The Use of Stabilised Biowaste in Land Remediation
Information Sheet
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Land Remediation
Introduction
The implications of the EC Landfill Directive, the National Waste Plan and Area Waste Plans are fundamental to the introduction of integrated waste management strategies in Scotland. The Landfill Directive requires 65% of the biodegradable fraction contained in municipal solid wastes to be diverted from landfill by 2020.
Several local authorities are already planning mixed municipal solid waste composting to help them achieve the required diversion, in addition to the introduction of any segregated organic waste collection.
The Scottish Executive is well aware of the important role composting must play in order to meet Biodegradable Municipal Waste (BMW) diversion targets and has initiated a review of those factors influencing the overall viability of mixed waste composting by mechanical biological treatment (MBT) of mixed Municipal Solid Waste (MSW) through its Stabilised Biowaste Working Group.
The Executive's Stabilised Biowaste Working Group
The Executive's Stabilised Biowaste Working Group comprises members from local authorities, representation from Scottish waste sector contractors (Scottish Environmental Services Association, SESA), Scottish Environment Protection Agency (SEPA), Waste and Resources Action Programme (WRAP) and other interested organisations.
REMADE Scotland has been commissioned by the Executive to research and report on framework specifications for remediation application of stabilised biowaste to closed former landfills.
REMADE's research work will focus on key aspects
of stabilised biowaste production and use including technological options appraisal; waste stability, sampling protocols and analytical testing methods; and planning and licensing aspects specific to application of biostabilised waste to land.
Current Regulatory Position
Mixed waste derived compost (stabilised biowaste) continues to be regulated as waste up to the point where it has been fully recovered through its use for ecological improvement. Stabilised biowaste can be a valuable material for land remediation, for example of former landfill sites. The remediation activity can take place under a Waste Management Licence issued by SEPA, subject to planning and other regulatory requirements.
In consultation with the Working Group, SEPA has produced a Composting Position Statement. The Statement presents an indicative standard for stabilized biowaste use which, when supported by a site specific risk assessment showing no risk of pollution to the environment or harm to human health, SEPA will regard as adequate for use in land remediation. The statement is intended to provide a higher degree of regulatory predictability, to assist local authorities and their industry partners who are considering investment decisions.
Stabilised Biowaste
The relatively small quantities of MBT stabilised biowaste currently being produced from MSW sources in Scotland exhibits variations in physical, chemical and bacteriological characteristics. The physical appearance of the treated waste can be significantly influenced by the volume of non-compostable elements (NCE) present. These NCE's are predominantly glass, plastic, stones and batteries. Batteries can also have a detrimental effect on the level of metals contamination contained in the biostabilised waste. For this reason, a review of the range of screening technologies available and capable of removing such NCEs, is being undertaken.
These technologies have been examined at various sites across Europe in fully operational environments. The level of effectiveness in treating wastes to specified hygiene standards has been recorded. The ability of equipment suppliers to treat typical mixed MSW from a Scottish environment to current national standard and SEPA's Composting Position Statement, 2004 will be fully investigated. The outcome of these trials, together with equipment suppliers' output-based performance specification and costs, will help to determine the viability of high quality waste biostabilisation processes.
Biowaste Stabilisation
The diversion of biodegradable waste from landfill and a detailed assessment of the technological aspects of the MBT process necessitates a close examination of the scientific principles associated with waste stabilisation. This scientific part of the research will examine the level of microbial activity throughout the composting process and also the chemical characteristics of the waste.
Stabilised Biowaste
The level of microbial activity will be measured by the volume of carbon dioxide (CO 2) emitted from the earliest stages of decomposition to a time where activity has stabilised. At this point the more reliable oxygen uptake will be measured to assess whether stabilisation of the composting process has been reached, at which stage the stabilised biowaste may be considered to be no longer biodegradable .
MSW heavy metals contamination levels can be affected by the leaching of domestic batteries. The research will identify and measure the degree of concentration of heavy metals that takes place when the waste is naturally reduced by the organic metabolisation. Bacteriological activity levels will also be measured.
The requirements of the Animal By-products Regulation (ABPR) and SEPA's Composting Position Statement, 2004 shall also be taken into consideration.
Planning and Waste Management Licensing
The research considers the planning and waste management licensing/permitting regulatory processes which apply to applications made to regulatory bodies for the use of stabilised biowaste to remediate closed former landfills. An initial desktop exercise identified the relevant legislation, guidance and advisory instruments.
Requirements for both forms of application include, site restoration plans (conditions), site specific risk assessments, biostabilised waste quality/standards, waste application rates and method statements.
A good practice guidance in the form of a roadmap, for both planning and licence/permit applications is being produced and shall be suitable for use by both regulatory bodies and applicants.
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