Challenges and solutions for biofiltration of hydrophobic volatile organic compounds.

https://cyberleninka.org/article/n/966059.pdf

Fungal pollution of indoor environments and its management.

The Middle East Dust storms have greatly affected the south and west parts of Iran during the last decade. The main purpose of this study was to examine and compare culturable airborne bacteria concentration in particulate matter (PM) during normal, semi-dust, and dust event days in different places and seasons in Ahvaz from November 2011 to May 2012. Sampling was performed every 6 days and on dust event days at different sampling stations. The overall mean concentrations of PM10, PM2.5, and PM1 for the entire study period were 598.92, 114.8, and 34.5 μg/m3, respectively. The PM concentrations during the dust event days were much higher than normal and semi-dust event days. The highest mean PM concentrations were observed in March 2011. The low PM2.5/PM10 ratios indicate that these PM are mostly originating from natural sources such as dust storms. The overall mean concentration of total bacteria during the study period was 620.6 CFU/m3. The greatest bacterial concentrations were observed during dust event days and at areas with high traffic and more human activities compared with normal days and greener areas. The percentage of gram-positive bacteria was significantly higher than that during the study period (89 vs 11 %). During this study, 26 genera of culturable bacteria were identified from all the sampling stations. The most dominant genera in all sampling stations were Streptomyces, Bacillus, Kocuria, Corynebacterium, and Paenibacillus. The results also showed that there were positive correlations between PM and bacterial concentrations during the study period (p < 0.05).

Particulate matter and bacteria characteristics of the Middle East Dust (MED) storms over Ahvaz, Iran

The first purpose of our study was to determine culturable indoor airborne fungi in different places in Ahvaz during normal and dust event days. Ahvaz is the biggest city in southwest of Iran which has suffered from dust storms in recent decade. To minimize personal exposure to polluted air, governmental and private sectors excluding critical places such as hospitals, fire department and security organization are closed during dust event days. Therefore, the second objective of this survey was to see whether this plan (forced shutdown) is in place. Samples were collected from July 2010 to March 2011 by using quick take 30 equipped with a single-stage sampler. Fungal population was measured in school, university and hospital during normal and dust event days. Five dominant fungi genera in three sampling stations were Cladosporium, Alternaria, Aspergillus, Penicillium and Rhizopus the concentrations (CFU/m3) of which were higher during dust events than normal days. Airborne fungi such as Aspergillus, Mucor and Rhizopus are opportunistic fungi which can cause aspergillusis and mucormycosis infections in immunodeficiency individuals, vulnerable groups as well as healthy people. The results of this study confirmed the measure of forced shutdown in Ahvaz city due to increased concentration of fungi during dust event days.

Determination of culturable indoor airborne fungi during normal and dust event days in Ahvaz, Iran

Tandem solar cell structures require a high-performance wide band gap absorber as top cell. A possible candidate is CuGaSe2, with a fundamental band gap of 1.7 eV. However, a significant open-circuit voltage deficit is often reported for wide band gap chalcopyrite solar cells like CuGaSe2. In this paper, we show that the open-circuit voltage can be drastically improved in wide band gap p-Cu(In,Ga)Se2 and p-CuGaSe2 devices by improving the conduction band alignment to the n-type buffer layer. This is accomplished by using Zn1−xSnxOy, grown by atomic layer deposition, as a buffer layer. In this case, the conduction band level can be adapted to an almost perfect fit to the wide band gap Cu(In,Ga)Se2 and CuGaSe2 materials. With an improved buffer band alignment for CuGaSe2 absorbers, evaporated in a 3-stage type process, we show devices exhibiting open-circuit voltages up to 1017 mV, and efficiencies up to 11.9%. This is to the best of our knowledge the highest reported open-circuit voltage and efficiency for a CuGaSe2 device. Temperature-dependent current-voltage measurements show that the high open-circuit voltage is explained by reduced interface recombination, which makes it possible to separate the influence of absorber quality from interface recombination in future studies.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/pip.2914

Record 1.0 V open‐circuit voltage in wide band gap chalcopyrite solar cells

Distribution characteristics of airborne bacteria and fungi in the feedstuff-manufacturing factories.

A laboratory-scale biofiltration system, the rotatory-switching biofilter (RSB), was operated for 199 days using toluene as a model pollutant. The target gaseous pollutant for the biofiltration experiment was ∼300 ppmv of toluene. Toluene removal efficiency (RE, %) was initially approximately 20% with a 247-ppmv concentration (0.9 g m−3) of toluene during the first 10 days. Although the RE decreased several times whenever nitrogen was consumed, it again reached almost 100% when the nitrogen source was in sufficient supply. Denaturing gradient gel electrophoresis (DGGE) analysis was employed to assess the transformation of microflora during operation of the biofilter. The results based on a 16S rRNA gene profile showed that the microbial community structure changed with operation time. Although the microflora changed during the initial period (before day 40), transformation of the bacterial component was hardly observed after day 51. Statistical analyses of the DGGE profiles indicated that the bacterial co...

https://www.tandfonline.com/doi/pdf/10.1080/10962247.2012.672396

Transformation of microflora during degradation of gaseous toluene in a biofilter detected using PCR-DGGE.

Impact of Ga/(In + Ga) profile in Cu(In,Ga)Se2 prepared by multi-layer precursor method on its cell performance

Cu(In,Ga)Se2 (CIGS) thin films were deposited on the Mo/heat-resistant glasses (SS-8, Nippon Electric Glass) by the three-stage evaporation process. The coefficient of thermal expansion (CTE) of SS-8 is 8.4×10–6/K, strain point of SS-8 is 582 °C. SS-8 has the CTE similar to that of SLG but higher thermal tolerance. Substrate temperature (Tsub) during deposition and Ga/(In+Ga) atomic ratio of CIGS thin films were controlled to 550∼600 °C and 0∼0.7, respectively. The effect of Tsub and Ga/(In+Ga) atomic ratios of CIGS films have been characterized by electron backscatter diffraction (EBSD) measurements. Grain size and ∑3 grain boundary ratio increased at higher Tsub. ∑3 grain boundary ratio was calculated from the fraction of the length of ∑3 grain boundary by the length of the total grain boundaries on EBSD image. There was the correlation among Ga contents, Tsub, grain size and efficiency. It is difficult to distinguish between effect of grain size and effect of grain boundary to efficiency. However, it is found that high Ga content up to 0.7 results in both high efficiency and ∑3 grain boundary ratio. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Effect of Ga content and growth temperature on Cu(In,Ga)Se2 thin film deposited on heat‐resistant glass substrates

Although the appropriate supply of nutrients has been extensively researched, more information is required on the effects of nutrients in treating gaseous volatile organic compounds (VOCs) in biofi...

Takashi Higuchi

Papers

Distribution characteristics of airborne bacteria and fungi in the feedstuff-manufacturing factories.

Transformation of microflora during degradation of gaseous toluene in a biofilter detected using PCR-DGGE.

Impact of Ga/(In + Ga) profile in Cu(In,Ga)Se2 prepared by multi-layer precursor method on its cell performance

Effect of Ga content and growth temperature on Cu(In,Ga)Se2 thin film deposited on heat‐resistant glass substrates

Influence of phosphorus and trace metals in biofilters treating gaseous VOCs using a novel irrigation system.