Microbial reduction of uranium (VI) by Bacillus sp. dwc-2: A macroscopic and spectroscopic study

The microbial reduction of U(VI) by Bacillus sp. dwc-2, isolated from soil in Southwest China, was explored using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge spectroscopy (XANES). Our studies indicated that approximately 16.0% of U(VI) at an initial concentration of 100 mg/L uranium nitrate could be reduced by Bacillus sp. dwc-2 at pH 8.2 under anaerobic conditions at room temperature. Additionally, natural organic matter (NOM) played an important role in enhancing the bioreduction of U(VI) by Bacillus sp. dwc-2. XPS results demonstrated that the uranium presented mixed valence states (U(VI) and U(IV)) after bioreduction, which was subsequently confirmed by XANES. Furthermore, the TEM and high resolution transmission electron microscopy (HRTEM) analysis suggested that the reduced uranium was bioaccumulated mainly within the cell and as a crystalline structure on the cell wall. These observations implied that the reduction of uranium may have a significant effect on its fate in the soil environment in which these bacterial strains occur.     

Ambient volatile organic compounds pollution in China

Owing to rapid economic and industrial development, China has been suffering from degraded air quality and visibility. Volatile organic compounds (VOCs) are important precursors to the formation of ground-level ozone and hence photochemical smog. Some VOCs adversely affect human health. Therefore, VOCs have recently elicited public concern and given new impetus to scientific interest. China is now implementing a series of polices to control VOCs pollution. The key to formulating policy is understanding the ambient VOCs pollution status. This paper mainly analyzes the species, levels, sources, and spatial distributions of VOCs in ambient air. The results show that the concentrations of ambient VOCs in China are much higher than those of developed countries such as the United States and Japan, especial benzene, which exceeds available standards. At the same time, the ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP) of various VOCs are calculated. Aromatics and alkenes have much higher OFPs, while aromatics have higher SOAFP. The OFPs of ambient VOCs in the cities of Beijing, Guangzhou and Changchun are very high, and the SOAFP of ambient VOCs in the cities of Hangzhou, Guangzhou and Changchun are higher.     

Increasing the application of gas engines to decrease China’s GHG emissions

This paper employs a review of the technical literature to estimate the potential decrease in greenhouse gas (GHG) emissions that could be achieved by increasing the application of gas engines in China in three sectors: urban public transport vehicle; shipping; and thermal power plants. China’s gas engine development strategies and three types of gas resource are discussed in the study, which indicates that gas engines could decrease GHG emissions by 520 megatonnes (Mt) of carbon dioxide equivalent (CO_2e) by 2020. This would account for 9.7 % of the government’s target for decreasing GHG emissions and is dominated by methane recovery from the use of coal mine gas (CMG) and landfill gas (LFG) for power generation. In the public urban transport vehicle and shipping sectors the low price of natural gas and the increasing demand for the control of harmful emissions could spur the rapid uptake of gas engine vehicles. However, the development of CMG- and LFG-fuelled power plants has been limited by the unwillingness of local enterprises to invest in high-performance gas engine generators and the associated infrastructure. Therefore, further compulsory policies that promote CMG use and LFG recovery should be implemented. Moreover, strict regulations on limiting methane leakage during the production and distribution of gas fuels are urgently needed in China to prevent leakage causing GHG emissions and largely negating the climate benefits of fuel substitution. Strategies for increasing the application of gas engines, promoting gas resources and recovering methane in China are instrumental in global GHG mitigation strategies.     

遂宁市主城区环境空气质量现状及原因分析研究

利用遂宁市2017年1月份4个国控环境空气自动监测数据,分析了遂宁市主城区环境空气质量现状,与整个成渝地区和周边城市的空气质量进行了横向比较,并阐述了遂宁市空气质量变化的原因.结果发现遂宁市主城区2017年1月份空气质量指数的范围为32～203,优良率为54.8％,首要污染物为PM2.5,空气质量同比下降了22.8％,环比下降了26.1％,但均显著优于成渝地区和周边城市的平均水平,并从4个方面阐述了空气质量下降的原因.最后,根据遂宁市大气污染现状,提出了4条针对性的防治措施.     

土壤镉污染的现状及修复研究进展

镉是一种对人类和动物健康危害严重的重金属。土壤镉污染问题已经成为全球研究热点。重点分析了镉污染土壤中镉的来源,镉对动植物、人体的危害,并提出了对镉污染土壤的修复的方法。     

Adsorption of 2-mercaptobenzothiazole from aqueous solution by organo-bentonite

The adsorption behavior of 2-mercaptobenzothiazole onto organo-bentonite was investigated.Natural bentonite from Gaozhou in Guangdong Province,China was collected.Organo-bentonite was prepared by intercalation of cetyltrimethyl ammonium bromide into the natural bentonite.The physicochemical properties of the prepared organo-bentonite were characterized by X-ray diffraction,N2 adsorption-desorption isotherm and Fourier transform infrared spectroscopy.The results showed that montmorillonite is the main component of the natural bentonite.The basal spacing of the natural bentonite is 1.47 nm,which increased to 1.98 nm on intercalation with cetyltrimethyl ammonium bromide.Moreover,both the surface area and pore volume increased with intercalation.Clear CH2 stretching(3000-2800 cm-1) and scissoring(1480-1450 cm-1) modes of the intercalated surfactants were observed for organobentonite.Compared with the pseudo first-order kinetic model,the pseudo second-order kinetic model is more suitable to describe the adsorption kinetics of 2-mercaptobenzothiazole onto organo-bentonite.The adsorption capacity of 2-mercaptobenzothiazole onto organo-bentonite increased with increasing initial concentration of 2-mercaptobenzothiazole,but decreased with increasing adsorbent dosage.The adsorption isotherm of 2-mercaptobenzothiazole onto organo-bentonite fits well with the Langmuir model.The maximum adsorption capacity of organo-bentonite for 2-mercaptobenzothiazole was 33.61 mg/g,indicating that organo-bentonite is a promising adsorbent for 2-mercaptobenzothiazole.     

Supercritical water oxidation of polyvinyl alcohol and desizing wastewater：Influence of NaOH on the organic decomposition

Polyvinyl alcohol is a refractory compound widely used in industry. Here we report supercritical water oxidation of polyvinyl alcohol solution and desizing wastewater with and without sodium hydroxide addition. However, it is difficult to implement complete degradation of organics even though polyvinyl alcohol can readily crack under supercritical water treatment. Sodium hydroxide had a significant catalytic effect during the supercritical water oxidation of polyvinyl alcohol. It appears that the OH ion participated in the C-C bond cleavage of polyvinyl alcohol molecules, the CO2-capture reaction and the neutralization of intermediate organic acids, promoting the overall reactions moving in the forward direction. Acetaldehyde was a typical intermediate product during reaction. For supercritical water oxidation of desizing wastewater, a high destruction rate (98.25%) based on total organic carbon was achieved. In addition, cases where initial wastewater was alkaline were favorable for supercritical water oxidation treatment, but salt precipitation and blockage issues arising during the process need to be taken into account seriously.     

杭州市环境保护背景下的工业产业发展研究

通过对杭州市工业产业发展现状的调研,分析杭州市工业产业发展与环境保护之间存在的问题,制定产业发展的环境约束指标,引导发展符合资源节约型、环境友好型的产业,在保持经济高度增长的同时降低污染物排放,最终形成节约资源和保护环境的产业结构.杭州市在今后一段时期内,需进一步明确各区域产业发展重点,利用总量减排倒逼产业结构调整和优化升级,积极推进行业发展环境准入,区域建设项目环境准入,最终实现经济效益与生态效益的有机统一.     

城市排水系统沉积物特性研究

重点阐述了沉积物的来源和组成,沉积物的颗粒粒径、有机物含量(VSS/SS)、颗粒粘性和颗粒密度等物化性质,以及附着于沉积物上的金属污染物的相关特征。其粒度分布范围是D10为1.89～223.21μm,D50为12.38～437.30μm,D90为39.06～1 572.52μm;VSS/SS的范围是1%～38%;密度范围是1.80～2.47 g/cm3。金属污染物主要的附着对象是沉积物中的细小颗粒如生物膜上。以上沉积物性质对于解决排水系统的泥沙淤积问题以及水体污染的控制都具有重要意义。     

丁二烯缓冲罐自聚物的生成原因及防范措施

分析了ABS树脂生产装置丁二烯缓冲罐中丁二烯自聚物的生成原因,提出了预防措施,避免丁二烯自聚物的生成,保证装置的安全平稳运行。