INFLUENCE OF ORGANIC VOLUMETRIC LOADING RATE, NUTRIENT BALANCE AND ALKALINITY - COD RATIO ON THE ANAEROBIC SLUDGE GRANULATION OF AN UASB REACTOR TREATING SUGAR-CANE MOLASSES

Using sugar cane molasses (a byproduct of the sugar industry) as subst rate an experimental work was carried out with the aim to obtain a gra nulated anaerobic sludge at controlled conditions of alkalinity and mi cronutrients. The experiment was carried out in a laboratory-scale-upf low anaerobic sludge blanket (UASB) reactor of 16.51 capacity. The sub strate concentration was adjusted at a COD value of 3750 mg l(-1) by a ddition of tap water. The ratios of Alkalinity:COD, N:COD and P:COD we re maintained at 1.06, 0.018 and 0.0028 respectively. Under such condi tions the production of spherical granules was observed after thirty d ays of operation. The average diameter of the granules grew progressiv ely with the increase of the organic volumetric loading (Bv) achieving a maximum average value of 3.1 mm at the 90th day of operation and re mained constant furtherly in spite of the increase of By. It was found that after the granules formation the addition of nutrients could be suspended while the Alkalinity: COD ratio could be reduced to 0.4 with out changes on the process performance. (C) 1998 Elsevier Science Ltd. All rights reserved.