Investigating measurements of fine particle (PM2.5) emissions from the cooking of meals and mitigating exposure using a cooker hood

There is growing awareness that indoor exposure to particulate matter with diameter ≤ 2.5 μm (PM_2.5) is associated with an increased risk of adverse health effects. Cooking is a key indoor source of PM_2.5 and an activity conducted daily in most homes. Population scale models can predict occupant exposures to PM_2.5, but these predictions are sensitive to the emission rates used. Reported emission rates are highly variable and are typically for the cooking of single ingredients and not full meals. Accordingly, there is a need to assess PM_2.5 emissions from the cooking of complete meals. Mean PM_2.5 emission rates and source strengths were measured for four complete meals. Temporal PM_2.5 concentrations and particle size distributions were recorded using an optical particle counter (OPC), and gravimetric sampling was used to determine calibration factors. Mean emission rates and source strengths varied between 0.54—3.7 mg/min and 15—68 mg, respectively, with 95% confidence. Using a cooker hood (apparent capture efficiency > 90%) and frying in non‐stick pans were found to significantly reduce emissions. OPC calibration factors varied between 1.5 and 5.0 showing that a single value cannot be used for all meals and that gravimetric sampling is necessary when measuring PM_2.5 concentrations in kitchens.     

酸性废水中As(Ⅲ)、Cu(Ⅱ)与铁粉的反应行为

在Fe-As(Ⅲ)-Cu(Ⅱ)-H₂O体系中, 研究了酸性废水中As(Ⅲ)、Cu(Ⅱ)与金属铁粉的反应行为, 考察了反应过程中As在气、液、固三相中的分配比。结果表明, As(Ⅲ)和Cu(Ⅱ)离子被Fe还原为单质As和Cu后, As、Cu进一步结合成Cu₅As₂等金属间化合物, 从而促进As(Ⅲ)沉淀反应的发生, 且无AsH3生成。在反应时间40min、铁粉过量系数1.2、溶液初始pH=0.0、温度40 ℃、Cu/As摩尔比1.0条件下, As在气、液、固三相中的分配比分别为0、20.7%和79.3%, 沉砷率为79.3%。     

V2O5/RGO/Pt nanocomposite on oxytetracycline degradation and pharmaceutical effluent detoxification

The cover image is based on the Research Article V₂O₅/RGO/Pt nanocomposite on oxytetracycline degradation and pharmaceutical effluent detoxification by Mohan, H et al., DOI: 10.1002/jctb.6238 .

     

Performance optimization of microbial electrolysis cell (MEC) for palm oil mill effluent (POME) wastewater treatment and sustainable Bio-H2 production using response surface methodology (RSM)

Microbial electrolysis cells (MECs) are a new bio-electrochemical method for converting organic matter to hydrogen gas (H₂). Palm oil mill effluent (POME) is hazardous wastewater that is mostly formed during the crude oil extraction process in the palm oil industry. In the present study, POME was used in the MEC system for hydrogen generation as a feasible treatment technology. To enhance biohydrogen generation from POME in the MEC, an empirical model was generated using response surface methodology (RSM). A central composite design (CCD) was utilized to perform twenty experimental runs of MEC given three important variables, namely incubation temperature, initial pH, and influent dilution rate. Experimental results from CCD showed that an average value of 1.16 m³ H₂/m³ d for maximum hydrogen production rate (HPR) was produced. A second-order polynomial model was adjusted to the experimental results from CCD. The regression model showed that the quadratic term of all variables tested had a highly significant effect (P < 0.01) on maximum HPR as a defined response. The analysis of the empirical model revealed that the optimal conditions for maximum HPR were incubation temperature, initial pH, and influent dilution rate of 30.23 ^°C, 6.63, and 50.71%, respectively. Generated regression model predicted a maximum HPR of 1.1659 m³ H₂/m³ d could be generated under optimum conditions. Confirmation experimentation was conducted in the optimal conditions determined. Experimental results of the validation test showed that a maximum HPR of 1.1747 m³ H₂/m³ d was produced.     

Degradation studies of epoxy coatings on printed circuit boards after pressure cooker test

The present work focuses on the investigation of the degradation of screen-printed epoxy coatings on printed circuit boards under multiple corrosion loads realized by the pressure cooker test (PCT). Since methods like the common mechanical shear strength tests are destructive and limited in information, the authors' approach used electrochemical impedance spectroscopy to study the change of their electrochemical behavior and the state of degradation. Complementarily, the Fourier-transformed infrared spectroscopy was used to investigate the possible molecular change of the polymer due to the exposition. The experiments were carried out after different times of load. It could be shown that the complex conditions of the PCT initiate a controversial mechanism. The harsh corrosion load already results in a degradation of the polymer after 8 h but simultaneously the enhanced test temperature leads to ongoing curing processes consuming the remaining parts of resin and curing agents. As a result, the degradation kinetic seems to be delayed and after the test time of 96 h, the epoxy is less degraded than it was expected based on the results after a shorter time exposition.     

Economical treatment of reverse osmosis reject of textile industry effluent by electrodialysis–evaporation integrated process

Membrane separation methods such as electrodialysis (ED) can reduce the volume load on evaporators by facilitating further concentration of rejects from reverse osmosis (RO) plants. ED studies were carried out on a bench-scale system using five membrane cell pairs to obtain a textile effluent concentrate containing approximately 6 times the quantity of salts present in the RO reject. The limiting current densities were determined to be in the range 2.15–3.35 amp/m² for feed flow rates varying from 18 to 108 L/h. Apart from feed rate, the influence of volume of concentrate and current on membrane performance was evaluated to optimize current utilization. An estimation of energy requirement of an integrated process constituting ED and evaporation for concentration of inorganics present in textile effluent from 4.35% to 24% was made and found to be approximately one eighth of the operating cost incurred by evaporation alone. Detailed design of a commercial ED system revealed that a membrane area of 13.1 m² was required to treat a feed rate of 1500 L/h. The payback period to recover capital investment was found to be 110 days.     

三维电极法处理印染废水二级出水的试验研究

印染废水二级出水中含有难生物降解的有毒有害物质,国家和地方制定了日益严格的污染物排放标准。这就要求企业对二级出水进行深度处理,实现废水重复利用。文章以广州某印染废水处理厂的二级出水为研究对象,利用三维电极法进行CODCr去除试验,考察了电解时间、直流电压、进水pH及曝气量对CODCr去除率的影响。试验表明:三维电极法对印染废水二级出水CODCr有良好的去除效果:当电解时间为15 min、直流电压为28 V、进水pH为3.5、曝气量为一般强度时,出水CODCr浓度可从88 mg/L降低到37 mg/L,对应的去除率为57.9%。     

我国油田废水处理工艺的现状及研究进展

油田废水处理中包括回注水处理,稠油油田采出水回用注汽锅炉处理,油田外排水处理三大应用方向。本文从油田回注水除油除悬浮物,稠油废水阻垢缓蚀、脱硫消毒,生物法处理油田外排水几个方面介绍了国内外油田废水处理的新技术、工程实例及发展方向。     

600（300）MW机组加热器系统事故分析和处理措施

分析了一例哈尔滨汽轮机厂汽轮机3#高加加热器疏水液位高、正常疏水管路振动的原因,针对类似情况,从高加疏水系统设备结构、系统运行方式等方面提出了相应的解决措施,解决了疏水管路的振动,保证了机组安全经济运行.并对另一例哈尔滨汽轮机厂600 MW机组轴封加热器水侧管束破裂,凝结水大量进入轴封加热器汽侧,满水后,进入轴封系统,进入汽轮机事故进行分析,提出轴封系统及其他系统如何进行排查,系统设置中存在类似的问题,采取相应措施进行整改的具体方法进行了介绍.