How ACTI-Mag provides a sustainable biogas production solution


By Michael Wheatland, Calix business development manager – Australia and New Zealand

Given Australia’s drought-stricken status, the use of water in industry and agriculture is a sensitive topic. Maximising the value of water is essential. Responsible leaders in these industries are, therefore, looking to treat the resulting wastewater to create biogas, which can then provide a viable source of renewable energy.

Doing this provides a renewable energy source that can potentially reduce reliance on fossil fuels, and it ensures that the water used by these industries serves a second purpose; the wastewater isn’t completely wasted. The energy created through wastewater treatment has zero harmful emissions, making it a perfect solution to help combat pollution and climate change.

Not only does biogas creation have no harmful emissions, it actually reduces overall emissions because it captures methane to use it as fuel. The effluent load in untreated wastewater includes carbon, which can be converted into methane to provide clean renewable power. Importantly, no fossil-fuel energy is used in creating biogas, so it’s highly sustainable.

While the value of creating biogas is clear, there are some challenges around doing so effectively. Maximising the methane yield of the anaerobic digestion process of biogas creation can be tricky. Breaking down complex particulate matter into lower molecular weight compounds, which can be more easily broken down by biological means, is key. This is known as the hydrolysis step, and it has been seen to be one of the rate-limiting steps in the digestion process in anaerobic systems. ACTI-Mag addresses this using the high surface area to facilitate rapid breakdown of these organics.

Creating sustainable energy sources is a key focus area for Calix, which saw an opportunity to improve the hydrolysis step in biogas creation. Calix has developed ACTI-Mag using its very high surface area magnesium oxide powder. When hydrated, it forms a highly-stable and easily-flowable slurry (also called magnesium hydroxide) that can be dosed in wastewater management systems. Compared to caustic and lime, ACTI-Mag is safer to handle, non-toxic, and non-hazardous to humans or the environment. It’s also significantly more cost-effective.

ACTI-Mag has been proven to increase biogas production, reduce chemical oxygen demand (COD), and improve process stability. By managing alkalinity and controlling pH, ACTI-Mag can maximise the economics of biogas generation from anaerobic systems.

ACTI-Mag supports bacteria and the breakdown of complex organic chains including proteins, carbohydrates, and lipids, into smaller units such as amino acids, sugars, and long-chain fatty acids. This improves COD in the final effluent. Due to the high surface area of the ACTI-Mag particle, it is able to capture phosphate in the sludge in a form that is beneficial for flowering plants, which can then be used as a fertiliser.

ACTI-Mag helps improve wastewater quality to make recycling the water possible. It improves sludge volume from clarifiers, and improves the removal of flocculation and fat, oil, and grease (FOG) in dissolved air flotation (DAF) systems. It can help organisations gain more throughput with minimal capital expenditure, comprehensively addressing the issue of maximising methane yield from wastewater.

At one of Calix’s customers, the use of ACTI-Mag in its anaerobic ponds helped cut the organisation’s energy bill significantly. This customer, a large food manufacturing plant in Queensland, used ACTI-Mag to boost nitrogen removal and capture phosphorous from the final effluent before using it for irrigation as well as reducing energy usage.

Calix’s high-quality magnesite is locally mined, calcined and hydrated in Australia, making it a local solution, which can be exported to solve the significant global challenge with sustainability.