Granulation of a mixture of suspended anaerobic and aerobic cultures under alternating anaerobic/microaerobic/aerobic conditions: A preliminary study

This paper focuses on a new granulation study area where a mixture of suspended anaerobic and aerobics cultures was used as seed. Mixed suspended anaerobic and aerobic cultures exposed to alternating anaerobic/microaerobic/aerobic conditions developed granulates up to 2.5 mm in size. The granules developed displayed both oxygen uptake (3.83-8.75 mg dissolved oxygen g^-1 volatile suspended solids h^-1) and methanogenic activities (7.5 cm³ CH₄ d^-1) comparable to those of aerobic and anaerobic control cultures, respectively. Oxygen doses of 60, 100 and 120% of the total chemical oxygen demand added (23, 38 and 45 cm³ ) and ethanol (among ethanol, glucose, acetic acid, and glucose+acetic acid) resulted in the largest and the most stable granules.