Process & contact
Struvite enhanced: acid (MSE-mobile)
Member of DPP
Sewage sludge before dewatering, from sewage works using chemical or biological P-removal.
Phosphorus-depleted dewatered sewage sludge (filter cake)
- Sulphuric acid is added to sewage sludge, to dissolve phosphorus
- Solid/liquid separation is then done with a filter press; the phosphorus depleted filter cake contains <2%P/DM
- The acid liquor is treated with citric acid (to complex and remove metal ions) then neutralised with sodium hydroxide and magnesium oxide is added to precipitate struvite
40-60 % of P in the inflow sewage sludge is recovered in the struvite.
One mobile (two containers) pilot-scale installation has been operated since 2016 at 7 sewage works. Capacity 50 t/day inflow sewage sludge (wet weight before dewatering).