The WASP - Taking the Sting out of Sydney's Waste

All of the waste coming into the Woodlawn facility arrives at the Crisps Creek Intermodal Transfer Station Credit: Grahame C Located alongside one of the world's largest and deepest bioreactor landfills, Veolia's proposed MBT facility 250 km outside of Sydney has had its doubters. Originally given the green light in 2007, the company says that market conditions are now right to proceed. However, a recent redesign means the project requires a new consent and it's also dependent on the delivery of a major new rail terminal in Sydney. by Ben Messenger In common with nearly all wealthy cities, as Sydney has grown, so too has the amount of waste it produces. In fact, as a country it has been estimated that Australia is the second highest producer of municipal solid waste per capita in the world, at around 700 kg per person per year. Of that it is thought that as much as 40% is food waste, which in Australia is categorised as putrescible waste. To help tackle rising tide of putrescible waste, back in 2000 the Minister of Planning approved proposals from waste company Collex (now Veolia Environmental Services) for the Woodlawn Bioreactor. Located 250 km south of Sydney, near Goulburn in New South Wales, the bioreactor landfill is sited in a former open cast copper, lead and zinc mine. Following a protracted approval process for a rail transfer terminal in Clyde, a suburb of Sydney located 21 km west of the city's Central Business District, the bioreactor came on-line in 2004. Based on an independent assessment of landfill capacity and demand at the time, the facility was consented to receive 400,000 tonnes of putrescible per year, rising to 500,000 if required. However, in 2012, Veolia was granted approval to increase the annual waste input rate to the Woodlawn Bioreactor to 1.13 million tonnes per year. This included a provision for the residual material from a proposed Mechanical Biological Treatment (MBT) facility located at the site to be disposed of in the Bioreactor. Logistics All the waste currently delivered by rail to Woodlawn comes from the Clyde Transfer Terminal, which is operating at full capacity. To transport waste to the proposed MBT facility, additional rail transfer infrastructure would be required in Sydney. To this end, Veolia is proposing to develop a new rail transfer terminal at Banksmeadow within the southern Sydney region. The facility is planned to operate in a similar manner to Clyde and will be able to transfer additional wastes from Sydney to Woodlawn for processing at the MBT and Bioreactor facilities. All the waste coming into the Woodlawn facility by rail arrives at the Crisps Creek Intermodal transfer station, which is 8 km from the site. From there it is completes its journey by road. The proposed Banksmeadow terminal would have a capacity of 400,000 tonnes per annum. Combined with the existing capacity at Clyde of 500,000 tonnes, that would enable up to 900,000 tonnes per annum of waste to be received at Woodlawn via Crisps Creek. Subject to approval, the terminal, which would accept dry waste, general household and commercial waste, is anticipated to be up and running by the end of 2015. Why MBT? To date, the Woodlawn site currently accepts 20% of Sydney's putrescible waste, and comprises several key elements including the Bioreactor landfill, which recovers energy from methane produced by decomposing putrescible waste. Waste heat is used for fish farming, which incorporates hydroponics in the filtrations system to remove excess nutrients. Veolia has also taken on the requirements to rehabilitate the former Woodlawn mine site. As such, the company says that the next planned development is the construction of the MBT facility. The plant is will separate organics from mixed household waste to create a compost suitable for the mine rehabilitation, while reducing the amount of waste going to landfill. The bioreactor is located in a former open mine To this end, an Environmental Assessment was prepared in 2006, and the facility was approved by the Minister for Planning in 2007. However, according to Veolia, before it could make the significant investment required to build the MBT facility, the right market conditions were needed. These include: Greater regulatory certainty to ensure an appropriate use for the compost produced from the facility Increased affordability of alternative treatment facilities compared with landfill disposal The need to secure waste volumes for processing at the facility. The company says that these conditions have now been met. The Environmental Protection Authority (EPA) has now approved the use of the compost to rehabilitate the site, waste levy increases have led to price parity between processing and disposal and an agreement has been reached between Veolia and seven of the councils within the Southern Sydney Region of Councils to process mixed household waste. Redesign Since gaining approval in 2007, Veolia says that it undertook a detailed design review based on its experience operating similar plants throughout Europe. The result has been a redesign, which the company says will improve the quality of the compost from the facility and minimise the potential environmental impacts. However, while this redesign is expected to improve the overall environmental and operational outcomes of the facility, it will require a modification to the existing consent to assess any changes to the design. The company says that it is therefore liaising with the Department of Planning and Infrastructure regarding that process, but that it expects to commence construction in 2014. Technology & Design Waste will be directed into the 200,000 tonne per year Woodlawn Alternative Sorting and Processing facility, or WASP, from the Crisps Creek Intermodal transfer station. After weighing it will be emptied into the reception hall, before being inspected and initially sorted using a remote grapple hook. Any large or obvious contaminants that would compromise the compost will be removed. The waste will then introduced to the BRS® drums, which will form a critical element of the facility and ensure the maximum diversion of organics from the mixed waste stream can be achieved. According to VINCI Environment, the recycling equipment manufacturer which developed the BRS technology, it primarily involves leaving municipal waste in a revolving drum for two to four days. The combined action of rotation, rising temperature and attrition on the inert matter converts fermentable matter to fines, which are easily recovered by screening. After pre-treatment in the BRS, waste will be passed through a mechanical sorting system comprised of trommels and drum sieves. Magnetic separation will also take place using overband magnets to separate ferrous materials for recycling. The smaller fractions of waste will pass into an area where further mechanical treatment takes place to allow the extraction of additional organic material from the residues. Mobile loaders will then take the organic fraction through to the charging hopper, to be conveyed to the fermentation hall using an automated system designed to minimise the amount of mobile plant and operators needed. Here it will compost in windrows for six weeks. The design of the facility also allows for the processing of some green wastes, which will be shredded and mixed with the compost prior to sending to the windrows. At the end of this phase the compost will be fully pasteurised and be transferred from the windrows to the open air maturation area to again be laid out in windrows for a minimum of six weeks. The final refining stage will see the removal of small amounts of glass and ceramics, prior to the compost being used in the remediation of the heavily degrade and contaminated Woodlawn Mining site. Veolia says that it expects that approximately 60% of the waste received will be diverted from landfill and any residual waste will be delivered to the Bioreactor for further energy recovery. Odour control To control odours at the site Veolia says that it plans to incorporate advanced environmental control systems based on similar facilities it operates in Europe, and include a biofilter that utilises organic material to treat air in the waste reception, refining and initial composting areas. According to the Veolia, its forced ventilation and monitoring systems, called Aerocontrol will enable accurate oxygen transfer and moisture control in the compost, providing optimum conditions for composting to occur. The company also uses a patented bio-cover system called BioKap, which it says controls odours from the waste and reduces biofilter costs. Conclusions In a country as vast as Australia, there is always going to be a need to transport waste further than in more densely populated European countries. But Sydney is a major city, and some have queried the rationale behind transporting mixed wastes over 250 km for treatment. Others have questioned the delay since the original planning approval in 2007. However, Veolia says that the issues that caused the delay have been resolved and claims that the environmental credentials of using rail to transport the waste mitigate the distance it will travel. As such the company hopes to secure planning consent for the Banksmeadow rail transfer station next year. If all goes to plan construction of the MBT facility will commence in 2014 and the transfer station will enter service in late 2015. Ben Messenger is managing editor of WMW Magazine e-mail: benm@pennwell.com