Macroalgae Bioremediation - A Fully Circular and Cost-Effective Solution to Treat Wastewater

Summary

This video discusses a pioneering trial conducted by Sydney Water and Regen Aqua in Pikton, NSW, which explores the use of green filamentous algae for wastewater treatment. The trial, conducted since 2023, utilizes macroalgae to reduce bioavailable nutrients in wastewater, enhancing water quality for downstream ecosystems. By treating secondary effluent in open raceway ponds, the trial aims to protect local waterways like Stone Quarry Creek and the Upper Nepean River. The project emphasizes cost-effective, nature-based solutions for sustainable water management, with potential for large-scale implementation to improve environmental health and community benefits.

Takeaways

• 😀 The Sydney Water and Regen Aqua trial in Pikton, southwest of Sydney, uses macro algae, specifically *Udiggonium*, for wastewater treatment in open raceway ponds.
• 😀 The trial aims to reduce harmful bioavailable nutrients like nitrogen and phosphorus in treated wastewater to protect local waterways such as the Upper Nepean River and Stone Quarry Creek.
• 😀 The treatment process uses a low-cost, nature-based technology that reduces the need for chemicals and energy in wastewater treatment while improving water quality.
• 😀 The algae-based system has demonstrated a 99-100% removal of ammonia and significant reductions in phosphorus, metals, and pathogens like E. coli and fecal coliforms.
• 😀 The trial is designed to be scalable, with a future goal of expanding to a large-scale facility that could treat up to 6 megalitres of effluent per day.
• 😀 The trial site in Pikton consists of three raceways with different flow rates to test the impact of residence time on treatment performance.
• 😀 Secondary treated wastewater is fed into the algae raceways, and the system is shown to effectively reduce concentrations of nitrogen and phosphorus to near undetectable levels.
• 😀 The trial supports broader environmental and cultural goals, including the protection of aquatic life such as platypus, native fish, and koalas, as well as safeguarding the cultural values of local Indigenous communities.
• 😀 Sydney Water's adaptive management approach includes continuous monitoring and improvement of performance to ensure protection of local waterway ecosystems.
• 😀 Future steps include exploring the beneficial reuse of algae biomass as organic fertilizers, biofuels, bioplastics, and fibers, further contributing to sustainability and resource recovery.

Q & A

What is the main objective of the trial conducted by Sydney Water and Regen Aqua at Pikton?

The main objective of the trial is to explore how low the concentrations of wastewater contaminants can be reduced through treatment with macroalgae, specifically green filamentous algae called Udigonium, grown in open raceway ponds.

Why is protecting the waterways around Pikton important?

Protecting the waterways is critical due to their ecological and cultural value. The waterways support diverse wildlife, such as platypus, dragonflies, and various species of native fish, as well as important cultural significance for the Darowal and Gandangara people.

How does the algae treatment system work in the trial?

The algae treatment system works by feeding secondary treated effluent into three open raceways, where algae grows and absorbs contaminants like nitrogen and phosphorus. The raceways are designed with varying flow rates to test how long water remains in contact with the algae for optimal treatment.

What benefits does the Regen Aqua technology offer in wastewater treatment?

The Regen Aqua technology is a low-cost, resilient solution that uses sunlight and algae growth to remove nitrogen and phosphorus from wastewater. It also sequesters carbon dioxide and reduces the need for chemicals and energy, with additional potential for producing biofuels and bioplastics from the algae biomass.

What pressures are impacting the local waterways in the Pikton region?

The local waterways face pressures from urban development, increasing wastewater volumes, poorly treated stormwater runoff, and other activities like mining, agriculture, and industry, all of which need to be managed to protect the waterways.

What measures are being taken to optimize effluent management at Pikton?

Effluent management at Pikton is being optimized through reducing inflows, increasing water reuse, improving treatment methods (such as the algae remediation system), and minimizing discharge impacts on the waterways. These measures are designed to protect waterway values and reduce the overall volume of wastewater that needs to be treated.

How effective is the algae treatment in removing contaminants from the wastewater?

The algae treatment has shown to be highly effective, with 99-100% removal of ammonia, 95-98% reduction in phosphorus, and 90-95% reduction in fecal coliforms and other microbial indicators. It also reduces metals like iron, aluminum, and copper by up to 80%.

What role does community engagement play in managing the local waterways?

Community engagement is integral to managing the local waterways, as understanding community values and incorporating them into water quality management goals ensures that both ecological and cultural aspects are preserved. The adaptive management approach incorporates community input, guiding the monitoring and actions needed for effective waterway protection.

How do the raceways at Pikton differ in terms of their treatment effectiveness?

The raceways at Pikton are designed with varying flow rates. Raceway 1 has a faster flow rate, replacing about 20% of its water each day, while raceways 2 and 3 have slower flow rates, providing more time for algae to treat the effluent. This variation allows for testing the impact of different residence times on treatment performance.

What are the next steps for scaling up the algae treatment technology?

The next steps involve delivering a large-scale algae bio-remediation facility that would be 200 times the size of the trial facility. This scaled-up system would treat between 1 and 6 megaliters of effluent per day, with the goal of discharging low-bioavailable nutrient concentrations similar to those in the local creeks.