Impact of pH and Ionic Molar Ratios on Phosphorous Forms Precipitation and Recovery from Different Wastewater Sludges

Saba Daneshgar, Armando Buttafava, Doretta Capsoni, Arianna Callegari and Andrea G. Capodaglio
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Saba Daneshgar: Department of Civil Engineering and Architecture, University of Pavia, 27100 Pavia, Italy
Armando Buttafava: UN.E.CO srl, Academic Spinoff of the University of Pavia, 27100 Pavia, Italy
Doretta Capsoni: Department of Chemistry, University of Pavia, 27100 Pavia, Italy
Arianna Callegari: Department of Civil Engineering and Architecture, University of Pavia, 27100 Pavia, Italy
Andrea G. Capodaglio: Department of Civil Engineering and Architecture, University of Pavia, 27100 Pavia, Italy

Resources, 2018, vol. 7, issue 4, 1-22

Abstract: Phosphorus is an essential nutrient for plants, which use it as a basic fertilizer component and is expected to increase significantly in the coming years due to higher food crops demand. Unfortunately, the available phosphorus natural reserves are not renewable, and estimates indicate their rapid decline in the future. Urban wastewater, due to its abundance and relatively high phosphorus content, is an excellent candidate for phosphorus recovery, while the element’s removal from urban effluents was introduced in the 1970′s to limit the undesired effects of eutrophication. In this study, the process of struvite (and related phosphorous compounds) crystallization was investigated for three different sludge types, and the results were compared. While most studies focus strictly on anaerobically digested sludge for high struvite precipitation efficiency, this study investigated the possibility of inducing precipitation on both aerobic (extended aeration) and anaerobic sludges produced by two wastewater treatment plants in northern Italy. Analysis of precipitates from sludge samples was compared, where the focus was on the aerobic sludge, and its potential for struvite recovery. The effect of different reaction parameters was studied under different operating conditions, and the use and effects of Ca(OH) 2 addition as an inexpensive potential pH adjustment reagent was investigated.

Keywords: phosphorous recovery; wastewater; calcium hydroxide; calcium phosphate; struvite precipitation (search for similar items in EconPapers)
JEL-codes: Q1 Q2 Q3 Q4 Q5 (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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