Formation of phenylacetic acid and phenylpropionic acid under different overload conditions during mesophilic and thermophilic anaerobic digestion

Table 1 Starting total carbon (TC) concentrations (mean ± SD) in the liquid phase and calculated COD (mean ± SD) of flasks containing different substrates at various overload levels

Substrate	Overload	Mesophilic		Thermophilic
Substrate	Overload	TC [g L⁻¹] (± SD)	COD^a (± SD)	TC [g L⁻¹] (± SD)	COD^a (± SD)
Control		4.4 (0.49)	17.9 (1.22)	4.2 (0.08)	17.8 (1.20)
Tryptophan	Low	4.8 (0.12)	20.1 (0.43)	5.1 (0.03)	22.4 (0.5)
Tryptophan	Medium	7.5 (0.21)	26.8 (1.43)	7.9 (0.23)	28.7 (0.26)
Tyrosine	Low	4.8 (0.07)	20.5 (0.96)	5.1 (0.21)	21.9 (0.76)
Tyrosine	Medium	6.4 (0.32)	28.9 (1.78)	6.1 (0.17)	27.8 (1.4)
Phenylalanine	Low	4.9 (0.26)	21.7 (0.39)	5.1 (0.09)	22.5 (0.7)
Phenylalanine	Medium	9.5 (0.24)	34.1 (1.18)	9.2 (0.30)	35.6 (0.05)
Meat extract	Low	5.8 (0.21)	23.6 (0.61)	5.9 (0.06)	25.6 (0.26)
Meat extract	Medium	10.3 (0.34)	35.5 (1.39)	9.3 (0.73)	35.2 (0.77)
Meat extract	High	21.0 (0.83)	60 (1.19)	18.1 (0.72)	57.5 (0.97)
Casein	Low	5.9 (0.04)	23.5 (0.31)	6.0 (0.19)	24.4 (0.25)
Casein	Medium	10.8 (0.27)	34.1 (0.89)	10.1 (0.35)	36.9 (0.24)
Casein	High	21.5 (0.71)	65.3 (2.57)	20.4 (0.51)	64.2 (0.7)

ISSN: 2731-3654