[Effects of carbon source types on denitrification performance at low temperature]

Area of Science:

• Environmental Microbiology
• Water Treatment Technologies

Context:

• Denitrification is crucial for removing nitrogen pollution from wastewater.
• Understanding microbial responses to various carbon sources is key to optimizing treatment processes.
• Batch experiments were conducted using sludge from a Carrousel oxidation ditch at a low temperature (15.4°C ± 0.8°C).

Purpose:

• To investigate the impact of diverse carbon sources (methanol, ethanol, sodium acetate, sodium propionate, glucose, domestic wastewater, and endogenous carbon) on denitrifying bacteria.
• To determine the optimal carbon source for maximizing denitrification rates and yields.
• To assess the performance of denitrification under low-temperature conditions.

Summary:

• Sodium acetate resulted in the highest maximum specific denitrification rate (MSDR) of 6.51 mg/(g x h), but exhibited the lowest denitrification yield (0.48) and significant nitrite accumulation.
• Methanol use led to a lower MSDR (0.91 mg/(g x h)), indicating a need for sufficient adaptation time.
• Fermented domestic wastewater achieved an MSDR of 3.63 mg/(g x h), comparable to volatile fatty acids (VFAs).
• Endogenous carbon sources supported denitrification but at the lowest rates.

Impact:

• The study provides critical insights into selecting appropriate external carbon sources to enhance denitrification efficiency in wastewater treatment, particularly under suboptimal temperatures.
• Findings suggest that while sodium acetate boosts denitrification rate, careful consideration of yield and potential byproducts like nitrite is necessary.
• Optimizing carbon source addition can improve nitrogen removal performance in biological wastewater treatment systems.