What is a trickling filter in wastewater treatment?
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
When are trickling filters suitable for solid separation?
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 are the controls on the ecology of the trickling filter?
Other important controls on the ecology of the trickling filter include cold temperature and direct application of toxins. These slow down or stop predator activity and thus increase the likelihood of clogging.
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 ).
What are the macroinvertebrates in trickling filters?
The major macroinvertebrates present in trickling filters are insect larvae (e.g., chironomids).
What are the disadvantages of trickling filters?
The principal disadvantage of trickling filters is that treatment is not as complete – there is a lower limit on the mass of oxygen demand that can be removed and the open media does not provide effluent clarification.
Why is air flow important in a trickling filter?
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.
What is the effluent from a filter?
The effluent from the filter carries with it living and dead organisms and waste products of the biological reactions. Effluent sludge flocs are indicators of the efficient functioning of the trickling filter and are separated from the water in settling banks.
What are the organisms that are found in trickling filters?
Fungi, which are also to be found in trickling filters, are active in the biofilm and are actively involved in waste stabilization. These organisms tend to dominate at lower pH values, which are usually associated with industrial waste treatment.
What causes a reed bed to overflow?
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.
Is a biorock a trickling filter?
Trickling filters such as the BIOROCK system are now becoming generally accepted as the ideal non-electric sewage treatment solution by wastewater professionals who have re-evaluated the suitability of reed beds. To fully understand the advantages of a “vertical” trickling filter when compared with a reed bed it’s important to go back to ...
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.
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 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.
Why is tertiary treatment necessary?
Besides, the tertiary treatment is also necessary for the safe disposal of the effluent, as this step eliminates the pathogenic microorganisms. In contrast, the oxidized or decomposed organic matter sloughed down and recycled back in the trickling filter mediated via return pump.
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 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 is aerobic air maintained?
Aerobic conditions are maintained by splashing, diffusion, and either by forced-air flowing through the bed or natural convection of air if the filter medium is porous. The treatment of sewage or other wastewater with trickling filters is among the oldest and most well characterized treatment technologies.
What is the biofilm in a filter?
Biofilm. The bio-film that develops in a trickling filter may become several millimetres thick and is typically a gelatinous matrix that contains many species of bacteria, cilliates and amoeboid protozoa, annelids, round worms and insect larvae and many other micro fauna.
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 are the filters used in sewage treatment?
The filters which are mostly used in sewage treatment can be classified as follows: 1. The Intermittent Sand Filters 2. The Contact Beds 3. The Trickling Filters . 1. Intermittent Sand Filters: These are the early development of sewage treatment units. These are similar in Construction to the slow-sand filter of water treatment.
What is a trickling filter?
Trickling filters are used for the biological treatment of domestic sewage and industrial wastes, which are amenable to aerobic biological processes. These are used for the complete treatment or moderately strong wastes and as roughing filter for strong wastes prior to activated sludge units.
How many sewage beds can be constructed in parallel?
If the quantity of sewage is more 3 to 4 such beds can be constructed in parallel. For cleaning these filters, the sand from the top is scraped from time to time and are refilled with fresh clean sand. (i) Operation is simple, only mechanical equipment is required for dosing.
How deep is a sewage distribution trough?
While applying the sewage the flooding is done from 3 to 10 cm depth after an interval of 24 hours.
How long does it take to fill a contact bed with sewage?
The sewage is allowed to be filled 5-10 cot above the surface of contact beds. The filling may take one hour or so.
Where is intermittent sand filter best for?
The intermittent sand filters are most suitable for hospitals, institutions, small towns and factories, where it is not possible to dispose of the effluent of septic tanks on the ground surface. 2. Contact Beds:
What are the advantages of intermittent sand filters?
The following are the advantages of intermittent sand filters: (i) Operation is simple, only mechanical equipment is required for dosing. (ii) The effluent is very clean and can be directly disposed of in natural watercourses without any further treatment. (iii) There is no trouble of odour and insects.