IMAGINE if you could turn your agricultural wastewater streams into profit?
A new collaboration between Murdoch University and Wilson Inlet Catchment Committee (WICC) is looking at doing just that through anaerobic digesters and microalgae cultivation systems.
The idea is simple - use algae to create a clean waste water and as a result have an algae by-product that can be sold as a high protein feed or fertiliser.
The masterminds behind this idea are professor Navid Moheimani and Dr Mark McHenry who previously worked together looking at algae production for biofuels in the aviation industry.
When the problem was raised of how to deal with high nutrient water ponds, algae presented an excellent solution.
A nutrient hungry single cell plant, algae thrives on water that has high concentrations of nitrogen and phosphorus in them.
Businesses in agriculture that usually have to adhere to additional regulations when it comes to waste such as horticulture, abattoirs, or dairies are set to benefit the most.
"The issue with a dairy for example, and the regulations in Western Australia, is that no one really wants to put that huge amount of nutrient in their local water way and there's only so much they can re-apply to their farm before it becomes excess and runs off into the rivers anyway," Dr McHenry said.
"At this stage dairies need costly effluent ponds that stop a lot of the contamination issues but it doesn't take much nutrient out and it doesn't provide any useful product.
"Hence why WICC is interested because the farmers really want to keep the right amount of nutrients on their farm and from an environmental view, you don't want any excess nutrients from the farm in the local waterways.
"So if you can find a technology that suits both and is cost effective - that's ideal."
According to professor Moheimani, algae provides that solution.
"We use the tendency of microalgae in absorbing nitrogen and phosphorus from wastewater to clean the waste effluent and convert these wastes to profit - the algal biomass can be animal feed, protein concentrates and bioplastics," professor Moheimani said.
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He said that about 75 per cent of the waste in the world was not being fully treated, finding its way into waterways.
While this broader issue is what first sparked his interest, the revenue it can produce as a result has become a motivating factor.
"That's what makes this process unique as we can generate significant revenue by selling the algal biomass," professor Moheimani said.
While research is still underway, it could prove a profitable additional income stream for farmers, with small adoption costs and the ability to turn a profit at a low price point.
"Depending on the size of the operation and the availability of waste, it seems that a central operation may be more profitable," he said.
"We would remove the waste from farmers' hands and convert it in a central facility to bio-methane via anaerobic digestion, to generate electricity, then we convert the effluent to high value biomass products.
"Right now our economic assessment indicates that above 3300 kilolitres per day of effluent will result in a positive net present value if we sell the algal biomass at $1.7 per kilogram."
This high protein algal alternative has already piqued the interest of aquaculture farms as an sustainable feed alternative.
"Some algae cultures are about 50pc protein, that's a really high level, lupins are about 30 pc and wheat is around 12pc," Dr McHenry said.
"If you have a plant with high levels of protein that's grown on wastewater from a dairy, which is a pretty reliable source, you can even start looking at growing your fish a bit closer to where your population wants to source their fish from."
WICC executive officer Shaun Ossinger is excited by the many applications the project will bring, and what it might mean for his local community.
"There are avenues for organic food waste and compostable waste to be used in the system, along with potential for the algae to be used as fertiliser or to use the gas created in the anaerobic digestion process as a fuel," Mr Ossinger said.
Both Professor Moheimani and Dr McHenry would have to agree.
"There are so many uses and methods for the algae biomass, you can use solvents to extract it say like ethanol from vegetables, or you can compress it just like olive oil, you can put it through centrifuges and spin it, you can even just dry it and have it like a cake, just like spirulina," Dr McHenry said.
"The water that is left can be used for irrigation, water for animals in troughs, or you can use it back on the farm.
"Plus there is a local renewable source of biogas, it wouldn't be a major fuel, but you could burn it and make onside renewable electricity for pumps, along with storing it.
"That's the best part of the project, there are so many options and we get to figure out what is going to work best."
