Ammonium and urea removal by Spirulina platensis

Area of Science:

• Biotechnology
• Environmental Science
• Microalgal Cultivation

Background:

• Nitrate is a common nitrogen source for microalgae but can be expensive.
• Wastewater biotreatment offers a potential source of reduced nitrogen compounds.
• Spirulina platensis is a widely studied microalga with potential for wastewater remediation.

Purpose of the Study:

• To investigate the feasibility of using ammonium chloride and urea as nitrate substitutes for Spirulina platensis cultivation.
• To determine the optimal concentrations and feeding strategies for these reduced nitrogen sources.
• To assess the potential for using these compounds in wastewater biotreatment.

Main Methods:

• Batch and fed-batch cultivation of Spirulina platensis.
• Use of varying concentrations of ammonium chloride and urea.
• Monitoring microalgal growth and nitrogen utilization.
• Analysis of inhibition effects at different nitrogen levels.

Main Results:

• Maximum nitrogen concentration for batch growth without inhibition was 1.7 mM for both ammonium chloride and urea.
• Ammonium chloride limited growth at low concentrations and caused inhibition at high concentrations.
• Urea showed a less pronounced inhibition effect due to urease-controlled ammonia release.
• Fed-batch experiments demonstrated sustained long-term cultivation with optimized pulse-feeding of ammonium or urea.

Conclusions:

• Ammonium chloride and urea can substitute nitrate for Spirulina platensis cultivation.
• Optimized feeding strategies are essential for successful long-term cultivation using these alternative nitrogen sources.
• This approach holds promise for cost-effective wastewater biotreatment using microalgae.