Innovative approaches for sludge minimization from municipal wastewater treatment

Three innovative technical solutions for sludge minimization in wastewater treatment are under investigation in Routes project ("Novel processing routes for effective sewage sludge management") co-funded by the European Commission in the framework of the Seventh Framework Programme: 1) the use of Sequencing Batch Biofilter Granular Reactor (SBBGR) based technology, 2) the integration of membrane bioreactors with anaerobic side-stream process (MBR+AnSSR), and 3) the adoption of alternate cycles process applied in the sludge line (ACSL). The results obtained have shown that: 1) SBBGR is able to reduce up to 75% the sludge production during raw municipal wastewater treatment, and to offer satisfactory performances allowing the discharge limits to be met; 2) MBR+AnSSR offers a sludge production reduction comparable or even greater than that obtained in a conventional system (MBR + aerobic digestion), and 3) ACSL permits to obtain an Observed Yield reduction on average equal to 46% compared with the expected one, without a worsening of the final effluent quality.