纤维加筋市政污泥固结特性试验研究

城市内河环境整治及清淤过程中往往产生大量污泥, 安全高效处理和处置这类市政污泥并实现资源化利用对改善城市生态环境和经济可持续发展具有重要意义。污泥具有高含水率、高孔隙比和高压缩性等特点, 由于其含有较多有机质和细颗粒, 一般难以通过机械脱水达到减容的目的。因此, 提高污泥的脱水速率和改善其固结特性是实现污泥安全处置及资源化利用的首要任务, 也是目前该课题的研究难点。本文提出了一种离散短丝纤维加筋技术, 为了研究该技术对污泥固结特性的影响, 对不同纤维掺量(0, 0.05%, 0.1%, 0.2%, 0.4%和0.8%)的污泥进行了一系列固结压缩试验, 分析了固结过程中纤维掺量对固结系数和渗透系数的影响。结果表明:在相同的荷载条件下, 随着纤维掺量的增加, 试样的压缩量、孔隙比变化显著增加, 固结时间和压缩系数相对减小, 且当纤维掺入量为0.1%时变化最显著, 为最优掺量。此外, 研究结果表明, 纤维的掺入增大了污泥的固结系数和渗透系数, 固结效率和固结效果得到明显改善。

EXPERIMENTAL INVESTIGATION ON CONSOLIDATION PROPERTIES OF FIBER REINFORCED MUNICIPAL SLUDGE

A large amount of sludge is often produced in the environment regulation and dredging process of urban river. It has important significance for improving the urban ecological environment and economic sustainable development to safely and efficiently dispose this kind of municipal sludge. Municipal sludge usually has high moisture content, void ratio and compressibility. More importantly, it has a very high fraction of organic and fine particles. It is therefore hard to reduce the total volume through mechanical dehydration. For this reason, accelerating the mechanical dehydration rate and improving the consolidation properties are the top priority during disposing and utilizing the sludge, which is also one of the most significant issues in this subject. In this investigation, the method of discrete short fiber reinforcement technique is proposed and applied to deal with municipal sludge. In order to study the effect of fiber reinforcement on sludge consolidation properties, a series of oedometer tests are conducted on sludge with different fiber contents(0, 0.05%, 0.1%, 0.2%, 0.4% and 0.8%).The effect of fiber addition on the coefficient of consolidation and permeability is analyzed. The results show that the deformation and void ratio of sample increase significantly with increasing fiber content while the consolidation time and coefficient of compressibility decrease with increasing fiber content under the same load conditions. When the fiber content is 0.1%, these changes are most significant, which can be considered as the optimal fiber content. In addition, the results prove that the inclusion of fiber can increase the consolidation coefficient and hydraulic conductivity of sludge. The corresponding consolidation efficiency and mechanical properties are also improved.