Optimization of environmental factors for enhancing growth and pollutant removal efficiency of the cyanobacterium Synechocystis salina M8 in domestic wastewater

Tóm tắt

Microalgae biotechnology has attracted widespread attention due to its potential for wastewater treatment and the recovery of biomass with economic value. This study focuses on evaluating the effects of several environmental factors on the growth and domestic wastewater treatment efficiency of the photoautotrophic cyanobacterium Synechocystis salina M8, which was isolated from agricultural water sources in Vietnam. Laboratory-scale experiments were conducted using two types of culture media (BG-11 and domestic wastewater), under different pH levels and C:N:P nutrient ratios, to determine the optimal conditions for the growth of S. salina M8 and its pollutant removal performance. The study employed standard methods for sampling and wastewater analysis in the laboratory, along with techniques for assessing the growth of S. salina M8. The results showed that S. salina M8 exhibited good growth in both culture media, particularly in domestic wastewater under mixotrophic conditions with aeration. Biomass productivity reached 1.34 g/L in non-sterilized BG-11 medium and peaked at 1.64 g/L in domestic wastewater. After 8 days of cultivation under optimal conditions - including an inoculum ratio of 20–25% (v/v), pH 7, temperature of 27°C, aeration at 0.1 vvm, light intensity of 4500 Lux, and a C:N:P ratio of 100:10:1 - the treatment efficiency reached approximately 75% for COD, and over 80% for N–NH₄⁺, total nitrogen (T-N), P–PO₄³⁻, and total phosphorus (T-P). The treated water met the standards set by QCVN 14:2008/BTNMT, Column B. These findings confirm the potential of S. salina M8 for application in sustainable and environmentally friendly domestic wastewater treatment, while simultaneously generating biomass for the production of valuable products. This contributes to the advancement of green technologies and supports the development of a circular economy model.