Co-application of energy uncoupling and ultrafiltration in sludge treatment: Evaluations of sludge reduction,supernatant recovery and membrane fouling control

• Effects of metabolic uncouplers addition on sludge reduction were carried out. • TCS addition effectively inhibited ATP synthesis and reduced sludge yield. • The effluent quality such as TOC and ammonia deteriorated but not significantly. • Suitable dosage retarded biofouling during sludge water recovery by UF membrane. Energy uncoupling is often used for sludge reduction because it is easy to operate and does not require a significant amount of extra equipments (i.e. no additional tank required). However, over time the supernatant extracted using this method can deteriorate, ultimately requiring further treatment. The purpose of this study was to determine the effect of using a low-pressure ultrafiltration membrane process for sludge water recovery after the sludge had undergone an energy uncoupling treatment (using 3,3′,4′,5-tetrachlorosalicylanilide (TCS)). Energy uncoupling was found to break apart sludge floc by reducing extracellular polymeric substances (EPS) and adenosine triphosphate (ATP) content. Analysis of supernatant indicated that when energy uncoupling and membrane filtration were co-applied and the TCS dosage was below 30 mg/L, there was no significant deterioration in organic component removal. However, ammonia and phosphate concentrations were found to increase as the concentration of TCS added increased. Additionally, due to low sludge concentrations and EPS contents, addition of 30–60 mg/L TCS during sludge reduction increased the permeate flux (two times higher than the control) and decreased the hydraulic reversible and cake layer resistances. In contrast, high dosage of TCS aggravated membrane fouling by forming compact fouling layers. In general, this study found that the co-application of energy uncoupling and membrane filtration processes represents an effective alternative method for simultaneous sludge reduction and sludge supernatant recovery.     

Dechlorane plus (DP) in indoor and outdoor air of an urban city in South China: Implications for sources and human inhalation exposure

Dechlorane Plus (DP) is a chemical of emerging concern due to the restrictions on brominated flame retardant formulations. However, very little information is known about the occurrence of DP in indoor and outdoor air and its associated health risk to the exposed human population. In this study, we examined the concentrations and isomer profiles of DP in archived air samples collected from 14 homes, 6 offices, and 10 public microenvironments in Guangzhou, China in 2004–2005. The average (median) value of atmospheric ΣDP (sum of anti-DP and syn-DP) concentration in the three indoor air was 5.73 ± 5.33 (3.62) for offices, 8.08 ± 5.17 (6.87) for homes, and 57.27 ± 83.08 (32.58) pg/m³ for public microenvironments, respectively. ΣDP concentration was significantly higher in the public microenvironments than those in homes and offices. The arithmetic mean and median concentrations of ΣDP in outdoor air were 36.00 and 28.76 pg/m³, respectively. Spatially and temporally consistent indoor and outdoor samples comparison suggested that outdoor air might be a relevant source of DP for indoor air. Average anti-DP fractional abundance (f_anti = 0.65 ± 0.04) in all outdoor samples was similar to those reported in other studies and indistinguishable from that of the commercial mixture (f_anti = 0.65). In contrast, a relatively large variation of f_anti values was found in the indoor samples, suggesting a complex degradation process of DP existing in these microenvironments. The calculated average daily doses of ΣDP were in the range of 0.38–2.21 ng/day for people intake through air inhalation, which was in the same order of magnitude compared with other exposure pathways for the general publics.     

CeO_2/三维石墨烯催化臭氧氧化降解刚果红

采用原位氧化还原法制备了三维石墨烯负载型CeO_2催化剂(CeO_2/3D GN),采用XRD、FTIR、SEM、比表面积和零电荷点测定等方法对其进行了表征,并考察了CeO_2/3D GN非均相催化臭氧氧化降解水中刚果红染料的影响因素。表征结果显示:CeO_2/3D GN具有相互连通的三维网络结构;CeO_2纳米颗粒均匀地分散在石墨烯片层中;比表面积为190.89 m~2/g;零电荷点pH_(zpc)为7.36。实验结果表明:CeO_2/3D GN非均相催化臭氧氧化体系比单独臭氧氧化体系对刚果红溶液的脱色率提高了60.56百分点;连续5次重复利用CeO_2/3D GN,刚果红溶液脱色率为96.50%~98.00%;在臭氧流量为20 mg/min、催化剂投加量为1.5 g/L、初始溶液pH为7.00的最佳工艺条件下反应15 min,刚果红溶液脱色率可高达94.65%。     

Impact of three different fungicides on fungal epi- and endophytic communities of common bean (Phaseolus vulgaris) and broad bean (Vicia faba)

In this study, the impacts of three different fungicides to fungal phyllosphere communities on broad bean (Vicia faba, Fabaceae) and common bean (Phaseolus vulgaris, Fabaceae) were analyzed. The fungicides included copper, sulfur, and azoxystrobin. The plants were sowed, grown, and treated under conditions occurring in conventional and organic farming. A culture-based approach was used to identify changes in the phyllosphere fungal community after the treatment. Different effects on species richness and growth index of the epiphytic and endophytic communities for common bean and broad bean could be shown. Treatments with sulfur showed the weakest effect, followed by those based on copper and the systemic azoxystrobin, which showed the strongest effect especially on endophytic communities. The epiphytic fungal community took five weeks to recover after treatment with azoxystrobin. However, the effect of azoxystrobin on the endophytic community lasted more than five weeks. Finally, the data suggest that the surface structure of the host leaves have a huge impact on the mode of action that the fungicides exert.     

新标准促进安全鞋“走出去”——GB 21148-2020《足部防护安全鞋》解读

1 标准任务的来源 根据2016年强制性标准整合精简结论,对GB21148-2007《个体防护装备安全鞋》、GB 21147-2007《个体防护装备防护鞋》、GB 21146-2007《个体防护装备职业鞋》、GB 12011-2009《足部防护电绝缘鞋》4项标准提出整合修订,并继续作为强制性标准执行. 2017年12月...     

Kinetics of base-catalyzed dehydrochlorination of hexachlorocyclohexanes: I. Homogeneous systems

Base-catalyzed dehydrochlorination of alpha-, beta-, and gamma-hexachlorocyclohexane (HCH) was examined at different pH and temperature conditions. No reaction was observed for beta-HCH under all tested conditions likely due to the fact that all chlorines are at the equatorial positions. Highly pH- and temperature-dependent reaction rates were observed for alpha- and gamma-HCH, and pentachlorocyclohexenes (PCCHs) and 1,2,4- and 1,2,3-trichlorobenzene (TCB) were detected as the intermediates and final products of the transformation of both alpha- and gamma-HCH. The pseudo-first-order rate constants of each step of the reactions were calculated at different T and pH conditions. For the first step, the rate constants were at approximately 0.0005 d-1 in solutions below pH 7.0, and increased by about an order of magnitude per pH unit from pH 7.01 to pH 12.02. The second-order reaction rate constants (kb) of this step were 3.57+/-0.03 and 3.19+/-0.19 M-1 d-1, respectively, and the associated activation energies (Ea) at pH 9.26 were 60.4+/-7.8 and 67.7+/-8.7 kJ mol-1, respectively, for alpha- and gamma-HCH. The rate constants for the formation of 1,2,3-TCB (k21) and 1,2,4-TCB (k22) were 0.0032+/-0.0001 d-1 and 0.051+/-0.003 d-1 from alpha-HCH, and 0.0017+/-0.0001 d-1 and 0.0041+/-0.0002 d-1 from gamma-HCH at pH 8.28 and 25 degrees C. Both k21 and k22 also showed an increase by about one order of magnitude per pH unit from pH 8.28 to pH 12.02. The Ea values were 64.4+/-6.8 and 88.8+/-5.2 kJ mol-1, respectively, for the formation of 1,2,4-TCB and 1,2,3-TCB from alpha-HCH, and 70.6+/-8.7 and 92.0+/-4.9 kJ mol-1, respectively, for the formation of 1,2,4- and 1,2,3-TCB from gamma-HCH at pH 9.26. Data provided by this study may be used for calculation of the percentages of the TCBs formed at different environmental conditions.     

冲天炉烟气净化与余热利用系统的设计和应用

结合云南某公司10t/h冷风冲天炉烟气除尘脱硫和烟气余热利用的工程实例,介绍和分析了冲天炉烟气净化与余热利用系统工程设计中应注意的问题。     

电化学法消毒处理医院污水的试验研究

采用电化学法消毒处理医院污水,通过选用不同阳极材料构建的电化学体系,探讨电化学法的消毒机理.试验表明,以涂有贵金属(钌、铂和铱)氧化物的钛板作阳极,不锈钢板作阴极,在电流密度为8 mA/cm2、水力停留时间为15 min、空气流量为40L/h、极水比为1.0的试验条件下,消毒后污水中总大肠菌群数＜500 cfu/L,达到国家一级排放标准(GB8978-1996).     

Methods,fluxes and sources of gas phase alkyl nitrates in the coastal air

The daily and seasonal atmospheric concentrations, deposition fluxes and emission sources of a few C3–C9 gaseous alkyl nitrates (ANs) at the Belgian coast (De Haan) on the Southern North Sea were determined. An adapted sampler design for low- and high-volume air-sampling, optimized sample extraction and clean-up, as well as identification and quantification of ANs in air samples by means of gas chromatography mass spectrometry, are reported. The total concentrations of ANs ranged from 0.03 to 85 pptv and consisted primarily of the nitro-butane and nitro-pentane isomers. Air mass backward trajectories were calculated by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model to determine the influence of main air masses on AN levels in the air. The shorter chain ANs have been the most abundant in the Atlantic/Channel/UK air masses, while longer chain ANs prevailed in continental air. The overall mean N fluxes of the ANs were slightly higher for summer than those for winter-spring, although their contributions to the total nitrogen flux were low. High correlations between AN and HNO₂ levels were observed during winter/spring. During summer, the shorter chain ANs correlated well with precipitation. Source apportionment by means of principal component analysis indicated that most of the gas phase ANs could be attributed to traffic/combustion, secondary photochemical formation and biomass burning, although marine sources may also have been present and a contributing factor.     

Airborne particulate matter and BTEX in office environments

Total suspended particulate (TSP), PM(2.5) and BTEX were collected in nine offices in the province of Antwerp, Belgium. Both indoor and outdoor aerosol samples were analysed for their weight, elemental composition, and water-soluble fraction. Indoor TSP and PM(2.5) concentrations ranged from 7-31 microg m(-3) and 5-28 microg m(-3), with an average of 18 and 11 microg m(-3), respectively. Of all the elements analysed in indoor TSP, more than 95% was represented by Al, Si, K, Ca, Fe, Cl and S, accounting for 12% of the TSP by mass. The other elements showed significant enrichment relative to the earth's crust. The water-soluble ionic fraction accounted for almost 30% of the sampled indoor TSP by weight, and was enriched by anthropogenic activities. It was shown that the indoor PM levels varied among the offices, depending on the ventilation pattern, location, and occupation density of the office. Indoor BTEX levels ranged together from 5-47 microg m(-3) and were considerably higher than the corresponding outdoor levels. It was observed that some recently constructed and renovated buildings were clearly burdened with elevated levels for toluene, ethyl benzene, and xylenes, while outdoor air was found to be the main source for BTEX levels at the 'older' offices.