灼烧净水污泥投加方式对磷吸附和磷形态的影响

以灼烧净水污泥为研究对象,探讨在其不同投加方式(混匀和覆盖)下,各底泥对外源磷的吸附效果以及间隙水和底泥中各形态磷的数量分布.结果表明,相比未灼烧净水污泥,灼烧净水污泥对磷的吸附能力显著改善,磷最大吸附量(Smax)提高了43.7%、底泥磷平衡浓度(EPC0)降低69.1%、磷饱和度(DPS)降低54.4%.混匀和覆盖对上覆水中磷消失的贡献率几乎一致,但明显高于对照实验.但如果考虑灼烧净水污泥与上覆水的接触几率,则混匀条件下,单位净水污泥对磷的吸附量为覆盖条件下的2.3倍.覆盖条件下,间隙水(1~2 cm)中溶解性磷酸盐浓度是混匀条件的33.17倍(平均值),这主要源于覆盖导致溶解氧渗透深度明显降低.混匀条件下,外源磷更易形成Ca-P,而覆盖条件下,易释放的NH_4Cl-P和Fe/Al-P占比更多,这暗示了混匀对底泥微环境的改造更有利于外源磷的吸附和内源磷的持留.

Effect of Different Adding Means of Ignited Water Purification Sludge on Phosphorus Adsorption and Forms

The adsorption of external phosphorus (P) and the distribution of dissolved inorganic P (DIP) in the sediment interstitial water and sedimentary P forms were researched under the ignited water purification sludge (IWPS) addition (mixing and capping). The results showed that the adsorption ability of the IWPS increased obviously, compared with the water purification sludge (WPS). It indicated that the S_max increased by 43.7%, the EPC₀ decreased by 69.1% and the DPS decreased by 54.4%. The contribution of P disappearance in the overlying water had almost no difference between the mixing and capping with IWPS, but it was obviously higher than the control in both cases. Under the mixing condition, the adsorption of external P by unit IWPS was 2.3 times of that under the capping condition, if the contacting probability between the IWPS and the overlying water was considered. Under the capping condition, the DIP in the sediment interstitial water (1-2 cm) was 33.17 times (average) of that under the mixing condition. It was attributed to the decrease of the dissolved oxygen penetration due to capping. Under the mixing condition, the external P tended to form Ca-P, while the percentages of NH₄Cl-P and Fe/Al-P to Tot-P were bigger under the capping condition. It was suggested that the improvement of the sedimentary microenvironment by mixing with the IWPS was favorable for the adsorption of the external P and the immobilization of the internal P.