Treatment of high loaded swine slurry in an aerobic granular reactor.
ABSTRACT Aerobic granular sludge grown in a sequential batch reactor was proposed as an alternative to anaerobic processes for organic matter and nitrogen removal from swine slurry. Aerobic granulation was achieved with this wastewater after few days from start-up. On day 140 of operation, the granular properties were: 5 mm of average diameter, SVI of 32 mL (g VSS)(-1) and density around 55 g VSS (L(granule))(-1). Organic matter removal efficiencies up to 87% and nitrogen removal efficiencies up to 70% were achieved during the treatment of organic and nitrogen loading rates (OLR and NLR) of 4.4 kg COD m(-3) d(-1) and of 0.83 kg N m(-3) d(-1), respectively. However, nitrogen removal processes were negatively affected when applied OLR was 7.0 kg COD m(-3) d(-1) and NLR was 1.26 kg N m(-3) d(-1). The operational cycle of the reactor was modified by reducing the volumetric exchange ratio from 50 to 6% in order to be able to treat the raw slurry without dilution.
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ABSTRACT: A continuous stirred tank reactor (CSTR) was operated in order to define the appropriate operational conditions to obtain aerobic biomass grown in the form of granules. A selection pressure of 10 m/h of solids settling velocity was imposed while the hydraulic retention time (HRT) was gradually decreased from 6 to 1 h to promote the wash-out of the suspended biomass. At HRT values of 6 and 3 h, filamentous bacteria were dominant in the biomass. The formation of aerobic granular-type biomass was only achieved when the HRT was fixed at 1 h. The physical properties of these granules were: sludge volumetric index of 127 mL/g TSS, density of 11 g VSS/Lgranule, settling velocity of 36–48 m/h and average diameter of 6.8 mm. Abundance of filamentous species was different at the tested HRTs. When the HRT was fixed at 6 h filamentous shape bacteria appeared in large amounts, while at the HRT of 1 h the bacterial shape was mainly bacillus and filamentous shape bacteria were absent. Microbial populations were mainly composed by members of Comamonadaceae and Rhodocyclaceae families within β-Proteobacteria, and members of the subclass γ-Proteobacteria.Separation and Purification Technology 03/2012; 89(22):199-205. · 2.92 Impact Factor