Uso di microalghe come substrato per la produzione di biogas in impianti di depurazione
Presenta: Valeria Mezzanotte, ( Università degli Studi di Milano-Bicocca )
The seminar will focus on the results of an experimental study aiming at verifying the feasibility of including a photobioreactor within the sketch of a wastewater treatment plant, growing microalgae on the centrate from anaerobic sludge dewatering. The growth of algal biomass would take advantage of the available nitrogen and provide substrate for biogas production by anaerobic digestion. Tests have been carried out in semi-continuous by feeding a photobioreactor with a centrate/effluent blend and by increasing the fraction of centrate. The experimental results show that the centrate does not induce any toxicity and, on the contrary, can be well utilized by microalgae, whose average specific growth rate (µ), on centrate as such, was within 0.04 and 0.06 d-1. The maximum biomass concentration in the photobioreactor effluent was 1.6 gSS/L at 10 days HRT. Methane production tests lead to BMP values of 335±39, and 284±68 mL0°C, 1 atm CH4/g VS for the two tested samples, in agreement with literature values. Settling tests show that the settling capacity of microalgae, yet satisfactory, could be effectively improved after mixing with activated sludge, confirming the potential to use the existing primary settler for microalgae thickening in order to feed them to anaerobic digestion with primary/secondary sludge.
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