过氧化钙在处理厌氧底泥中的应用初探

Preliminary study about application of calcium peroxide in the heavily contaminated sediments remediation

为改善河道厌氧底质及内源氮、磷等营养盐释放问题，考察对沉水植被恢复的影响，研发可同步解决沉积物供氧和削减内源氮、磷释放的氧缓释材料．实验通过向沉积物一水界面处散点注射不同剂量的过氧化钙（CaO2），研究界面处溶解氧的动态变化特征及表层沉积物与底层水体之间溶解态氮、磷的交换过程．结果表明：添加CaO，显著提高了界面处底层上覆水溶解氧浓度，随着CaO2浓度的增加溶解氧浓度增加，不同处理组之间具有显著差异；CaO2对沉积物中PO3-4-P释放具有明显的抑制作用，且随CaO2浓度的增加抑制效果愈加明显，上覆水中可溶性活性磷浓度最大可削减98％．实验开始时，磷释放速率可降至一241．916±22．501mg／（m2·d），降幅最高可达到144％；CaO2对沉积物NH4＋-N释放的抑制效果不佳，上覆水中NIV-N浓度随着时间的变化波动性较大，且有逐渐增大的趋势．另外，添加CaO2会显著提高底层上覆水pH值，不同处理组之间差异显著，但当CaO2投加量小于0．529kg／m2时，不会对苦草种子的萌发生长有显著影响，pH值波动在可接受范围内（7．62～10．87）．因此，结合污染沉积物的状况，适当地投加CaO2有望同步解决底质厌氧、内源磷释放及后期沉水植被定植底质生境改善的问题，可推荐为一种黑臭污染底泥治理技术在实际的河道生态工程中应用，其适宜浓度为0．176ks／m2左右．

In order to rehabilitate the anaerobic sediment in Moon River, a controllable indoor experiment was carried out. It aimed at finding a synchronization solution of providing oxygen for the anaerobic sediment, reducing the endogenous nutrients release rate, as well as building up plant communities during the later recovery. In the controllable experiment, different concentrations of CaO2 was injected to the surface of sediment separately. It suggested that adding CaO2 could significantly improve the concentrations of dissolved oxygen in the lying water, even more it had a positive correlation with the changes of CaO2 concentration. It had a signifi- cantly negative impact on the release of PO43 - -P in the sediment, more significant with the increasing concentrations of CaO2. The concentration of PO3-4 -P could be decreased by 98% mostly in the overlying water contrasted with the control group. The release rate of PO3- -P could be decreased from - 99. 069 ± 55. 991 rag/（ m2 · d） to - 241. 916 ± 22. 501 mg/（ m2 · d）. On the other hand, the concentration of NH4＋ -N in the overlying water rose with fluctuations. It had significantly improved the pH in the overly- ing water. But it had little impact on the growth of Vallisneria natans when the concentrations of CaO2 was lower than 0. 529 kg/m2. Considering the pollution status, adding CaO2 could reduce the release of PO3- -P and enhance the anaerobic sediment suited for submerged macrophytes growth. Consequently, adding CaO2 could be routinely performed to solve heavily contaminated sediments in the actual river ecological engineering, with the proper dosage of 0. 176 kg/m2.