engleski

Sorption of exhaust gases, CO2 and NH3, during biodegradation of solid waste in reactor system

Composting is a biological treatment in which aerobic mesophilic and thermophilic microorganisms transform the biodegradable organic matter into CO2 and H2O, as well as into more stable organic matter. Two major byproducts of microbial transformation during biodegradation of solid waste are carbon dioxide (CO2) and ammonia (NH3). Carbon dioxide is a greenhouse gas, while ammonia is a noxious, toxic gas that can cause serious damage to human health and to the environment. Therefore, it is important that studies be carried out to find ways to efficiently control the emission of these gases. The purpose of this work was to investigate sorption of gases, ammonia and carbon dioxide, on different sorbents during composting of mixture of tobacco waste and grape marcs. Composting process was carried out with forced aeration (0.645 dm3 min-1 kgVS-1) in column reactor (10 dm3) under adiabatic conditions during 21 days. During the process, temperature changes in the reactor, pH value, COD of condensate, C/N ratio were closely monitored while evolved CO2 and NH3 were analyzed periodically. Ammonia was measured both in the condensate and in 4 % boric acid trap (which was placed after adsorbent), while CO2 was trapped in 1 M NaOH. The results showed that zeolite and potting soil are good adsorbents for sorption of ammonia gas. The concentration of ammonia in exhaust gas increased after 12 days of composting process, when the pH- value in composting mass increased to 9. It can be concluded that ammonia emission mainly depended on increase of pH-value of composting mass. The amount of ammonia in condensate was higher than in exhaust gases. The emission of carbon dioxide is in correlation with the temperature in the reactor and it was found that the highest CO2 concentrations were measured in thermophilic stage during high activity of microorganisms.

: Composting of winery and tobacco waste; sorption of exhaust gases; zeolite; potting soil; adiabatic reactor.

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