Impact of shock loading with mid-stage pulping wastewater on a magnetic micro-aerobic activated sludge system

The effect of mid-stage pulping wastewater (as shock load) on micro-aerobic magnetic activated sludge system was studied. Micro-aerobic activated sludge systems with and without magnetic particles were shocked with mid-stage wastewater for 16 days. "Recovery" experiments were conducted by using simulated wastewater for 12 days. Upon the addition of mid-stage wastewater, COD_Cr removal pertaining to the use of magnetic particles reached 71.57% and remained above 80% in the "recovery" experiment. However, the efficiency of the reactor in the absence of magnetic particles was only 37.29%, and reached about 40% in the "recovery" experiment. After the micro-aerobic activated sludge was shocked, the flocculation performance and surface properties of the sludge were analyzed, and the results showed that all indicators of the reactors in the presence of magnetic particles were superior to those of reactors without magnetic particles. After 12 days of "recovery", the indicators of the sludge pertaining to the reactors containing magnetic particles "recovered" completely.