FOGO // A drone shot of JR Richards’ Molong ORF.
Inside a tunnel composting facility By Jan Arreza THERE is a lot to be proud of when we look at the Australian waste and resource recovery sector. Sure, there are rogue elements and challenges but there is much to applaud as well. Just cast your eye on NSW, where JR Richards’ two organics recycling facilities (ORFs) have been operating for several years, successfully producing high quality mulch and compost products that meet the AS4454 standard. The beauty of being in the sector here in Australia is that often time, while innovation is encouraged, we also do not need to reinvent the wheel. Instead, we can look within and beyond our shores for proven technologies and lessons. And as councils begin to drive FOGO, they may find a reliable partner in JR Richards. Here’s why. JR Richards’ Rich Earth compost business which launched in 2012, grew out of the development of the Grafton ORF on the NSW mid-north coast, established as part of Clarence Valley Council’s kerbside organics collection service contract. This was followed by the establishment of the Molong ORF, near Orange in central west NSW, as part of Orange City Council’s organics processing contract. The state-of-the-art in-tunnel composting facilities process kerbside organic waste (garden and food waste) collected from households and businesses in these areas along with other organic waste residents transport to their local transfer stations or landfills. Combined, they have the 22
capacity to produce more than 30,000 tonnes of high quality Rich Earth compost per annum.
The rite of passage Over in Clarence Valley, the plant receives FOGO from JR Richards’ collection fleet daily, along with self-hauled garden organics. These materials are teased apart to remove contamination, and then shredded and loaded directly into the tunnel. “With multiple tunnels we always stagger our loads to ensure at least one is available to accept material at all times. This allows us to control the storage area and all material is sealed in at night, which negates odour and access by animals. This process continues on a daily basis until the tunnel is full,” said Rob Marlow, chief operating officer at JR Richards & Sons. “All tunnels are computer-controlled via an automated SCADA system with our staff being able to monitor and adjust if required either onsite or remotely. This system controls air pressure, temperature and moisture to ensure no escaping odour along with optimum conditions for the composting process. “When the process is completed, the tunnels are unsealed and the raw compost is relocated to windrows. The product stays in windrows for several weeks, breaking down before being passed through a screen with a wind sifter attachment.”
Inside the tunnels Both ORFs are tunnel-composting facilities built under contract with
INSIDEWASTE FEBRUARY/MARCH 2018
Mission accomplished - Andreas Pichler smiling after successfully commissioning the Grafton plant.
the councils. Each tunnel module is a fully enclosed concrete built structure, which is offered in various sizes ranging from 20-35m lengths and 5-8m widths. The tunnels are arranged sideby-side and the shredded feedstock material is loaded through a door by means of a front-end loader. Each tunnel is equipped with its own air ventilation, leachate collection, and recycling system. The key objectives of the technology are to contain all emissions from this intense composting phase; provide an optimal and consistent environment inside the tunnel for aerobic biological activity as far as temperature, oxygen, and moisture levels are concerned; and to deliver a product that is guaranteed pasteurised and odour stable for outdoor maturation. Tunnel composting technology provider AP Business and Technology Consultancy (APBTC) owner Andreas Pichler said in order to achieve those objectives, the company employs high aeration rates to maintain an even temperature profile across the entire tunnel. “The process further auto controls the mixing ratio of recycled and fresh air into the tunnel to minimise odorous air which needs treatment in the bio-filter and on the other hand, to keep humidity and oxygen levels high,” Pichler said. “Temperature and moisture are our
primary control parameters; running the process on oxygen levels alone would not be sufficient to keep the temperature in the desired range between 55 and 65 degrees. “We know that above 65°C biological activity slows down and more nitrogen is driven out as ammonia. Our process integrates a watering regime, which the operator sets up in order to maintain moisture levels above 50%. This removes the need for watering during subsequent maturation. The process control system (SCADA) takes control of each tunnel batch, once the tunnel is loaded and locked and the operator has selected the desired recipe for the batch to start the process. “The recipe basically allows the operator to select the residence time in the tunnel, the temperature progression over the time, watering regime, etc. The SCADA has remote log-in capability and monitors and controls all process parameters, fans, pumps and alike so that full supervisory control is achieved.” A “run” report is also produced, recording all key performance data such as pasteurisation temperature, water/power consumption etc.
A range of applications The composting industry is certainly the main area of application, with typical feedstock being FOGO, biosolids, commercial food wastes
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