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Combined pretreatment by ultrasound and struvite precipitation of raw substrates: a strategy to overcome C/N ratio unbalance in nitrogen-rich anaerobic co-digestion systems
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Orientador(es)
Resumo(s)
The present study aimed to optimize the struvite chemical precipitation process in nitrogenrich
anaerobic co-digestion systems. Struvite precipitation experiments were carried out using a
mixture of cattle slurry liquid fraction and sewage sludge, with and without ultrasound pretreatment.
Marine salt or MgCl2 were used as magnesium source in NH4
+:Mg2+ stoichiometric proportions of
1:1.5 and 1:3. Under the tested conditions, ammonium nitrogen and orthophosphate were removed
from the mixed liquor with a maximum observed efficiency of 43% and 92%, respectively, when
the ultrasound treatment was applied prior to struvite precipitation, using MgCl2 as source of
magnesium (NH4
+:Mg2+ of 1:3). The operating time was 40 min. Different pretreatments were tested
prior to the biomethanization experiments, struvite precipitation, ultrasound and a combination of
both pretreatments. The application of ultrasound (with an energy input of 218 kJ L1) and struvite
precipitation (NH4
+:Mg2+ of 1:3) increased the methane content in the biogas by 82% and reduced
hydraulic retention time by 28%, when compared to the anaerobic co-digestion assays without
pretreatment. The hydrolytic pretreatment increased the bioavailability of nitrogen by 5%, thus
enhancing the removal efficiency of ammonium nitrogen by 20%. Consequently, an increase in the
carbon to nitrogen ratio was observed, favoring the methanogenesis process
Descrição
Palavras-chave
ultrasound pretreatment struvite precipitation nutrient recovery circular economy anaerobic (co)digestion
Contexto Educativo
Citação
Coura, R.D.; Rodrigues, A.C.; Alonso, J.M.; Ferraz, A.I.; Brito, L.M.; Abrantes, J.C.C.; Brito, A.G. Combined Pretreatment by Ultrasound and Struvite Precipitation of Raw Substrates: A Strategy to Overcome C/N Ratio Unbalance in Nitrogen-Rich Anaerobic Co-Digestion Systems. Sustainability 2021, 13, 2175
Editora
MDPI