Improvement of biological sulfate reduction by supplementation of nitrogen rich extract prepared from organic marine wastes

• Marine waste extract (MWE) supports high growth of sulfate reducing bacteria (SRB).
• Chemical method based extracts perform better than biological method.
• Multi parameter optimization of pH, Sulfate and MWE achieves higher Sulfate removal.

Organic marine waste was treated by both chemical and biological method to supplement it as nitrogen source in the growth media of sulfate reducing bacteria (SRB), and the resulting extracts were termed as marine waste extract (MWE) and Lactobacillus fermented MWE, respectively. Because of higher nitrogen content and other micro-nutrients, MWE could support higher sulfate reduction (83%) as compared to Lactobacillus fermented MWE (71%). The study further demonstrated that when compared to each optimized single process parameters (pH, MWE and sulfate concentration), optimization of multiple parameters based on Box-Behnken design and response surface methodology improved SRB growth and sulfate reduction by 5–6% and 10–11%, respectively. The experimentally optimized process parameters (1500 mg/L sulfate, pH 7.5 and 20% v/v MWE) resulted in 98% sulfate reduction which was close to the values derived from the theoretical model. This study highlights the use of MWE to improve the treatment of sulfate and metal rich wastewater.