Efficient formation of vivianite without anaerobic digester: Study in excess activated sludge

It was recently discovered that vivianite (Fe₃(PO₄)₂.8H₂O) could be magnetically extracted from digested activated sludge which opened a new route for phosphorus recovery (Wijdeveld et al. 2022). While its formation in digested sludge is regularly reported, it is not yet studied for fresh,...

Vivianite scaling in wastewater treatment plants: Occurrence, formation mechanisms and mitigation solutions

The presence of soluble iron and phosphorus in wastewater sludge can lead to vivianite scaling. This problem is not often reported in literature, most likely due to the difficult identification and quantification of this mineral. It is usually present as a hard and blue deposit that can also be brown or black depending on its composition and...

Full-scale increased iron dosage to stimulate the formation of vivianite and its recovery from digested sewage sludge

The recovery of phosphorus from secondary sources like sewage sludge is essential in a world suffering from resources depletion. Recent studies have demonstrated that phosphorus can be magnetically recovered as vivianite (Fe(II)₃(PO₄)₂∗8H₂O) from the digested sludge (DS) of Waste Water Treatment...

Magnetic separation and characterization of vivianite from digested sewage sludge

To prevent eutrophication of surface water, phosphate needs to be removed from sewage. Iron (Fe) dosing is commonly used to achieve this goal either as the main strategy or in support of biological removal. Vivianite (Fe(II) ₃ (PO ₄ ) ₂ * 8H ₂ O) plays a crucial role in capturing the phosphate, and...

Understanding and improving the reusability of phosphate adsorbents for wastewater effluent polishing

Phosphate is a vital nutrient for life but its discharge from wastewater effluents can lead to eutrophication. Adsorption can be used as effluent polishing step to reduce phosphate to very low concentrations. Adsorbent reusability is an important parameter to make the adsorption process economically feasible. This implies that the adsorbent...

Effect of pore size distribution on iron oxide coated granular activated carbons for phosphate adsorption – Importance of mesopores

Adsorption is often suggested for to reach very low phosphate levels in municipal wastewater effluent and even to recover phosphate. Adsorbent performance is usually associated with surface area but the exact role of the pore size distribution (PSD) is unclear. Here, we show the effect of the PSD on phosphate adsorption. Granular activated...

Vivianite as an important iron phosphate precipitate in sewage treatment plants

Iron is an important element for modern sewage treatment, inter alia to remove phosphorus from sewage. However, phosphorus recovery from iron phosphorus containing sewage sludge, without incineration, is not yet economical. We believe, increasing the knowledge about iron-phosphorus speciation in sewage sludge can help to identify new routes...