Abstract
Struvite from nutrient-rich wastewaters has been identified as a potential substitute for commercial mineral fertilisers, with the added benefit of reducing threats to global food security by prolonging phosphate rock reserves. A fertilisation test using grass (Brachiaria brizantha Marandú) and a sand column leaching test was conducted to determine the agronomic effectiveness of struvite precipitates produced from the supernatant of dewatered sewage sludge (centrate) from a municipal Wastewater Treatment Plant (WWTP). The performance of this struvite as a fertiliser was compared with biosolids and commercial fertilisers (Urea and Triple15). The results show that the concentration of heavy metals in struvite was lower than in biosolids and below the limits of Colombia and European fertiliser regulations. Struvite increased the uptake of N and P in grass, resulting in crop yields similar to other treatments tested. Struvite use as an effective slow-release fertiliser is highly dependent on the size of crystal particles, particularly in achieving low P losses, but resulted in high N loss in the sand columns tested; N loses from struvite were higher than in the commercial fertilisers due to the struvite small particle size. Therefore, struvite represents a suitable opportunity to recover and recycle nutrients from municipal sewage sludge, facilitating the effective reuse of P and N in agriculture and uptake by plants.
Highlights
Struvite (MgNH4PO4·6H2O) recovered from wastewaters, as a secondary phosphate source, has the potential to reduce the pressure on phosphate rock mining and contribute to a more sustainable fertiliser production (Talboys et al )
Many studies have evaluated the potential of struvite as a fertiliser using synthetic struvite produced in the laboratory or granular struvite commercially produced with high particles sizes (e.g. Crystal GreenTM) (Degryse et al ), but only few works have compared the agronomic effectiveness of resulting struvites from nutrient recovery units at Wastewater Treatment Plant (WWTP)
The X-ray diffraction (XRD) data indicated that all crystals of SR1, SR2 and Synthetic struvite (SS) were mainly composed of struvite, with a similarity to the struvite pattern of 97, 90 and 59%, respectively
Summary
Struvite (MgNH4PO4·6H2O) recovered from wastewaters, as a secondary phosphate source, has the potential to reduce the pressure on phosphate rock mining and contribute to a more sustainable fertiliser production (Talboys et al ). Struvite is considered an eco-friendly fertiliser because nutrients are released at a slower rate compared to other fertilisers; plants can take up the nutrients before they are rapidly leached, and less frequent application is required, while phosphorus (PO43À), nitrogen (NH4þ) and magnesium (Mg) can be absorbed simultaneously without using any other artificial components. Struvite has 2–3 times lower heavy metals impurities than commercial fertilisers (Hall et al ) and can help to reduce greenhouse gas emissions from agriculture because plants take up most of the N after its application, avoiding other biological transformations of N leading to nitrous oxide formation and release from the soil (Lee et al ). The use of struvite as a fertiliser can be highly dependent on the size of the crystal particles (Warmadewanthi et al ): an increase in size (>1 mm) leads to a slower fertiliser release rate due to a lower surface to volume ratio. Many studies have evaluated the potential of struvite as a fertiliser using synthetic struvite produced in the laboratory or granular struvite commercially produced with high particles sizes (e.g. Crystal GreenTM) (Degryse et al ), but only few works have compared the agronomic effectiveness of resulting struvites from nutrient recovery units at WWTPs
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
