Dr Paul Jensen – Program Leader Anaerobic Digestion Unit – University of Queensland. Advanced Water Management Centre.www.awmc.uq.edu.au – Anaerobic Digestion Technology
Full-scale demonstration plant in operation. UQ Biosolids Demo Plant hosted by Teys Bros Pty Ltd Beenleigh. Dealing with paunch waste from butchering cattle in abbatoirs.
Organic waste and energy process.
Main point: There are some established technology and there are people working in Greater Brisbane with expertise in these areas and they are available to talk to and ask about it.
Anaerobic digestion is a biological decompostion process converting organic waste to methane CH4 and carbon dioxide CO2.
Classic treatment processes for organic waste:
[ul]lime stabliisation
composting
aerobic digestion
anaerobic digestion
solar drying
Thermal drying[/ul]
Anaerobic digestion produces usable energy instead of using energy.
It is a well-established technology in a number of industries.
Luggage Point Waste Water Treatment Plant concrete digesters running at 35degrees.
But don’t need complex vessels. Quite a number of agricultural digesters run in open ponds with a cover. (Ex. A piggery digesting pig waste; a banana farm digesting banana palm waste to produce quite a high amount of biogas and using it to run the vehicles on their farm and the packing shed)
Also advanced technology at Oxley Wastewater Treatment Plant at high temperature for difficult to treat materials. Exceptional digestion performance.
Primary sludge 400-600 cubic metres methane/dry tonne
Activated sludge 15-200 cubic metres methane/dry tonne
Animal manure 5-200 cubic metres methane/dry tonne
Fruit and veg scraps 250-400 cubic metres methane/dry tonne
Take-home message: Anaerobic digestion is not one-size fits all. There’s a lot of options.
Domestic or industrial wastewater
Sewage solids activated sludge
Animal manure
Organic solid wastes
Time 10-50 days.
Economics
Income streams
Trade waste reduction
gas production (30cubic metres methane produces about 1Gj energy)
Electricity
Nutrients (if waste water is high in N and P)
Possibly water for reuse
Costs
Capital (offset by federal and state grants)
Cost of capital
pH adjustment (mostly caustic)
Maintenance
Nutrients (N P Mg Ca..) – does not remove. It mobilises them so they are in a readily capturable form. A significant stream
[b]The real primary driver is minimising disposal cost of trade waste.
[/b]
Biogas’s real niche is the waste to energy market.