Wheeler, R.S., Gibbs, P.A., Rudd, C., 4R Group(free)
There are multiple mechanical biological treatment (MBT) facilities treating non-source segregated municipal solid waste (MSW) in the UK, with many more being planned and constructed. The origin of feedstock automatically funnels the utilisation of the organic fractions produced into a constrictive and limited set of regulations relating to land application. This determines how these materials are used unless significant constructive and innovative provision is made to expand the standard regulatory applications.
Growing numbers of facilities and consequential material volumes increases inevitable pressure on eligible land bank and competition between recyclers. This has a knock-on effect on restoration site gate fees, which continue to rise as more non-source segregated material floods the market.
With mounting site and compliance costs it is even more important that non-source segregated outputs are produced to highest possible standards to facilitate recovery to land. If done correctly, this should expand usability to include agricultural applications.
This paper will consider whether the current Environmental Permitting Regulations reflect the need for land recovery of organic MBT outputs.
Key Words: Agriculture, Environmental Permitting, Land Bank, MBT, AD, Compost, Organics, Restoration
The ways in which we deal with our waste extend from the reduction of waste production to burying it in its raw form in the ground. The well documented ‘Waste Hierarchy’ presents the different means of how waste materials can be handled in preferential order in terms of the impact that activity has on the local and overall environment. The Hierarchy is currently under review in the UK, results of which are due to be published at the end of 2012 or early 2013 (Defra, 2012). For obvious reasons, the prevention of waste production is the most favoured option (i.e. by using less material in manufacturing, using materials for longer etc.), followed by material re-use (in its existing form), recycling and recovery (by changing the waste into something else which has a use) and finally waste disposal (i.e. permanent disposal as it is). The stages of the Hierarchy are presented in Figure 1.
In terms of the Waste Hierarchy as it currently stands, it appears that anaerobic digestion (AD) does not sit comfortably in either the ‘recycle’ or ‘recovery’ sections as demonstrated in Figure 1. Defra (2012) states that composting firmly falls into the recycling section as long as relevant quality standards (e.g. PAS100 compliant and certified under the Quality Protocol) are met. However, as energy is also produced as an additional beneficial by-product of AD, waste treatment by AD falls under recovery, which is currently designated as less preferable in terms of environmental impact. Despite this current position, Defra (2012) state that AD is environmentally preferable to composting and other recovery options as it has the added benefit of energy production.
Like compost, the digestate produced has a definitive use for land application regardless of whether it is derived from source-segregated waste or mixed waste feedstock. It is therefore arguable from an organics recycler’s perspective that any compost or digestate produced can be fully recycled as long as it is of appropriate quality for its intended use i.e. fit for purpose. To be fully recycled it does not necessarily need to be of a standard deemed suitable for agriculture (i.e. PAS compliant and QP certified) under current regulation. Using materials derived from mixed waste feedstock for land restoration for ecological benefit is as much recycling as using materials from source-segregated wastes for agricultural benefit. Both can be, and are widely used throughout England and Wales under the Environmental Permitting Regulations 2010 (Anon., 2010).
This paper therefore predominantly discusses waste recycling and recovery which are located in the middle spectrum of the Hierarchy. Organic wastes are typically dealt with in this part of the Hierarchy as there are seldom opportunities for prevention or re-use, however the treatment of organics can provide useful outputs which can be recycled. All of these outputs are therefore competing for land as a viable end use post treatment or energy recovery. As some source segregated materials will also be competing for restoration land (due to off-specification production, plant failures, contractual agreements, distance, or outcompeted for agricultural land by manufactured fertilisers or on-farm livestock manures), both the agricultural and restoration market are considered.