Energetic and biochemical valorization of cork boiling wastewater by anaerobic digestion

Table 3 Experimental parameters

Parameter	CBW	AD0	AD3	AD6
pH	7.20 ± 0.10	8.23 ± 0.09	7.67 ± 0.02	7.52 ± 0.06
VFA (kg m^-3)	0.215 ± 0.023	0.185 ± 0.036	0.178 ± 0.048	0.137 ± 0.013
Total phenols (mg mL^-1)	1.20 ± 0.02	0.05 ± 0.00	0.90 ± 0.00	1.41 ± 0.02
OD (254 nm)	43.50 ± 0.22	8.41 ± 0.64	29.08 ± 0.66	43.96 ± 0.00
DPPH inhibition (%)	74.00 ± 0.84	78.90 ± 0.42	76.07 ± 1.56	80.80 ± 1.06
EC^a₅₀ (antiradical activity)	7.20 ± 0.11	2.22 ± 0.08	5.90 ± 0.08	8.74 ± 0.06
Conductivity (mS cm^-1)	1.50 ± 0.10	4.00 ± 0.11	4.60 ± 0.00	5.40 ± 0.11

^aAntiradical activity defined as the amount of antioxidant (expressed as μg of total polyphenols) necessary to decrease the initial DPPH concentration by 50%. Values presented as an average ± standard deviation. AD0, blank anaerobic digestion assay; AD3, anaerobic digestion assay at 3 kg COD m^-3 of CBW; AD6, anaerobic digestion assay at 6 kg COD m^-3 of CBW; CBW, cork boiling wastewater, reactor influent; DPPH, 2,2-diphenyl-1-picrylhydrazyl; EC₅₀, half maximal effective concentration; OD, optical density; VFA, volatile fatty acid.

ISSN: 2731-3654