Utilizzo dei processi a membrana nei trattamenti biologici di reflui organici concentrati

The main limits of the technologies currently used in the field of wastewater treatments could be recognized in the need of large areas, a low removal efficiency of complex organics and nutrients, a poor ability of disinfection, the production of high quantity of surplus sludges. A revision of the conventional systems is required, particularly in reducing the volume of the biological reactors, promoting the combination of various processes of treatment and introducing advanced technologies and more efficient metodologies for the measure and control of the process parameters. Good efficiencies in the biological suspended growth processes for removal of carbonious substrate and nutrients are related to the retention of high concentration of specialized biomass. This condition allows to minimize the volumes of the reactor and promote the degradation of specific substrates and the reduction of the quantity of produced surplus sludges, operating long sludge retention time. The separation of the suspended solids from the liquid phase is the mechanism of fundamental importance to operate an effective recycle of the biomass and obtain high treatment capacity and a clear effluent. Also when different composition and variable loading rates of the the influent wastewater change, steady operational condition in biological system have to be realized to obtain good performance of the process. In such a case, conventional settling techniques do not seem completely feasible as close connected to physiological makers, not completely known. Beyond, these mechanisms of biomass retention do not warrant the selection of a more efficient microbial populations in the degradation of the available substrate. Ultrafiltration and microfiltration processes can find application for treatment of urban and industrial wastewater realizing the separation of suspended solids not depending on physiological and environmental factors. But efficient and secure operations require accurate studies and further research is necessary to better understand the different chemico-physical and biological processes involved. On the base of surveys which are described in literature, the present paper describes the beginnings and the applications of combined biological processes and membranes modules for the treatment of high organic wastewater, particularly with regard to high organic wastewater.