Case Study Type
Toscopaper is a relatively small brown paper mill located in Tuscany. Producing high quality corrugating medium paper from 100% waste paper and surface treated via a size press with starch and lignin. The paper mill has the need to achieve the river quality effluent discharge and very limited space available due to the old plant configuration.
A new WWTP based on MBBR (Moving Bed Biofilm Reactor) technologies has been implemented by substituting and existing old clarifier. The WWTP included an existing primary clarifier, a brand new 3-stage MBBR and a final DAF unit before the river discharge pipe. The WWTP has been studied to achieve the effluent quality and give the requested paper mill circuit wastewater management flexibility in terms of peaks and Calcium content in the given space. The solution (see figure 1) is a 3-stage MBBR by having the third stage that can become an IFAS (Integrated Fix biofilm Activated Sludge) to increase the sludge age and treat also some harder COD. This solution also enables the paper mill to increase the paper production by 30%, since the middle stage is ready to be converted into an anaerobic DACS® (Down Flow Anaerobic Sludge carrier system) system, followed by the remaining two stages of aerobic treatment.
After a startup that lasted for 6 weeks, the AGAR MBBR produced a high quality effluent well within the regulation limit imposed by the local environmental authority. The System is operated for last 3 years with any biological or hydraulic malfunctions achieving 96% reduction in COD levels.
The AGAR® MBBR WWTP produced an effluent within the spec. The AGAR® MBBR allows high and stable removal efficiency of organic loads and solids. In addition, it was proved that the MBBR is a stable process that can cope with Calcium Carbonate, toxic compounds and hydraulic shocks.