Читать книгу Handbook of Biomass Valorization for Industrial Applications - Группа авторов - Страница 62

In some cases, when several substrates belonging to different classes, mentioned above, are in mixed form and are classified in this category [52]. Municipal generated biomass is organic waste rich in carbohydrates that have great potential to be utilized as renewable energy source. It ranges from food waste to paper or any material collected from residential or commercial place. Broadly, it is classified into three major categories such as municipal solid waste, municipal sewage, and urban wood biomass [53]. The characteristics of municipal biomass differ a lot in developing and developed countries. It is available in relatively huge amount in urban areas and need proper waste management program. Through direct combustion or anaerobic digestion in landfills or processing plants, municipal waste can convert into energy. Similarly, waste from sewage which is also substantial source of biomass can be subjected to energy production using anaerobic digestion, pyrolysis or drying and incineration (direct combustion).

The physio-chemical properties of biomass determine the selection of conversion method and its underlying processing difficulty. The main properties are moisture content, calorific value, ash/residue content, alkali metal content, cellulose/lignin ratio and proportions of fixed carbon and volatiles. The soil and other detritus contaminants present in biomass affect ash and alkali metal content of material. Depending on the conversion process undertaken, particular property of material becomes important. In case of wet biomass conversion, properties like moisture content and cellulose/lignin ratio predominates. Whereas, if conversion process is subjected to dry biomass, then, all properties are of interest except cellulose/lignin ration which is not of much concern. The low moisture containing woody and herbaceous biomass is most suitable for thermal conversions like gasification, pyrolysis/combustion. The feedstocks high in moisture content are economically more fitted for fermentation derived biological conversions producing. The higher cellulose proportions compared to lignin determine the rate of biodegradability of material and act as major factor in selecting type of biomass for lignocellulosic bioconversions.

Aqueous processing reactions are used for those material for which moisture content is such that, energy input for drying process is more than energy of product to be formed [47].