The bacterial inoculum was added, at 1% (v/v), to 100 L of treated wastewater. Cultivation was accomplished in anaerobiosis inside 100 L glass reactors at 32 + 2oC and 2,000 + 500 lux for seven days.

For the biomass recuperation, the culture was filtered at 0.2 pm, 1.5 m3 h-1 and 4.5 bar (Frings), giving origin to a concentrate containing the cells and a permeate. The concentrate was centrifuged at 3,400 g for 30 min at 5°C (Incibras Spin VI) and the resulting slime was frozen at — 40oC and lyophilized (Liobras L 101) for 48 h. Hand grinding was performed to obtain the power biomass. Procedures were repeated six times.

1.2 Process analyses

Cell mass concentration was determined from 20 mL of concentrate, after successive centrifugation (900 g/15 min) and washing cycles followed by drying at 80°C until it gets constant weight.

For productivity determination, it was considered the mean production of dry biomass per liter per day.

TN, OG, COD and pH determinations in permeate were accomplished as previously described for crude wastewater (APHA, AWWA and WPCF, 2005).