(478f) Phosphorus Recovery From Municipal Wastewater Treatment Sludge

Phosphorus recovery from municipal wastewater treatment sludge

Kamal Lamichhane Upadhyaya¹, W. Todd French¹ and Rafael Hernandez²

¹Dave C. Swalm School of Chemical Engineering, Mississippi State University, MS, 39762, USA

 ²Department of Chemical Engineering, University of Louisiana at Lafayette, Lafayette, LA, 70503, USA

Abstract

Phosphorus is an essential nutrient for plants, animals and humans. Phosphorus is primarily used in agriculture, as it is one of the important components in fertilizer. Besides, phosphorus is also used in laundry detergent, matchstick, steel production and pesticides. The United States phosphate reserves are declining, which could lead to phosphorus shortage in near future. The United States now imports 10% of its phosphorus supply after exporting for several decades. Hence, there is need to search for renewable and sustainable source of phosphorus such as municipal wastewater sludge. Municipal wastewater sludge contains up to 10 wt% phosphorus and recovering these could significantly decrease the phosphorus shortage in the United States. In this study, the potential of phosphorus recovery from primary and secondary sludge through acidic and basic leaching processes will be investigated. The wastewater treatment sludge will be incinerated to obtain sewage sludge ash (SSA) and subjected to acidic and basic leaching at different acid and base concentration and pH levels. After leaching process, the supernatant will be separated from residue through filtration. Phosphorus will then be recovered from the supernatant mixture through the addition of calcium chloride in basic medium. The recovered phosphorus (Ca₅(PO₄)₃OH) has various agricultural and industrial usage as it resembles the phosphate mineral ore (apatite).