Technology
Technology Comparisons
Table 1: ranking of technologies with regard to costs and footprint size
Type of plant |
Assumed method |
OPEX |
CAPEX |
Ease of upgrading |
Footprint |
HYBACS System |
Biological |
2 |
3 |
2 |
3 |
Activated sludge |
Biological |
3 |
3 |
3 |
4 |
Biological aerated flooded filter (‘BAFF’) |
Chemical |
3 |
4 |
4 |
2 |
Membrane biological reactor |
Biological |
5 |
3 |
3 |
2 |
| Percolating Filtration | Chemical |
1 |
5 |
5 |
5 |
Note: Larger ranking means higher cost, or footprint.
The technologies giving the smallest footprint are biological aerated flooded filters (BAFFs) and membrane reactors, but these technologies generally have higher overall costs. On the other hand, percolating filtration has the smallest OPEX but the highest CAPEX and footprint. Activated sludge, including its variants such as sequencing batch reactors and oxidation ditches, has the lowest CAPEX and, accordingly, has found widespread application.
The HYBACS process has OPEX and footprint advantages over activated sludge and similar CAPEX values. The reduced OPEX arises because Stage 1 of the treatment removes about 40% of the organic load from the wastewater but consumes very little electricity. This is demonstrated in the graph below:
