垃圾填埋场微生物气溶胶粒径分布研究

为了了解垃圾填埋场微生物气溶胶粒径分布规律,在北京市某垃圾卫生填埋场填埋区、渗滤液处理区、生活区分别选定监测点,利用安德森六级微生物采样器,对填埋场空气微生物进行了系统的定点取样、测定和分析。研究结果表明,空气细菌粒径分布均为第Ⅰ级(>8.2 μm)最高,填埋区空气细菌粒径呈偏态分布,渗滤液处理区、生活区分别在第Ⅳ级和第Ⅲ级出现第2个峰值。携带细菌的可吸入微粒在渗滤液处理区比例最大。空气真菌与放线菌均在第Ⅳ级分布最高,携带真菌和放线菌的可吸入粒子的比例显著大于细菌(P<0.05)。填埋区不同作业时段空气微生物粒径在各级分布比例基本一致。填埋区细菌气溶胶中值直径为5.7 μm,渗滤液处理区为3.7 μm,生活区为5.3 μm,显著大于真菌气溶胶和放线菌气溶胶的中值直径(P<0.05)。     

北京市某城市污水处理厂微生物气溶胶污染特性研究

以北京市某城市污水处理厂的格栅间、曝气池、污泥浓缩池和污泥脱水间为对象,研究不同功能区的空气微生物浓度、粒径分布及微生物组成.结果表明:(1)该污水处理厂4个功能区空气异养细菌浓度平均值为3.3×104cfu/m3,范围为1.0×102～4.3×105cfu/m3;真菌浓度平均值为6.1×103cfu/m3,范围为7.5×10～7.6×104cfu/m3.异养细菌和真菌浓度存在显著性差异,尤以曝气池上空最高,其次是污泥脱水间,浓度最低的区域为格栅间和污泥浓缩池.各功能区均存在不同程度的异养细菌和真菌污染.(2)该污水处理厂不同功能区逸散出的异养细菌分布比例最高的为第2～5级,真菌主要分布在第3～5级.4个功能区空气中粒径为2.10～4.70μm(第3、4级)的异养细菌和真菌粒子分别占到了总数的37％～40％和46％～56％,而粒径为0.65～2.10μm(第5、6级)的异养细菌和真菌粒子则分别占到了总数的30％～33％和31％～37％,说明该污水处理厂不同功能区内的空气微生物存在一定的健康风险,可能对人呼吸道构成感染威胁.(3)假单孢菌(Pseudomonas)为该污水处理厂不同功能区均检出的优势异养细菌,而优势真菌种属为毛霉(Mucor)和曲霉(Aspergillus).     

种植不同植物的表面流人工湿地净化效果和微生物群落差异分析

为了解植物种类对表面流人工湿地的净化效果的影响及其与微生物群落的关系,研究了4种植物条件下表面流人工湿地的氮磷平衡以及微生物群落结构。结果表明,各组人工湿地对氨氮(45.53%～80.95%)、总氮(53.67%～80.30%)和总磷(32.97%～55.77%)都有较好的处理效果,种植植物的人工湿地比未种植的人工湿地具有更高的氨氮、总氮和总磷去除效果,其中黄菖蒲组对氮的去除效果最好,美人蕉组对磷的去除效果最好。在表面流人工湿地中,微生物作用(34.84%～45.44%)是人工湿地氮去除的主要途径,基质吸附(20.90%～23.91%)是人工湿地磷去除的主要途径,但是种植植物的人工湿地的氮磷通过微生物去除的量更高。高通量测序分析表明,相较于未种植植物的人工湿地,种植植物的人工湿地显示出更高的微生物丰富度、多样性和更高的脱氮除磷功能微生物的丰度。假单胞菌属、不动杆菌属、芽孢杆菌属和硝化螺菌属是人工湿地中主要的脱氮菌属,也是种植植物的人工湿地高生物脱氮的原因。假单胞菌属和不动杆菌属丰度增加是种植植物的人工湿地高生物除磷的原因。     

垂直潜流人工湿地有机物积累及去向初步分析

为防治湿地堵塞、改善湿地处理效果,初步探讨了湿地中有机物的积累规律,并估算湿地中有机物不同去除途径的贡献率。结果表明,垂直潜流人工湿地中基质间积累的有机物主要是不可溶有机物,且粒径主要集中在5.00μm以上,分析是不同粒径有机物凝聚积累的缘故;垂向沿程基质间有机物的积累量受进水水力负荷影响明显;进入垂直潜流人工湿地中的有机物绝大部分都被生物(植物和微生物)吸收和利用而得以去除,该途径贡献率可达99.9%以上。     

多层介质水平潜流人工湿地对微塑料的去除研究

以具有相同结构的两个多层介质水平潜流人工湿地为研究对象,考察了湿地单元进水、出水和植物根系附近的微塑料丰度、物理尺寸变化特征,并分析了湿地内部植物根系、湿地生物系统、悬浮物等去除微塑料的机理。结果表明,近年来在河道水质提升工程中常使用的较大粒径多层介质人工湿地能够有效降低天然河流水体中的微塑料丰度。在连续7 d的监测中,两个湿地单元对微塑料的平均去除率分别为26.91%和27.00%,最高分别达到了44.83%和44.59%。湿地单元对400～<800μm的微塑料去除率在20%～50%,而对800～<1 200μm和≥1 200μm的较大尺寸微塑料去除率可达到50%以上。湿地单元前部的植物根系对微塑料具有更明显的截留作用,且对≥800μm的较大尺寸微塑料截留效率更佳。人工湿地去除微塑料的效率可能与微塑料形状、湿地植物、水流速度、内部填料粒径及生物膜生长状况等多种因素有关。     

基质粒径与排空时间对潮汐流人工湿地运行效能的影响

潮汐运行是强化人工湿地供氧的一种有效途径。为了解基质粒径对潮汐流人工湿地(TFCWs)处理效果及复氧过程的影响,研究了不同基质粒径TFCWs的处理性能,建立了TFCWs排空期氧转移过程的研究方法。结果表明基质粒径影响湿地对NH4+的吸附性及排空期基质孔隙氧体积占比进而影响处理效果,7～9 mm基质粒径的湿地达到最佳的氨氮去除率82.6%,3～5 mm基质粒径的湿地达到最佳的COD去除率88.2%,粒径基质小的湿地中氨氧化菌属和反硝化菌属的相对丰度更高,脱氮能力强;分析排空期基质孔隙氧体积占比变化与湿地微生物耗氧过程的联系,能够优化潮汐流湿地系统的排空时间,湿地微生物的耗氧活动主要集中在氧体积占比快速下降阶段,更长的排空时间对复氧能力没有明显提升,本研究中8 h的排空时间即可满足湿地系统的氧需求。     

城市固体废弃物综合处理厂微生物气溶胶污染特性

以鄂尔多斯市某城市固体废弃物综合处理厂的生活垃圾预处理区、餐厨预处理区、粪便预处理区及联合厌氧发酵区为对象,研究不同功能区的微生物气溶胶污染特性。研究结果表明,不同功能区空气异养细菌和真菌的浓度存在显著性差异(p<0.05),尤以生活垃圾集料间产生的异养细菌和真菌浓度最高。对照空气微生物评价标准,不同功能区产生的异养细菌和真菌大都有不同程度的污染。粒径分析表明,不同功能区异养细菌粒径主要集中在第1、2、3、4级,各功能区之间无显著性差异(p>0.05),与细菌粒径分布不同,不同功能区真菌粒径主要分布在第3级和第4级,也无明显差异(p>0.05)。     

二氧化钛气溶胶颗粒在石英玻璃纤维上的沉积

利用雾化挥发发生原理制备二氧化钛气溶胶,将二氧化钛气溶胶颗粒负载在石英玻璃纤维上,制备二氧化钛-石英玻璃纤维功能性空气过滤材料。实验研究了二氧化钛气溶胶发生相关参数、石英玻璃纤维直径分布、透过率曲线、最易透过粒径,并对二氧化钛气溶胶颗粒在石英玻璃纤维上的负载过程和负载形态进行了探讨。研究结果表明,发生的二氧化钛气溶胶具有可控的粒径分布和较好的分散性;中值粒径128 nm的二氧化钛气溶胶颗粒能够稳定负载在3μm的石英玻璃纤维上;二氧化钛在石英玻璃纤维上的沉积量受沉积时间的影响,沉积过程中阻力开始变化不大,随后在沉积饱和点后阻力迅速增大,滤料填充度越高沉积饱和点出现时间越早;二氧化钛粒子在纤维表面的负载形态除颗粒、团簇外,还有三维的树枝状空间结构。     

人工湿地中氨化细菌去除有机氮的效果

人工湿地去除有机氮主要由于氨化细菌的作用.为了了解人工湿地中氨化细菌去除有机氮的效果,对人工湿地基质中5株氮化细菌进行了初步鉴定,比较了不同氨化细菌去除有机氮的效果,氨化细菌去除有机氮的量通过其生成的NH4< >-N来衡量.结果表明,芽孢杆菌属(Bacillus)、假单胞菌属(Pseudomonas)为人工湿地中氧化细菌的优势菌属;氨化细蒲-1、氨化细菌-2及氨化细菌-5对有机氮的去除效果相对较好,分别达到46.2%、49.4%和52.6%.添加沸石对玄除氨氮有明显效果,从而能够提高有机氮的去除率.     

生物滤池高径比对其去除恶臭物质和微生物气溶胶特性的影响

为研究生物滤池不同高径比对恶臭物质(H2S、NH3)和微生物气溶胶(细菌和真菌)的去除率影响,设计了不同高径比(1∶1、2∶1、4∶1、6∶1和8∶1)的生物滤池,研究其处理效果。结果表明:(1)H2S和NH3的去除率均随生物滤池高径比的增大而升高,高径比为8∶1时不同气体停留时间下的H2S和NH3去除率均最高。(2)细菌和真菌的去除率也均随高径比的增大而升高,也是高径比为8∶1时不同气体停留时间下的细菌和真菌去除率均最高。(3)生物滤池高径比较小时,细菌和真菌的粒径相对较小;而生物滤池高径比较大时,细菌和真菌的粒径相对较大。由此可见,增大生物滤池高径比可以有效提高恶臭物质和微生物气溶胶的去除率,减少小粒径的微生物气溶胶排放,最佳高径比为8∶1。     

Size distributions of airborne microbes in moisture-damaged and reference school buildings of two construction types

Any risk assessment of moisture-damaged buildings requires an accurate characterization of the factors contributing to the human exposure. In this study, the size distributions of indoor air viable fungi and bacteria and average mean diameters of the most common fungi in school buildings were determined. One special focus was to analyze how the microbial size distributions are affected by the building frame (either wooden or concrete) and moisture damage in the building. The study was performed in 32 school buildings classified as moisture-damaged (index) and non-damaged (reference) schools according to technical building investigations. Sampling for indoor air microbes was carried out using a cascade impactor that collects particles on six stages (range from 0.65 to >7 μm) according to their aerodynamic diameters. Both wooden and concrete schools had their highest fungal levels in the size range of 1.1–4.7 μm. However, the concentrations of fungi in all size classes were higher in wooden schools than in concrete schools. Moisture damage-associated differences in size distribution, in the particle size range of 1.1–2.1 μm, were seen in concrete schools but not in wooden schools. In general, the average geometric mean diameter (d_g,ave) of total viable fungi was smaller in wooden schools than in concrete schools, and smaller in index schools of both construction types than in their reference schools. Variation in particle size, however, by genus was observed. No differences in particle size distributions of viable airborne bacteria were found. Our results on the dependency of the particle size on the building type and presence of moisture damage provide an interesting point to be considered in assessing the complex issue of indoor-related bioaerosol exposures.     

Bioaerosol Concentration at an Outdoor Composting Center

ABSTRACT

Compost centers are one of many environments that produce airborne microorganisms. The objective of this study was to compare the bacterial, fungal, and acti-nomycete concentrations at the Norman, OK, compost center to background concentration of these same microorganisms. For this comparison, a modified Andersen Microbial Sampler was used. Sampling was performed at three sites at the outdoor compost center and at two background sites. The concentration of each microorganism was measured as total colony forming units per cubic meter (CFU/m³). The predominantly downwind compost center site had a 10-fold increase in all the microorganisms in comparison with the other sites (p < 0.05). The median concentrations (95% confidence interval) of total viable bacteria, Gram-negative bacteria, fungi, and actinomycetes at this site were 5059 (CI₉₅= 4952-9600) CFU/m³, 2023 (CI₉₅= 2586-6806) CFU/m³, 972 (CI₉₅= 964-1943) CFU/m³, and 2159 (CI₉₅= 1755-4190) CFU/m³, respectively.     

Simultaneous monitoring of SARS-CoV-2, bacteria,and fungi in indoor air of hospital: a study on Hajar Hospital in Shahrekord,Iran

The novel SARS-CoV-2 outbreak was declared as pandemic by the World Health Organization (WHO) on March 11, 2020. Understanding the airborne route of SARS-CoV-2 transmission is essential for infection prevention and control. In this study, a total of 107 indoor air samples (45 SARS-CoV-2, 62 bacteria, and fungi) were collected from different wards of the Hajar Hospital in Shahrekord, Iran. Simultaneously, bacterial and fungal samples were also collected from the ambient air of hospital yard. Overall, 6 positive air samples were detected in the infectious 1 and infectious 2 wards, intensive care unit (ICU), computed tomography (CT) scan, respiratory patients’ clinic, and personal protective equipment (PPE) room. Also, airborne bacteria and fungi were simultaneously detected in the various wards of the hospital with concentrations ranging from 14 to 106 CFU m^?3 and 18 to 141 CFU m^?3, respectively. The highest mean concentrations of bacteria and fungi were observed in respiratory patients’ clinics and ICU wards, respectively. Significant correlation (p < 0.05) was found between airborne bacterial concentration and the presence of SARS-CoV-2, while no significant correlation was found between fungi concentration and the virus presence. This study provided an additional evidence about the presence of SARS-CoV-2 in the indoor air of a hospital that admitted COVID-19 patients. Moreover, it was revealed that the monitoring of microbial quality of indoor air in such hospitals is very important, especially during the COVID-19 pandemic, for controlling the nosocomial infections.

     

Concentrations and diversity of microbes from four local bioaerosol emission sources in Finland

Microbial particles can readily be released into the air from different types of man-made sources such as waste operations. Microbiological emissions from different biological sources and their dispersion may be an issue of concern for area planning and for nearby residents. This study was designed to determine the concentrations and diversity of microbiological emissions from four different man-made source environments: waste center with composting windrows, sewage treatment plant, farming environment, and cattle manure spreading. Samples of airborne particles were collected onto polyvinyl chloride filters at three distances along the prevailing downwind direction, from each source environment during a period of approximately 1 week. These samples were analyzed for 13 species or assay groups of fungi, bacterial genus Streptomyces, and Gram-positive and -negative bacteria using quantitative polymerase chain reaction (PCR). Samples for determining the concentrations of viable fungi and bacteria were collected from all environments using a six-stage impactor. The results show that there were variations in the microbial diversity between the source environments. Specifically, composting was a major source for the fungal genera Aspergillus and Penicillium, particularly for Aspergillus fumigatus, and for the bacterial genus Streptomyces. Although the microbial concentrations in the sewage treatment plant area were significantly higher than those at 50 or 200 m distance from the plant area, in the farming environment or cattle manure spreading area, no significant difference was observed between different distances from the source. In summary, elevated concentrations of microbes that differ from background can only be detected within a few hundred meters from the source. This finding, reported earlier for culturable bacteria and fungi, could thus be confirmed using molecular methods that cover both culturable and nonculturable microbial material.     

Airborne fungi in low and high allergic prevalence child care centers

Fungi exposure has been linked to asthma and allergies among children. To determine the association between fungal exposure and wheeze and rhinitis symptoms, we examined concentrations of culturable indoor and outdoor fungi of various aerodynamic sizes in low and high allergic prevalence child care centers (CCCs) in Singapore. Environmental parameters were also performed for air temperature, relative humidity and ventilation rates, while information on CCC characteristics was collected via an inspection. Most commonly recovered fungi were Penicillium, Aspergillus, Geotrichum, Cladosporium and sterile mycelia with Geotrichum and sterile mycelia amounting to an average of 71.5% of the total airborne culturable fungi studied. Indoor and outdoor total culturable fungi concentrations and those in the size range of 1.1–3.3 μm were significantly higher in high allergic prevalence CCCs. When fungal types/genera were compared, indoor and outdoor Geotrichum and sterile mycelia of aerodynamic sizes 1.1–3.3 μm were found to be significantly elevated in high allergic prevalence CCCs. Indeed, average geometric mean diameters (D_{g, ave}) of indoor and outdoor culturable fungi were consistently smaller in CCCs with high prevalence of allergies than those with low prevalence. We found significant associations of higher fungal concentrations, especially those with smaller aerodynamic sizes in CCCs situated near parks. There were no differences in fungal levels between CCCs with respect to their dampness profile mainly due to high CCC ventilation rates. Since particle size is a factor that determines where a fungi particle deposits in the respiratory tract, this study provides useful information in the etiology of wheeze and rhinitis symptoms among the CCC attending children.     

Assessment of microbial contamination within working environments of different types of composting plants

The objective of the study was to determine the degree of microbiological contamination, type of microflora, bioaerosol particle size distribution, and concentration of endotoxins in dust in different types of composting plants. In addition, this study provides a list of indicator microorganisms that pose a biological threat in composting facilities, based on their prevalence within the workplace, source of isolation, and health hazards. We undertook microbiological analysis of the air, work surfaces, and compost, and assessed the particle size distribution of bioaerosols using a six-stage Andersen sampler. Endotoxins were determined using gas chromatography–mass spectrometry (GC-MS). Microbial identification was undertaken both microscopically and using biochemical tests. The predominant bacterial and fungal species were identified using 16S rRNA and ITS1/2 analysis, respectively.?The number of mesophilic microorganisms in composting plants amounted to 6.9 × 10²–2.5 × 10⁴ CFU/m³ in the air, 2.9 × 10²–3.3 × 10³ CFU/100 cm² on surfaces, and 2.2 × 10⁵–2.4 × 10⁷ CFU/g in compost. Qualitative analysis revealed 75 microbial strains in composting plants, with filamentous fungi being the largest group of microorganisms, accounting for as many as 38 isolates. The total amount of endotoxins was 0.0062–0.0140 nmol/mg of dust. The dust fraction with aerodynamic particle diameter of 0.65–1.1 μm accounted for 28–39% of bacterial aerosols and 4–13% of fungal aerosols. We propose the following strains as indicators of harmful biological agent contamination: Bacillus cereus, Aspergillus fumigatus, Cladosporium cladosporioides, C. herbarum, Mucor hiemalis, and Rhizopus oryzae for both types of composting plants, and Bacillus pumilus, Mucor fragilis, Penicillium svalbardense, and P. crustosum for green waste composting plants. The biological hazards posed within these plants are due to the presence of potentially pathogenic microorganisms and the inhalation of respirable bioaerosol. Depending on the type of microorganism, these hazards may be aggravated or reduced after cleaning procedures.

Implications:?This study assessed the microbial contamination in two categories of composting plants: (1) facilities producing substrates for industrial cultivation of button mushrooms, and (2) facilities for processing biodegradable waste. Both workplaces showed potentially pathogenic microorganisms, respirable bioaerosol, and endotoxin. These results are useful to determine the procedures to control harmful biological agents, and to disinfect workplaces in composting plants.     

施用城市污泥堆肥对土壤微生物群落结构变化的影响

在温室条件下进行了15周的盆栽实验,考察了施用城市污泥堆肥后,土壤中养分含量的变化规律,重点研究了施用城市污泥堆肥对土壤微生物群落结构变化的影响。实验发现,污泥堆肥能改善土壤养分,有机质和氮、磷含量得到显著提高。经PCR—DGGE分析,施肥1周后土壤中细菌和真菌的群落结构均发生了较大的变化。随着施肥时间的延长,细菌在富含有机质及氮、磷等养分的土壤环境下大量生长,多样性提高,其优势菌群属于γ变形菌、α变形菌和芽单胞菌;随着有机质的不断消耗,细菌的生长活性受到抑制,最终由于养分的缺乏,细菌种群多样性呈现小幅度的降低,优势菌群变为绿弯菌门、γ变形菌亚纲和厚壁菌门。对于真菌,其多样性指数在堆肥前3周逐渐提升,在第3～12周的监测中呈现相对稳定的变化趋势,优势菌群主要为座囊菌纲和散囊菌纲。     

Workplace exposure to bioaerosols in pet shops, pet clinics, and flower gardens

The present study evaluated exposure to bioaerosols at three different types of facilities (pet shops, pet clinics, and flower gardens) by measuring the bacterial, fungal and/or PM(10) concentrations in indoor and outdoor air. Regardless of the season, the total bacteria and total fungi were detected for all samples, whereas the fungal genera were not. The bioaerosol concentrations measured in the flower gardens were significantly higher than those of the pet shops and pet clinics. The mean microbial concentrations at the three types of facilities were close to or exceeded the Korean indoor bioaerosol guidelines (800 CFU m(-3)), thus suggesting the need for remedial action regarding indoor microorganisms, in order to reduce the exposure at the surveyed facilities. Another suggestion was that contrary to the airborne microbes, flower gardens are not an important microenvironment for PM(10) (particulate matter 10 microm in aerodynamic diameter) exposure. Two temporal characteristics (seasonal variation and the summer survey period) were important regarding exposure to airborne microbes, depending upon the type of facility surveyed, microbial or sample types, whereas the sampling time of the day was not. The microbial concentration ratio of indoor air to outdoor air depended upon the facility and season.     

潮汐流-潜流组合人工湿地污水净化效率

构建了潮汐流-潜流组合和潜流-潮汐流组合人工湿地对污水进行处理,分别研究2种组合人工湿地对污水的净化效果。结果表明,在平均进水COD浓度为214．28mg／L、NH4＋-N浓度为10．57mg／L、PO34--P浓度为5．44mg／L、TN浓度为10．25mg／L,水力负荷为o．2m3／（m2·d）的条件下,潮汐流-潜流组合人工湿地对COD、PO34--P的去除率分别为58．28％和46．99％,与潜流-潮汐流组合人工湿地处理效果相近;对NH4＋-N、TN,潮汐流-潜流组合人工湿地的去除率分别为69．93％和71．03％,比潜流-潮汐流组合人工湿地分别高15％和33％。潮汐流-潜流人工湿地的组合,在系统内实现了硝化-反硝化的组合,强化了系统对TN的净化效果,其对TN的净化效果比-般的潜流和表面流人工湿地组合提高20％～30％。总体上,潮汐流-潜流组合人工湿地具有更好的净化效果。     

Biodegradation of phthalate esters in polluted soil by using organic amendment

This study investigated the biodegradation of the phthalate esters (PAEs) di-n-butyl phthalate (DBP) and di-(2-ethyl hexyl) phthalate (DEHP) in sludge and sludge-amended soil. DBP (100 mg kg(-1)) and DEHP (100 mg kg(-1)) were added to sewage sludge, which was subsequently added to soil. The results showed that sewage sludge can degrade PAEs and the addition of sewage sludge to soil enhanced PAE degradation. Sludge samples were separated into fractions with various particle size ranges, which spanned 0.1-0.45 μm to 500-2000 μm. The sludge fractions with smaller particle sizes demonstrated higher PAE degradation rates. However, when the different sludge fractions were added to soil, particle size had no significant effect on the rate of PAE degradation. The results from this study showed that microbial strains F4 (Rhodococcus sp.) and F8 (Microbacterium sp.) were constantly dominant in the mixtures of soil and sludge.