Microalgal-bacterial immobilized co-culture as living biofilters for nutrient recovery from synthetic wastewater and their potential as biofertilizers

This study investigates nutrient recovery from synthetic municipal wastewater using co -immobilized cultures of Chlorella vulgaris TISTR 8580 (CV) and plant growth -promoting bacteria, Bacillus subtilis TISTR 1415 (BS) as living biofilters for a subsequent biofertilizer activity. The optimal condition for nutrient recovery was at the 1:1 ratio of CV/BS using mixed guar gum/carrageenan (GG/CG) binders. After 7 -day wastewater treatment, the living biofilters removed 86.7 +/- 0.5% of ammonium and 99.3 +/- 0.3% of phosphates and were tested subsequently as biofertilizers for 20 days to grow selected plants. The highest optimal biomass and chlorophyll a content was 2 +/- 0.3 g (CV/BS 3:1) and 12.4 +/- 0.7 mu g/g (CV/BS 1:1) from cucumber respectively, however, the close -to -neutral pH (8.0 +/- 0.3) was observed from sunflower using CV/BS 1:1 living biofilters. Conclusively, the designed living biofilters exhibit the potential to recover nutrients from wastewater and be used as biofertilizers for circular agriculture.