The technology uses concentrated anaerobic bacteria to digest 70% of the organic matter (COD, or Chemical Oxygen Demand) in Oakey Abattoir’s waste water to produce effluent that is better quality than typical open lagoons.
Reduces carbon emissions
The project should be up and running by late 2015.
Michael Bambridge, managing director, CST Wastewater Solutions, whose company represents GWE technologies in Australasia, told FoodProductionDaily.com Oakey previously used open anaerobic lagoons combined with aerobic treatment and irrigation to treat its wastewater, like a number of industries worldwide.
“This system had its limitations such as not using the energy potential and producing odours that are of increasing concern worldwide as agribusiness and urban centres come closer together through urban expansion,” he said.
“The Choral system greatly reduces Oakey’s carbon emissions.
“The new plant, in addition to producing gas equivalent to one megawatt of electricity, takes out about 70% of the COD, then passes the cleaner effluent to the aerobic stage, where it is refined to get total COD extraction in the 95% range.”
Processing costs
Pat Gleeson, general manager, Oakey, said the project cost approximately $5m, but the investment is expected to pay off within four to five years.
He added, like all processors, the company had to look at its processing costs and its impact on the environment, and for both reasons, the waste treatment project made good business sense.
Oakey Abattoir’s plant will reuse the biogas in its boilers, where it is initially expected to replace usage of about 50,000 gigajoules natural gas a year.
“The investment was reflective of the decisions being made by parent company, Nippon Ham,” said Gleeson.
“Looking at it from the bottom-line impact, natural gas costs are only going one way. Energy is a significant and rising component of our operating costs.”
Anaerobic digestion facilities are recognised by the United Nations Development programme as one of the most useful decentralised sources of energy supply because they are less capital-intensive than large power plants.
They can also benefit communities by providing local energy supplies and eliminate the need for large, smelly and environmentally challenging settling lagoons. COHRAL gets rid of many of the odours associated with open lagoons often used in meat, dairy and crop waste processing.
According to Bambridge, a feature of the COHRAL system is its feed distribution, post reactor Supersep settler for solids removal and recycling and a separate inflatable gas storage vessel, which stores gas as it builds up between production shifts.
COHRAL
COHRAL anaerobic lagoons consist of two zones, with the complete surface of the lagoon being covered with an influent distribution system.
The first and largest zone receives the major part of the incoming wastewater. This reaction zone is where the anaerobic digestion occurs.
The second, smaller part of the lagoon serves as a post-digestion and pre-settling zone where a partial clarification of the effluent wastewater takes place. Settled sludge collected in this zone is pumped back to the inlet of the lagoon.
Part of the anaerobic effluent is recycled back to the lagoon. The remaining effluent of the lagoon flows by gravity towards complementary technology such as the GWE proprietary SuperSep-CFS separation technology being used in the first Australian installation.
“In addition to lowering the plant’s dependence on expensive supplies of natural gas, the GWE anaerobic digestion plant will simultaneously reduce the plant’s carbon footprint and produce waste water far cleaner than typical waste lagoons,” added Gleeson.
Oakey Abattoir employs 750 people and is a major operator across Australia and exports to 34 countries.