Q: Why is the mechanical biological treatment (MBT) facility located at Brookhurst Wood, north of Horsham?
A: The County Council sought to procure a solution for the management of the ‘black bag’ household and commercial waste produced within West Sussex, and collected by West Sussex’s local authorities, for the duration of the twenty-five year contract envisaged. This included the design, build, operation and management of a suitable solution. During the procurement process, bidders were evaluated against a pre-determined, robust methodology designed to select the most economically advantageous tender. As part of that process, bidders were required to identify the location of facilities required for their solution(s), and any land associated with its delivery. Biffa’s proposals offered the most advantageous financial, technical and legal tender and their proposed solution involved the use of land located at Brookhurst Wood, north of Horsham, adjacent to their existing landfill site. Furthermore, the wider Brookhurst Wood site is also identified in the Waste Local Plan as a strategic site for the management of waste within the county of West Sussex.
Q: What will be the environmental impact of the mechanical biological treatment (MBT) facility?
A: The mechanical biological treatment (MBT) facility has been designed and tested to ensure that the quantity and biodegradable content of waste sent to landfill in West Sussex is minimised. This significantly reduces the amount of methane emitted to the atmosphere when compared to the alternative of sending the County’s waste direct to landfill. Methane is a greenhouse gas 25 times more potent than carbon dioxide and is considered to have a significant negative impact on climate change. This is a key significant environmental benefit of the MBT process when compared to the alternative landfill option.
The MBT process utilises electricity and mains water, discharges wastewater to sewer, combustion emissions from combined heat and power (CHP) engine exhaust stacks, treated air from within the process areas, discharged via a stack on the odour control system, generates solid residues for landfill and is a source of noise. The facility has been designed to minimise these impacts and during commissioning it underwent a period of testing to ensure that utility use and emissions were within limits set by the Environment Agency. The facility also has to meet stringent conditions set out in its environmental permit (issued by the Environment Agency) to minimise environmental impacts. The Permit requires that the operator monitors emissions and reports performance to the Environment Agency on a routine basis. The Environment Agency makes periodic inspections of the facility to ensure it is complying with permit conditions and therefore limiting its impact on the environment.
Q: Now the mechanical biological treatment (MBT) facility will sort waste, why do I need to have two bins? Why do I need to separate out my recycling, doesn’t the MBT facility do it for me?
A: WSCC is committed to moving waste away from landfill disposal by the following means - in order of preference and in line with the waste hierarchy:
- preventing material from becoming waste;
- reusing products / materials;
- recycling and composting; and
- recovering energy.
All recyclables collected separately from the kerbside in West Sussex are processed through the County Council’s Recycling and Waste Handling Contract (RWHC) with Viridor. Under this Contract, recyclable materials are sorted and separated through the materials recycling facility (MRF) located at Ford, near Arundel. For further information please visit: www.recycleforwestsussex.org
Separately collecting recyclables from the kerbside enables the County Council and its District and Borough partners to increase the amount of material collected (such as paper, plastics, card, glass bottles, cans, etc.) and sell it at a higher price.
The purpose of the MBT facility is not to sort and separate recyclable materials, but rather to sort and treat any leftover waste that cannot be moved up the waste hierarchy through prevention, reuse or recycling. The MBT facility, does however, have the capability to separate any metals (ferrous and non-ferrous), that remain in the black bag and residual waste which can be sent for recycling. Typically, the process captures in excess of 75% of the metals that remain in the black bag waste.
Q: Will my pre-sorted recyclables end up going to the mechanical biological treatment (MBT) facility?
A: No. All recyclables collected separately from the kerbside in West Sussex are processed through the County Council’s Recycling and Waste Handling Contract (RWHC) with Viridor. Under this Contract, recyclable materials are sorted and separated through the materials recycling facility (MRF) located at Ford, near Arundel. For further information please visit: www.recycleforwestsussex.org
Q: What happens to food waste produced by households in West Sussex?
A: At present, all black bag waste (which includes food waste) that arises from households in West Sussex is delivered to the mechanical biological treatment (MBT) facility. When processed through the mechanical biological treatment (MBT) facility, the food waste forms part of the organic fraction that is separated from the rest of the waste through mechanical pre-treatment (MPT). This organic fraction is further processed through wet pre-treatment (WPT) to remove as much glass, plastic and other contaminants as possible. Following pre-treatment, the organic fraction is then processed in the absence of air (anaerobic digestion (AD) process) to produce biogas (which in turn is used to generate renewable electricity and heat) and a compost-like material.
Q: After processing through the mechanical biological treatment (MBT) Facility, what happens to the end products?
A: The County Council is working on its strategy for managing the outputs from the mechanical biological treatment (MBT) facility in order to minimise the amount of waste sent to landfill. This is in accordance with the aim of the County Council’s Waste Local Plan to achieve zero waste to landfill by 2031. This may mean that interim arrangements are established to increase diversion from landfill, while longer-term solutions are sought.
Ferrous and non-ferrous metals are separated from the local authority collected ‘black bag’ household and commercial waste by mechanical pre-treatment (MPT) and sent for recycling.
The strategy for the use of refuse derived fuel (RDF) is to increase diversion from landfill for this output. The County Council is looking to divert at least 50% of this output from landfill and plans to increase this to 100% as quickly as is reasonably possible.
The anaerobic digestion (AD) process produces a compost-like output that can be used as daily cover in the adjacent landfill site. Should markets become available, some or all of this material could be diverted from landfill by using it for landfill remediation or landfill restoration, and/or potentially dried and used together with RDF as a fossil fuel alternative.
Biogas is used to generate renewable energy in combined heat and power engines. Electricity generated from the biogas is used to power parts of the MBT facility and can be exported at night to the national grid. To reduce the need to import fuel, heat is used to dry and pasteurise the compost-like output to reduce its volume and make it more marketable.
Rejects and residues from the MBT process are sent for landfill disposal at the adjacent Brookhurst Wood landfill site. This landfill site is owned and operated by Biffa Waste Services Ltd.
Q: How far away do the products get transported?
A: Ferrous and non-ferrous metals are sent to reprocessors for recycling. These reprocessors are selected according to market conditions and are mindful of transport distance.
At present all other outputs/products from the mechanical biological treatment (MBT) facility are being managed on site at Brookhurst Wood.
Q: Presumably the mechanical biological treatment (MBT) facility will reduce the amount of West Sussex waste going to landfill?
A: Yes. The key objective of the Materials Resource Management Contract (MRMC) is to reduce waste going to landfill. The MBT facility is a significant step in achieving this key objective. The County Council is working on its strategy for managing the outputs from the MBT facility in order to minimise the amount of waste sent to landfill. This is in accordance with the aim of the County Council’s Waste Local Plan to achieve zero waste to landfill by 2031. This may mean that interim arrangements are established to increase diversion from landfill, while longer-term solutions are sought.
Q: What will be the environmental impact of the next stage of processing of those outputs that are not processed via anaerobic digestion (AD) or sent to landfill?
A: Ferrous and non-ferrous metals are separated from by mechanical pre-treatment (MPT) and sent for recycling i.e. smelted down for subsequent manufacture of new metal products. This represents the best environmental option for these material streams, which helps to alleviate the environmental impacts of extracting and processing ore for virgin metal production. The alternative would be to landfill the metal, which would be a waste of valuable materials.
The facility generates a refuse derived fuel (RDF) output, principally comprising paper, card and plastic. As the name suggests, this material can be combusted to generate power and heat and can be used in cement kilns as an alternative to fossil fuel. These benefits and that of reducing greenhouse gas emissions would be lost if the output was landfilled. When combusted, RDF produces solid residues (e.g. ash) as a by-product. Some of this by-product may be recycled and some will be landfilled. The facilities where RDF is combusted are highly regulated with strict controls over environmental emissions.