Performance evaluation of circulating fluidized bed incineration of municipal solid waste by multivariate outlier detection in China

This first nationwide survey was conducted to evaluate the overall performance of the circulating fluidized bed (CFB) incineration of municipal solid waste (MSW) in 2014-2015 in China. Total 23 CFB incineration power plants were evaluated. The data for monthly average flue gas emission of particles, CO, NO _x , SO₂ and HCl were collected over 12 consecutive months. The data were analyzed to assess the overall performance of CFB incineration by applying the Mahalanobis distance as a multivariate outlier detection method. Although the flue gas emission parameters had met the Chinese national emission standards, there were 11 total outliers (abnormal behavior) detected in 6 out of 23 CFB incineration power plants from the perspective of the MSWincineration performance. The results demonstrate that it is more important for a better performance of CFBs to reduce the frequencies of the MSW load changes, rather than the magnitudes of the MSW load changes, particularly reducing the frequencies in the range of 10% and more of the load changes, under the same and stable conditions. Furthermore, the overloading occurs more often than the underloading during the operation of the CFB incineration power plants in China. The frequent overloading is 0% to 30% of the designed capacity. To achieve the stable performance of CFBs in practice, an appropriately designed MSW storage capacity is suggested to build in a plant to buffer and reduce the frequency of the load changes.

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Assessment and potential sources of metals in the surface sediments of the Yellow River Delta,Eastern China

The Yellow River Delta is the most intact estuary wetland in China and suffers from great pressure of metals. Seventy-seven surface sediment samples were collected in the delta, and contents of Cu, Pb, Cd, Cr, Zn, Ni, and Mn were analyzed by inductively coupled plasma spectrometry and those of Hg and As by atomic fluorescence spectrometry. The results showed that means of metal contents (ppm, dry weight) were as follows: Hg, 0.04; Cr, 61.72; Cu, 20.97; Zn, 60.73; As, 9.47; Pb, 21.91; Cd, 0.12; Ni, 27.24; and Mn, 540.48. 43.8% of Hg and 14.3% of Cd were from the allogenic source while others from the authigenic source. The results of the geoaccumulation indexes appeared that 6.5% of sites from the estuarine and the Gudao areas were moderately polluted by Hg. All ecological risk index values of Hg and 37.7% of Cd were more than 40, which were the main factors of strongly and moderately potential ecological risks of 37.7% of sites in the delta. High Cd contents may be due to the alkaline conditions of the delta and the unreasonable management of the farmland, while the abnormal distribution of Hg to the wet or dry deposition and the erosion of the seawater. It was suggested to monitor Hg content in the atmosphere of the Yellow River Delta. The results were expected to update the pollution status of metals in the delta and created awareness of preserving the sound condition of the Yellow River Delta.     

Urinary metabolomic profiling in rats exposed to dietary di(2-ethylhexyl) phthalate (DEHP) using ultra-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (UPLC/Q-TOF-MS)

Di(2-ethylhexyl) phthalate (DEHP) is an omnipresent environmental chemical with widespread nonoccupational human exposure through multiple ways. Although considerable efforts have been invested to investigate mechanisms of DEHP toxicity, the key metabolic biomarkers of DEHP toxicity remain to be identified. The aim of this study was to assess the urinary metabonomics of dietary DEHP in rats using the technique of ultra-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (UPLC/Q-TOF-MS). Fourteen female Wistar rats were divided into two groups and given increasing dietary doses of DEHP for 30 consecutive days. The urinary metabolite profile was studied using ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry. Principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) enabled clusters to be clearly separated. Eleven principal urinary metabolites were identified as contributing to the clusters. The clusters in the positive electrospray ionization (ESI) mode were xanthurenic acid, kynurenic acid, nonate, N6-methyladenosine, and L-isoleucyl-L-proline. The clusters in the negative ESI mode were hippuric acid, tetrahydrocortisol, citric acid, phenylpropionylglycine, cPA(18:2(9Z, 12Z)/0:0), and LysoPC(14:1(9Z)). The urinary metabonomic changes indicated that exposure to dietary DEHP can affect energy-related metabolism, liver and renal function, fatty acid metabolism, and cause DNA damage in rats. The findings of this study on the urinary metabolites and metabolic pathways of DEHP may form the basis for future studies on the mechanisms of toxicity of this commonly found environmental chemical.     

Application of phosphate solubilizing bacteria in immobilization of Pb and Cd in soil

Environmental Science and Pollution Research - In the present study, heavy metal (HM)-tolerant phosphate solubilizing bacteria (PSB) were isolated and their performance during the remediation of Pb...     

NOx emission calculations for bulk carriers by using engine power probabilities as weighting factors

An important marine pollution issue identified by the International Maritime Organization (IMO) is NO_x emissions; however, the stipulated method for determining the NO_x certification value does not reflect the actual high emission factors of slow-speed two-stroke diesel engines over long-term slow steaming. In this study, an accurate method is presented for calculating the NO_x emission factors and total amount of NO_x emissions by using the actual power probabilities of the diesel engines in four types of bulk carriers. The proposed method is suitable for all types and purposes of diesel engines, is not restricted to any operating modes, and is highly accurate. Moreover, it is recommended that the IMO-stipulated certification value calculation method be modified accordingly to genuinely reduce the amount of NO_x emissions. The successful achievement of this level of reduction will help improve the air quality, especially in coastal and port areas, and the health of local residents.

Implications: As per the IMO, the NO_x emission certification value of marine diesel engines having a rated power over 130 kW must be obtained using specified weighting factor (WF)-based calculation. However, this calculation fails to represent the current actual situation. Effective emission reductions of 6.91% (at sea) and 31.9% (in ports) were achieved using a mathematical model of power probability functions. Thus, we strongly recommend amending the certification value of NO_x Technical Code 2008 (NTC 2008) by removing the WF constraints, such that the NO_x emissions of diesel engines is lower than the Tier-limits at any load level to obtain genuine NO_x emission reductions.     

火电汽轮机组热电解耦技术研究

针对供热机组受传统“以热定电”运行模式限制,单机调峰能力低(最大仅有50%),无法满足深度调峰的问题,以国电集团西北地区所辖火电供热机组的实际运行情况为出发点,结合汽轮机组节能诊断及机组改造经验,提出了高、低压旁路联合供热,低压缸切缸运行两种热电解耦技术方案,通过比选得出两种技术方案的优缺点及适用范围。     

无功交换对含大量风电场地区电网稳定性影响

针对含大量风电场的地区电网外送电时,外送联络线通道发生永久故障问题,运用电力系统综合分析程序(power system analysis softwarepackage, PSASP)仿真其动态过程,分析无功交换潮流对地区电网形成孤网后稳定性的影响,提出稳定控制策略。结果表明:无功交换潮流较小时,对孤网影响不大;当无功交换潮流较大时,应及时采取如:投退无功补偿装置、限制风电出力、切除部分负荷等措施进行稳定控制。     

Characteristics of PM<Subscript>2.5</Subscript>, CO<Subscript>2</Subscript> and particle-number concentration in mass transit railway carriages in Hong Kong

Fine particulate matter (PM_2.5) levels, carbon dioxide (CO₂) levels and particle-number concentrations (PNC) were monitored in train carriages on seven routes of the mass transit railway in Hong Kong between March and May 2014, using real-time monitoring instruments. The 8-h average PM_2.5 levels in carriages on the seven routes ranged from 24.1 to 49.8 µg/m³, higher than levels in Finland and similar to those in New York, and in most cases exceeding the standard set by the World Health Organisation (25 µg/m³). The CO₂ concentration ranged from 714 to 1801 ppm on four of the routes, generally exceeding indoor air quality guidelines (1000 ppm over 8 h) and reaching levels as high as those in Beijing. PNC ranged from 1506 to 11,570 particles/cm³, lower than readings in Sydney and higher than readings in Taipei. Correlation analysis indicated that the number of passengers in a given carriage did not affect the PM_2.5 concentration or PNC in the carriage. However, a significant positive correlation (p < 0.001, R ² = 0.834) was observed between passenger numbers and CO₂ levels, with each passenger contributing approximately 7.7–9.8 ppm of CO₂. The real-time measurements of PM_2.5 and PNC varied considerably, rising when carriage doors opened on arrival at a station and when passengers inside the carriage were more active. This suggests that air pollutants outside the train and passenger movements may contribute to PM_2.5 levels and PNC. Assessment of the risk associated with PM_2.5 exposure revealed that children are most severely affected by PM_2.5 pollution, followed in order by juveniles, adults and the elderly. In addition, females were found to be more vulnerable to PM_2.5 pollution than males (p < 0.001), and different subway lines were associated with different levels of risk.     

山东半岛城市群人居环境质量综合评价

随着中国城市化的高速发展,"城市病"问题日益突出,城市群作为统筹区域协调发展、建设宜居人居环境的重点地区,其人居环境发展状况备受关注。基于此,本文以山东半岛城市群为例,从人文环境、经济环境、社会环境和生态环境4个方面构建人居环境质量综合评价指标体系,利用人居环境质量计算模型和系统协调度模型,对其人居环境质量进行静态定量化评价和动态综合性评价。研究表明:(1)山东半岛城市群人居环境质量与社会环境的关联性最大,经济实力、基础设施水平时空发展不均衡、地域差异大,是制约山东半岛城市群人居环境发展的突出问题。(2)2000—2014年山东半岛城市群人居环境综合水平呈现良好的上升趋势,且增速较稳,增幅较小;各要素间的协调性均达到了中级协调等级;系统层的评价值除人文环境外,均呈现不同程度的波动式上升态势;领域层的评价值差异明显,发展不均衡。(3)城市群内部各城市人居环境综合质量水平逐步提高,且排名相对稳定;各要素间的协调度等级差异较小,但起伏变化较大;人居环境质量时空分异特征明显,呈现东西高、中间低的格局,内部级别差异显著,可分为较好、一般、较差、差4个等级。在今后的发展中,应针对山东半岛不同城市人居环境问题采取因时因地制宜的协调对策,创造整体最优人居环境。不仅要提高城市群的整体经济水平,提升城市群的短板建设,推动人居环境协调发展,还要符合新常态下城市发展与建设的要求,加快山东半岛城市群的区域创新体系构建,科学引领产业转型升级,优化产业结构,加强山东半岛城市规划研究与实施力度,探索"多规合一"模式。     

KOH活化花生壳生物质炭对亚甲基蓝吸附性能研究

以花生壳生物质炭(P-BC)为原料,KOH为活化剂,采用化学活化法制得活化生物质炭(K-BC),通过考察对亚甲基蓝的吸附性能,研究了花生壳生物质炭的最佳活化条件,并利用N2吸附-脱附实验、SEM等对最佳活化条件下的生物质炭进行表征。结果表明,K-BC活化的最佳条件为碱炭比为1.5∶1,活化温度为800℃,活化时间为90 min,此时K-BC的比表面积达到597.93 m2/g,总孔容达到0.76 cm3/g。并考察了亚甲基蓝初始浓度、pH等对K-BC吸附亚甲基蓝的影响,随着初始浓度的增加,吸附平衡时间显著延长,亚甲基蓝去除率显著降低;当pH=6时,K-BC对亚甲基蓝的吸附量最大;K-BC对亚甲基蓝的吸附动力学曲线符合伪二阶动力学模型,吸附平衡时K-BC对亚甲基蓝的吸附能力为80~149.95 mg/g。