The process of ultrafiltration membranes allows not only to carry out an effectively filtering action, thus preventing the entrainment of biomass and colloidal particles in the effluent, but also to operate in high concentrations of sludge with an accurate control of sludge age.
In the conventional technologies, where the sludge-water separation is performed by a static sedimentation, the purification process efficiency depends on the rate of settling of the sludge flocs, which determines the solids concentration in oxidation tank (fundamental parameter for treatment success).
In membrane processes, the sludge-water separation is ensured by a semi-permeable membrane and consequently the capacity of sedimentation of suspended solids does not affect in any way the ability of the plant.
In essence, the membrane bioreactor allows to operate the system with operating parameters significantly different than the traditional activated sludge technology.
The ability to separate the mud with a physical system in the bioreactor, such as that of the membranes, allows to maintain a very high sludge concentration (8 ÷ 10 g/l) that does not compromise the filtration system ability.
The membrane type that we use are hollow fiber membranes. Thanks to contained cost production, large density of filter surface per unit of volume and low energy consumption, the hollow fiber is the geometric shape more favorable to contain the cost of investment and management of a membrane process. During the "Outside-In" filtration process, solids remain outside of the "spaghetto" membranes, so, only the permeate flows inside the fiber, thereby reducing the clogging risk.
The membrane consists of a macro porous polymer support externally covered by a further polymer that acts as a filtering element.
The porosity sits between the ultrafiltration and microfiltration.
The application of membranes to biological systems allows to take full advantage of the biological process without worrying about the ability of activated sludge settling.
The process offers significant advantages compared to alternative processes.
Reduced sensitivity to the flow alimentation: The ultrafiltration membranes efficiency, don’t depend from biological flocs's settling; sludge are retained even if the bioreactor undergoes the entry of a toxic substance or a sudden increase of the organic or hydraulic load or a shock of pH. Another benefit arising from the use of ultrafiltration membranes is the ability to maintain circulating biomass concentrations considerably higher than those characteristics of traditional technologies.
Accurate control of the average age of the biological sludge: since virtually no solid passes through the membranes and since the purging of mud is strictly regulated, the sludge age can be precisely controlled, thereby ensuring the management parameters chosen by the operators.
Reduced sludge production: As a consequence of the possibility to keep the sludge age significantly higher than in conventional systems, is reduced sludge production (resulting in lower costs of disposal and dehydration of sludge).
Effluent best quality: The ultrafiltration membranes provide absolute separation of suspended solids, preventing the entrainment of biological sludge responsible of high values of COD and suspended solids in the waste water and thus allowing further stages of treatment subsequent normally sensitive to suspended solids (such as reverse osmosis or, as in this case, the tertiary ozonation).
Simple and compact dimension: The ability to develop the height of the bioreactor (MBR) and the absence of the final clarification basin provide an increased space savings compared to other traditional solutions (for the same pollutant load down).
Easy management: The high technological level expressed by the system allows an easy management.
The presence of ultrafiltration allows having a controlled hydraulic system: the work parameters are controlled , managed and collected by an electronic system / PLC that also allow a modem connection.
HERE BELOW ARE LISTED DETAILS OF SOME PLANTS WE HAVE INSTALLED.
THE COMPLETE LIST OF PLANTS INSTALLED BY FIDIA ENGINEERING SRL IS AVAILABLE UPON REQUEST.
WASTEWATER TREATMENT PLANT FOR THIRD PARTIES
Realization of an ultrafiltration section for the performance’s optimization and implementation of the existing biological treatment with activated sludge, as well as the replacement of the units of the first stage of sedimentation of the biological oxidation to a rate of 600 cubic meters/day and 5000 mgO2/lt. of COD.