Briquetting and carbonization of naturally grown algae biomass for low-cost fuel and activated carbon production

Abstract

This study reports the briquetting and carbonization processes of naturally grown algae biomass collected from regional lakes. After drying them in air and chopping them into small pieces (similar to 2.5 x 2.5 cm), three different briquetting pressures (e.g., 2, 3, and 5 tons/cm(2)) were applied to form algae briquettes with 3-5% moisture content. Three major investigations were performed on the prepared samples. The first test was to investigate the briquettes' handleability, in which the algae briquettes were dropped 100 times from a height of 1.524 m to resemble a handling mechanism. The second test was conducted on the samples to resolve the residual strength of the briquettes before and after the carbonization process at 800 degrees C. Ignition points of the algae briquettes were reviewed in the third analysis. Test results showed that briquettes under 2, 3, and 5 tons/cm(2) of pressure had density values of 1303, 1423, and 1553 kg/m(3), respectively. Drop tests demonstrated that the weight contractions of the briquettes were reduced from 10.2% to 2.1%, when the pressure was intensified from 2 to 5 tons. Ignition temperatures for the non-carbonized briquettes under 2, 3, and 5 tons/cm(2) were 492, 510, and 520 degrees C, respectively; however, after carbonization, these temperatures were reduced to 474, 487, and 492 degrees C, respectively. Compression strength tests for the non-carbonized briquettes under 2, 3, and 5 tons/cm(2) resulted in 22.1, 29.2, and 33.5 MPa, respectively. These test outcomes can be suitable for future guidance of an algae-based biomass and fuel system for reducing environmental impacts.