LAUSR

Abstract Removal of phosphate (PO43-) and nitrate (NO3-) from wastewater is essential to combat the major issue of eutrophication and other harmful associated threats. Hence, this study focused on designing feasibly applied adsorbents for efficient removal of PO43- and NO3-. A novel material, Porous Floating Meretrix lusoria Shell Composite (PFSC) pellet prepared from 75-85% soda lime silica, 6-16% dolomite and 4-14% M. lusoria F800 shell powder was able to float on water surface, which made it remarkable to apply, collect and reuse. PFSC pellets were found to effectively remove PO43-, and were used as the carriers for immobilization of various bacteria to develop Bacterial immobilized PFSC (Bac-immo-PFSC) pellets for NO3- removal from Domestic Wastewater (DWW). Highest NO3- removal was shown by immobilized PFSC pellets in the order of B. megaterium >P. aeruginosa >Pseudomonas sp. (Isolate 2) > Bacillus sp. (Isolate 4), respectively. Interestingly, the immobilization of PFSC pellets with mixed culture of B. megaterium and P. aeruginosa can remove 100% of NO3- alongwith removal of PO43-. Maximum adsorption capacity (Qmax) of PFSC pellets for PO43- and NO3- was 362 mg/g and 3.51 mg/g, respectively, whereas, among Bac-immo-PFSC pellets, Qmax of B. megaterium-immo-PFSC and P. aeruginosa-immo-PFSC pellets were 156 mgPO43-/g, 16.9 mgNO3-/g and 169 mgPO43-/g, 13.8 mgNO3-/g, respectively. This research identified higher expression of nitrous oxide reductase gene (nosZ) in case of B. megaterium, P. aeruginosa followed by Isolate 2 and Isolate 4, respectively. Hence, the application of novel PFSC and Bac-immo-PFSC pellets can be easily applied for effective PO43- and NO3- removal and thus, can be easily collected and reused for wastewater treatment.