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Abstract：
High concentration of orthophosphate ion (OP) in anaerobically digested sludge can lead to struvite crystallization, deterioration of sludge dewaterability, and elevated mainstream OP loading through centrate recirculation. The Upper Occoquan Service Authority (UOSA) has observed seasonally high OP levels in its dewatering blend tank, which was found in this study to be a consequence of unwanted biological phosphorus accumulation during the intensified winter denitrification operation and the subsequent OP release in the course of anaerobic digestion. In order to control the nuisance struvite scaling issues, a bench study was conducted and cerium chloride (CeCl3 ) was dosed as an effective OP precipitant. The results of this study demonstrated that CeCl3 dosing showed higher OP removal efficiency than other commonly used OP precipitants. In addition, bench-scale simulations indicated sludge dewaterability improvements which were used to predict lower polymer and dewatering energy demands at the full scale. The economic analysis conducted in this case study showed that the seasonal dosing of CeCl3 at UOSA has the potential to provide a net annual saving of US $47,000. PRACTITIONER POINTS: Biological phosphorus accumulation during the intensified denitrification operation caused seasonally high sludge OP and struvite scaling issues at UOSA. CeCl3 was evaluated as an effective OP precipitant for struvite control and dewaterability improvement when aluminum and iron were determined to be unfavorable. Seasonal dosing of CeCl3 at UOSA projected a net annual saving of US $47,000.
摘要：
厌氧消化污泥中高浓度的正磷酸根离子(OP)可导致鸟粪石结晶,污泥脱水性能恶化，和提高主流OP负荷通过浓缩液再循环。上奥科泉服务管理局（UOSA）在其脱水混合罐中观察到季节性高的OP水平，在这项研究中发现，这是在冬季反硝化操作强化过程中不必要的生物磷积累以及随后在厌氧消化过程中释放OP的结果。为了控制令人讨厌的鸟粪石结垢问题，进行了一项实验室研究，并将氯化铈（CeCl3）作为有效的OP沉淀剂。这项研究的结果表明，CeCl3剂量显示出比其他常用的OP沉淀剂更高的OP去除效率。此外,实验室规模的模拟表明，污泥脱水能力的改善，用于预测较低的聚合物和脱水能源需求在全规模。在本案例研究中进行的经济分析表明，在UOSA的CeCl3的季节性剂量有可能每年净节省47,000美元。实践要点：强化反硝化操作过程中的生物磷积累导致UOSA的季节性高污泥OP和鸟粪石结垢问题。当铝和铁被确定为不利时，CeCl3被评估为有效的OP沉淀剂，用于鸟粪石控制和脱水性改善。UOSA季节性添加CeCl3预计每年净节省47,000美元。
