The ManureEcoMine pilot installation: advanced integration of technologies for the management of organics and nutrients in livestock waste

Abstract

Manure represents an exquisite mining opportunity for nutrient recovery (nitrogen and phosphorus), and for their reuse as renewable fertilisers. The ManureEcoMine proposes an integrated approach of technologies, operated in a pilot-scale installation treating swine manure (83.7%) and Ecofrit (16.3%), a mix of vegetable residues. Thermophilic anaerobic digestion was performed for 150 days, the final organic loading rate was 4.6 kgCOD m d, with a biogas production rate of 1.4 Nm m d. The digester was coupled to an ammonia side-stream stripping column and a scrubbing unit for free ammonia inhibition reduction in the digester, and nitrogen recovery as ammonium sulphate. The stripped digestate was recirculated daily in the digester for 15 days (68% of the digester volume), increasing the gas production rate by 27%. Following a decanter centrifuge, the digestate liquid fraction was treated with an ultrafiltration membrane. The filtrate was fed into a struvite reactor, with a phosphorus recovery efficiency of 83% (as orthophosphate). Acidification of digestate could increment the soluble orthophosphate concentration up to four times, enhancing phosphorus enrichment in the liquid fraction and its recovery via struvite. A synergistic combination of manure processing steps was demonstrated to be technologically feasible to upgrade livestock waste into refined, concentrated fertilisers.

Towards a methodology for recovering K‐struvite from manure

“…Therefore, in the present study, a combination of different technologies is used for manure treatment in the framework of a European project (ManureEcoMine, FP7/2007‐2013; http://www.manureecomine.ugent.be/). The process flow allowed the recovery of energy (anaerobic digestion), ammonium sulphate (stripping unit), water (secondary N removal unit with partial nitritation plus Anammox) and struvite and/or K‐struvite (crystallizer) . The present work paves the way for K‐struvite recovery from manure by establishing a methodology to determine the suitable operational conditions (pH and temperature) to enhance its recovery.…”

“…The process flow allowed the recovery of energy (anaerobic digestion), ammonium sulphate (stripping unit), water (secondary N removal unit with partial nitritation plus Anammox) and struvite and/or K-struvite (crystallizer). 3 The present work paves the way for K-struvite recovery from manure by establishing a methodology to determine the suitable operational conditions (pH and temperature) to enhance its recovery. The theoretical operational conditions were established by modelling and experimentally adjusted with the ADox manure (digested and centrifuged manure, after a partial nitritation plus Anammox process).…”

“…Anaerobic digestion is a well‐established technology for the valorisation of the organic content of manure in the form of biogas . Its supernatant is rich in nutrients (N, P, K) and other ions.…”

Effect of suspended solids and its role on struvite formation from digested manure

“…Few studies on struvite recovery from digested manure have been performed, and mainly they have been focused on proving the viability of struvite recovery from manure . They have highlighted the content of solids in the influent used as one of the main limitations for struvite recovery from manure.…”

“…Few studies on struvite recovery from digested manure have been performed, and mainly they have been focused on proving the viability of struvite recovery from manure. [10][11][12][13][14] They have highlighted the content of solids in the influent used as one of the main limitations for struvite recovery from manure. Nevertheless, the role of solids during struvite crystallization was not specifically targeted, and for this reason, more knowledge is considered to be essential to overcome the challenges that a complex matrix such as as manure represents.…”