Improved methane yield from wastewater grown algal biomass

Area of Science:

• Environmental Microbiology
• Biotechnology
• Waste Management

Background:

• Algal biomass cultivated in photobioreactors (PBRs) using sewage offers a sustainable resource for methane production.
• Wastewater treatment by algae effectively removes pollutants like phosphorus, nitrogen, and chemical oxygen demand.
• Optimizing methane yield from algal biomass requires efficient pretreatment methods.

Purpose of the Study:

• To evaluate methane production from algal biomass grown in a continuous PBR using sewage.
• To investigate the effect of natural storage as a pretreatment method on methane yield.
• To assess the efficiency of algal cultivation in removing wastewater contaminants.

Main Methods:

• Cultivation of algal biomass in a laboratory-scale continuous photobioreactor (PBR) fed with sewage.
• Anaerobic digestion of fresh and naturally stored algal biomass.
• Analysis of wastewater contaminant removal (TDP, NO3-N, TAN, sCOD).
• Microscopic analysis (SEM, fluorescence) to confirm storage effects.

Main Results:

• Algal biomass reached 1.69 ± 0.35 g L-1 in 12 days, with high removal rates for TDP (75%), TAN (92%), and sCOD (100%).
• Fresh algal biomass yielded 180 mL g-1 VSfed methane.
• Natural storage for 72 hours led to >48% COD solubilization.
• Methane yield increased to 284.38 mL g-1 VSfed from biomass stored for 60 hours.

Conclusions:

• Natural storage of algal biomass for a specific period is an effective pretreatment for enhancing methane production.
• Wastewater-grown algal biomass shows significant potential for biogas generation.
• This approach integrates wastewater treatment with renewable energy production.