| OPEX costs @1%TotalSolids | % Removal Rates@1%TS | ||||||
| Chemical | Dose rate/m3 slurry (l) | Costs/m3 slurry (£) | Total/m3 slurry (£) | Total/100 cows (£) | CHEMICAL OXYGEN DEMAND (COD) | 89.33 | |
| PAC (18%) | 2 | 1.64 | TOTAL SUSPENDED SOLIDS (TSS) | 96.09 | |||
| PAM (0.14% active) | 40 | 0.67 | TOTAL NITROGEN (TN) | 68.07 | |||
| Sub Total Costs | 2.31 | 4,795 | TOTAL PHOSPHATE (TP) | 99.63 | |||
| Power Consumption @15p/kWh | 4 | 8,304 | ORTHO – PHOSPHATE (OP) | 99.09 | |||
| Total Costs | 6.31 | 13,098 | TOTAL POTASSIUM | 29.33 |
- Current Solid Capture Rates
Screw press – ~37% (Average)
| Sample location | %TS (Average) | Range |
| Raw Pit | 5.4 | 1.03-8.53 |
| SP Filtrate | 3.4 | 1.05-5.08 |
| SP Cake | 23.29 | 21.33-26.23 |
| DW Store | 0.84 | 0.48-1.14 |
| Decanter Centrate | 0.46 | 0.33-0.63 |
| Decanter Cake | 16.42 | 15.33-22.54 |
| DAF Subnatant | 0.29 | 0.18-0.44 |
| DAF Sludge | 2.24 | 0.32-5.41 |
Slurry Store – ~ 36% (as a result of dilution factor and lower %TS Averages
feed solids earlier in the season and sedimentation)
Decanter – ~ 46% (Average)
DAF – ~ 37% (Average)
- ~50% of %TS is dissolved (will increase as slurry thickens)
- Statistical Analysis of %TS shows a good degree of confidence (P-Value = 0.05)
within data sets (indicating stability-low variance in decanter feed) and between data
sets ((indicating significant differences between influent (decanter feed) and effluent
(DAF subnatant)).
- Still early days for reedbed performance data (180 day retention)
Next Steps
- Maximise decanter efficiency
- Optimise chemical dosing for higher feed %TS and flow rates
N:P:K Ratios (Cows out)
| Sample location | NPK Ratios |
| Raw Pit | 5.5:1:5.5 |
| SP Filtrate | 5.5:1:6.75 |
| SP Cake | 4.75:1:3.75 |
| DW Store | 4:1:5 |
| Decanter Centrate | 145:1:365 |
| Decanter Cake | 8.75:1:1.4 |
| DAF Subnatant | 542:1:1192 |
| DAF Sludge | N/A |