One of the factors contributing to the environment negative impact of poultry factories is the presence of unpleasant smelling substances in the air emissions of these enterprises. These smells are causing a significant problem for the employees of the poultry farmы, as well as for the residents of nearby settlements. The growing number of complaints from people living nearby to the authorities create an negative company image of poultry farms, and, ultimately, can lead to the intensification of the sanctions policy against the violating enterprise. Penalties may be imposed due to the design and implementation of methods for controlling odorous emissions. In particular, during the period from 2015 to 2019, several state standards in the area were issued (for example, GOST 32673-2014, GOST R 58578-2019 "Rules for establishing standards and controlling odorous emissions into the atmosphere"). In addition, the packages of amendments on the monitoring of odors were submitted for consideration to the legislatures of several subjects of the Russian Federation.
All of the above mentioned determines the need to develop new solutions and implement new techniques for cleaning gases from odorous substances. We have proposed that within a poultry farm, the biological method of waste air treatment can effectively remove odorous substances.
The process of biological purification (biofiltration) is based on the oxidation of biodegradable organic and inorganic pollutants with the help of microorganisms immobilized on the surface of solid particles or in the liquid. The use of this method will improve the quality of atmospheric near the enterprise without high operating costs. Biological technologies are recognized to be more effective than traditional methods due to the advantages in economic and ecological terms.
To prove the assumption, we first conducted a quantitative analysis of the list of dominant odorous compounds in the emissions of the poultry farm. Then we set up a series of experiments on the adaptation and cultivation of the association of odorous substances degrading bacteria. Activated sludge was a source of microflora, and was provided from the treatment facilities of the poultry farm. A Laboratory setup consisting of a tank filled with manure and a bottle for the cultivation of microorganisms was constructed for the experiments. A metagenomic analysis of the active sludge microbial community was also performed.
It was shown that the concentrations of foul-smelling substances were under the limits of acceptable levels (MAC). Analysis of the gas emissions of the poultry farm revealed the dominant odorous compounds: ammonia, mercaptan, dihydrosulfide, dimethyl sulfide, methylamine and dust. The last one acts as a carrier of odorous compounds over long distances. At the same time, the concentrations obtained are hundreds of times higher than the perception threshold. For example, the concentration of dihydrosulfide was 4.52 mg/m3, which is less than the MAC of 10 mg/m3, but 322 times greater than the perception threshold of 0.014 mg/m3 of dihydrosulfide.
In a series of four experiments, laboratory methods for selecting cultivation conditions were studied. Analyzing the operation mode of the laboratory unit, certain patterns of behavior of the monitored parameters were revealed (in particular, an increase in pH and ammonium ions content in the liquid was observed), which may be indirectly related to inaccurate selection of the microflora source.
Conducted metagenomic analysis revealed the presence of several species -destructors of odorous substances in the active sludge of poultry farms. Candidatus Nitrocosmicus dominates among the detected ammonia destructor species (about 5 percent of the studied genome).
|Affiliation of speaker||ITMO University|
|Publication||Impact Factor journals|