Bioremoval of heavy metals and nutrients from sewage plant by Anabaena oryzae and Cyanosarcina fontana

The present study demonstrated the growth of two species of cyanobacteria on wastewater isolated from sewage plant in Aswan, Egypt. We evaluated their efficiency for eliminating nitrogen, phosphorus, chemical oxygen demand (COD) and heavy metals (Fe²⁺, Pb²⁺, Cu²⁺, and Mn²⁺). The growth of Cyanosarcina fontana has supported wastewater as a growth medium than Anabaena oryzae compared to standard medium. The nutrients concentration such as COD, NO₃–N and PO₄–P were decreased by the growth of A. oryzae and C. fontana in the wastewater after primary settling and centrate. However, the reduction of COD was less efficient than the other nutrients. The reduction percentage of COD, NO₃–N and PO₄–P reached 39.3, 84.1 and 90.7% as well as 54.6, 83.1, and 89.8%, in cultures of A. oryzae and C. fontana grown in the wastewater after primary settling, respectively. The reduction amounted to 10.1, 76.8, and 63.0% by A. oryzae and 43.2, 62.1, and 74.8% by C. fontana, grown in the centrate, respectively. Cyanobacteria species have the ability to accumulate the heavy metals from the wastewater to level far than the exceeding metal level in the water. Whereas, the heavy metals biosorption performance of C. fontana was higher in accumulating Fe²⁺ (93.95%), Pb²⁺ (81.21%), Cu²⁺ (63.9%), and Mn²⁺ (48.49%) compared to A. oryzae. The biosorption ability is dependent on the nature of the adsorbent studied and the type of wastewater treated. Therefore, removal of heavy metals and nutrients by the tested algae is strongly recommended as a powerful technique for the removal of pollutants from wastewater.