MOVING BED BIOFILM REACTOR
In the aerobic aerated activated sludge systems we offer MBBR process, that is characterized by the presence of filling pieces on which adheres biomass.
Generally, we forecast an oxidation section, where the biofilm’s growth on a support, which is the result of the interaction between substrates biological process and substrates transport processes. In particular biofilm formation is mainly due to the growth of microbial cells and to the production of extracellular polymers. Generally is quite negligible the contribution of the catching of solids present in suspension in the liquid phase outside the biofilm. Biofilm growth will vary according to the composition of wastewater and transport processes, from which depends the availability of substrates (for the microorganisms inside the biofilm).
The biolfim's detachment phenomena are mainly related to the following contributions:
1 . Predation: by organisms such as protozoa or metazoan;
2 . Cutting actions: induced by tangential water flow to the biofilm, it can be reduced by protecting the biofilm, for example by corrugated surfaces;
3 . Abrasion: this mechanism is important when the particles ON which it is present the biofilm are in free movement and subjected to reciprocal collision;
4 . Spontaneous detachment (collapse): occurs randomly, for example when in biofilm’s deep areas are realized limiting conditions of oxygen and substrates.
The transport of soluble substrates from the bulk liquid within the biofilm, and the transport of the reaction products from the biofilm to the outside depends on the molecular diffusion in the biofilm and in the liquid film outside the biofilm (Harremoës, 1982). The combination between the consumption of the substrate by the microorganisms and diffusive resistances can determine the absence of substrate in the deeper parts of the biofilm. In this way, for example, oxygen transport's diffusive resistance can lead the inhibition of some bacterial specie , such as nitrifying bacteria. The latters, when present together with heterotrophic bacteria, characterized by faster growth, can find suitable conditions for their only development in deeper biofilm layers. In the biofilm, the diffusion coefficients in the substrates, such as oxygen and ammonia, are less than those in clean water (Hem, 1991). Internal biofilm activity is also influenced by biofilm structure, the changes in the long term to which it is subject, and the hydrodynamic conditions in which the biofilm grows.
MBBR's technology use (Moving Bed Biofilm Reactor) foresees the presence of filling bodies within the aeration tank, realized by different synthetic material types; such fills are maintained in suspension in the liquid by insufflation - diffusion of compressed air (generated for example by a volumetric blower) through specific medium sized bubbles aeration/mixing system installed on biological tank's bottom.
MBBR’s technology objective is to improve the conventional activated sludge process, through the adoption of a higher biomass concentration in aeration tank; this technology offers the possibility to greatly reduce the necessary tank dimension, with equal applied organic load.
For these systems we usually use a total suspended solids (TSS) separation section. In the most of our plants, finds application a dissolved air flotation unit, A-DAF type (with low liquid level) where separation efficiency and sludge thickening occurs through pressurization and special distributions systems, that ensure a uniform air diffusion in the water.
The high effluents clarification performance and thickening efficiency are achieved thanks to the pressurized dissolver (ADR) and thanks to the diffusion, at low water level and at micro air bubbles bed. The inlet flow and the output’s sludge take place through the multifunctional central column, while the clarified water is collected in a perimeter collector. The flotation sludges are continuously removed, without disturb on the mantle, by a special radial double spoon collector. The suspended solids present in the input mix reach the surface and are distributed homogeneously over the entire surface of the flotation tank. This system allows a better separation efficiency than the existing flotation. The machine works with continuous water supply and discharge with level control.
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.
WASTE WATER TREATMENT PLANT FOR CHEMICAL-PHARMACEUTICAL COMPANY
Engineering Procurement Construction and Commissioning of new WWTP for upgrading the existing WWTP, treating different kind of water (process water, wash abatement towers, backwashing filters, decontamination of the equipment, supernatants and various purges).
- New biological oxidation system with MBBR technology (Moving Bed Biological Reactor), with carriers in the tank;
- biological sludge separation by lamellar decanters, after polyelectrolyte dosing.
- Average influential flow: about 350 m3/day;
- max Organic load input to the biological: 500 kgCOD/day.
WASTE WATER TREATMENT PLANT FOR FATTY ACID HYDROGENATOR'S PRODUCTION COMPANY
Implementation of a waste water treatment plant with high load of BOD5 and suspended solids (with some tips of COD) consisting of:
- a flotation for suspended solids separation;
- an aerobics section for BOD conversion, activated sludge immobilized on floating bodies in aerobic tank (MBBR).
- Flow capacity 850 cubic meters/day;
- COD ≤ 500 mg/l - 150kg/day;
- BOD ≥ 55% of COD;
The pollutants are removed in accordance with Table A of D.Lgs 152/06