The Search For Additional Value From Food Waste Using Anaerobic Digestion and Pyrolysis

Rethinking food waste could be an effective means to bridge the gap between local liabilities and finding value from this lost resource. While traditionally biomass has been used as a renewable energy source through combustion, there are more clever solutions. Biomass conversion can undergo both biotechnological (anaerobic digestion) and thermal (pyrolysis) conversion processes to produce end products that could sequester carbon from the environment. To date, both processes are being used independently for a number of energy carriers; however, no research at the moment has focused on converting biomass using anaerobic digestion to produce a fertilizer and extract further value by subjecting the digestate to pyrolysis. In the pyrolysis system, this feedstock is burned creating valuable carbon allotropes used to reshape next-generation energy devices, while removing carbon from the atmosphere. The objectives of this thesis are to determine if the digestate can be a suitable fertilizer as is. Based on N:P:K ratio, the digestate may not be as useful as a fertilizer. The second objective is to use the digestate as a suitable feedstock for pyrolysis in the search of high value nanocarbons. Although, the digestate was successful in being a feedstock, it did not provide insight to high value nanocarbons. Lastly, the solid product from pyrolysis (coke) was exfoliated to retrieve the advanced carbons using electrochemical exfoliation and sonication.

The Search For Additional Value From Food Waste Using Anaerobic Digestion and Pyrolysis

Rethinking food waste could be an effective means to bridge the gap between local liabilities and finding value from this lost resource. While traditionally biomass has been used as a renewable energy source through combustion, there are more clever solutions. Biomass conversion can undergo both biotechnological (anaerobic digestion) and thermal (pyrolysis) conversion processes to produce end products that could sequester carbon from the environment. To date, both processes are being used independently for a number of energy carriers; however, no research at the moment has focused on converting biomass using anaerobic digestion to produce a fertilizer and extract further value by subjecting the digestate to pyrolysis. In the pyrolysis system, this feedstock is burned creating valuable carbon allotropes used to reshape next-generation energy devices, while removing carbon from the atmosphere. The objectives of this thesis are to determine if the digestate can be a suitable fertilizer as is. Based on N:P:K ratio, the digestate may not be as useful as a fertilizer. The second objective is to use the digestate as a suitable feedstock for pyrolysis in the search of high value nanocarbons. Although, the digestate was successful in being a feedstock, it did not provide insight to high value nanocarbons. Lastly, the solid product from pyrolysis (coke) was exfoliated to retrieve the advanced carbons using electrochemical exfoliation and sonication.

Adaptability of Powdered Activated Carbon Production from Ground Catering Waste Pyrolysis Coke

Three mixture of catering waste was pyrolyzed at 650, 725 and 900 °C and the solid residue (coke) was examined for powdered activated carbon production. For this, the carbon content, iodine number, particle size distribution and scanning electron microscopic images were analysed. Based on the carbon content, these cokes are suitable for activated carbon production, which were 60-85 wt.% (depending on the base material and pyrolysis temperature). The studied cokes showed slightly porous structure with smooth surfaces. Because of this, the iodine number was mostly small (13-30). Based on the grinding experiments, 10 minutes of grinding was found to be optimal. After this grinding time, the reached iodine number of powdered activated carbon was 350-610.

Plasma recycling of chloroorganic wastes

A high temperature of thermal plasma provides more efficient decomposition of the wastes in comparison to traditional combustion. Due to the high temperature and high density of energy in the plasma, the destruction rate is high, which determines a high efficiency waste decomposition. The main products of pyrolysis plasma chloroorganic compounds are pyrolysis gas and pyrolysis coke.In order to reduce carbon soot, the steam supported reaction was used. Application of plasma at a temperature range from 1000 to 1750 K enabled destruction of the chloroorganic compounds with a very good yield. Several degradation products were received , which were analyzed. In the research electric arc plasma was used in the process of pyrolysis chloroorganic waste utilization. The reactor with a rotating arc was applied. Selected chloroorganic compounds were selected as the model: chloromethane (CH3Cl), carbon tetrachloride (CCl4), chlorobenzene (C6H5Cl) and dichlorobiphenyl (PCB-C12H8Cl2). Based on the amount of the individual components, chloroorganic in the exhaust gases, and the amount introduced to the plasma decomposition, percentage yield was calculated.Research results indicated that decomposition efficiency was more than 99,8% with the exception of CCl4 pyrolysis, which in the exhaust had a content of 0.2% CCl4.