Research Article
Microbiological Evaluation of the Effectiveness of Sewage Sludge Sanitization with Solar Drying Technology
Table 2
Average results of physicochemical analyses of sewage sludge in summer cycles.
| | | Average results for summer cycles (replications number = 3) | Parameter | Unit | Sampling terms for the research (days) | | | 0 | 7 | 14 | 21 | 28 |
| Dry matter of sludge after centrifuge | % | 16.22 (±0.16)* | — | — | — | — | Dry matter of sludge in the pile | % | — | 40.30 (±4.00) | 47.20 (±10.68) | 69.90 (±10.81) | 86.40 (±13.01) | Organic substance | % D.M. | 66.90 (±0.71) | 67.00 (±0.71) | 66.60 (±0.90) | 65.70 (±1.45) | 65.30 (±1.71) | pH | — | 6.70 (±0.16) | 6.70 (±0.16) | 6.69 (±0.13) | 6.70 (±0.16) | 6.70 (±0.18) | Total nitrogen content | % D.M. | 4.08 (±1.27) | 4.05 (±1.28) | 3.60 (±1.19) | 3.30 (±1.04) | 3.20 (±1.04) | Ammonium nitrogen content | % D.M. | 0.19 (±0.09) | 0.16 (±0.10) | 0.17 (±0.06) | 0.15 (±0.02) | 0.15 (±0.02) | Total phosphorus | % D.M. | 2.14 (±0.99) | 2.12 (±0.98) | 2.12 (±0.98) | 2.05 (±0.94) | 2.12 (±0.98) | Calcium content (Ca) | % D.M. | 1.13 (±0.14) | 1.12 (±0.15) | 1.12 (±0.15) | 1.13 (±0.14) | 1.13 (±0.14) | Magnesium content (Mg) | % D.M. | 0.43 (±0.03) | 0.43 (±0.03) | 0.43 (±0.03) | 0.43 (±0.03) | 0.43 (±0.03) |
| Heavy metals | | | | | | | Lead (Pb) | mg/kg D.M. | 31.50 (±0.58) | 31.50 (±0.58) | 31.50 (±0.58) | 31.50 (±0.58) | 31.51 (±0.53) | Cadmium (Cd) | mg/kg D.M. | 2.41 (±0.09) | 2.42 (±0.07) | 2.40 (±0.11) | 2.41 (±0.09) | 2.41 (±0.09) | Mercury (Hg) | mg/kg D.M. | 1.03 (±0.60) | 1.00 (±0.57) | 1.00 (±0.57) | 1.00 (±0.57) | 1.00 (±0.57) | Nickel (Ni) | mg/kg D.M. | 16.30 (±3.90) | 16.31 (±3.76) | 16.30 (±3.90) | 16.30 (±3.90) | 16.31 (±3.75) | Zinc (Zn) | mg/kg D.M. | 1100.00 (±84.97) | 1100.00 (±84.97) | 1100.00 (±84.97) | 1100.00 (±84.97) | 1100.00 (±84.97) | Copper (Cu) | mg/kg D.M. | 240.50 (±19.05) | 240.50 (±19.05) | 240.52 (±20.17) | 240.51 (±20.15) | 240.50 (±19.05) | Chromium (Cr) | mg/kg D.M. | 38.37 (±23.56) | 38.30 (±23.58) | 38.37 (±23.56) | 38.36 (±23.55) | 38.37 (±23.56) |
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*Standard deviation.
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