Table 1.
Wastewater treatment and associated processes
| Process step | Description | Products | Volume |
|---|---|---|---|
| Primary treatment | Physical and mechanical removal of solids | Cleaner wastewater | 100% |
| Secondary treatment | Aerobic biodegradation of organics creating biomass (waste activated sludge) | Cleaner water, biomass | 100% |
| Tertiary treatment | Trace contaminant and nutrient removal through creating biomass | Clean water, biomass, CO2 fixation | 99% |
| Anaerobic digestion | Solids from primary and secondary treatments are microbiologically converted to biogas and residual solids | Biogas energy, cleaner wastewater, residual solids | 1% |
| Composting | Residual solids from anaerobic digestion and/or biomass are aerobically composted to produce fertilizer | Fertilizer | < 1% |
| Biomass utilization | Multiple products | Animal feed, nutraceuticals, pharmaceuticals, lipids for biodiesel, carbohydrates for ethanol, biogas production, fertilizer |