镁质碱式盐对污泥力学性能的影响

Influence of MgO-Based Basic Salt Cement on the Mechanical Properties of Sewage Sludge

摘要:

采用一种镁质碱式盐（magnesium oxychloride cement, MOC）进行了改善浓缩污泥力学性能的实验研究。结果表明，在MOC/污泥为5/100~20/100，MgO/MgCl2为3/1~5/1时，可以使污泥无侧限抗压强度提高到85.14 kg/cm，50kPa下的污泥渗透性能可达到2.17×10-3 cm/s；塑性指数IP最低可降到7.9。同时污泥的粒径呈线性增加，当污泥粒径在45~72 μm之间时，污泥比阻的下降较明显。采用XRD和SEM进行微观分析，发现MOC在污泥中发生胶凝水化反应。在Mg2+和OH-激发下，MOC与污泥中的Si2+、Al3+、Cu2+形成了Mg-Si-Al凝胶体系，并以晶体结构的形式存在，对污泥的稳定化起到了积极的作用。

Abstract:

Magnesium oxychloride cement (MOC) was used in the sludge stabilization experiments as a new type stability agent in this paper. When the mass ratios of MOC/Sludge are 5/100-20/100, molar ratios of MgO/MgCl2 are 3/1-5/1, the highest compressive strength of stabilized sample can be achieved at 85.14 kg/cm2, the coefficient of permeability up to 2.17×10-3 cm/s, the plasticity index is as low as 7.9, and the grain size increases in linear. When the range of the sludge grain size gets to 45-72 μm, sludge specific resistance decreases sharply. XRD and SEM were used to characterize the macroscopic and microscopic effects of sludge caused by MOC. The results reveal that gelling and hydration reaction would be happened in the MOC-sludge system. Mg-Si-Al gel system is formed with Si2+, Al3+, Cu2+ in the sludge under alkaline condition. The hydrate can be seen and it plays an important role in the sludge stabilization.