Reduction and characterization of bioaerosols in a wastewater treatment station via ventilation

Bioaerosols from wastewater treatment processes are a significant subgroup of atmospheric aerosols. In the present study,airborne microorganisms generated from a wastewater treatment station(WWTS) that uses an oxidation ditch process were diminished by ventilation.Conventional sampling and detection methods combined with cloning/sequencing techniques were applied to determine the groups,concentrations,size distributions,and species diversity of airborne microorganisms before and after ventilation. There were 3021 ± 537 CFU/m3 of airborne bacteria and 926 ± 132 CFU/m3 of airborne fungi present in the WWTS bioaerosol.Results showed that the ventilation reduced airborne microorganisms significantly compared to the air in the WWTS. Over 60% of airborne bacteria and airborne fungi could be reduced after4 hr of air exchange. The highest removal(92.1% for airborne bacteria and 89.1% for fungi) was achieved for 0.65–1.1 μm sized particles. The bioaerosol particles over 4.7 μm were also reduced effectively. Large particles tended to be lost by gravitational settling and small particles were generally carried away,which led to the relatively easy reduction of bioaerosol particles0.65–1.1 μm and over 4.7 μm in size. An obvious variation occurred in the structure of the bacterial communities when ventilation was applied to control the airborne microorganisms in enclosed spaces.     

Electrocatalytic oxidation of PCP-Na by a novel nano-PbO2 anode: degradation mechanism and toxicity assessment

Environmental Science and Pollution Research - This study aims at investigating the electrocatalytic oxidation of sodium pentachlorophenate (PCP-Na) using a novel nano-PbO2 powder anode. The...     

软锰矿浆烟气同步脱硫脱硝资源化利用新工艺

燃煤烟气中的SO2和NOx是大气中重要的污染物,开发高效、经济的同步脱硫脱硝技术是环保领域的研究热点。针对现有同步脱硫脱硝技术存在的氧化剂成本较高和产物不能资源化利用等突出问题,提出了软锰矿浆烟气同步脱硫脱硝,并副产硫酸锰和硝酸锰的资源化新工艺。研究结果表明:软锰矿浆可以有效的脱除烟气中的SO2和NOx,反应产物分别为硫酸锰和硝酸锰。在烟道中注入臭氧,将难溶于水的NO快速氧化为NO2,可大大提高脱硝效率,在O3/NO=1.2的条件下可以达到72%的脱硝率、90%的脱硫率和85%的锰浸出率;吸收液经过空气氧化除铁和加入铜试剂除重金属后,结晶分离溶液得到的硫酸锰和硝酸锰可分别达到HG/T 2962—1999标准的硫酸锰产品和HG/T 3817—2006标准的工业硝酸锰产品要求。该工艺实现了SO2和NOx污染治理与低品位软锰矿资源化利用的双重目的,为SO2和NOx的资源化污染治理技术的开发和应用提供了新的思路。     

Spatiotemporal variations of dissolved organic matter in a typical multi-source watershed in northern China: a fluorescent evidence

Environmental Science and Pollution Research - The amount of dissolved organic matter (DOM) in a multi-source watershed is important for complete management and assessing the river basin’s...     

低盐度对EGSB厌氧氨氧化反应器启动和运行的影响

考察了低盐度(以NaCl计,w/v)对厌氧氨氧化反应器启动和运行的影响。在水力停留时间为11 h的条件下,以普通活性污泥为接种污泥,分别以进水盐度为8 g/L和进水不含盐度启动并运行厌氧氨氧化反应器。结果表明,进水含有盐度和进水不含盐反应器启动时间分别为125 d和107 d,总氮去除率分别为(73.0±13.9)%和(78.4±3.7)%。运行阶段,进水含有盐度反应器总氮去除率始终低于进水不含盐度反应器。随回流比提升,两反应器颗粒污泥中值粒径增大。在不同回流比条件下,进水含有盐度反应器颗粒污泥中值粒径均小于进水不含盐度反应器。当回流比为7时,进水含有盐度反应器颗粒污泥EPS中多糖、蛋白质和腐殖质的含量均低于进水不含盐度反应器。两反应器EPS多糖与蛋白质的比值分别为2.8和3.1。低盐度对EGSB厌氧氨氧化反应器的启动、运行和颗粒污泥的形成有一定的影响。     

钛基锡锑阳极电化学氧化去除水中的四环素

以钛基锡锑电极为阳极,研究了电化学氧化技术对水中四环素的去除效果。考察了电流密度(5~25 mA·cm-2)、极板间距(5~25 mm)、四环素初始浓度(5~100 mg·L-1)和电解质种类(NaClO4、Na2SO4和NaNO3)对四环素电化学降解效率的影响。研究表明:钛基锡锑电极电化学降解四环素反应符合一级反应动力学规律(R2>0.95);四环素降解效率随电流密度增大而增大,当电流密度大于15 mA·cm-2时,四环素的降解反应受传质控制;四环素降解效率随极板间距增大而减小,在传质控制条件下,反应速率与极板间距成反比;初始浓度小于20 mg·L-1时,受传质影响,四环素降解效率基本不随初始浓度变化,当初始浓度大于20 mg·L-1时,四环素降解效率随初始浓度增大而减小;Na2SO4为电化学降解水中四环素较合适的电解质。     

高镍杂铜低温生产电解铜粉试验

用杂铜电解生产铜粉时，电解液的温度一般可控制在２０￣６０℃。本文介绍了在３０℃较低温度和６００￣１２００Ａ／ｍ＾２的较低电流密度下，用杂铜电解生产铜粉的试验过程。试验结果表明：低温和低铜离子浓度对生产细粒铜粉有利，而料低电流密度在保证铜粉粒度的情况下，对节约电能有利。     

A review on analytical methods for pharmaceutical and personal care products and their transformation products

Pharmaceutical and personal care products (PPCPs) and corresponding transformation products have caused widespread concern due to their persistent emissions and potential toxicity. They have wide octanol-water partition coefficients (K_ow) and different ionization constants (pK_a) resulting in a poor analysis accuracy and efficiency. A suitable analytical method is the first prerequisite for further research on their environmental behavior to prioritize the substances. This study reviewed a full-scale analytical protocol for environmental samples in the recent ten years: from sampling to instrumental methods. Passive sampling techniques were compared and recommended for long-term continuous and scientific observation. A quick and effective sample extraction and clean-up method are highly required. Chromatographic methods coupled to mass spectrometry for determining PPCPs with a wide range of logK_ow (?7.53 to 10.80) were summed up. High-resolution mass spectrometry was confirmed to be a promising strategy for screening unknown transformation products, which would provide a nanogram level of detection limits and more accurate mass resolution. Screening strategies and mass change principles were summarized in detail. The recovery rate was important in multiple contaminants analysis identification and factors affecting the recovery rate of PPCPs were also discussed in this review, including sample matrix, target compounds characteristics, extraction method and solid-phase adsorbent. This review provides useful information for the selection of appropriate analytical methods and future development directions.     

软锰矿浆烟气同步脱硫脱硝尾液氧化除铁的研究

软锰矿浆烟气同步脱硫脱硝尾液中的铁离子杂质会影响后面的硫酸锰、硝酸锰产品的纯度,而铁离子主要以Fe2+的形式存在,因此必须先将Fe2-氧化成Fe3+以Fe(OH),的形式除铁.对空气、双氧水和二氧化锰三种氧化剂进行了投加量、pH值、反应时间等操作参数对氧化除铁效果影响的对比实验研究.结果表明,空气为性价比较高的氧化剂.     

Adsorption behavior of imidacloprid pesticide on polar microplastics under environmental conditions: critical role of photo-aging

● Small molecular chains formed on photo-aged polylactic acid microplastics (MPs). ● Oxygen-containing functional groups generated on photo-aged polyamide MPs. ● Photo-aging has the opposite influence on the imidacloprid adsorption on two MPs. ● Electrostatic interactions and hydrogen bonds were the main mechanisms. ● High pH value and low ionic strength increase the adsorption capacity. The photo-aging behavior of microplastics (MPs) in natural environment has become a global concern. The ultraviolet radiation has enough energy to change the polymer structure and physical-chemical properties of MPs. Less attention has focused on the interactions of the photo-aged polar and biodegradable MPs with organic pollutants. This work investigated the structural properties of aged polar polyamide (PA) MPs and biodegradable polylactic acid (PLA) MPs exposed to ultraviolet irradiation and their adsorption behavior and mechanism for neonicotinoid insecticide imidacloprid (IMI). The results showed that the MPs had extensive changes in surface morphology and chemical properties after photo-aging. The C–N bond of PA MPs was disrupted to form more carbonyl groups. The oxygen-containing functional groups on the surface of aged PLA MPs were broken and generated relatively smaller molecules. The adsorption capacity of IMI on PA MPs decreased by 19.2 %, while the adsorption capacity of IMI on PLA MPs increased by 41.2 % after photo-aging. This depended on the natural structure of the MPs and their ability to absorb ultraviolet light. The electrostatic interactions, hydrogen bonds, van der Waals interactions, and polar-polar interactions were the main adsorption mechanisms of IMI on MPs. High initial solution pH and low ionic strength favored the adsorption of IMI by altering charge distribution on the MPs surface. The formation of the humic acid-IMI complexes decreased the concentration of IMI in the water phase and further decreased the adsorption on MPs. These results are enlightening for a scientific comprehension of the environmental behavior of the polar MPs.