污泥干化床与芦苇床稳定化污泥中多环芳烃的含量比较

通过传统污泥干化床和芦苇床污泥稳定系统的比较,研究有无植物污泥稳定系统中污泥所含多环芳烃的去除效能差异.中试规模的污泥干化床和芦苇床规格相同,长宽高皆为3.0 m×1.0 m×1.3 m,其中高度由65 cm填料层和65 cm超高组成.二者填料底部均设通风管,直接与大气相连.试验共进行了3 a,前两年为污泥负荷期,第三年为自然稳定期.两年期间进泥总厚度为8.4 m,污泥负荷(以TSS计)平均41.3 kg·(m2.a)-1.经过3 a的稳定化处理,污泥干化床和芦苇床中污泥多环芳烃含量随着污泥稳定时间的延长,16种多环芳烃含量皆呈明显下降趋势.污泥干化床表层、中层和底层污泥的总PAHs含量分别为4.161、3.543和3.118 mg·kg-1(DW),对应的去除率为26.91%、37.77%和45.23%.芦苇床表层、中层和底层污泥的总PAHs含量分别为2.722、1.648和1.218 mg·kg-1(DW).对应的去除率为52.18%、71.05%和78.60%.芦苇床较传统干化床去除污泥中PAHs的效率平均高出29.86个百分点,去除的PAHs中以2～3环芳烃为主,芦苇在稳定污泥中PAHs方面发挥了积极的促进作用.

Comparison of PAHs Distribution in Stabilized Sludge by Sludge Drying Bed and Reed Bed

The difference in the removal efficiencies of polycyclic aromatic hydrocarbons (PAHs) in planted and unplanted sludge drying bed was investigated. Pilot-scale sludge drying bed and reed bed had the same size of 3.0 m×1.0 m×1.3 m (L×W×H), and the bed height consisted of a 65 cm media layer and a 65 cm super height. Both beds had a ventilation pipe which was mounted on the drainage pipes. The experiment lasted for three years, and the first two years was the sludge loading period, and the third year was the natural stabilization period. In the first two years, a total thickness of 8.4 m of sludge was loaded and the average sludge loading rate was 41.3 kg·(m²·a)^-1. After the three-year stabilization, the contents of the sixteen PAHs decreased with time in both the sludge drying bed and the reed bed. The total PAHs contents in the surface, middle and bottom sludge layers in the sludge drying bed were 4.161, 3.543 and 3.118 mg·kg^-1(DW), corresponding to 26.91%, 37.77% and 45.23% of removal; and the values in the reed bed were 2.722, 1.648 and 1.218 mg·kg^-1 (DW), corresponding to 52.18%, 71.05% and 78.60% of removal. The average PAHs removal in the reed bed was 29.86% higher than that in the sludge drying bed. In the stabilized sludge, the removal of low-molecular-weight PAHs predominated. The results suggested that reed played a positive role in the removal of PAHs.