Response of the Diatom Melosira varians to Domestic Wastewater Effluents

This study investigates the physiological and ecological responses of the benthic diatom Melosira varians to varying concentrations of domestic wastewater effluents under laboratory conditions. Effluent dilutions of 12.5%, 25%, and 50% were used to assess the species’ capacity for nutrient removal, growth, morphological alterations, and pigment composition over a 10-day period. The results demonstrated remarkable phosphate removal efficiencies (≥97%) across all treatments and a progressive nitrate removal response, reaching up to 70.59% in the highest effluent concentration. Morphometric analysis revealed significant increases in cell width and length, particularly under moderate (25%) and high (50%) effluent exposures. Chlorophyll analysis indicated a predominance of chlorophyll c and a reduction of chlorophyll b and c in response to nutrient-rich conditions, suggesting a possible shift towards heterotrophic or mixotrophic metabolism. Multivariate analysis highlighted strong associations between cell morphology and biomass, while chlorophyll content showed no direct correlation with biomass accumulation. These findings demonstrate the metabolic flexibility and nutrient uptake potential of M. varians, reinforcing its applicability in sustainable wastewater treatment systems.