Product Distribution and Characteristics of Pyrolyzing Microalgae (Nannochloropsis oculata), Cotton Gin Trash, and Cattle Manure as a Cobiomass

Abstract

Microalgae has proven potential for producing products that are accepted as an alternate energy source. An attempt is made to further improve the efficiency of pyrolysis in terms of product yields and characteristics by adding cotton gin trash and cattle manure as a mixed feedstock (cobiomass). A statistically significant number of treatments were made by mixing different amounts of cotton gin trash and cattle manure with microalgae (Nannochloropsis oculata). These treatments were pyrolyzed at different temperatures (400 to 600 °C ) and product yields and characteristics were analyzed. The pyrolysis of cobiomass resulted in higher yield for bio-oil and char as compared to microalgae alone. An operating temperature of 500 °C was found to be the best suitable for high bio-oil yield. The high heating values (hhv) of bio-oil were observed to be maximum at 500 °C and for syngas and char, the heating value slightly increased with further increase in temperature. Comparatively, the bio-oil (30 MJ/kg) had higher heating values than char (17 MJ/kg) and syngas (13 MJ/kg). The combustible material decreased whereas fixed carbon and ash content increased in char with an increase in temperature. The bio-oil produced from cobiomass had abundant aliphatics and aromatics with low nitrogen content making it a better alternative fuel than bio-oil produced by microalgae alone. The mixing of different biomass helped improving not just the quantity but also the quality of products.