Optimization of the flocculating capacity of a new micro-atomization extract from a Nostoc cyanobacterium species from the High Andes

Wastewater from domestic sources presents significant challenges for treatment and reuse. Conventional treatment methods often depend on chemical coagulants and flocculants, which can pose serious risks to both human health and aquatic ecosystems. As a result, there is an increasing interest in substituting these chemicals with more sustainable and natural alternatives. However, the method used to extract these natural materials determines their active components and efficacy. This study aims to optimize the flocculating capacity of a novel micro-atomized extract derived from a Nostoc cyanobacterium species found in the High Andes for the treatment of synthetic wastewater. Synthetic wastewater was prepared, and a mixture of the coagulant aluminum sulfate (AS) and the Nostoc (NS) extract as flocculant was added at different concentrations, pH levels, and agitation velocities, following a factorial experimental design with three factors, each evaluated at two levels (2³). The flocculation process was assessed by measuring the percentage removal of physical and chemical water quality parameters. Empirical equations were used to optimize these parameters. The NS/AS mixture exhibited good flocculant capacity under acidic conditions, achieving significant removal of color, conductivity, turbidity, total dissolved solids (TDS), chemical oxygen demand (COD), total organic carbon (TOC), and nitrites. However, its removal efficiency for biological oxygen demand (BOD₅) and phosphates was lower. Optimization results identified ideal conditions as 30 mg·L⁻¹ of NS, 20 mg·L⁻¹ of AS, a pH of 5.5, and an agitation speed of 100 rpm (RPM), achieving up to 50.17 % turbidity removal. Overall, NS demonstrated promising flocculation capacity for the treatment of synthetic wastewater.