2. Material and methods
2.1. Wastewater characterization
During the period of the biological tests, 110 L of wastewater from a fish canning industry of northern Portugal were collected at each time and left to settle for 1.5 h. DOC and total soluble nitrogen (Ntotal soluble) of each effluent sample were determined following the Standard Methods for the Examination of Water and Wastewater [18]. DOC was determined by using Total Organic Carbon analyzer (5000 A analyzer from Shimadzu, Japan). The values reported represent the average of at least two measurements; in most cases each sample was injected three times, being the validation performed by the apparatus only when coefficient of variation (CV) was smaller than 2%.