The effect of annual additions of composted sewage sludge (CS) and thermally dried sewage sludge (TS) at 80 t ha-1 on soil chemical properties was investigated for three years in a field experiment under semiarid cond...The effect of annual additions of composted sewage sludge (CS) and thermally dried sewage sludge (TS) at 80 t ha-1 on soil chemical properties was investigated for three years in a field experiment under semiarid conditions. Humic acids (HAs) isolated by conventional procedures from CS, TS, and unamended (SO) and sludge amended soils were analysed for elemental (C, H, N, S and O) and acidic functional groups (carboxylic and phenolic) and by ultraviolet-visible, Fourier transform infrared and fluorescence spectroscopies. With respect to CS, TS had similar pH and total P and K contents, larger dry matter, total organic C, total N and C/N ratio and smaller ash content and electrical conductivity. Amendment with both CS and TS induced a number of modifications in soil properties, including an increase of pH, electrical conductivity, total organic C, total N, and available P. The CS-HA had greater O, total acidity, carboxyl, and phenolic OH group contents and smaller C and H contents than TS-HA. The CS-HA and TS-HA had larger N and S contents, smaller C, O and acidic functional group contents, and lower aromatic polycondensation and humification degrees than SO-HA. Amended soil-HAs showed C, H, N and S contents larger than SO-HA, suggesting that sludge HAs were partially incorporated into soil HAs. These effects were more evident with increasing number of sludge applications.展开更多
A field survey was carried out to collect monthly samples from sewage sludge beds. The samples were collected from three sewage treatment plants namely; Jahra, Rekka, and Um Al-Hayman; over 12 months＇ period started ...A field survey was carried out to collect monthly samples from sewage sludge beds. The samples were collected from three sewage treatment plants namely; Jahra, Rekka, and Um Al-Hayman; over 12 months＇ period started from January and ended by December 2002, 2004 and 2006 to assess the temporal changes on the pollutants associated with sewage sludge. The collected samples were analyzed for organic matters, nutrients and heavy metals. It was observed that the quantities of organic matter, organic carbon and nutrients were varied in a wide range of values. The levels of heavy metals were generally below than reported by the Kuwait Environment Public Authority Limits for application of dry sludge. Temporal changes in the levels of heavy metals and other pollutants may be affected by temporal variation in the level of heavy metals, nutrients and organic matters in the influent of wastewater or in the efficiency of the treatment involved.展开更多
文摘The effect of annual additions of composted sewage sludge (CS) and thermally dried sewage sludge (TS) at 80 t ha-1 on soil chemical properties was investigated for three years in a field experiment under semiarid conditions. Humic acids (HAs) isolated by conventional procedures from CS, TS, and unamended (SO) and sludge amended soils were analysed for elemental (C, H, N, S and O) and acidic functional groups (carboxylic and phenolic) and by ultraviolet-visible, Fourier transform infrared and fluorescence spectroscopies. With respect to CS, TS had similar pH and total P and K contents, larger dry matter, total organic C, total N and C/N ratio and smaller ash content and electrical conductivity. Amendment with both CS and TS induced a number of modifications in soil properties, including an increase of pH, electrical conductivity, total organic C, total N, and available P. The CS-HA had greater O, total acidity, carboxyl, and phenolic OH group contents and smaller C and H contents than TS-HA. The CS-HA and TS-HA had larger N and S contents, smaller C, O and acidic functional group contents, and lower aromatic polycondensation and humification degrees than SO-HA. Amended soil-HAs showed C, H, N and S contents larger than SO-HA, suggesting that sludge HAs were partially incorporated into soil HAs. These effects were more evident with increasing number of sludge applications.
文摘A field survey was carried out to collect monthly samples from sewage sludge beds. The samples were collected from three sewage treatment plants namely; Jahra, Rekka, and Um Al-Hayman; over 12 months＇ period started from January and ended by December 2002, 2004 and 2006 to assess the temporal changes on the pollutants associated with sewage sludge. The collected samples were analyzed for organic matters, nutrients and heavy metals. It was observed that the quantities of organic matter, organic carbon and nutrients were varied in a wide range of values. The levels of heavy metals were generally below than reported by the Kuwait Environment Public Authority Limits for application of dry sludge. Temporal changes in the levels of heavy metals and other pollutants may be affected by temporal variation in the level of heavy metals, nutrients and organic matters in the influent of wastewater or in the efficiency of the treatment involved.
