Agricultural wastes, municipal solid wastes, sludge, waste water and food wastes, are currently seen as low-valued materials. However, they are beginning to be recognized as resources for the production of a variety products. Agricultural wastes, for instance, contain high levels of cellulose, hemicelluloses, starch, proteins, as well as lipids. As such, they constitute inexpensive candidates for the biotechnological production of liquid biofuels without competing directly with the ever-growing need for world food supply. As bio-wastes are generated in large scales, in the range of billions of kilograms per year, thus largely available and rather inexpensive, these materials are seriously considered to be potential sources for the production of bio-fuels.
As defined in the revised Waste Framework Directive7, bio-waste includes:
• Garden and park waste;
• Food and kitchen waste from households, restaurants, caterers, retail premises and comparable waste from food processing plants.
Bio-waste does not include forestry or agricultural residue and, thus, should not be confused with the wider term “biodegradable waste” as defined in the Landfill Directive (1999/31/EC), which also covers other biodegradable materials such as wood, paper, cardboard, sewage sludge, natural textiles.
The value chain of biomass waste
For waste biomass is the waste hierarchy not so clear due to the emerging technologies. Biological materials can be radically transformed, either physically, chemically or biologically into a broad plethora of end use products with significantly different properties and end-use market values. Generally speaking there is rough correlation between the technological cost and complexity input into the transformation of the biomass waste and its end-use market value. These end-use products and applications are therefore better considered as a value chain than a hierarchy, where biomass waste is the input feedstock.
Figure: The value chain of biomass waste
|Recycling of biowaste kg per capita geo/ time||2014||2015||2016|
|Former Yugoslav Republic of Macedonia||68||70||77|
|Source of Data: ec.europa.eu/eurostat|
|Short Description:The indicator is indirectly measured as the ratio of composted/methanised municipal waste (in mass unit) over the total population (in number). The ratio is expressed in kg per capita.
The underlying assumption is that, by and large, the only reasonable treatment of biowaste is composting or anaerobic digestion.