08.08.2015   BIOGAS

Two-phase Olive Mill Solid Waste (OMSW)

The OMSW used for the experiments was collected from a two-phase technology mill. The OMSW was derived from olives with a high ripening index (6.5) and an intense purple colour. Before use the small stone pieces were removed by sieving the OMSW through a 3.15 and 2.00 mm sieve. Two influent substrate concentrations were used for the experiments: 35 g COD/L (OMSW 1) and 150 g COD/L (OMSW 2). These concentrations were obtained by dilution of the collected waste. The features and composition of these two- phase OMSWs are summarised in Table 1.

Units

OMSW 1

OMSW 2

pH

*

5.6

5.8

COD

g O2/L

35

150

SCOD

g O2/L

15

67

TVFA

g acetic acid/L

0.70

2.90

Alkalinity

g CaCO3/L

0.74

2.20

TS

g/L

40.2

165.3

MS

g/L

5.6

21.1

VS

g/ L

34.6

144.2

TSS

g/ L

35.2

142.2

MSS

g/ L

4.1

15.7

VSS

g/ L

31.1

126.5

Total phenolic compounds

g caffeic acid/L

0.61

2.44

COD: total chemical oxygen demand; SCOD: soluble chemical oxygen demand; TVFA: total volatile fatty acids (as acetic acid); Alkalinity (as CaCO3). Values are averages of five determinations; there was virtually no variation (less than 3 %) between analyses.

Table 1. Composition and features of the OMSWs.