Engineers at Aquanos Energy Ltd. began looking several years ago for a more sustainable method of treating wastewater that could benefit developing countries. Traditional facilities can have high operational costs and also may be big energy users.

In an effort to address these problems, a biological wasterwater treatment technology developed by Aquanos and further enhanced by World Water Works seeks to produce a high-quality effluent and a reduce total energy consumption by 90%.

(Read “Technology Innovations Turn Wastewater Plants Into Energy Producers” from IHS Engineering360.)

Aquanos engineers used algae to produce the oxygen required for aerobic wastewater treatment, which then takes place on a fixed-film system. The approach uses two reactors to separate the oxygen production capabilities of algae from the bacterial oxidation of both organic and nitrogenous compounds that occur on an attached-growth aerobic system.

In addition, the method is considered a carbon sequestering technology, capturing greenhouse gases (CO₂) rather than releasing them to the atmosphere.

In this process, biological oxidation is achieved on an attached biomass by recycling an oxygen-rich algae stream through a moving bed biofilm reactor. This results in a high-quality effluent and a controllable process that requires less energy than what is required for aeration with mechanical aeration or blowers. It also occupies a smaller footprint than traditional algae-based systems.

(Read “Water Filtration Trends” from IHS Engineering360.)

The algae-growing pond is shallow, so light can penetrate it. The retained microorganisms are in a different reactor close by so there can be high concentrations of microorganisms without interfering with the algae. A pump transfers the highly oxygenated water into the fixed-film reactor. Energy use could be further reduced if a solar pump was used to transfer the oxygenated water.

Developers say that the algae produced during the process can be used as slow-release nitrogen and phosphorus fertilizer for agriculture. With additional treatment, the algal biomass could be used to produce animal feed and possibly other high value algae-derived products.

The companies involved say this process results in a 90% reduction in plant energy. It also reduces a wastewater treatment system’s operational costs by 40-60% and reduces capital expenditures.

The process is now being launched to municipal markets in India and Africa. Further enhancements could include an enhanced nutrients removal system and resource harvesting of the algae for use as a fertilizer and other useful products.

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