Trickling filters are amongst the oldest attached growth treatment processes , were originally designed to reduce the ‘energy utilization’ of aerobic treatment systems. While older T.F. systems used rock and gravel as the media for attached growth, newer filters use plastic media. Trickling Filters based on plastic media such as the COOLFill Bio Media series provide a versatile and cost effective solution for the treatment of wastewater.
Modern Trickling Filters with Plastic Media consumes least amount of energy in comparison with any other treatment processes like activated sludge process, sequential batch reactors etc. It has been established most cases that the energy consumption is less than 50% in comparison with other process. The only energy requirement is to lift the wastewater to the top of the tower.
In this process microorganisms (helps to consume the biodegradable organic constituent from the wastewater) attach them self to media forming a thin layer. This process enhances concentration of microbial population inside the tower and helps in faster waste treatment.
The plastic media has given a new lease of life to trickling filters (also called biotowers) because of its lighter weight, longer life, availability , inertness, compactness, minimum to zero chocking, increase on the performance of the system in smaller footprint area and more importantly simple civil structure.
Older Trickling Filters could go up to amaximum of 2 meters because huge weight of the rock media, thus occupying larger footprint areas. The use of lightweight and high compressive strength structured plastic bio media made it possible to go up to 6 to 14m & reducing the footprint area.
The influent wastewater is equally distributed on the stacked PVC COOLFill media through the top distribution arms. The cross corrugation of the media along with microstructures on the surface helps in housing the microorganisms and wastewater to form a thin layer. It also helps in periodic sloughing off, thereby active thin layer of microbes is maintained throughout.
The perpendicular stacking arrangement of the media layers further redistributes the flowing wastewater throughout the depth of the system. Calculation shows, there are about 6000+ mixing points available per cu.m of media. This avoids canalization of wastewater through the system. The arrangement of COOLFill also aids in increasing the retention time of the wastewater within the tower and assisting in the maximum mass transfer possible.
Clear opening at both the ends and more than 97% voidage gives low resitance to incoming are thus circulating it through out the depth of Tower. This gives maximum xontact between air , wastewater & biomass. It also avoids the system to go anaerobic and reduce odor problems and fly nuisance. Spiral angles and crimped design within the media gives enough shear force to the down flowing wastewater to slough off the excess bio films, creating place for new microorganisms to form biofilm.
Details of COOLFill Trickling Filter media, depending upon process application viz, BOD removal, nitrification and type of effluent , levels of BOD & COD , nature of SS the COOOLFill series have been designed to suit every requirement.
The crossflow media is made of sheets formed with flutes at 30 degree to the horizontal. This structure gives the highest number of mixing points as well as the highest surface area configuration amongst all media configurations. CD-B19 with an available surface area of 250m2/m3 is suited for nitrification while CD-B27 with an available surface area of 108 m2/m3 is ideal for BOD/ NH4-N removal. Additional crimped design available for enhancing unprotected surface area.
Vertical –Fluted (CD-B 33:01) is primarily used for the BOD treatment of high strength effluent with high TSS at the inlet, the vertical flutes allow continuous slough off without plugging /choking the media.
The open flow media configurations are better suited for high BOD, high TDS, high TSS industrial effluent. This media structure is based upon alternating Crossflow and vertical flow sheets thereby reducing chances of plugginf=g while giving high unprotected surface area and protected surface area. Incase of CD-B27:53 media protected surface area is 82 m2/m3. However unprotected surface area is more than 100 m2/m3 due to specialized design of crimped surface.