Microwave Treatment of Three Different Types of Sewage Sludge Based on Their Solar Drying Exposure Time: Effect on Microorganisms, Water Content and Agronomic Aspects
Metadatos
Mostrar el registro completo del ítemAutor
Kodom, Piyabalo; Aragón Barroso, Antonio J.; Koledzi, Edem K.; Segbeaya, Kwamivi; González López, Jesús Juan; Osorio Robles, FranciscoEditorial
MDPI
Materia
Sewage sludge Pathogenic microorganisms Microwave
Fecha
2024-01-18Referencia bibliográfica
Kodom, P.; Aragón-Barroso, A.J.; Koledzi, E.K.; Segbeaya, K.; González-López, J.; Osorio, F. Microwave Treatment of Three Different Types of Sewage Sludge Based on Their Solar Drying Exposure Time: Effect on Microorganisms, Water Content and Agronomic Aspects. Water 2024, 16, 321. https://doi.org/10.3390/w16020321
Resumen
This study aimed to treat sewage sludge through microwave irradiation at a laboratory scale.
The objective was to investigate the effect of microwave irradiation on microorganisms, water content,
organic matter, and agronomic nutrients present in sewage sludge. Three types of sewage sludges
obtained from a full-scale wastewater treatment plant were considered: Sludge A (raw sludge),
Sludge B (subjected to 15 days of solar exposure, achieving 48% dryness), and Sludge C (exposed to
solar conditions and left open to the air for 23 months, reaching 94% dryness). These diverse sludges
were exposed to microwave irradiation at various power levels (analysed variables: ε (Watts/g),
θ (ºC), T (min)). The specific exposure powers and temperature levels for the water reduction analysis
were: 555, 955, 1355, and 1500Watts/g and 55, 75, 95, and 105 ºC, respectively. On the other hand,
microbiological and agronomic nutrient analyses were conducted at 75 ºC–1355Wand 95 ºC–1355W.
After microwave exposure experiments, the results demonstrated the high effectiveness of microwave
technology in eradicating indicator microorganisms of faecal contamination and reducing sludge
volume while not affecting trace elements of significant agricultural value. The reduction in Escherichia
Coli revealed that 4 min of irradiation was necessary to completely eliminate it to 0 ulog, indicating a
100% reduction, in Sludge A. In Sludges B and C, an additional 1 min was needed under conditions
of 75 ºC and 1355 W for a mass of 50 g. Moreover, Sludge A (46.27 × 105 or 4.80 ulog of dry matter),
Sludge B (1.29 × 106 or 6.11 ulog of dry matter), and Sludge C (8.77 × 104 or 4.94 ulog of dry matter)
were heavily contaminated with faecal coliforms. It took 6 min to reduce faecal coliforms to below
the detection threshold.