Production and utilization of the Chlorella vulgaris microalgae biochar as the fuel pellets combined with mixed biomass

Abstract

The current study focuses on the capability of microalgae biochar as fuel pellets. Additionally, the study aims to investigate the treatment of synthetic saline wastewater through microalgae cultivation, which is an essential tool for meeting the sustainable environment requirements of nations. Microalgae have the tendency to absorb harmful pollutants from wastewater and use them as nutrients for their growth. In this study, Chlorella vulgaris was cultivated in sewage wastewater, and the cultivated samples were collected to produce biochar through a microwave-assisted pyrolysis process. Growing microalgae in wastewater reduces the concentration of ammonia and total phosphorus, and both toxic pollutants are completely absorbed after 60 days of cultivation. The cultivated microalgae underwent pyrolysis to produce biooil, synergetic gas, and biochar. The microwave-assisted pyrolysis process was used to produce the biochar, which was then mixed with agro-waste to form fuel pellets at an equal mass ratio. Three different samples at various concentrations of biochar were examined. Based on the findings, it is evident that the calorific value of the fuel pellets is enhanced upon the addition of biochar. Moreover, there is an increase in the burning time of the pellets made from microalgae-based biochar. Furthermore, microalgae cultivation in wastewater reduced ammonia and total phosphorus content, and the biochar produced from the harvested microalgae improved the ultimate stress, heating value, and bulk density of the pellets. The addition of biochar to the pellets reduced moisture content and increased combustion time, making it a highly justifiable option.