| | Lab, small scale | Field, medium scale | Lab, medium scale | Modelling study | Field, large scale | Field, small scale | Laboratory and field, medium scale |
|---|
| (Vermi)composting | 9 | 5 | 1 | 3 | | 4 | |
| Algal turf scrubber | | | 1 | | | | |
| Ammonia stripping | 1 | | | | | | |
| Anaerobic digestion | 13 | 1 | 3 | 3 | 2 | 1 | |
| Aquaponics | 1 | | | | | | 1 |
| Bioreactors | 4 | | | | | | |
| Combination | 13 | 1 | 4 | 1 | 1 | | |
| Constructed wetlands | | | 1 | 1 | | | |
| Cover crops | | 9 | | | | | |
| Crop management | 1 | 5 | | 1 | 3 | | 1 |
| Electrocoagulation | 1 | | | | | | |
| Gasification | | | 1 | | | | |
| Industry systems | | | 3 | | 2 | | |
| Manure treatment/management | 4 | 1 | 1 | | 2 | | |
| Membrane filtration | 6 | | 3 | | | | |
| Microalgae cultivation | 3 | | | | | | |
| Microbial fuel cells | 1 | | 1 | | | | |
| Nanoparticles to control P leaching | 1 | | | | | | |
| Nutrient biofilters | | 1 | | | | | |
| P removal from drainage ditches | | | | | 1 | | |
| Pyrolysis | 4 | | 1 | | | | |
| Scrubber for NH4 recovery | | 1 | | | | | 1 |
| Soil amendments | 13 | 10 | | 2 | | 1 | 1 |
| Source separation | | | | 1 | | | |
| Struvite precipitation | 13 | | 2 | | | | |
| Number of studies | 88 | 34 | 22 | 12 | 11 | 6 | 4 |
