Algae-bacterial aquaculture can enhance heavy metals (Pb2+ and Cd2+) remediation and water re-use efficiency of synthetic streams

The synergistic interaction between algae and bacteria can be exploited to develop the next-generation waste-water treatment systems as the traditional activated sludge process are expensive, time-consuming, and release several greenhouse gasses. Thus, the protocooperation of algae bacterial consortia was studied during bioremediation of Pb2++Cd2+, followed by a bioassay study with bioremediated stream using Sorghum bicolor. Bacterial [Bacillus sp., (NCBI Acc. No. MK999907), Bacillus sp. (NCBI Acc. No. MN005950) and Micrococcus sp. (NCBI Acc. No. MN005949)]-algal [Scenedesmus acutus (NCIM 5584) and Chlorella pyrenoidosa (NCIM 2738)] consortium was constructed in such as way, which can tolerate and efficiently remove 200 ppm Pb2+ +1.5 ppm Cd2+. The individual consortia showed higher bioremediation attributes when they were mixed in equal quantities. However, the algae-bacterial consortia in the protocooperation study showed similar to 30-33% higher bioremediation than individual consortia of algae/bacteria. Due to positive protocooperation 30% higher algal AFDW, 13% higher bacterial CFU mL(-1), 82% lower dissolved oxygen, and 62% higher bicarbonates were reported as compared to individual consortia systems. For reuse of water, Sorghum plants were treated with bioremediated mixed metal stream (amino acid rich) reported higher total chlorophyll, Fv/Fm, and dry weight. The FTIR signal patterns and SEM-EDX images of Sorghum roots treated with bioremediated mixed metal stream were found negative for presence of any metals, whereas the seedlings treated with mixed metal showed deposition of Pb2+ and Cd2+. Therefore, algal bacterial consortia-based bioremoval approaches can be adopted as an efficient tool for metal bioremediation and reuse of wastewater.