In order to obviate the economic issues associated with pit latrine emptying and transport such as high water additions and rheologically difficult sludge properties, the implications of prompt solid/liquid separation were investigated. This was achieved through rheological characterisation of fresh human faeces and synthetic faeces, and comparison with aged faecal sludges. Shear yield stress, thixotropy and post-shear structural recovery were characterised for a total solids (TS) concentration range of 5–35% total solids (TS) and stickiness yield stress was determined for concentrations up to 100% TS. Fresh faeces rheology proved to be favourable when compared to aged matrices, evidenced by a lower shear yield stress and higher gel point solids concentration, suggesting that aging could alter the physico-chemical properties of faecal sludge. Fresh and synthetic faeces exhibited similar shear thinning, thixotropic behaviour with the majority of structural breakdown occurring at a low shear rate of 10 s⁻¹, and the extent increasing with higher solids concentrations. At 32% TS, fresh faeces shear yield stress was permanently reduced by 80%, suggesting that low shear pumping could reduce the energy demand required for faeces transport. The sticky phase, which represents the region to avoid faecal transport and mechanical drying processes, was identified to range from 30 to 50% TS, with 25% TS as ideal to commence dewatering processes. This also coincides with the average solids concentration of faeces, which is achievable by source separation. This study has identified that handling of fresh faeces as opposed to aged faecal sludges would result in economic and environmental benefits, with energy, water and labour savings.

为了避免与坑式厕所排空和运输相关的经济问题，例如高水添加和流变学困难的污泥特性，对快速固/液分离的影响进行了调查。这是通过对新鲜人类粪便和合成粪便进行流变学表征，并与老化粪便污泥进行比较来实现的。剪切屈服应力、触变性和剪切后结构恢复的特征在于总固体 (TS) 浓度范围为 5-35% 总固体 (TS)，粘性屈服应力确定为浓度高达 100% TS。与老化的基质相比，新鲜粪便的流变学证明是有利的，这可以通过较低的剪切屈服应力和较高的凝胶点固体浓度来证明，这表明老化可以改变粪便污泥的理化性质。^-1，并且程度随着固体浓度的升高而增加。在 32% TS 时，新鲜粪便剪切屈服应力永久降低 80%，这表明低剪切泵送可以减少粪便运输所需的能量需求。粘性相代表避免粪便运输和机械干燥过程的区域，被确定为 30% 到 50% TS，25% TS 是开始脱水过程的理想选择。这也与粪便的平均固体浓度一致，这可以通过源分离实现。这项研究表明，处理新鲜粪便而不是处理陈旧的粪便污泥会带来经济和环境效益，并节省能源、水和劳动力。