Deciphering sustainability and carbon neutrality for effective treatment of rural wastewater: A review of development and perspectives of biofiltration process

With the growing emphasis on green, low-carbon, energy-efficient, and emission-reduction practices in wastewater management, rural wastewater, characterized by its decentralized nature and fluctuating water quality, requires the urgent development of carbon-neutral treatment technologies. In water-scarce regions, rural populations often reuse domestic wastewater, leading to higher concentrations of organic pollutants compared to urban wastewater. Biofiltration process has become widely adopted in rural wastewater treatment due to its advantages, such as minimal land use, high resistance to impact loads, low operational costs and potential sustainability. This study examines the importance and necessity of carbon-neutral treatment for rural wastewater by critically analyzing the strengths and weaknesses of current carbon-neutral processes. Results of this study also highlight the potential of biofiltration process in achieving carbon neutrality in effective treatment and management of rural wastewater. Various advanced processes that align with carbon neutrality principles (e.g., sulfur autotrophic denitrification, pyrite autotrophic denitrification, anammox, and simultaneous short-range nitrification, anammox, and denitrification) are introduced and discussed as promising future directions for organic and inorganic pollutants removal. This study offers a novel approach to the development of biological treatment technologies for rural wastewater, emphasizing the integration of carbon-neutral concepts to enhance energy efficiency and reduce emissions in wastewater treatment.