Soil bioamendment as a low-carbon approach for microbial remediation of organic and inorganic pollutants

Soil contamination is an important aspect of concern as environmental pollution continues to be a global problem. This is because soil provides diverse ecological functions important to humans, animals, microbes, and other life forms. Petroleum and its derivatives, as well as metals whose toxicity has been extensively studied, are the most common contaminants found in soil. Because of the ongoing persistence of these contaminants in soil and their physicochemical characteristics, many studies in the field of environmental remediation have been conducted. However, in recent years, the environmental remediation field has paid increased attention to sustainability, which entails addressing risks in a safe and timely manner while maximising the environmental, social, and economic benefits of the remediation work. The use of soil bioamendments such as biochar and spent mushroom compost presents a sustainable strategy for the remediation of soils contaminated by hydrocarbons and metals. These materials have been shown to affect the bioavailability of organic and inorganic contaminants in soil, and improve soil properties, making the soil environment more conducive to microbial growth and activity. Evidence exists that these materials improve soil nutrients, and directly improve the functions of microbes for the biotransformation of these contaminants. The efficiency and cost-effectiveness of these materials (since they are derived from readily available agricultural and industrial waste), their physicochemical and functional properties which affect contaminants and promote microbial degradation function, make them important bioresources for sustainable remediation of these organic and inorganic contaminants. Hence, this chapter focuses on the effects of hydrocarbons and metals on soil microbial community, and the efficiency of biochar and spent mushroom compost in soil remediation. The chapter also examines the effects of biochar and spent mushroom compost on the environmental fate and behaviour of petroleum hydrocarbons and metals, and the effects of biochar and spent mushroom compost addition on the indigenous soil microbial community. It concluded by outlining the challenges and potential future research directions.