Research Article
Microbiological Evaluation of the Effectiveness of Sewage Sludge Sanitization with Solar Drying Technology
Table 3
Average results of physicochemical analyses of sewage sludge in winter cycles.
| | | Average results for winter cycles (replications number = 3) | Parameter | Unit | Sampling terms for the research (days) | | | 0 | 7 | 14 | 21 | 28 |
| Sludge dry matter after centrifuge | % | 13.86 (±0.62)* | — | — | — | — | Sludge dry matter in the pile | % | — | 18.90 (±3.21) | 21.43 (±4.33) | 25.12 (±3.93) | 24.54 (±4.84) | Organic substance | % D.M. | 64.20 (±2.17) | 65.50 (±2.04) | 64.20 (±2.65) | 63.40 (±2.87) | 62.40 (±3.50) | pH | — | 6.90 (±0.06) | 6.90 (±0.06) | 7.00 (±0.11) | 6.98 (±0.10) | 6.90 (±0.06) | Total nitrogen content | % D.M. | 2.10 (±0.15) | 2.12 (±0.17) | 2.00 (±0.06) | 2.12 (±0.17) | 2.09 (±0.23) | Ammonium nitrogen content | % D.M. | 0.10 (±0.06) | 0.10 (±0.06) | 0.11 (±0.04) | 0.09 (±0.03) | 0.15 (±0.01) | Total phosphorus | % D.M. | 2.20 (±0.12) | 2.22 (±0.13) | 2.21 (±0.11) | 2.20 (±0.12) | 2.20 (±0.12) | Calcium content (Ca) | % D.M. | 1.15 (±0.03) | 1.13 (±0.03) | 1.12 (±0.02) | 1.15 (±0.03) | 1.15 (±0.03) | Magnesium content (Mg) | % D.M. | 0.23 (±0.04) | 0.23 (±0.04) | 0.23 (±0.04) | 0.34 (±0.05) | 0.23 (±0.03) |
| Heavy metals | | | | | | | Lead (Pb) | mg/kg D.M. | 22.23 (±2.79) | 22.20 (±2.76) | 22.20 (±2.76) | 22.20 (±2.76) | 22.20 (±2.76) | Cadmium (Cd) | mg/kg D.M. | 1.98 (±0.26) | 1.97 (±0.21) | 1.89 (±0.20) | 1.89 (±0.20) | 1.87 (±0.18) | Mercury (Hg) | mg/kg D.M. | 0.05 (±0.03) | 0.05 (±0.03) | 0.05 (±0.03) | 0.00 (–-) | 0.05 (±0.03) | Nickel (Ni) | mg/kg D.M. | 19.50 (±1.94) | 19.50 (±2.12) | 19.50 (±1.94) | 19.50 (±1.94) | 19.50 (±1.94) | Zinc (Zn) | mg/kg D.M. | 1248.00 (±131.15) | 1248.00 (±131.15) | 1248.00 (±131.15) | 1249.00 (±125.87) | 1250.00 (±126.26) | Copper (Cu) | mg/kg D.M. | 220.70 (±17.43) | 220.70 (±17.43) | 220.70 (±17.43) | 220.70 (±17.50) | 220.70 (±17.43) | Chromium (Cr) | mg/kg D.M. | 27.64 (±2.08) | 27.64 (±2.08) | 27.64 (±2.08) | 27.64 (±2.08) | 27.64 (±2.08) |
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*Standard deviation.
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