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The variability of the concentration of bioaerosols above the chambers of biological wastewater treatment

Michałkiewicz M., Kruszelnicka I., Widomska M.

Ecological Chemistry and Engineering. S

2018

Vol. 25, nr 2

267--278

The article presents the results of research over microorganisms (psychrophilic and mesophilic bacteria and microscopic fungi) found in wastewater in denitrification and nitrification chambers and specifies the proportion of these microorganisms in bioaerosol at various levels above wastewater level (20, 50 and 100 cm). In the denitrification chamber (anoxic) in 1 cm3 of sewage there were on average 30.35 · 106 CFU of mesophilic bacteria, 72.88 · 106 CFU of psychrophilic bacteria, and 37.3 · 105 CFU of microscopic fungi. In the nitrification chamber, where the oxygen concentration ranged from 0.37 to 2.32 mg O2·dm−3 of wastewater, the number of microorganisms was lower. In 1 cm3 of wastewater there were on average 20.2 · 106 CFU of mesophilic bacteria, 51.76 · 106 CFU of psychrophilic bacteria, and 15.22 · 105 CFU of microscopic fungi. In sewage bioaerosols above these chambers, higher numbers of psychrophilic bacteria than mesophilic ones and microscopic fungi were reported. At the same time differences in the number of microorganisms at different heights above the surface of wastewater could be observed in bioaerosol, as well as between the chambers of the bioreactor. It was found that most frequently the amount of microorganisms decreased with height. The percentage emission ratio (ER) of microorganisms in bioaerosols coming from wastewater accounted for only a fraction of a percent and ranged from 1.13 · 10−8 % (microscopic fungi over the denitrification chamber) to 24.53 · 10−9 % (psychrophilic bacteria over the denitrification chamber). It was found that the process of mixing, aeration of wastewater, have an effect on the emission of microorganisms.

Experimental investigation of gas degradation by methanotrophs at different air flow-rates

Yu H., Feng T., Zhang R., Liu J.

Journal of Power Technologies

2015

Vol. 95, nr 2

112--118

A technical approach based on microbial technology is proposed to help resolve the problems caused by explosive gases in coal mines. The proposed technique uses methanotrophic bacteria to oxidize methane. In laboratory experiments, the oxidation effect of hanging nets impregnated with liquid containing methanotrophic bacteria was investigated at different air flow-rates. The experimental results showed that the volume of gas degraded and the gradient of degradation both increased as the gas concentration increased at constant air flow-rates. At fixed gas concentrations, the volume of degraded gas increased with increasing flow-rates of air at low flow-rates. However, the volume of degraded gas slightly decreased with increasing flow-rates of air at high flow-rates. These experimental results provide a theoretical basis for the treatment of explosive gases during exploration for natural gas and to treat potentially dangerous concentrations of gas in gobs, caves and upper corners of mineshafts. They will also be of great practical significance in coal mining.