Research School for Socio-Economic and
Natural Sciences of the Environment
Research School for Socio-Economic and
Natural Sciences of the Environment

Jorge Ricardo Cunha

Date: 30 November 2018
Time: 16:00 - 17:30
Location: De Kanselarij, Turfmarkt 13, Leeuwarden

Dissertation title: 

Anaerobic calcium phosphate bio granulation

Group: Wetsus, Leeuwarden / Wageningen University
Supervisors: Prof. dr. Grietje Zeeman; dr. Renata D. van der Weijden, and dr. Lucía Hernández Leal
Promotor: Prof. dr. Cees Buisman

Extra information:


The goal of this thesis is to understand the fundamental mechanism behind calcium phosphate granulation and to explore technological options for enhancing the phosphate recovery efficiency. The calcium phosphate granulation was reproduced in lab scale UASB reactors. Addition of calcium increased the retention of phosphorus in the reactor and stimulated the calcium phosphate granulation. An increasing pH gradient from the edge to the granule centre was measured, favouring enrichment of phosphorus over bulk precipitation. Anaerobic treatment of glucose and bulk pH 7.5 yields similar calcium phosphate granules as black water. With volatile fatty acids, granulation was not observed. The operation and performance of a novel reactor design combining upflow anaerobic sludge blanket and internal recirculation gas-lift concepts are described. The internal gas mixing enhanced the concentration of phosphorus at the harvesting location. Application of harvested calcium phosphate granules in agriculture and as replacement of phosphate rock in fertilizer industry is discussed.