Wastewater treatment plant revamping works Papiro Sarda S.r.l. – Assemini (CA)

The “main topic” dealt with by the company is the purification of waste water and everything that embraces this topic starting from feasibility studies up to the executive design, also including the drafting of technical / economic documents for participation in design tenders and / or works inherent in the treatment of civil or industrial wastewater and sewer works. In some cases, AGquadro also took care of the construction aspect of the works. Particular attention has always been paid to innovative techniques that embrace new technologies for the biological treatment of wastewater such as systems with alternating cycles of anoxic and oxidative phases, Membranes (MBR) or mobile bed systems (MBBR). The Papiro Sarda plant is an example of an MBBR plant with mud recirculation, therefore to be classified as HYBRID.

Papiro Sarda Srl

IA.01. The final amount of the work is € 169,400.00


Construction of expansion works of the purification plant for Cartiera Papiro Sarda Srl


The wastewater treatment plant produced by the paper mill is located inside the square, south-east side, in a dedicated space, in the immediate vicinity of the production facility located in Macchiareddu, in Assemini (CA). It was designed according to an adhered biomass process with oxidation sludge recirculation known as “hybrid MBBR” or as “IFAS” – Integrated Fixed-film Activated Sludge System. The works and installations involved various sections of the plant, some have maintained their functionality, others have been completely adequate, and still others have been built from scratch. In particular, the flow rate at the entrance to the plant was completely revised and automated, the air blowing system was completely revised, the rectangular sedimenter with lamellar packs was replaced with a circular one with a diameter of 4.5 meters in steel. A degassing tower was also inserted downstream of the biological compartment and a sludge incubator called EBF Reactor designed and built by AGquadro was implemented in the layout. In this reactor, operating in batch mode, both the biomass taken from the biological cycle and some selected nutrients are introduced. By intervening on the nutritional elements of the wastewater, the native biomass, favored by the operating conditions created inside the reactor, is allowed to grow and proliferate. The cell culture thus biostimulated is inoculated in the oxidative compartment, inevitably leading to an acceleration of the purification processes and a complete consumption of the nutritional substrate, with consequent reduction of the polluting load. The new works were made entirely in Aisi 304.


1) The purification performance of the plant has been significantly improved also thanks to the installation of the EBF reactor.
2) an efficient exchange of oxygen with the wastewater was ensured thanks to a fine bubble air diffusion system;
3) the sedimentation phase has been improved both by installing a degassing tower and by creating a new sedimenter with a larger surface;
4) maintenance interventions on the dissolved oxygen measurement probe have been reduced to a minimum;
5) a precise and punctual control of the QIN is allowed