A new strategy to increase phosphorus recovery yield from wastewater sludge

Abstract

International audiencePhosphorus (P) recovery as struvite from wastewater activated sludge (WAS) is a developing technology usually applied to recycle dissolved P by adding magnesium (Mg) and increasing pH in the liquid effluent from the digestate dewatering step after anaerobic digestion (AD) of WAS. Consequently, the P recovery yield is depending on the dissolved P concentration in digestate which is usually only a small fraction of the P in WAS. The aim of this study was to increase the P recovery yield by favouring P dissolution by a biological way, not after but just before the AD of WAS as described in figure 1. Recovering P before AD is also a way to prevent struvite crystallization on pipes and equipment, reducing maintenance cost in AD plants. For that, acidogenesis was favoured by adding several different wastes as co-substrate in thickened WAS