Abatement of odor emissions from wastewater treatment plants using biochar

Odor is a critical environmental problem that negatively affects people's quality of life. Wastewater treatment plants (WWTPs) often emit various odorous compounds, such as ammonia, sulfur dioxide, and organosulfur. Abatement of odor emissions from WWTPs using biochar may contribute to achieving carbon neutrality due to the carbon negative nature, CO₂ sorption, and negative priming effects of biochar. Biochar has a high specific surface area and microporous structure with appropriate activation, which is suitable for sorption purposes. Various research directions have been proposed to determine the biochar removal efficiency for different odorants released from WWTPs. According to the literature survey, the pre- and post-treatments (e.g., thermal treatment, chemical treatment, and metal impregnation) of biochar could enhance the removal capacity for the odorants emitted from WWTPs at comparable conditions, compared to unmodified biochar. The feedstock and production condition (particularly, pyrolysis temperature) of a biochar and initial concentration of an odorant markedly affect the biochar's odorant removal capacity and efficiency. Moreover, different adsorption systems for the removal of odorants emitted from WWTPs follow different adsorption models. Further research is required to establish the practical use of biochar for the mitigation of odors released from WWTPs.