软/硬磁粉剩磁属性对磁载活性污泥处理效率的影响

Effect of Residual Magnetic Properties of Soft/Hard Magnetic Powder on The Efficiency of Its Supported Active Sludge Process in Water Treatment

传统活性污泥对有毒污染物及负荷变化耐受力有限,受冲击时污泥容易松散,处理效率降低。为此人们开发了磁载活性污泥技术,所用磁粉以硬磁四氧化三铁为主。硬磁在回收时存在剩磁现象,因此循环使用时需要做消磁处理,成本较高。软磁回收时无剩磁现象,但软磁磁载活性污泥至今未见有报道。本文首次研究对比了预磁化后四氧化三铁与软磁铁硅铝负载活性污泥处理效率,以推动软磁磁载活性污泥技术的发展。相同条件下铁硅铝组与四氧化三铁组对模拟污水的COD_(Cr)和NH_(3)^(-)N去除率分别达到94.21%和97.01%,及90.03%和92.10%,均高于对照组的86.81%和76.40%。处理实际印染污水有相似的结果,FeSiAl组的COD_(Cr)和NH_(3)^(-)N去除率分别达到93.98%和93.74%,而Fe_(3)O_(4)组为90.30%和88.25%,均高于对照组的86.27%和76.04%。磁粉回收的结果表明,铁硅铝的回收效率达到90.94%,而四氧化三铁的回收效率仅有81.39%。结合上述结果及消磁处理单元的费用,软磁铁硅铝载活性污泥法具有更好的应用前景。

Traditional activated sludge method is always poorly tolerant of toxic pollutants and the big change of sludge loading,and then leading to a decreased treatment efficiency.Magnetic powder-supported activated sludge technology has been developed to possibly overcome this problem,in which hard magnetic ferroferric oxide is always used.Demagnetization treatment is needed because of residual magnetic properties in recycle of ferroferric oxide,leading to high cost.Soft magnetic powder has no residual magnetic properties,but its supported-activated sludge has not been studied so far.The study investigated the difference in treatment efficiency of self-prepared wastewater and dyeing wastewater by the pre-magnetized ferroferric oxide-supported activated sludge process and soft ferrosilicon aluminum-supported one,thus promoting the development of latter technology(without demagnetization equipment).The results showed that the removal rates of COD_(Cr)and NH_(3)^(-)N were 94.21%and 97.01%,90.03%and 92.10%in ferrosilicon aluminum group and ferroferric oxide group under the same conditions,respectively,both higher than those of the controlled one(86.81%and 76.40%).Similar results were obtained in treatment of dyeing wastewater.the removal rates of COD_(Cr)and NH_(3)^(-)N were 94.21%and 97.01%,90.03%and 92.10%in ferrosilicon aluminum group and ferroferric oxide group,respectively,both higher than those of the controlled one(86.27%and 76.04%).The results of sludge-magnetic powder separation efficiency indicated that the recovery rates of powder were 90.94%and 81.39%for ferrosilicon aluminum and ferroferric oxide,respectively.Considering the above results and the cost of demagnetization(including equipment investment and energy consumption),ferrosilicon aluminum-supported activated sludge has better application prospect.