engleski

Aerobic composting of tobacco solid waste

Solid waste from tobacco factory mainly contains tobacco particles and flavoring agents. Solid waste containing alkaloid nicotine is categorized as hazardous waste according to Croatian legislation and cannot be disposed in sanitary landfill. Thus, two solutions remained to get rid of that solid waste: incineration or composting process. The aim of this work was to stabilize tobacco solid waste by aerobic composting process. The first experiment was carried out in thermally insulated column reactor (1 dm3) under adiabatic conditions, 0.09 L min-1 airflow rate and 0.1-2.0 mm particle size during 17 days and the second one in larger reactor (25 dm3) under the same conditions. HPLC method was used for measuring the content of nicotine in solid waste and in compost. The changes of temperature in reactor were closely monitored during the experiments. The lag period was not observed and after several hours the temperature in the composting mass has started rising due to intensive biodegradation process. It reached maximum on the second day, remained high to the sixths day and then gradually decreased until the compost and ambient temperatures levelled. The curve of carbon dioxide formation followed the pattern of temperature curve because mesophilic microorganisms initially used most readily degradable carbohydrates what resulted in the evolution of carbon dioxide, and rapid temperature increase. It was estimated that at the end of the composting 415 g of CO2 per 1 kg of the substrate (dry weight) evolved. Changes in the number of mesophilic and thermophilic population in the mixed microbial culture was recorded at different stages of composting. In mixed culture prevailed bacteria and yeasts. After 17 days, the volume and mass of solid waste were reduced to about 50% and 95% of nicotine was removed from solid waste. The advantage of closed reactor system in comparison with open one is that stabilization of organic waste is obtained in shorter time. Furthermore, air pollutants such as CO2, NH3, or other gasses and formation of unacceptable odours during composting can be more easily controlled.

tobacco solid waste; aerobic composting; column reactor; modeling the process

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