Nutrient Removal and Recovery

The CALAGUA group studies both biological nutrient removal (nitrogen and phosphorus) from wastewater and their recovery in the form of commercially saleable products


For biological nutrient removal CALAGUA studies and optimises advanced treatment systems such as the SHARON and BABE reactors in lab and pilot plants. We also study the primary sludge fermentation process to obtain the volatile fatty acids required to improve nutrient removal in activated sludge systems. We have also developed control systems designed to reduce energy consumption in nitrification and simultaneous nitrification-denitrification processes.


For nutrient recovery we have studied the struvite crystallisation process. Struvite (magnesium and ammonia phosphate) can be used as slow-release fertiliser. Different sludge treatment line configurations have been evaluated in WWTPs to maximise phosphorus recovery while minimising uncontrolled precipitation problems in anaerobic digestion processes, pipelines, pumps and digested sludge thickeners. We have also studied struvite recovery in highly phosphorus-rich (urine) flows. CALAGUA also works on semi-permeable membrane efficiency for ammonia recovery, absorption by sulphuric acid and conversion to ammonium sulphate for agricultural use, as well as nitrogen and phosphorus recovery in the form of algal biomass.