University of Kuopio, Laboratory of Applied Environmental Chemistry, Patteristonkatu 1, FI-50100 Mikkeli, Finland.
J Hazard Mater. 2010 Jan 15;173(1-3):54-61. doi: 10.1016/j.jhazmat.2009.08.046. Epub 2009 Aug 19.
This paper reports the migration of ions and organic matter, initially present in anaerobically digested sludge taken from the effluent of an anaerobic digestion unit in Mikkeli Wastewater Treatment Plant (SE Finland) during electro-dewatering process, employing various experimental strategies such as freeze/thaw and polyelectrolyte conditioning and various sludge loading rates. It was found that a decrease in sludge loading rate (from 20 to 5 kg DS m(-2)) resulted in an increase in the maximum current density (145-467 Am(-2)). The principle component analysis (PCA) showed a significant correlation between the dry solid (DS) content in the final sludge cake, sludge loading rate, freezing conditions, energy consumption and maximum current density during electro-dewatering process. The decrease in sludge loading rate resulted in the reduced time to achieve the highest concentrations of Na(+) and K(+) in the removed water at the cathode. Moreover, concentration of Na(+) and K(+) was reduced by 51 and 78% in the sludge cake, respectively, in comparison to blank experiments. Fe ions, Ca(2+) and Mg(2+) concentrations were found lower in the sludge cake at the anode and higher at the cathode. According to the statistical analysis, Fe and Ca ion concentrations at the anode and sludge loading rate had a negative correlation with the volatile solids/dry solids (VS/DS) ratio in sludge at the anode. High P concentration at the anode was only observed in experiments using freeze/thaw conditioned sludge samples and highly depended on the initial sludge freezing temperatures. Furthermore, at the end of experiments, concentration of problematic elements in the sludge cake such as Cr(6+), Zn(2+) and Mn ions increased from 63 to 100% and decreased from 23 to 70% at the anode, respectively, in comparison to the blank experiment.
本文报告了离子和有机物的迁移，这些离子和有机物最初存在于来自芬兰米凯利废水处理厂（SE）厌氧消化单元出口的厌氧消化污泥中，在电脱水过程中采用了各种实验策略，如冷冻/解冻和聚电解质调理以及各种污泥加载率。研究发现，降低污泥加载率（从 20 降至 5 kg DS m(-2))会导致最大电流密度（145-467 Am(-2))增加。主成分分析（PCA）表明，在电脱水过程中，最终污泥饼中的干固体（DS）含量、污泥加载率、冷冻条件、能耗和最大电流密度之间存在显著相关性。降低污泥加载率会导致在阴极处达到去除水中 Na(+)和 K(+)最高浓度所需的时间减少。此外，与空白实验相比，污泥饼中 Na(+)和 K(+)的浓度分别降低了 51%和 78%。Fe 离子、Ca(2+)和 Mg(2+)在阳极处的污泥饼中的浓度较低，而在阴极处的浓度较高。根据统计分析，阳极处 Fe 和 Ca 离子浓度与阳极处污泥挥发性固体/干固体（VS/DS）比呈负相关，且与污泥加载率呈负相关。仅在使用冷冻/解冻调理污泥样品的实验中观察到阳极处高 P 浓度，且该浓度高度依赖于初始污泥的冷冻温度。此外，在实验结束时，与空白实验相比，污泥饼中诸如 Cr(6+)、Zn(2+)和 Mn 离子等问题元素的浓度在阳极处增加了 63%至 100%，在阳极处降低了 23%至 70%。
