沉淀时间及生物膜对实际生活污水形成好氧硝化颗粒污泥的影响

利用3个间歇式活性污泥反应器（sequencing batch reactor,SBR,命名为R1、R2、R3）和1个间歇气提式内循环反应器（sequencing batch airlift reactor,SBAR,命名为R4）,处理低碳氮比实际生活污水,系统考察改变沉淀时间的方式及器壁生物膜对快速启动硝化好氧颗粒污泥（aerobic granular sludge,AGS）反应器的影响.结果表明,R1、R2、R4的沉淀时间骤降为2、4、2 min,由于一次性施加的沉速选择压过强,造成污泥大量流失,反应器崩溃,而后反应器器壁不断长出生物膜,混合液和出水中出现大量絮状、棒状、颗粒状污泥,经过35～40 d的培养,出水NH⁺₄-N小于1 mg/L,这主要是器壁生物膜的作用.反应器中的松软颗粒状污泥并非AGS,但它和AGS周围都有大量的轮虫等原生动物和后生动物,这表明生物膜和AGS同源.根据污泥沉淀的实际情况,逐步降低R3反应器的沉淀时间为8、6、5、4 min,当沉速达到10 cm/min时,污泥开始颗粒化;沉速达到12 cm/min时,污泥颗粒化基本完成,共经历了33 d.AGS与絮状污泥长期共存,以0.3 mm为界,两者质量比约为2∶1,AGS平均粒径在0.5　mm左右, NH⁺₄-N降解速率是污泥未颗粒化之前的5倍.

Effects of Settling Time and Biofilm on the Cultivation of Nitrifying Aerobic Granular Sludge

In order to investigate the effects of decreasing settling time and biofilm on the rapid start-up of aerobic granular sludge reactor for nitrification, the real domestic wastewater was treated in three sequencing batch reactors (SBR, named as R1, R2 and R3) and one sequencing batch airlift reactor (SBAR, named as R4). After decreasing the settling time from 20 min directly to 2, 4 and 2 min respectively in R1, R2 and R4, for the reason that the selective pressure of settling velocity was so strong that the activated sludge was all washed out of the reactors, the three SBRs lost their function of treating wastewater. Then the biofilm grew on the walls of the three reactors, and lots of soft granular-like sludge appeared in the reactors, 35 - 40 days later. The biofilm made the effluent ammonia of R1, R2 and R4 lower than 1 mg/L. The soft granular-like sludge was not the aerobic granular sludge, but there were lots of rotifers both around the soft granular-like sludge and the aerobic granular sludge. The phenomena showed that aerobic granular sludge was one type of biofilm. In R3 the settling time was shortened gradually from 20 min to 8, 6, 5 and 4 min. When the settling velocity was 10 cm/min, the activated sludge began to granulate, and when the settling velocity reached 12 cm/min, the aerobic granular sludge became dominant in the reactor, but the sludge floc coexisted with aerobic granular sludge. It took 33 days to cultivate aerobic granules in R3. The average diameter of the aerobic granular sludge was 0.5 mm, the ratio of aerobic granular sludge to sludge floc by weight was 2:1, and the ammonia oxidized rate of aerobic granular sludge was 5 times as the sludge floc's.