S, SO₂ and NH₃ in the emission gases. NH₄ ⁺-N, S^2? and AS are suggested as the key odour control indexes for reducing odours emitted from these recreational rivers. The study provides useful information for effective pollution control, especially for odour emission control for the recreational rivers of the city. It also provides a demonstrate example to show how to monitor and assess a contaminated river when odour emission and its control need to be focused on.     

2013年度新疆环境申报统计工作思考与建议

对2013年度新疆环境申报统计的创新工作方法进行了较详细的总结。通过统一工作部署,整合统计申报报表制度,严格执行数据质量核查制度,开发“污染源管理系统”,形成了较完善的工作体系,对今后申报统计工作质量的提高提出了思考与建议。     

深化内部改革的实践与思考

介绍了杭州市环境监测中心站进行内部改革的总体目标,指导思想、基本做法和初步成效。提出了统一思想,提高认识,转变观念是做好改革工作的前提;征询意见,深入调查是制订改革方案的必要过程;完善考核制度是改革工作取得成效的保障。指出改革是大趋势,需要以科学、严谨的态度,不断充实和完善其实质内容。     

Discriminant analysis for the prediction of sand mass distribution in an urban stormwater holding pond using simulated depth average flow velocity data

The approach of this paper is to predict the sand mass distribution in an urban stormwater holding pond at the Stormwater Management And Road Tunnel (SMART) Control Centre, Malaysia, using simulated depth average floodwater velocity diverted into the holding during storm events. Discriminant analysis (DA) was applied to derive the classification function to spatially distinguish areas of relatively high and low sand mass compositions based on the simulated water velocity variations at corresponding locations of gravimetrically measured sand mass composition of surface sediment samples. Three inflow parameter values, 16, 40 and 80 m³ s^?1, representing diverted floodwater discharge for three storm event conditions were fixed as input parameters of the hydrodynamic model. The sand (grain size?>?0.063 mm) mass composition of the surface sediment measured at 29 sampling locations ranges from 3.7 to 45.5 %. The sampling locations of the surface sediment were spatially clustered into two groups based on the sand mass composition. The sand mass composition of group 1 is relatively lower (3.69 to 12.20 %) compared to group 2 (16.90 to 45.55 %). Two Fisher’s linear discriminant functions, F ₁ and F ₂, were generated to predict areas; both consist of relatively higher and lower sand mass compositions based on the relationship between the simulated flow velocity and the measured surface sand composition at corresponding sampling locations. F ₁?=??9.405?+?4232.119?×?A???1795.805?×?B?+?281.224?×?C, and F ₂?=??2.842?+?2725.137?×?A???1307.688?×?B?+?231.353?×?C. A, B and C represent the simulated flow velocity generated by inflow parameter values of 16, 40 and 80 m³ s^?1, respectively. The model correctly predicts 88.9 and 100.0 % of sampling locations consisting of relatively high and low sand mass percentages, respectively, with the cross-validated classification showing that, overall, 82.8 % are correctly classified. The model predicts that 31.4 % of the model domain areas consist of high-sand mass composition areas and the remaining 68.6 % comprise low-sand mass composition areas.