Application Note: Sludge Analysis with Precisa’s prepASH Thermogravimetric Analyser
Moisture content is a critical criterion to determine the acceptability of treated sewage sludge.
Starting with fresh sludge, the moisture content should be around 70%-80%. Dried sludge (cake) needs less than 10% of moisture. The sludge is ashed at 550°C to determine the volatile solid. Volatile solids are a substance that can easily transform from its solid phase to its vapor phase without going through a liquid phase – domestic waste water volatile solids are about 50% organic. For local sewage stations with only a few samples per day the XM66 would be a perfect alternative to determine the moisture content, continuing to manually ash in a muffle.
In this application note, we determine the moisture content in sewage sludge using Precisa’s prepASH Thermogravimetric Analyser.
Method: ABWASSER_105_550.log
| Step | Temp 1 [ºC] | Temp 2 [ºC] | Gas | Gas Flow [l/min] | Time [min] | Auto Stop [mg/min] | Manual Stop | Results |
| 1 | 20 | 105 | 10 | |||||
| 2 | 105 | 105 | 360 | 1mg/10 | Residue [%]/Start (A) | |||
| 3 | 105 | 550 | 30 | |||||
| 4 | 550 | 550 | 180 | 0.5mg/30 | Residue [%]/W0 (B) |
Results: A: Res[%]/Start B: Res[%]/W0
| Group | Pos. | Sample | ID | Tare [g] | Weight [g] | Result | Weight [g] | Calc. | Time |
| R | Reference | – | 28.1532 | 28.1532 | A B | 28.1539 28.1576 | 100.002 100.013 | 00:22 05:22 | |
| 1 | 1 | 12129 | – | 30.9529 | 5.0043 | A B | 0.2817 0.1374 | 5.629 48.764 | 03:35 05:56 |
| 1 | 2 | 12129 | – | 30.5737 | 5.0135 | A B | 0.2349 0.1171 | 4.685 49.859 | 03:08 05:49 |
| 1 | 3 | 12129 | – | 26.9335 | 5.0143 | A B | 0.1740 0.0846 | 3.471 48.602 | 03:06 05:49 |
| 1 | 4 | 12129 | – | 26.9404 | 5.0372 | A B | 0.1819 0.0802 | 3.612 44.074 | 03:22 05:49 |
| 2 | 5 | 12131 | – | 28.0151 | 3.1216 | A B | 0.9561 0.4737 | 30.629 49.547 | 03:50 07:35 |
| 2 | 6 | 12131 | – | 29.9249 | 3.0855 | A B | 0.9470 0.4708 | 30.693 49.716 | 03:58 07:11 |
| 2 | 7 | 12131 | – | 27.0472 | 3.1207 | A B | 0.9563 0.4735 | 30.645 49.509 | 03:48 07:28 |
| 2 | 8 | 12131 | – | 27.2395 | 3.1226 | A B | 0.9559 0.4741 | 30.613 49.600 | 04:10 07:36 |
| 3 | 9 | 12136 | – | 27.8015 | 5.0009 | A B | 0.2222 0.0614 | 4.443 27.611 | 04:19 05:41 |
| 3 | 10 | 12136 | – | 28.7898 | 5.0538 | A B | 0.2537 0.0715 | 5.019 28.186 | 04:06 05:41 |
| 3 | 11 | 12136 | – | 23.3292 | 5.0445 | A B | 0.2442 0.0683 | 4.841 27.951 | 03:59 05:41 |
| Group 1: | A-Result | A-Calc. | B-Result | B-Calc. |
| Mean | 0.21813 | 4.34938 | 0.10483 | 47.82468 |
| STD | 0.05027 | 1.01089 | 0.02725 | 2.56205 |
| RSTD | 23.04829 | 23.24215 | 25.99314 | 5.35717 |
| N | 4 | 4 | 4 | 4 |
| Group 2: | A-Result | A-Calc. | B-Result | B-Calc. |
| Mean | 0.95383 | 30.64503 | 0.47303 | 49.59288 |
| STD | 0.00455 | 0.03441 | 0.00150 | 0.08998 |
| RSTD | 0.47733 | 0.11229 | 0.31799 | 0.18145 |
| N | 4 | 4 | 4 | 4 |
| Group 3: | A-Result | A-Calc. | B-Result | B-Calc. |
| Mean | 0.24003 | 4.76790 | 0.06707 | 27.91603 |
| STD | 0.01616 | 0.29482 | 0.00516 | 0.28912 |
| RSTD | 6.73160 | 6.18344 | 7.69640 | 1.03567 |
| N | 3 | 3 | 3 | 3 |
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prepASH Thermogravimetric Analyser | TGA
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