Friday, December 26, 2014

BEAUTIFUL BIOWASTE

European trends in garden and food waste management

by Tony Breton

Biowaste (food and garden waste) makes up at least 32% - or 120 million tonnes - of municipal solid waste (MSW) in European Union (EU) countries.1 It is therefore unsurprising that biowaste is playing an increasingly important role in some Member States’ waste management strategies.
As early as 1983, Germany introduced source-separate collection schemes for biowaste and a number of Member States, mainly from central Europe (such as the Netherlands and Austria), have since introduced local obligations requiring such schemes. 
It is often argued that separate collection schemes can be an expensive option and when viewed in isolation this is generally true; however, if the whole system is considered - including potential reductions in residual collections, high biowaste recovery rates, the benefits of returning organic matter to land, energy recovery and public acceptance - the overall economic and environmental benefits are significant.

Policy

Composting and anaerobic digestion (AD) have a pivotal role to play in closing the ‘organic loop’, returning organic matter and valuable plant nutrients to the soil, thus helping to underpin sustainable agricultural and horticultural practices. They also provide a more environmentally acceptable method for treating organic wastes compared with landfill and incineration. 
To date, the principal central policy driver has been the EU Directive on the Landfill of Waste (99/31/EC), which came into force in 1999. In addition to stipulating the way in which landfill sites should be operated, it places strict limits on the amount of biodegradable municipal waste that can be disposed of to landfill, and introduces a requirement for pre-treatment of all wastes prior to landfill. 
Whilst the directive does not extend to specifying how biowastes should be collected or treated, it is likely to continue to have a profound effect on the way in which they are managed and will inevitably stimulate the development of the composting and digestion sectors.
In 2006, the European Commission launched a broad ‘Thematic Strategy on Soil Protection’, with the restoration of organic fertility being regarded as a key tool to enhance the agronomic and environmental functions of soils, including:
  • prevention of soil erosion and flooding
  • carbon sequestration
  • enhancement of biodiversity
  • reduction in use of mineral fertilizers and pesticides, with subsequent prevention of related pollution.
It is clear that the Soil Strategy should encourage further development of the composting and digestion markets by creating demand for high-quality products. However, there is currently no EU policy to link the diversion of biowaste from landfill with the application of the resultant products on land. From experience to date, it is very clear that well-performing source-separation programmes that generate high-quality/low-contaminant feedstocks are a prerequisite to manufacturing high-quality composts and digestates. 
It is also important to have clear guidelines on compost quality and standards, what is acceptable to go onto the land and what is not. During the preparation of the Soil Strategy, one of the recommended actions was the development of a ‘Biowaste Directive’, which would seek to address this issue and provide long-term clarification enabling further market development. Although a further discussion document was published, no policy-directed action was taken. 
More recently, the topic of the Biowaste Directive arose during discussions on the revised Waste Framework Directive (WFD). The European Parliament tabled an amendment to the WFD calling for specific measures on biowaste, namely a directive, but whilst this has favour amongst some members of the Commission, not all Member States are currently supportive; discussions are ongoing. 
Across the countries of Europe there is a wide range of approaches relating to biowaste, which can be generalized into four categories. 
  1. Countries where source-separation programmes are widely implemented and quality standards for products are developed - Austria, Belgium (Flanders), Germany, Switzerland, Spain (Catalonia), Italy, Sweden, Luxembourg and the Netherlands. 
  2. Countries where source separation is being implemented and quality standards are developed - Denmark, the UK, Norway and Belgium (Wallonia).
  3. Countries that are developing policy, and separation programmes are in their infancy - Ireland, France and Finland.
  4. Countries that have yet to develop policy or wide-scale separation programmes - Portugal, most parts of Spain, Greece, Slovenia, Hungary, Czech Republic.
The vast majority of separately collected biowaste is treated through controlled composting processes although in some countries, such as Denmark, Sweden (see box) and Germany, there is increasing evidence that AD is growing in prevalence. There are no comprehensive data concerning home composting but it is widely promoted.

Biowaste strategy

When developing a strategy for the management of biowaste, it is imperative to consider the environmental and economic impact of the whole system and not just one variable within that system. Biowaste management systems can broadly be split into three components: collection, processing and products, with each component affecting the efficiency and impact of the next.

Collection

Waste streams
Biowaste consists essentially of two components, garden waste and food waste, each with contrasting physical and biochemical properties. Garden waste has a low bulk density, relatively low putrescence and is generally collected using compaction vehicles, whereas food waste has a high bulk density, does not require compaction but has a very high water content and level of putrescence.

FIGURE 2. Seasonal fluctuations in garden and food waste1. Adapted from G. Zanon & W. Giacetti (19/4/01) based on data from the PD1 district in Italy. Click here to enlarge image 
Garden waste generation is affected by a large number of factors such as garden size, climate, types of plant and how often the garden is attended to. Seasonality also plays a significant role, with much greater quantities expected in the spring, summer and autumn, as shown in Figure 2.
Predicting garden waste capture via kerbside collection is an extremely difficult task as compositional analysis of residual waste will not take into account any additional material that the scheme will attract (diverting from central collection points, home composting, etc.). However, what is clear from experience in Austria, Belgium, Germany, Switzerland and the UK is that free garden waste collection in large containers will not only increase recycling rates but also lead to significant increases in overall MSW.3
The generation of food waste is affected by fewer factors, which include household size, culture and time available for food preparation. Quantities of food waste have been shown to be fairly consistent throughout the year (see Figure 2) and are more predictable than garden waste as fewer alternative disposal methods exist.

Collection systems

The choice of system for collecting biowaste will be affected by the local availability of suitable processing facilities (see below) and choice of targeted material. There are a number of options to collect garden w.

...http://www.waste-management-world.com/articles/print/volume-8/issue-4/features/beautiful-biowaste.html
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