The use of engineered algae to deliver clean water and valuable co-products from treated wastewater opens new opportunities for water treatment.

An engineered alga (Chlamydomonas reinhardtii) has been grown directly in treated wastewater effluent to produce a valuable co-product. This work by a KAUST team led by Kyle Lauersen in collaboration with WDRC environmental scientist Professor Peiying Hong is the first of its kind to show that the algae used in genetic engineering studies could also have real-world translation in direct production-relevant conditions.

Conventional aerobic and chemical wastewater nutrient-removal methods use a lot of energy, have long process times and produce both carbon emissions as well as excess sludge discharge. “Anaerobic membrane bioreactors (AnMBRs) require less energy and produce at least ten times less sludge, while efficiently removing organic matter and suspended solids,” says Hong, whose research focuses on solving water scarcity in arid regions by developing high-quality, treated wastewater as an alternative water resource.

For the past 18 months, Hong and her team have run a demonstration-scale AnMBR-based wastewater treatment plant in Jeddah — a joint initiative between KAUST and the Saudi Authority for Industrial Cities and Technology Zones (MODON). Using technology developed by Hong, the plant treats 25,000 to 50,000 liters of wastewater per day. The outputs from AnMBR — methane and carbon dioxide gas plus water containing ammonium and phosphate — can be used to grow algae, which uses up CO2 as well as nitrogen and phosphate from the effluent to feed algal biomass.

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