ABSTRACT

Recovering phosphorus (P) from excess sludge of wastewater treatment plants (WWTPs) has attracted considerable attention. An efficient P release method is undoubtedly critical for a satisfactory recovery performance. In this study, the effectiveness of three sludge pretreatment methods, i.e. anaerobic digestion (AD), EDTA-anaerobic digestion (EA) and ultrasound combined with EA (U-EA), on P release and struvite recovery from excess sludge was investigated. The results showed that different pretreatment methods resulted in the different characteristics of P release and recovery. For P release, the highest P release rate (57.14% of sludge total phosphorus, TP) was achieved by U-EA pretreatment, followed by EA and AD. Furthermore, U-EA was beneficial for sludge disintegration and reduction, by which the mixed liquor suspended solids (MLVSS) reduction rate reached 42.00% at a specific energy of 110,000 kJ/kg TS. For the P recovery (in the form of struvite), there was only a little difference in the optimal conditions and P recovery rate (89.29–94.49% of TP in the supernatant). AD pretreatment was beneficial for the purity of products and achieved the highest struvite purity (85.14%), followed by EA (80.95%) and U-EA (77.56%). In summary, the highest recovery rate of TP from excess sludge (53.50% of sludge TP) and struvite yield (26.10 mg/gSS) was obtained by U-EA.

摘要

从废水处理厂 (WWTP) 的剩余污泥中回收磷 (P) 已引起相当大的关注。高效的 P 释放方法对于令人满意的恢复性能无疑是至关重要的。在这项研究中，研究了三种污泥预处理方法，即厌氧消化 (AD)、EDTA-厌氧消化 (EA) 和超声结合 EA (U-EA) 对剩余污泥中 P 释放和鸟粪石回收的有效性。结果表明，不同的预处理方法导致磷的释放和回收特性不同。对于磷释放，最高的磷释放率（污泥总磷的 57.14%，TP）通过 U-EA 预处理实现，其次是 EA 和 AD。此外，U-EA有利于污泥分解和减量，在110,000 kJ / kg TS的比能下，混合液悬浮固体（MLVSS）降低率达到42.00％。对于 P 回收（以鸟粪石的形式），最佳条件和 P 回收率（上清液中 TP 的 89.29-94.49%）只有很小的差异。AD预处理有利于产品的纯度，鸟粪石纯度最高（85.14%），其次是EA（80.95%）和U-EA（77.56%）。总之，U-EA 获得了剩余污泥中 TP 的最高回收率（污泥 TP 的 53.50%）和鸟粪石产量（26.10 mg/gSS）。AD预处理有利于产品的纯度，鸟粪石纯度最高（85.14%），其次是EA（80.95%）和U-EA（77.56%）。总之，U-EA 获得了剩余污泥中 TP 的最高回收率（污泥 TP 的 53.50%）和鸟粪石产量（26.10 mg/gSS）。AD预处理有利于产品的纯度，鸟粪石纯度最高（85.14%），其次是EA（80.95%）和U-EA（77.56%）。总之，U-EA 获得了剩余污泥中 TP 的最高回收率（污泥 TP 的 53.50%）和鸟粪石产量（26.10 mg/gSS）。