Micro-aerobic granulation for actual coking wastewater treatment in an expanded granular sludge bed (EGSB) reactor: Intermittent oxygenation

摘要

To accomplish rapidly the micro-aerobic granulation process of digestion sludge for the treatment of actual coking wastewater and meanwhile achieve high COD, the EGSB reactor was employed with two operation stages. Stage I: Granular sludge was formed from digestion sludge using brewery wastewater as substrate in the anaerobic way (meanwhile adding little granules, which were 1/7 of the total biomass). Stage II: Granular sludge was acclimatized with the actual coking wastewater through intermittent micro-oxygenation way of 800–20000ml·min−1 18–12 times at 20–60min intervals, 1h each time. The experimental results showed that the granular sludge could quickly form in 10d in the EGSB reactor seeded with digestion sludge and little loose granules. It took only about 6 months for the successful micro-aerobic acclimating of the granular sludge by the actual coking wastewater. With 631–1220mg·L−1 influent COD concentration, 1.0L·h−1 influent flow, 12h HRT, 20000ml.min−1 air flow and 3g·L−1 NaHCO3 supplement, the micro-aerobic EGSB reactor could have 75% high COD removal efficiency. The actual coking wastewater was not restrain the granules at the primary stage (at least for more than 1 month), but at 4 months, the SMA reduced 62.9% compared with the parallel, before treating CWW. The supplement of some oxygen and NaHCO3 was very important. Directly using the actual coking wastewater and through an intermittent oxygenation way was an effective acclimation approach.