Three waste streams. One process.
Sugar mills, distilleries and municipalities all hold organic waste they currently pay to get rid of. The digester does not care which one it came from — but the pre-treatment line, the seasonality and the economics differ sharply, and that is where a project is won or lost.
The mill already collects the feedstock for you. Press mud arrives at the gate, sorted, in tonnage, for five months of the year — and the fertiliser goes back to the cane growers who supply the mill.
Spent wash is a compliance liability under zero liquid discharge. Biomethanation turns the most expensive line on the effluent budget into a saleable fuel and a potash-rich residue.
The organic fraction of a city's waste is the only feedstock that comes with a tipping fee attached. It is also the dirtiest, and the pre-treatment line is most of the engineering.
What actually differs between them.
| Dimension | Sugar | Distillery | Municipal Solid Waste |
|---|---|---|---|
| Feedstock cost | Low to nil at the mill gate; may carry a disposal credit | Negative — the distillery pays today to treat it | Negative — tipping fee paid by the urban local body |
| Availability | Seasonal: the crushing season, roughly 150–180 days | Follows the distillery's own run days | Year-round, the steadiest of the three |
| Consistency | High — one process, one residue, predictable | Very high — a liquid stream with known COD | Low — composition shifts by ward, day and season |
| Pre-treatment | Light: screening and moisture correction | Minimal: the stream is already liquid and pumpable | Heavy: depackaging, trommel, density and inert separation |
| Off-season plan | Co-feed napier grass and crop residue from the catchment | Buffer storage sized to the distillery's shutdown | Not required |
| Fertiliser output | Potash-rich solid manure, sold back to cane growers | Concentrated potash residue; nutrient-dense, low volume | Solid organic manure, FCO-grade subject to inert control |
The spine does not change with the sector.
Characterisation and yield tests before anything is ordered. Moisture, volatile solids, C:N ratio and inhibitors, on the actual stream, not a table value.
Continuously stirred tank reactors sized to the proven yield, with retention time set by the hardest fraction in the mix, not the easiest.
Water-scrubbed upgrading with two-stage H₂S removal — water then chemical — so the gas meets specification at the bottling skid, every batch.
Digestate separated into solid and liquid organic fertiliser, tested for nutrients and organic carbon, and sold back into the catchment that supplied the residue.
Tell us what your site throws away.
A tonnage, a moisture figure and a crushing calendar are enough for us to size the first estimate.