Table 1.
Physicochemical characteristics of the granular sludge bed.
| Parameter | Unit | Average value |
|---|---|---|
| pH | – | 7.4 |
| COD (Chemical oxygen demand) | mg/L | 5330.5 |
| Alk (alkalinity) | mgCaCO3/L | 3250 |
| TS (total solid) | g/L | 32.99 |
| VS (volatile solid) | g/L | 27.28 |
| MS (mineral solid) | g/L | 5.71 |
| % TS | % | 3.21 |
| VS (%TS) | % | 82.70 |
| Moisture (%) | % | 96.79 |
| Diameter | mm | 1–1.5 |
| Color | – | Black |
The initial granular sludge had respectively 27.28 and 32.99 g/L as VS and TS value, and the COD equals to 5330.5 mg/L. In General, the alkalinity varies from 1000 to 5000 mg/L as CaCO3 in anaerobic [24].