Sewage Sludge: Is It a Sustainable Fertilizer or a Source of Contaminants?

Sewage sludge is the leftover from municipal and industrial wastewater treatment plants which contains both essential nutrients and contaminants such as heavy metals, pathogens, organic pollutants, etc. Due to having the nutrients, it can function as a soil conditioner for different types of crops, horticultural plants, and pastures. Nowadays, mineral fertilizers, due to the limited resources, are becoming more expensive, and treated sewage sludge as fertilizer can be an effective replacement for it. Moreover, random disposal of waste sewage sludge can induce environmental pollution and disrupt ecology which can be solved by utilizing sewage sludge as fertilizer. Hence, the application of processed sewage sludge as fertilizer could be a sustainable and cost-effective option for nutrient recycling and waste disposal. This chapter seeks to examine the effect of sewage sludge- derived fertilizer on soil fertility, crop quality, and the potential environmental hazards associated with it. Feasibility, challenge, and future directions of using sewage sludge as fertilizer are also highlighted in this chapter.