Wastewater Treatment in a Touristic Locality with a Plant Based on Moving Bed Biofilm Reactors (MBBR)

The wastewater treatment plant of Sanremo, an Italian touristic locality, is dimensioned for 50,000 person equivalent (p.e.) during winter and 130,000 p.e. during summer. The plant is made of primary treatments, a biological section based on a three-stage moving bed biofilm reactor (MBBR), clariflocculation and flotation, phosphorus precipitation, secondary settling and disinfection. This is one of the biggest Italian plants based on MBBR. During the period of study, the plant removed 89-92% of COD, 94-96% of BOD and 72-80% of TKN; total nitrogen removal efficiency was only 14% since all MBBR tanks were aerated. Specific energy consumption was 4.02 kWhkgBOD-1 in winter and 2.78 kWhkgBOD -1 in summer; these values were affected by the consumption due to forced aeration, since the plant is located in a cave underground. Specific sludge production was 0.36-0.43 kgSSkgCOD -1. These results confirm that plants based on MBBR and dissolved air flotation are suitable and compact solutions for wastewater treatment also in touristic areas.