The trickling filter fits into the wastewater treatment system as shown in the flow chart below.
The beginning of the trickling filter treatment process is like treatment in a packaged plant. The wastewater passes through a bar screen, a grit screen, a comminutor, and a primary clarifier. Sludge from the primary clarifier goes to the digester while the mostly liquid portion of the wastewater goes on to the trickling filter.
The Trickling Filter
The liquid portion of the B.O.D. and ammonia from the clarifier, as well as the supernatant from the digester, are pumped to the trickling filter. Both the B.O.D. and the ammonia are required to produce the right growth of microorganisms on the media to provide good treatment.
The liquid influent is piped to the spray heads at the
top of the trickling filter. The force of the water causes the spray
heads to rotate above the media, acting like a sprinkler and evenly
distributing water across the media.
The influent trickles down through the media. The media is covered with a slime of both aerobic and anaerobic microorganisms. These microorganisms remove the organic matter from the water. As we have mentioned previously, the microorganisms in a trickling filter are especially efficient at removing ammonia from the water.
Clarifier, Disinfection, and
As the water passed through the trickling filter, some of the slime was sloughed off of the filter bed. In addition, there is still some sludge in the wastewater. These solids are removed when the water flows from the trickling filter through the secondary clarifier. The solids from the clarifier are sent to the digester.
The final part of the treatment process is the step
aerator. As the effluent flows over the step aerator, the dissolved
oxygen levels are increased. The water is now ready to be released
into a stream or river.