Revolutionizing waste management: transforming sewage sludge into eco-friendly biochar for sustainable soil enrichment

Abstract

Urban sewage treatment plants have contributed more sewage due to the movement of people to earn money towards cities in recent years. Biochar from high-temperature sewage sludge has lower nitrogen but higher phosphorus, potassium, and less water-soluble nitrogen. It helps soil by slowly giving out nutrients. When pyrolysis temperatures rise, nitrogen decreases while phosphorus and potassium increase. Likewise, it is made at higher temperatures and shows less water-soluble nitrogen but more water-soluble phosphorus and potassium. Biochar production slows when temperatures elevate, and the best results show at 700 °C - higher alkalinity, better pore structure, lower dissolved salts, and better nutrients, but nitrogen levels are still low. The trace nutrient levels in biochar are less than in sewage sludge, but heavy metals increase with pyrolysis. Yet, it has lower leaching toxicity than sewage sludge and acts as a more stable soil enhancer, significantly improving the soil's nutrients.