Variation of alkalinity and regulation of interior diversion expanded granular sludge bed

The effect of substrate concentrations and alkalinity on the COD removal efficiency of a synthetic wastewater containing proportional was performed in the interior diversion expanded granular sludge bed. The results showed that the optimum COD/alkalinity value of different COD concentration is different, when the influent COD concentration in the range of 2130 to 12409mg/L, the optimum COD/alkalinity value changes from 0.73 to 0.84 steadily, when the influent COD concentration is larger than 17920 mg/L, the optimum COD/alkalinity value increases to about 1.06-1.26. Under different operating conditions, the pH value exhibits decrease first and then increase along the direction of water flow in the reactor, the alkalinity displayed the same change trend with pH value, with the increase of the influent COD concentration and reflux ratio, the location of the lowest alkalinity gradually elevated. The reactor can motion stably until the VFA concentration of effluent is above 3385mg/L.