This study explores the optimization of biochar derived from various sludge residuals, emphasizing the potential of waste activated sludge (WAS) as a precursor for biochar preparation. With a focus on alkaline pretreatment, the research aims to enhance anaerobic digestion and resource recovery. Results indicate a significant 22.1% increase in methane yield when using biochar from alkaline-pretreated sludge, along with a 21.4% rise in electron transport activity. This improvement is attributed to the upgraded characteristics of the biochar, including specific surface area and defect levels.

The approach involves recovering carbon sources and nutrients from sludge through pretreatment or fermentation before utilizing the sludge residuals for biochar production. The study underscores the dual benefits of not only obtaining high-quality biochar but also recovering valuable resources like carbon sources, nutrients, and bioenergy. The proposed strategy presents a green and sustainable solution for the final disposal of sludge.

Amidst the vast yield of WAS, recognized for its hazardous substances and rich organic content, anaerobic digestion emerges as a promising technique for resource recovery. However, challenges such as low methane yield and production rates hinder its development. The research identifies the potential of direct interspecies electron transfer (DIET) through the addition of conductive materials like biochar. Notably, the study suggests an innovative approach by first recovering resources from WAS and then using sludge residue for biochar preparation, a strategy that requires further optimization.

In conclusion, the study provides valuable insights into the role of alkaline-pretreated sludge residue biochar in enhancing anaerobic digestion, showcasing its potential for sustainable waste management and resource recovery.