What is a Single trickling filter used for?
Oct 24, 2016 · 15. A trickling filter system is generally used during which stage of sewage treatment? A. primary B. secondary C. tertiary. B . secondary. 16. Which of the following is NOT a problem associated with groundwater mining? A. saltwater intrusion B. subsidence C. exhaustion of water supply D. loss of wildlife habitat.
What are the different types of filters used in sewage treatment?
Trickling Filters DESCRIPTION Trickling filters (TFs) are used to remove organic matter from wastewater. The TF is an aerobic treatment system that utilizes microorganisms attached to a medium to remove organic matter from wastewater. This type of system is common to a number of technologies such as rotating
What is the difference between activated sludge treatment and trickling filter?
During wastewater treatment, a trickling filter is used for (a)Primary treatment (b)Secondary aerobic treatment (c)Secondary anaerobic treatment (d)Tertiary treatment Verified 135.6k + views Hint: Trickling filter is a sewage treatment system that utilizes micro-organisms attached to a medium to remove organic matter from waste-water.
How is sewage treated in a sewage treatment plant?
It is suitable for treatment of low to medium strength domestic wastewaters. The high rate trickling filter, single stage, and two stage are recommended for medium to relatively high-strength domestic and industrial wastewaters. The BOD removal efficiency is around 75–90%, but the effluent is only partially nitrified.
What is a trickling filter?
Trickling filters (TFs) are used to remove organicmatter from wastewater. The TF is an aerobictreatment system that utilizes microorganismsattached to a medium to remove organic matterfrom wastewater. This type of system is commonto a number of technologies such as rotatingbiological contactors and packed bed reactors (bio-towers). These systems are known asattached-growth processes. In contrast, systems inwhich microorganisms are sustained in a liquid areknown as suspended-growth processes.
What is TF in wastewater?
TF consists of permeable medium made of a bedof rock, slag, or plastic over which wastewater isdistributed to trickle through, as shown in Figure 1.Rock or slag beds can be up to 60.96 meters (200feet) in diameter and 0.9-2.4 meters (3 to 8 feet)deep with rock size varying from 2.5-10.2 cm (1 to4 inches). Most rock media provide approximately149 m2/m3 (15 sq ft/cu ft) of surface area and lessthan 40 percent void space. Packed plastic filters(bio-towers), on the other hand, are smaller indiameter (6 to 12 meters (20 to 40 feet)) and rangein depth from 4.3 to 12.2 meters (14 to 40 feet).These filters look more like towers, with the mediain various configurations (e.g., vertical flow, crossflow, or various random packings). Research hasshown that cross-flow media may offer better flowdistribution than other media, especially at loworganic loads. When comparing vertical mediawith the 60 degree cross-flow media, the verticalmedia provide a nearly equal distribution ofwastewater minimizing potential plugging at higherorganic loads better than cross flow media. Theplastic medium also required additional provisions,including ultraviolet protective additives on the toplayer of the plastic medium filter, and increasedplastic wall thickness for medium packs that areinstalled in the lower section of the filter whereloads increase.
What is a low rate filter?
Low-rate filters are commonly used for loadings ofless than 40 kilograms five day biochemical oxygendemand (BOD5)/100 meters cubed per day (25 lbBOD5/1000cu ft/day). These systems have fewerproblems than other filters with regards to filterflies, odors, and medium plugging because of thelower loading rate. Low-rate filters with a rockmedium range in depth from 0.9 to 2.4 meters (3-8 ft.). Most low-rate filters are circular with rotarydistributors, but some filters currently in use arerectangular. Both of these configurations areequipped with dosing syphons or periodic pumps toprovide a high wetting rate for short intervalsbetween rest periods. A minimum wetting rate of
What is a trickling filter?
Trickling filter is a widely used aerobic biological treatment system. Also called a biofilter, it is a downflow packed bed type of reactor. It consists of a fixed bed made up of different inert materials. Biofilm grows on the surface of the inert bed. Different cheap and porous materials such as rocks, lava, coke, gravel, slag, pumice stone, polyurethane foam, peat moss, ceramic, or plastic media can be used for making the porous bed. Wastewater enters from the top of the fixed bed making use of a rotating arm distributor or static nozzles fed with a variable head feed source. Microbial biofilm grown on the surface of the inert support helps to degrade the waste. Aerobic condition is achieved by active or passive aeration by using either a blower or fan (forced aeration) or natural convection of air due to the temperature difference between the water and ambient air. Low strength wastewaters (COD < 1000 mg l − 1) such as sewage (domestic wastewater) can easily be treated using the system and desired effluent quality can be achieved by maintaining a typical HRT of 1 day. Clogging and channeling are two very common problems associated with its operation. Periodic cleaning of the bed (biomass removal) is required to get desired performance. A typical trickling filter used for treating sewage uses 0.22 kWh energy to remove 1 kg-COD ( Evans et al., 2004 ).
How deep is a filter bed?
Media bed depths can vary, but traditional trickling filter beds have been between about 1 to 3 meters. The media size ranges from about 25 to 60 mm in diameter (e.g. round gravel). However, various shapes and materials (e.g. polyvinyl chloride) have been used successfully.
What is a fixed film bioreactor?
Fixed film reactors have high surface areas available for microbial growth. Also, these systems present a higher potential for use than suspended growth biomass reactors since the former can retain a higher concentration of biomass with higher metabolic activity when operated with continuous processes. Biofilm reactors have been constructed using different packing materials such as granular activated carbon, polyurethane, kaolin, polystyrene, wood chips, soil sand, gravel, ceramic saddles, polyvinyl chloride, and polyethylene.8 Trickling filters and RBCs are the main types of attached growth bioreactors. In recent years, hybrid systems such as moving bed biological reactors (MBBRs) and membrane bioreactors (MBRs) combine advantages of attached growth and activated sludge systems.
What is the driving force of air flow?
The principal factor responsible for air flow is natural aeration, the driving force for airflow being the temperature difference between air inside the filter and the surrounding air. 2. The trickling filter is a nonsubmerged fixed film biological reactor using rock or plastic support media.
What causes a septic tank to back up?
Clogging problems normally occur either at the inlet or at the outlet of the bed. A blockage at the inlet end may lead to the septic tank 'backing-up' to the house. A blockage at the outlet end may cause the reed bed to overflow and the gravel bed flooding.
What is reed bed?
Reed beds - operating principle. The common reed used in a planted sewage filter bed develops micro-organisms that digest the pollutants in sewage. This bacteria’s development is achieved by transferring oxygen from the plant leaves down through its stem and roots resulting in bacteria growing in the gravel bed.
How long do reed beds last?
Reed beds may be a long term solution when designed and maintained properly; however site experiences show that most planted filters may only be viable for up to 10 years.
Can you install a biorock tank at a depth?
The tanks can be installed at a depth which ensures that the water-dispersion system is out of the ground freezing zone. The use of a BIOROCK tank extension is a perfect solution. This "freezing zone" varies by region, and this essential point should be checked with local authorities.
Is reed bed a good option for sewage treatment?
Reed beds are not a cheap or easy option for sewage treatment, the costs involved for a complete non-electric sewage treatment plant are no more than that of reed beds. Substantial savings may be achieved with the installation due to shorter installation, fewer delays and the ease of burying of the tanks in the ground when compared to the often complicated construction of gravel beds and the time-consuming seeding and growing of the reeds.
Can reeds freeze?
In the event of cold winters and especially in cold climate zones, the possibility of reed beds freezing solid is a reality, this has forced companies involved in the design and building of reed beds to re-think the merits of planted filters in areas with a risk of freezing.
What is a trickling filter?
Trickling filter process is one of the types of aerobic wastewater treatment. It is a fixed-bed bioreactor that is the part of secondary wastewater treatment, which eliminates the coarse particles, suspended organic and inorganic waste, small colloids etc. out of the primary effluent. 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.
How does a filter bed work?
It works under the aerobic conditions and makes the use of aerobic microbes so that they can exploit or oxidize the organic matter into a simpler form. The filter bed is placed below the pebble filled media, which aids the separation of secondary effluent out of waste activated sludge.
What is a dosing bucket?
Primary influent that enter the trickling filter unit is free from coarse objects, suspended solids, rags etc. A dosing device (tipping bucket) is a piece of equipment allowing the supernatant to flow upwards to the arms of the perforated rotary distributor.
How does a rotary distributor work?
The treated primary sewage splashes through the arm of a rotary distributor provide the oxygen supply in the form of dissolved oxygen. Oxygen is drawn into the filter media via vacuum or chimney effect. The bio-film layer uses the dissolved oxygen trapped within the filter media and oxidize the organic compounds by releasing carbon dioxide gas, water and other oxidized end products.
What is a filter media?
The filter media is chiefly composed of porous media that increases the surface area for the decomposition of the organic matter by the microorganisms. Trickling filters are generally available as the standard rate and high rate filter, in which both have different hydraulic and organic loading rate.
What is secondary clarifier?
A secondary clarifier is a sedimentation unit, which separates the small colloids, suspended particles etc. at the bottom out of waste fluid. Besides, the tertiary treatment is also necessary for the safe disposal of the effluent, as this step eliminates the pathogenic microorganisms.
What is the slime layer?
Slime layer. It also refers as a slime layer, which contains aerobic biomass of the surface of the filter bed up to the thickness of 0.1-0.2mm. In contrast, the remaining area contains anaerobic biomass. The above surface containing aerobic microbes is considered as the rapid growth phase region, as the microorganisms harness direct sunlight ...
What is a single trickling filter?
Single trickling filters may be used for the treatment of small residential septic tank discharges and very small rural sewage treatment systems. Larger centralized sewage treatment plants typically use many trickling filters in parallel.
What type of media is used in trickling?
Media types. Trickling may have a variety of types of filter media used to support the biofilm. Types of media most commonly used include coke, pumice, plastic matrix material, open-cell polyurethane foam, clinker, gravel, sand and geotextiles.
What is a circular wall?
A circular wall, often of brick, contains a bed of filter media which in turn rests on a base of under-drains. These under-drains function both to remove liquid passing through the filter media but also to allow the free passage of air up through the filter media.
What is the treatment of industrial wastewater?
The treatment of industrial wastewater may involve specialized trickling filters which use plastic media and high flow rates. Wastewaters from a variety of industrial processes have been treated in trickling filters. Such industrial wastewater trickling filters consist of two types:
How thick is a biofilm?
This is very different from many other bio-films which may be less than 1 mm thick. Within the thickness of the biofilm both aerobic and anaerobic zones can exist supporting both oxidative and reductive biological processes. At certain times of year, especially in the spring, rapid growth of organisms in the film may cause the film to be too thick and it may slough off in patches leading to the "spring slough".