Environmental Engineering Research Centre, Department of Civil Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China.
School of Environment, Tsinghua University, Beijing, 100084, China.
Water Res. 2018 Feb 1;129:402-412. doi: 10.1016/j.watres.2017.11.035. Epub 2017 Nov 17.
A novel phosphorous (P) removal and recovery process using a membrane bioreactor (MBR) with ferric iron dosing and acidogenic co-fermentation was developed for municipal wastewater treatment. The very different solubility of Fe(III)-P and Fe(II)-P complex and the microbial transformation of Fe(III) to Fe(II) were utilized for P removal and recovery. By means of Fe-induced precipitation, chemical P removal was effectively achieved by an MBR with a flat-plate ceramic membrane; however, the Fe(III)-P solids accumulated in the MBR that constituted a significant fraction of the activated sludge. Anaerobic co-fermentation of the MBR sludge and food waste in a side-stream allowed the extraction of P and Fe from the sludge into the supernatant. The P in the supernatant was recovered as a fertilizer resource, while the sludge was returned to the MBR tank. The experimental results show that by adding FeCl at 20 mg Fe/L into the influent of domestic wastewater, about 95.6% of total P could be removed by the MBR. One fifth (20%) of the sludge in the MBR was circulated daily through the side-stream fermenters for co-fermentation with cooked rice as the model food waste. The sludge underwent acidogenesis and dissimilatory iron reduction, resulting in a drop of the pH to below 5.0 and reduction of Fe(III) to Fe(II). Owing to the high solubility of the Fe(II)-P complex, P and Fe were then dissolved and released from the sludge into the supernatant. By simply adjusting the solution pH to 8.0, the P and Fe(II) in the supernatant readily re-precipitated to form vivianite for the P recovery. Using the iron dosing MBR and side-stream sludge fermentation, an overall P recovery efficiency of 62.1% from wastewater influent can be achieved, and the problem of inorganic build-up in the MBR is effectively alleviated.
采用向膜生物反应器（MBR）中投加三价铁和产酸发酵协同作用的方法，开发了一种从城市废水中去除和回收磷的新型工艺。利用三价铁和二价铁磷配合物的不同溶解度以及三价铁向二价铁的微生物转化，实现了磷的去除和回收。通过铁诱导沉淀，采用平板陶瓷膜的 MBR 可有效实现化学除磷；然而，MBR 中积累的三价铁磷固体构成了活性污泥的重要部分。在侧流中将 MBR 污泥和食物垃圾进行厌氧共发酵，可将磷和铁从污泥中提取到上清液中。上清液中的磷被回收为肥料资源，而污泥则返回 MBR 罐。实验结果表明，向生活污水的进水添加 20mg/L 的 FeCl3 时，MBR 可去除约 95.6%的总磷。MBR 中的五分之一（20%）的污泥每天通过侧流发酵器循环，与米饭等模型食物垃圾进行共发酵。污泥发生产酸和异化铁还原，导致 pH 值降至 5.0 以下，三价铁还原为二价铁。由于二价铁磷配合物的高溶解度，磷和铁从污泥中溶解并释放到上清液中。只需将溶液 pH 值调节至 8.0，上清液中的磷和铁(II)就会重新沉淀，形成蓝铁矿用于磷回收。采用投铁 MBR 和侧流污泥发酵，从废水进水可实现 62.1%的磷总回收率，有效缓解了 MBR 中无机物积累的问题。
