Rheology and Material Processing Lab. (RMPC), Civil Environmental and Chemical Eng. Department, RMIT University, Victoria 3001, Australia.
Irstea, UR TSCF, Domaine des Palaquins, F-03150 Montoldre, France.
Water Res. 2014 Jun 1;56:156-61. doi: 10.1016/j.watres.2014.02.048. Epub 2014 Mar 11.
This study investigated the partially irreversible effect of thermal treatment on the rheology of digested sludge when it was subjected to temperature change between 20 °C and 80 °C and then cooled down to 20 °C. The yield stress, infinite viscosity and liquor viscosity of sludge were measured at 20 °C for different thermal histories and were compared to the evolution of the solubilised chemical oxygen demand (COD) of sludge liquor. The results showed that thermal history irreversibly affects sludge rheology as the yield stress of sludge which was heated to 80 °C then cooled down to 20 °C was 68% lower than the initial yield stress at 20 °C. This decrease was due to the irreversible solubilisation of solid matter during heating as underlined by soluble COD data which did not reach its original level after thermal treatment. Measured soluble COD of sludge which was heated and cooled down was much higher than the soluble COD of initial sludge. We found a proportionality of the increase of soluble COD with the decrease of the yield stress as well as increase of infinite viscosity.
本研究考察了热处理对消化污泥流变性的部分不可逆影响，当温度在 20°C 和 80°C 之间变化然后冷却至 20°C 时。在 20°C 下测量了不同热历史条件下污泥的屈服应力、无穷大粘度和液体粘度，并与污泥液体中溶解化学需氧量（COD）的演变进行了比较。结果表明，热历史会不可逆地影响污泥的流变性，因为加热至 80°C 然后冷却至 20°C 的污泥的屈服应力比 20°C 时的初始屈服应力低 68%。这种下降是由于加热过程中固体物质的不可逆溶解，正如可溶性 COD 数据所强调的那样，在热处理后并未达到原始水平。测量的加热和冷却后的污泥可溶性 COD 远高于初始污泥的可溶性 COD。我们发现，随着屈服应力的降低和无穷大粘度的增加，可溶性 COD 的增加与增加呈比例关系。
