厌氧工艺对含铬(Ⅵ)废水处理效果初探

以砂石和活性炭作为填料,自制厌氧生物滤床系统,并对系统进行驯化,发现完成驯化后的稳定系统具有良好的去铬(Ⅵ)能力.废水在系统中经过2 h运行,加入碳源的试验组与不加碳源的对照组的铬(Ⅵ)去除率分别为87.33%和66.31%.恒流泵最佳流量为47 mL/min,外加碳源后,铬(Ⅵ)的浓度由60 mg/L左右降到0.5 mg/L以下,需要4 h,而对照组需要14 h,铬(Ⅵ)浓度由64.66 mg/L提高到 75.53 mg/L时,对本系统负面影响甚微,提高到95.47 mg/L时,系统出水达标所需时间延长到7.5 h.本系统具有耐受一定程度的浓度冲击以及进一步驯化、提高处理负荷的潜力.     

对加快推进我国矿山生态修复的思考

绿色矿山建设是矿业领域践行"绿水青山就是金山银山"的重要体现。本文从矿山生态修复的内涵到外延，从问题识别到任务措施，从单一治理修复目标到生态系统功能修复目标，从矿山生态修复系统到与经济社会发展系统相结合等多个方面，系统地梳理矿山生态修复的解决路径，围绕矿业绿色发展提出一系列建议。     

On the dissipation rate of temperature fluctuations in stably stratified flows

Environmental Fluid Mechanics - In this study, we explore several integral and outer length scales of turbulence which can be formulated by using the dissipation of temperature fluctuations (...     

Aerosol transmission,an indispensable route of COVID-19 spread: case study of a department-store cluster

• Aerosol transmission is an indispensable route of COVID-19 spread. • Different outbreak sites have different epidemiologic feature. • SRAS-CoV-2 can exist for a long time in aerosol. • SRAS-CoV-2 RNA can be detected in aerosol in diverse places. • Some environmental factors can impact SARS-CoV-2 transportation in aerosol. Patients with COVID-19 have revealed a massive outbreak around the world, leading to widespread concerns in global scope. Figuring out the transmission route of COVID-19 is necessary to control further spread. We analyzed the data of 43 patients in Baodi Department Store (China) to supplement the transmission route and epidemiological characteristics of COVID-19 in a cluster outbreak. Incubation median was estimated to endure 5.95 days (2–13 days). Almost 76.3% of patients sought medical attention immediately upon illness onset. The median period of illness onset to hospitalization and confirmation were 3.96 days (0–14) and 5.58 days (1–21), respectively. Patients with different cluster case could demonstrate unique epidemiological characteristics due to the particularity of outbreak sites. SRAS-CoV-2 can be released into the surrounding air through patient’s respiratory tract activities, and can exist for a long time for long-distance transportation. SRAS-CoV-2 RNA can be detected in aerosol in different sites, including isolation ward, general ward, outdoor, toilet, hallway, and crowded public area. Environmental factors influencing were analyzed and indicated that the SARS-CoV-2 transportation in aerosol was dependent on temperature, air humidity, ventilation rate and inactivating chemicals (ozone) content. As for the infection route of case numbers 2 to 6, 10, 13, 16, 17, 18, 20 and 23, we believe that aerosol transmission played a significant role in analyzing their exposure history and environmental conditions in Baodi Department Store. Aerosol transmission could occur in some cluster cases when the environmental factors are suitable, and it is an indispensable route of COVID-19 spread.     

降解和压缩作用下城市生活垃圾的持水量变化

在自制的城市生活垃圾降解-压缩-渗流仪中开展了5组持水量试验,分别研究不同温度和逐级递增应力条件下新鲜高厨余垃圾的持水量随时间的变化,新鲜高厨余、新鲜无厨余和基本降解垃圾的持水量随应力的变化.试验结果表明：在恒定应力条件下,新鲜高厨余垃圾的持水量随时间呈指数下降,即MRC=a-b（1-exp（-ct^d））;在应力10kPa和室温（0～27℃）条件下,持水量下降较慢（c=0.003,d=1.18）;在应力10kPa和恒温（40±3℃）条件下,持水量下降较快（c=0.173,d=0.601）;应力从50kPa逐级递增至100kPa、200kPa和400kPa后,持水量分别瞬时下降3.0%、2.3%和1.9%;新鲜高厨余、新鲜无厨余和基本降解垃圾的持水量均随应力的对数呈线性下降,即MRC=m-n×lg（σ）;当应力从10kPa增大至400kPa时,新鲜高厨余、基本降解和新鲜无厨余垃圾的持水量分别从63.0%、46.5%和37.9%下降至46.0%、35.3%和30.4%.通过对比分析国内外持水量试验结果,揭示了在相同应力条件下新鲜垃圾持水量随厨余含量的增加而增大、不同组分老垃圾持水量基本相同的规律.分析了生化降解和应力压缩对新鲜高厨余垃圾持水量的影响机理,并提出了增大新鲜高厨余垃圾脱水速率和脱水量的工程建议.     

Effects of freshwater leaching on potential bioavailability of heavy metals in tidal flat soils

Environmental Geochemistry and Health - Leaching experiments were conducted to investigate the effects of desalination levels and sediment depths on potential bioavailability of heavy metal (Cd,...     

邻苯二甲酸酯降解细菌的多样性、降解机理及环境应用

邻苯二甲酸酯(phthalic acid esters,PAEs)是一类对人体内分泌系统有干扰作用的持续性有机污染物(persistent organic pol utants,POPs)。PAEs在环境介质如水体、底泥和土壤中长期赋存会对生物体产生毒害效应,其分布广、浓度高和难降解等特点是限制有效环境治理的主要因素。作为环境的重要组成部分,微生物对污染物有很强的适应能力和高效的降解能力,这为PAEs的生物修复提供了可能。与物理化学修复法相比,微生物修复技术具有可控性强、修复面广和灵活性高等优势。本文综述了已报道的大部分PAEs降解细菌的种类及其代谢机制,并分析了其在PAEs污染水体和土壤修复中的应用现状与前景,以期为PAEs环境行为与生物修复研究提供参考。     

Changes of microbial composition during wastewater reclamation and distribution systems revealed by high-throughput sequencing analyses

This study employed 454-pyrosequencing to investigate microbial and pathogenic communities in two wastewater reclamation and distribution systems. A total of 11972 effective 16S rRNA sequences were acquired from these two reclamation systems, and then designated to relevant taxonomic ranks by using RDP classifier. The Chao index and Shannon diversity index showed that the diversities of microbial communities decreased along wastewater reclamation processes. Proteobacteria was the most dominant phylum in reclaimed water after disinfection, which accounted for 83% and 88% in two systems, respectively. Human opportunistic pathogens, including Clostridium, Escherichia, Shigella, Pseudomonas and Mycobacterium, were selected and enriched by disinfection processes. The total chlorine and nutrients (TOC, NH₃-N and NO₃-N) significantly affected the microbial and pathogenic communities during reclaimed water storage and distribution processes. Our results indicated that the disinfectant-resistant pathogens should be controlled in reclaimed water, since the increases in relative abundances of pathogenic bacteria after disinfection implicate the potential public health associated with reclaimed water.     

Effect of salinity on community structure and naphthalene dioxygenase gene diversity of a halophilic bacterial consortium

The aim of this study is to analyze the effect of salinity on polycyclic aromatic hydrocarbons (PAHs) biodegradation, community structure and naphthalene dioxygenase gene (ndo) diversity of a halophilic bacterial consortium with the denaturing gradient gel electrophoresis (DGGE) approach. The consortium was developed from oil-contaminated saline soil after enrichment for six times, using phenanthrene as the substrate. The prominent species in the bacterial consortium at all salinities were identified as halophilic bacteria Halomonas, Alcanivorax, Marinobacter, Idiomarina, Martelella and uncultured bacteria. The predominant microbes gradually changed associating with the saline concentration fluctuations ranging from 0.1% to 25% (w/v). Two ndo alpha subunits were dominant at salinities ranging from 0.1% to 20%, while not been clearly detected at 25% salinity. Consistently, the biodegradation occurred at salinities ranging from 0.1% to 20%, while no at 25% salinity, suggesting the two ndo genes played an important role in the degradation. The phylogenetic analysis revealed that both of the two ndo alpha subunits were related to the classic nah-like gene from Pseudomonas stutzeri AN10 and Pseudomonas aeruginosa PaK1, while one with identity of about 82% and the other one with identity of 90% at amino acid sequence level. We concluded that salinity greatly affected halophilic bacterial community structure and also the functional genes which were more related to biodegradation.

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Simple model of sludge thickening process in secondary settlers

In wastewater treatment plants (WWTPs), a secondary settler acts as a clarifier, sludge thickener, and sludge storage tank during peak flows and therefore plays an important role in the performance of the activated sludge process. Sludge thickening occurs in the lower portions of secondary clarifiers during their operation. In this study, by detecting the hindered zone from the complete thickening process of activated sludge, a simple model for the sludge thickening velocity, u _s = aX ^b (a = 0.9925SSVI _3.5, b = 3.541ln(SSVI _3.5)+12.973), describing the potential and performance of activated sludge thickening in the hindered zone was developed. However, sludge thickening in the compression zone was not studied because sludge in the compression zone showed limited thickening. This empirical model was developed using batch settling data obtained from four WWTPs and validated using measured data from a fifth WWTP to better study sludge thickening. To explore different sludge settling and thickening mechanisms, the curves of sludge thickening and sludge settling were compared. Finally, it was found that several factors including temperature, stirring, initial depth, and polymer conditioning can lead to highly concentrated return sludge and biomass in a biologic reactor.