In the figures appearing with this paper, the following con versions to the metric system may be made. Randomly placed polypropylene media filters are designed within the depth ranges of the low and intermediate rate filters. In contrast, high rate filters are provided with return pump between the trickling filter tank and secondary clarifier that aids in effluent recirculation. Application of high rate nitrifying trickling filters for potable water. The average height of such trickling filter is 8 10m. Feb 22, 2019 the flies are most frequently found in low or standard rate filters with an intermittent dosing system. There are following three principal proprietary types of high rate trickling filters.
This study also noted an increase in nitrification performance from 67 to 87 percent when the recirculation ratio was increased from 2. Whenever it is available, crushed rock or gravel is the cheapest option. The high rate trickling filter, single stage or two stage are recommended for medium to relatively high strength domestic and industrial wastewater. Each stream consists of one primary clarifier, one first stage trickling filter, one intermediary clarifier, one second stage trickling filter, one final clarifier, dual. The high rate trickling filter, single stage, and two stage are recommended for medium to relatively the high strength domestic and industrial waste waters. For high rate niters, the recirculated flow is not considered in contribut ing an additional bod load. Trickling filter process definition, operation, design. Conventional trickling filter or ordinary trickling. Standard rate filter standard rate trickling filters are normally designed for hydraulic ratings of 1. The first use of trickling filters of record was in 1889. To increase the load rate of trickling filter the sewage is an essential and important feature of high rate filters. Aerobic conditions are maintained by splashing, diffusion, and either by forcedair.
Treatment of sulfite waste liquor on high rate trickling. One method of increasing the efficiency of a trickling filter is to incorporate recirculation. In this research, difficulties were en countered with growths of molds in the filters which produced clogging and with b. Provision should be made for flushing the underdrains unless high rate recirculation is utilized. However, they require higher land area as compared to conventional treatment system. From 1957 to 1962, there was an increase of 265 standard rate and 559 high rate filters. Roughing filters are basically high rate filters treating an organic load of more than 1. The collected liquid is passed to a settling tank used for solid liquid separation. Ubale assistant professor, civil engineering department, walchand institute of technology, solapur. For plastic packing type in trickling filters, the hydraulic rate is different. It is a fixedbed bioreactor that is the part of secondary wastewater treatment, which eliminates the coarse particles, suspended organic and inorganic waste, small colloids etc. None of these figures includes institutional or industrial data. For example, most secondary treatment devices for service areas on major turnpikes employ this method.
Trickling filters with this filling material have a height of 2 2. The results indicated that a 90% ammonium removal was achieved at a bod 5 surface loading rate of 2. Types of filters trickling filters are classified as high rate or low rate, based on the organic and hydraulic loading applied to the unit. The bod removal efficiency is around 75 to 90% but the effluent is only partially nitrified. The influent hydraulic flow rate was maintained at 8 m 3 h a1, resulting in a high hydraulic surface load per m 2 of filter crosssectional area of 125 m 3 m a2 d a1. However, some of the distinguishing features of high rate trickling filters are as indicated below. By significantly increasing nitrification in high rate trickling filters, the existing plants could save on the cost of addi tional nitrifying units.
For rock type packing in intermediate filtration trickling type filters, the hydraulic rate considered is 410 m 3 m 2. Although there is no welldemarcated practice, some important distinguishing design criteria and features for the three types of filters are presented in table 12. Instead of building new units the plants would only have to install a chemical feed system to adjust the ph of the sewage. Discuss the types of waste treated by a trickling filter and a rbc. All distribution devices, underdrains, channels, and pipes shall be installed so that they may be properly maintained, flushed or drained. Design of trickling filters sewage treatment sanitary. High rate filters high rate filters are generally loaded at the maximum organic loading capabilities of the filter and receive total bod 5 loading ranging from 64 to 160 kg bod 5100 m3d 40 to 100 lb.
Trickling filter for high efficiency treatment of dairy sewage. High rate trickling filter waste water engineering youtube. It is suitable for treatment of low to medium strength domestic wastewaters. Q 10,000 m3d influent bod 400 mgl temperature t 20 oc primary sedimentation tanks will be used before the trickling filter solution to design trickling filter the following things should be found. Trickling filter process is one of the types of aerobic wastewater treatment. Figure 1 shows acceptable recirculation systems for singlestage and twostage trickling filters treating domestic wastewater. The trickling filter consists of a cylindrical tank and is filled with a high specific surface area material, such as rocks, gravel, shredded pvc bottles, or special preformed plastic filter media. Pdf structure of nitrifying biofilms in a highrate. A trickling filter with a hydraulic loading rate of 75 galdayft2 would be considered what type of trickling filter a. Enoineer8 boston new york palo alto publication no. It consists of a fixed bed of rocks, coke, gravel, slag, polyurethane foam, sphagnum peat moss, ceramic, or plastic media over which sewage or other wastewater flows downward and causes a layer of microbial slime to grow, covering the bed of media. An introduction to trickling filter wastewater treatment plants. On the other hand, many other trickling filter installations in the. Trickling filters are classified on the basis of their hy draulic and organic loads.
Calculate hydraulic loading rates for trickling filters. A trickling filter is a type of wastewater treatment system. The ideal filter material is lowcost and durable, has a high surface to volume ratio, is light, and allows air to circulate. In high rate trickling filter the effluent is again sprinkled over the filter media, which is known as recirculation. High rate trickling filters are filled with plastic with a specific surface of 100230 m2m3. If the hydraulic loading rate for a particular trickling filter is too low, septic conditions will begin to develop.
The high rate filters of modern advancements also function on the same lines and. A trickling filter tf is one of the oldest biological wastewater technologies that has been used for over 100 years. It is not uncommon to load roughing filters at rates in excess. Design high rate trickling filter for the data given above except effluent bod5 40 mgl since polishing treatment is provided after high rate trickling filter. Chapter 6 trickling biofilters 6 3 is equivalent to the volume of filter effluent produced, i. Single stage unit consists of a primary settling tank, filter, secondary settling tank and facilities for recirculation of the effluent. High rate trickling filters, including primary and secondary sedimentation, should, under normal operation, remove from 65 to 85 percent of the bod of the wastewater. Trickling filters may be categorized as low rate, high rate, and super rate, primarily based on hydraulic and organic loading rates. Whether to use recirculation and the amount to be recycled when used are.
In case of high filtration rock type trickling filters packing it is considered as 1075 m 3 m 2. Treatment of sulfite waste liquor on high rate trickling filters. Detrimental effects of snail infestations include grazing of nitrifying biofilm and accumulation in aeration basins, process channels, and digesters. Trickling filter design shall consider peak organic load conditions including the oxygen demands due to recycle flows due to high concentrations of bod5 and tkn associated with such flows. This high hydraulic load was needed to obtain comparable ammonia and organic mass loads g m a2 d a1 to that of conventional wastewater ntfs table 1. Recirculation is employed in high rate filters to improve efficiency. It should be noted that, due to the multiple application of the wastewater to the filter, the actual. The trickling filter media may be crushed rock, slag, or manufactured material. Dec 04, 2015 distributor arms and an end spray nozzle to wet the edges of the trickling filter media. Conventional trickling filter ordinary trickling filter standard rate or low ratetrickling filter. Trickling filters are classified as high rate or low rate, based on. The free space in the bed is 90 98% and the wet weight is 250 400 kgm3. The settled sewage is applied to the filter bed and after trickling itpasses through the.
A high specific surface provides a large area for biofilm formation. The trickling filters at marlborough were designed as highrate units employing the flow pattern shown on figure 2. Secondary quality effluent is readily achievable if the lowrate trickling filter design incorporates filter media with. In case of high rate trickling filters the settled sewage is applied at much higher rate than for the low rate filter. Almost always included in high rate trickling filter systems improves distribution over the surface of filters reduces the clogging tendency if sufficiently high, aids in the control of filter flies the increase in applied total flow increases wetting efficiency, thus reducing short circuiting. An introduction to trickling filter wastewater treatment. The trickling filter solids contact water pollution control facility for the city of ames, iowa has successfully nitrified wastewater with trickling filters for the past decade. The high rate trickling filters are shallow in depth. High rate filters are usually characterized by higher hydraulic and organic loadings than low rate filters. The operator observes sludge depth and adjusts sludge pumping rate. Roy bingham 512 6586243 two stage high rate trickling filter plant. Introduction to trickling filters and rbcs study guide. The higher bod loading is accomplished by applying a larger volume of waste per acre of surface area of the filter. Consider recirculation ratio of 2 and filter depth of 1.
Secondary quality effluent is readily achievable if the low rate trickling filter design incorporates filter media with. Introduction to trickling filters and rbcs study guide september 1995 edition. Trickling filters with higher organic loading rates typically do not undergo problems with snails. Conventional trickling filter or ordinary trickling filter. The recirculation consists in returning portion of the treated or partly treated sewage to the treatment process i. What every operator should know about trickling filters. Low rate filters they are also known as standard rate conventional rate filters.
The trickling filter will be operated in the high rate mode, i. Synthetic media manufacturers recommend depths of 10 to 40 feet for columnar or stacked module media. Percentage of recirculation equals recirculated flow divided by. Introduction hydraulic as well as organic loading of high rate trickling filter is many times more than the low rate or standard rate trickling filter. Design a one stage high rate trickling filter to produce a bod effluent of 50 mgl. Performance of a high rate trickling filter using selected. Achieving a secondary quality effluent is less likely for a high rate filter without a secondstage process. With years of evolution, modern trickling filters can be built up to 12 m 40. Describe the effect of algae growth on the media of a trickling filter and a rbc. Assessment of singlestage trickling filter nitrification. Determine the hydraulic loading rate of a trickling filter using the following specifications. They may be classified as low or standard, intermediate, high, or super high rate table 1.
Media shall have a minimum depth of 6feet above the underdrains. Explain the purpose served by the media in a trickling filter and on a rbc. The bod removal efficiency is around 7590%, but the effluent is the only partially nitrified. The research results confirmed the possibility of high efficiency treatment of dairy sewage with daf and trickling filter technologies. Trickling filters do not require a high level of sophisticated operation in order to provide a.
Trickling filters may be categorised as low rate, high rate and super rate, primarily based on hydraulic and organic loading rates. The normal hydraulic loading rate ranges for standard rate and high rate trickling filters are. For example, the high rate t ickling filter plant in chapel hill, north carolina, typically gives ias removals of about 40%, with bo d removal of 7580%. A trickling filter is also called biological filter, as it makes the use of active microbial mass as a bioweapon to degrade the waste out of primary sewage.
L21 and l22 trickling filter partiii hrtf environmental engineeringii 2. Recirculation pump returns flow to trickling filter for further treatment types of trickling filters standard rate filter hydraulic loading 25 100 galdayft2 organic loading 5 25 lb bodday1,000 ft3 produce effluent bod of 20 25 mgl high rate filter hydraulic loading 100 2,000 galdayft2. Li the operator should plot and follow the trends of process indicators. Recirculation should be adequate to provide continuous dosage at a rate equal to or in excess of 10 million gallons per. The recirculation helps in providing seeding to the filter bed and also dilutes the strong. Modifications to high rate trickling filter process october 1970 research project 681 reprinted with permission of metcalf a body. To identify the characteristic difference between the two, one can look upon the table given below that specifies the efficiency and depth of the low and high rate trickling filter. To give a comparative idea of the working of conventional or standard trickling filters and high rate trickling filters, the salient features of both of them are compared in table 14. Request pdf application of high rate nitrifying trickling filters for potable water treatment the interference of ammonia with chlorination is a. Table 2 lists recommended recirculation rates for high rate filters.
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