A sustainable nanotechnology producing high-quality remediated sewage wastewater used for microalgal protein-rich biomass and biodiesel production

Water scarcity is a crucial environmental challenge. Wastewater remediation is an important way to tackle the challenge. Using nanoparticles of natural and agricultural wastes is considered a low-cost sustainable remediation technology. This study develops an effective prototype of a sustainable sewage wastewater (SWW) remediation process using zeolite and bagasse nanoparticles. All studied physico-chemical parameters and heavy metals of the SWW were reduced over the course of treatment with nanobagasse (NB), nanozeolite (NZ), and nanobagasse-nanozeolite double treatments ( DT ). After only 2 weeks of remediation, the chemical oxygen demand (COD), biological oxygen demand (BOD), total suspended solid (TSS), and total dissolved solid (TDS) concentrations were decreased (in NB 38, 33, 58, and 30%; in NZ 40, 30, 63, and 58%; and in DT 47, 38, 75, and 62%), respectively, compared to raw SWW. The DT for 4 and 6 weeks (DT4W and DT6W) show 0.94 and 0.67 Kelly ratios, respectively, which are suitable for irrigation. According to the water pollution index (WPI), all types of DT treatments produce excellent-quality water. DT6W recorded the highest significant rank of removal efficiency of COD, BOD, TSS, TDS, PO 4 , NO 3 , Ca, Mg, Na, Cu, Cd, Fe, and Ni (72.7, 59.6, 88.6, 74, 56.7, 88.2, 72.7, 58.7, 80.7, 94.6, 91.1, 65.3, and 84.4%). This remediated water may be used directly for irrigation or other purposes. Also, this study proves that DT4W and DT6W are suitable for Chlorella sorokiniana growth and production of safe protein-rich biomass, 26 and 31.8% protein, respectively. DT for 2, 4, and 6 weeks are suitable growth media for C. sorokiniana to produce diesel engines’ compatible biodiesel. Finally, this recent study presents an interpretation of the physiological status of C. sorokiniana cells grown in the raw SWW and DT media.