Category / type: industrial wastewater treatment.
Application: small, medium, wastewater treatment, car wash, workshops, warehouses, laundries, chemical industries, gas station.
Size: from 3 up to 40 m3.
Flow: tailored solution packaged and/or on site assembled;
Material: concrete, polyethylene, polypropylene, glass-reinforced plastic (GRP).
Chance: system revamping.
Bio-filtration becomes recently very common. The purpose of bio-filtration is to improve wastewater effluent quality. This method is very important and essential especially for recirculating systems and it is usually installed as part of a multicomponent system. Biological filters remove contaminants by three main mechanisms: biodegradation of biological component, adsorption of micro-pollutants, and filtration of suspended solids. Granular Activated Carbon (GAC) is often used to provide the necessary surface to promote the development of the biofilm.
How It Works
Any type of filter with attached biomass on the filter-media can theoretically defined a biofilter
Biofilter is one of the most important separation process deployed to remove pollutants from wastewater.
The basic principle of biofilter is the biodegradation of pollutants carried outby micro-organisms attached onto filter media.
The most important operating and design parameters which guides the process is the biomass attached to the medium.
Other parameters that can affect the performance of a biofilter are the characteristics of filter media, the hydraulic and organic loading rate and filter backwash techniques.
Bacterial masses attached onto the filter media, as biofilm, oxidize most of the organic matter using as energy supply (carbon source).
There are very few models reported in the literature that can predict the performance of a biofilter. Most of these models are based on the assumption of steady state condition.
Biofiltration processes are usually aerobic, which means that microorganisms require oxygen for their metabolism. Oxygen can be supplied to the biofilm, either concurrently or counter currently with water flow. The aeration occurs passively by the natural flow of air through the process or by forced air supplied by blowers.
Bio filtration is used to remove organic and some industrial pollutant, such as surfactants.
These latter are complex organic molecules used as detergent function, not entirely biodegradable, particularly those non-ionic surfactants.
Operation and maintenance
Microorganisms (aerobic, anaerobic, and facultative bacteria; fungi; algae; and protozoa) gradually develop on filter media surfaces and form a biological film or slime layer known as biofilm. The development of active biofilm may take few days or months depending on the influent organic concentration.
Maintenance must be performed by authorized personnel.
Exhaust filter media as granular activated carbon can be regenerated for further use.
Its handling and disposal must be carried out by specialized companies.
National and regional regulatory frameworks set the allowable pollutants in the effluent.
Features and benefits
Primary treatments as sedimentation and oil removal precede the biofiltration; conventional treatment as coagulation, flocculation and clarification can be added in the system scheme.
There are several types of biofilters with different characteristics depending on the pollutants to be removed.
The biofilter system effective also depends on the efficient maintenance of biomass attached to the filter media.
- simple structure;
- robustness of the process;
- shock loads resistance;
- low operating costs;
- higher concentration of relevant organisms.
- clogging and flow channeling;
- periodical maintenance.