关键词: 免滤膜, 秸秆排水体, 真空预压, 淤堵, 疏浚淤泥

Abstract:

[Objective] To address the engineering challenge of drainage efficiency reduction caused by filter membrane clogging in traditional plastic drainage bodies during vacuum preloading of dredged sludge, this paper innovatively proposes a fully biodegradable, non-filter membrane straw drainage body (NSD) technology. Model tests were conducted to verify the engineering applicability of the NSD, reveal its drainage consolidation mechanism, and provide sustainable solutions for the green treatment of dredged sludge. [Methods] A PVC cylinder with a height of 50 cm and a diameter of 30 cm was used as the test tank, filled with dredged sludge at a water content of 147.5% (approximately 2.5 ω_L). The sludge was collected from a disposal site in Wuhe County, Anhui Province, with a liquid limit of 59% and clay content of 21.7%. The control group used traditional plastic drainage bodies, consisting of rigid tubes wrapped with filter gauze and fabric. Two setups were tested: one with constant vacuum loading and another with staged vacuum loading. The experimental group employed NSDs, made of rigid tubes wrapped with straw ropes. Four setups were tested: (1) constant vacuum loading, (2) staged vacuum loading, (3) constant vacuum loading after installing a 2-5 mm self-filtering soil layer, and (4) staged vacuum loading with the pre-installed 2-5 mm self-filtering layer. During the testing period, the effluent discharge volume was recorded every 24 hours, and the solids content of the extracted tailwater was measured during each cycle. Upon completion of the vacuum preloading, the soil’s moisture content and particle gradation were determined. [Results] Drainage efficiency significantly improved, with the experimental group’s cumulative effluent volume 7.9%-22.1% higher than the control group, indicating that the three-dimensional pore structure of straw effectively alleviates the impact of clogging on drainage. Soil reinforcement was enhanced, with the experimental group’s average water content after vacuum preloading reduced by 6.8%-15.3% compared to the control group. Particle size distribution analysis revealed that when the self-filtering soil layer was pre-installed, the clay content (d<0.005 mm) increased by 5%-11.1%, confirming that the NSD, when combined with the pre-installed self-filtering layer, not only achieved effective soil filtration but also enhanced soil stabilization performance. [Conclusion] Technical innovation: The NSD achieves membrane-free drainage through its crisscrossing internal channels, overcoming the clogging bottlenecks of traditional plastic drains while increasing drainage efficiency by more than 15%. Mechanism breakthrough: A synergistic mechanism combining the NSD with the self-filtering soil layer has been proposed, demonstrating significantly enhanced drainage performance without compromising consolidation effectiveness. Application value: An efficient and eco-friendly dredged sludge treatment technology has been developed, providing a novel approach to vacuum preloading treatment of dredged sludge.

Key words: non-filter membrane, straw drainage body, vacuum preloading, clogging, dredged sludge