Reducing greenhouse gas emissions from groundwater treatment using carob seed-derived biochar

ABSTRACT This paper aimed to decrease the greenhouse gas (GHG) emissions from groundwater treatment using biochar-derived carob (Ceratonia siliqua) seeds. Carbon dioxide (CO2) and nitrous oxide (N2O) emissions from groundwater treatment were monitored for biodenitrification and biochar adsorption processes. Also, the adsorption process was applied using carob seed-derived biochar for the collected N2O and CO2. On the other hand, the analytical hierarchy process (AHP) was carried out to determine the correspondence between water quality and GHG emissions. The highest adsorption ratio of CO2 and N2O corresponded to carob seed-derived biochar produced at 250 °C (CSB1). When an average 32.6% of reduction in CO2 emissions was observed, the average amount of N2O reduction was 29.0% using carob seed-derived biochar. According to the AHP results, the highest correlation was found between CO2 emissions and total organic carbon. Nitrate (NO3−) was the most effective parameter for N2O emissions. The limitation of the study was that the indirect emissions were ignored, and the application was at laboratory-scale operational conditions. The biochar adsorption process should be performed on a full-scale drinking water treatment plant fed by groundwater to accurately assess the process as a GHG mitigation technique.