Municipal wastewater treatment plants in the USA generate around 8 million tons of dry biosolids each year, with similar trends observed in the European Union and China.

The rising production of biosolids raises significant environmental and health concerns, particularly due to the presence of pathogens, trace pollutants, and heavy metals.

Disposal of municipal sewage sludge (MSS) presents considerable environmental challenges due to the contamination from both inorganic and organic pollutants.

Traditional biosolid management methods, such as landfilling and incineration, contribute to environmental issues, including methane emissions and potential groundwater contamination.

While biochar derived from MSS has potential benefits, it often contains elevated levels of heavy metals, raising further environmental concerns.

The widespread application of biosolid-derived biochar faces challenges, including the need for standardized production methods, addressing heavy metal contamination, and assessing economic feasibility.

This review highlights various pyrolysis processes—slow, fast, and flash—that convert biosolids into biochar, emphasizing their impact on soil health and crop productivity.

The quality of the produced biochar is significantly influenced by factors such as the type of co-substrate, mixing ratios, and pyrolysis temperature.

Co-pyrolysis not only enhances the properties of biochar but also mitigates risks associated with micropollutants found in MSS biochar.

Future research should prioritize optimizing pyrolysis conditions, developing regulatory frameworks, and conducting economic analyses to promote sustainable agricultural practices.

Biosolid management practices differ globally; developed countries often utilize advanced technologies and regulations, while developing nations frequently face challenges due to inadequate infrastructure.

Various dewatering methods, including centrifugation, filter presses, and electro-dewatering, alongside drying techniques like biodrying, solar drying, and thermal drying, are employed in biosolid management.