Methods and Possibility for Recycling of Phosphorus from Sludge

Abstract

This thesis presents a review of the phosphorus cycle, environmental effect of excess phosphorus on environment, different methods approach taken to recover phosphorus compound from waste sludge, and possible uses for recovered phosphorus.

Phosphorus is a critical nutrient for the agricultural production and living organism survival. The use of phosphorus in fertilizer secures future food demand but threatens water resources. The uncontrolled use of agricultural phosphorus and commercial products are leading to contamination and environmental degradation in water bodies nearby agricultural land. The inefficient use of phosphorus creates uncertainties in supply and demand of this nonrenewable resource for future demand. The amount of phosphorus has a directly impact on the agricultural production which affects the food industry.

Sludge produced from sewage and water treatment plant are enriched with nutrients. This thesis focused on methods for recovery of phosphorus from sludge with four different methods: microalgae and cyanobacteria(Bio-extraction), wet extraction process, thermochemical method, nanofiltration in diafiltration mode. Recovery methods performed by different researchers suggest the efficiency range from 50-90% depending on properties of sludge composition and sludge extraction process in sludge and water treatment plant. All the experiments methods were performed in laboratory condition.

The extraction of phosphorus from sludge has high potential for fulfilling growing demand of phosphorus for fertilizer, commercial products like detergent and phosphoric acid. The side products obtained from recovering phosphorus from sludge can be used as additives for cement manufacturing.