Enhancing sustainability: co-pyrolysis of date palm branches and wastewater microalgae for tailored biochar production

Abstract

The use of waste products in different applications contains prime importance in today’s research and industry. Researchers are working on producing innovative technologies and processes to utilize waste and produce valuable products for different applications. Microalgae-derived char contains low aromaticity and heating values with relatively higher nitrogen content than lignocellulosic char. This study presents the use of waste from date palm branches and wastewater-derived microalgae through co-pyrolysis to produce char of improved properties. Two batches of experiments were conducted (a) single-step pyrolysis (SSP) and (b) two-step pyrolysis, in the range of highest treatment temperature of 400–600 °C. Single-step pyrolysed char showed lower aromaticity, higher yield, ash content and heating values of the char than two-step pyrolysed char. Similarly, ignition temperature and activation energy were higher during combustion by single-step pyrolysed char than two-step char. Economic analysis also showed slightly higher prices for single-step pyrolysed char. Hence, two-step pyrolysed char is suitable for energy applications, whereas low-temperature processing (400–500 °C) will result in optimum properties in terms of yield and heating values.