=Paper=
{{Paper
|id=Vol-3293/paper52
|storemode=property
|title=Sustainable Utilization of Pig Slurry During Anaerobic Digestion on Struvite Crystallization - Abstract
|pdfUrl=https://ceur-ws.org/Vol-3293/paper52.pdf
|volume=Vol-3293
|authors=Ioannis A. Fotidis,Nomiki I. Kallikazarou,Maria G. Antoniou
|dblpUrl=https://dblp.org/rec/conf/haicta/FotidisKA22
}}
==Sustainable Utilization of Pig Slurry During Anaerobic Digestion on Struvite Crystallization - Abstract==
<pdf width="1500px">https://ceur-ws.org/Vol-3293/paper52.pdf</pdf>
<pre>
Sustainable Utilization of Pig Slurry During Anaerobic Digestion
on Struvite Crystallization - Abstract
Ioannis A. Fotidis 1,2, Nomiki I. Kallikazarou 3 and Maria G. Antoniou 3
1
  Department of Environment, Ionian University, P.C. 29100 Zakynthos, Greece
2
  School of Civil Engineering Southeast University, 210096, Nanjing, China
3
  Department of Chemical Engineering, Cyprus University of Technology, P.C 3036, Limassol, Cyprus


                 Summary
                 High ammonia concentrations (>3 g NH4+-N L-1) released from the degradation of nitrogen-
                 rich organic waste could lead to suboptimal biogas production during anaerobic digestion (AD)
                 due to toxicity events. These toxic events are very common and can yield significant economic
                 losses in full scale AD plants. In addition, globally, nutrient-rich (e.g., nitrogen (N) and
                 phosphorus (P)) digestate effluents are still discarded in agricultural land, releasing nutrients
                 into the environment with adverse effects including the pollution of surface (eutrophication)
                 and ground waters, emissions of greenhouse gases, and soil erosion, that in return impact
                 human health. This study aimed to assess and advance the integrated scheme of nutrient
                 recovery in the form of struvite, and of energy formation as biogas from livestock waste.
                 Struvite is a crystalline mineral, which constitutes a slow-release high-value fertilizer,
                 containing equal molar concentrations (1:1:1) of magnesium, ammonium, and phosphate
                 (MgNH4PO4·6H2O), that can be recovered from nutrient-rich wastewater. The methane in
                 biogas is a renewable fuel, that can be produced by the biodegradation of organic matter. The
                 effect of a specific feeding strategy during AD on the crystallization of struvite from pig slurry
                 at pilot scale was first investigated, while a microbial tracking study was also conducted on
                 this experiment. The results showed that the stepwise feeding of the substrate to the digester
                 alleviated ammonia inhibition. Experimentally measured methane production efficiency
                 reached approximately 90% of the theoretical production, thus indicating an efficient anaerobic
                 digestion process. The produced struvite was of very high purity (> 95 w/w) (X-ray
                 crystallography (XRF) using reference intensity ratio method). Scanning electron microscope
                 analysis revealed the production of typical struvite crystals e.g., orthorhombic. The obtained
                 XRF spectra indicated that heavy metals were within the acceptable regulatory limits. No
                 carcinogens were detected (polycyclic aromatic hydrocarbons and Cr6+). Finally, pathogens
                 such as Salmonella spp. and Escherichia coli, were absent (Regulation (EU) 2019/1009). In
                 this study, the production of a high purity product, safe to use in agriculture and horticulture.
                 To conclude, this integrated innovative process for recovering energy and nutrients from pig
                 slurry can lead to high biogas yield and the production of high-purity struvite organo-mineral
                 fertilizer, thus minimizing nutrient losses, safeguarding the declining phosphate rock, and
                 making this process energy independent.

                 Keywords 1
                 Anaerobic Digestion, Biogas, Nutrients, Pilot Scale, Struvite




Proceedings of HAICTA 2022, September 22–25, 2022, Athens, Greece
EMAIL: ifotidis@ionio.gr (A. 1); ni.kallikazarou@edu.cut.ac.cy (A. 2); maria.antoniou@cut.ac.cy (A. 3)
ORCID: 0000-0003-4587-3617 (A. 1); 0000-0003-3266-8067 (A. 2); 0000-0003-0738-6068 (A. 3)
              ©️ 2022 Copyright for this paper by its authors.
              Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
              CEUR Workshop Proceedings (CEUR-WS.org)




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