Production, characterization, and applications of biochar from olive processing byproducts

Abstract

Olive oil production generates several byproducts, including olive mill wastewater, olive pomace, and olive pit. While olive pomace is frequently utilized as cattle feed valued at $10-$50 per ton, this project explores an integrated valorization strategy converting olive pomace into polyphenols, biochar, and biogas. Biochar derived from olive byproducts was evaluated as an adsorption agent for treating olive mill wastewater, measuring parameters including chemical oxygen demand (COD), total organic carbon (TOC), and total phosphorus. The lead adsorption efficiency of these biochar products was also assessed in lead nitrate solution, with kinetic models revealing adsorption mechanisms. Additionally, soil amendment trials were conducted through laboratory incubation using soil with 1% biochar, and the conductivity and pH were monitored at 15days, 30days, and 45days. Results demonstrated that biochar pyrolyzed at 300 °C and 600 °C reduced COD by up to 35.7%, TOC by up to 21.3% and total phosphorus by up to 60.2%, though less effectively than commercial biochar. The olive byproduct biochar pyrolyzed at 300 °C and 600 °C effectively adsorbed lead ions in lead nitrate solutions with maximum adsorption capacities ranging from 47 to 116 mg Pb2+/g biochar. The biochar increased soil pH by up to 1.6 units and conductivity by up to 246%. This study establishes a foundation for valorizing olive oil manufacturing byproducts into biochar for environmental remediation applications.