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Integrated biological–physical process for biogas purification effluent treatment

Journal of Environmental Sciences 2019年第9期31卷 110-122页

作者： roslan noorain Tomonori Kindaichi Noriatsu Ozaki Yoshiteru Aoi Akiyoshi Ohashi Department of Civil and Environmental Engineering Graduate School of Engineering Hiroshima University 1-4-1 Kagamiyama Higashihiroshima Hiroshima 739-8527 Japan Section of Environmental Engineering Technology Malaysia Institute of Chemical & Bioengineering Technology University Kuala Lumpur Lot 1988 Kawasan Perindustrian Bandar Vendor Taboh Naning 78000 Alor Gajah Melaka Malaysia Department of Molecular Biotechnology Graduate School of Advanced Sciences of Matter Hiroshima University 1-3-1 Kagamiyama Higashihiroshima 739-8530 Japan

Biogas purification via water scrubbing produces effluent containing dissolved CH4, H2S,and CO2, which should be removed to reduce greenhouse gas emissions and increase its potential for water regeneration. In this study, a reactor built with air supplies at the top and bottom was utilized for the treatment of biogas purification effluent through biological oxidation and physical stripping processes. Up to 98% of CH4 was removed through biological treatment at a hydraulic retention time of 2 hr and an upper airflow rate of 2.02 L/day. Additionally, a minimum CH4 concentration of 0.04% with no trace of H2S gas was detected in the off gas. Meanwhile, a white precipitate was captured on the carrier showing the formation of sulfur. According to the developed mathematical model, an upper airflow rate of greater than 2.02 L/day showed a small deterioration in CH4 removal performance after reaching the maximum value, whereas a 50 L/day bottom airflow rate was required to strip the CO2 efficiently and raise the effluent p H from 5.64 to 7.3. Microbiological analysis confirmed the presence of type 1 methanotroph communities dominated by Methylobacter and Methylocaldum. However, bacterial communities promoting sulfide oxidation were dominated by Hyphomicrobium.

关键词： Biogas purification effluent Dissolved methane pH elevation Biological oxidation CO2 stripping

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Effect of face masks on speech understanding: A clinical perspective during speech audiometry

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Journal of Otology 2022年第3期17卷 140-145页

作者： Rawish Kumar Sanjay Kumar Munjal Anuradha Sharma Md noorain Alam Naresh K.Panda Department of Otolaryngology PGIMERChandigarhIndia

The objective was to measure the effect of various face masks on speech recognition threshold and the word recognition score in the presence of varying background noise levels.20 normal-hearing adult subjects(a total of 40 ears)*** tone audiometry followed by speech recognition threshold and word recognition score at the most comfortable level in varying signal-to-noise ratios(SNR0,SNR10,and SNR15)using surgical,pleated cloth,and N95 *** surgical,cloth,and N95 masks,speech recognition thresholds increased by 1.8 dB,4.4 dB,and 5.05 dB,*** recognition scores decreased by 32%without a mask,43.7%in a surgical mask,46.3%in a cloth mask,and 46.7%in N95 mask conditions,between SNR15 and *** speech recognition threshold was negatively affected with cloth and N95 *** masks do not affect the word recognition scores at lower background noise ***,as the signal-to-noise ratio decreased,even the surgical,cloth,and N95 masks significantly impacted the word recognition score even in normal-hearing individuals.

关键词： Face masks Speech recognition threshold Word recognition score Signal-to-noise ratio Communication

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