How are trickling filters used in secondary wastewater treatment?
Explanation: In secondary wastewater treatments, trickling filters are used for aerobic treatment of wastes by microorganisms. It uses an attached growth process, where a bed of rocks, gavel, coke, slag, peat moss and plastic is made, through which the waste is flown and the microbes are attached on the surface of the bed.
Why should trickling filter recirculation be done during low-inflow periods?
Remove the packing grease from the filter bearings and replace with the proper grease 1, 3, 4, 5 *Why should trickling filter recirculation be done during low-inflow periods of the day and night? 1. To avoid clarifier problems from hydraulic overloading 2. To encourage the development of snail populations on the media 3.
What could cause a trickling filter plant effluent with suspended solids?
*A trickling filter plant effluent that is high in suspended solids could be caused by which factors? 1. Anoxic conditions in the primary clarifier 2. Gasification (denitrification) caused by septic sludge in the secondary clarifier 3. Heavy sloughing from the filters 4.
Which items are guidelines for maintaining trickling filters to prevent odor problems?
*Which items are guidelines for maintaining trickling filters to prevent odor problems? 1. Check the ventilation in the trickling filter 2. Do everything possible to maintain aerobic conditions in the sewer collection system and in the primary treatment units 3.
Which of the following are steps in primary sewage treatment?
Treatment StepsStep 1: Screening and Pumping. ... Step 2: Grit Removal. ... Step 3: Primary Settling. ... Step 4: Aeration / Activated Sludge. ... Step 5: Secondary Settling. ... Step 6: Filtration. ... Step 7: Disinfection. ... Step 8: Oxygen Uptake.
What is the difference between primary and secondary sewage treatment?
Primary sewage treatment is a physical process that removes large impurities while secondary sewage treatment is a biological process that removes organic matter of sewage through the action of microbes.
Which treatment method is used in primary wastewater treatment?
There are three basic biological treatment methods: the trickling filter, the activated sludge process, and the oxidation pond. A fourth, less common method is the rotating biological contacter.
Which would be more likely to cause illness and why a water sample that tested positive for fecal coliforms or one that tested positive for E coli O157 H7 quizlet?
coli O157:H7? The coliform-positive sample would be more likely to cause illness. Coliforms indicate the presence of fecal contamination, which always leads to illness.
What is primary secondary and tertiary treatment of wastewater?
Wastewater is treated in 3 phases: primary (solid removal), secondary (bacterial decomposition), and tertiary (extra filtration).
What are the 3 stages of sewage treatment?
There are three main stages of the wastewater treatment process, aptly known as primary, secondary and tertiary water treatment.
What is done during second stage of primary treatment?
Answer: Secondary Wastewater treatment is the second stage of wastewater treatment. In primary treatment, suspended solids, colloidal particles, oil, and grease are removed. In secondary treatment, biological treatment is done on the wastewater to remove the organic matter present.
What happens in the secondary stage of wastewater treatment?
Secondary Treatment The secondary stage of treatment removes about 85 percent of the organic matter in sewage by making use of the bacteria in it. The principal secondary treatment techniques used in secondary treatment are the trickling filter and the activated sludge process.
What are the 4 stages of sewage treatment?
4-Step Wastewater Sludge Treatment ProcessStep 1 – Sludge Thickening. The first step in the sewage sludge treatment plan is called thickening. ... Step 2 – Sludge Digestion. After amassing all the solids from the sewage sludge begins the sludge digestion process. ... Step 3 – Dewatering. ... Step 4 – Disposal.
What is the difference between coliforms and faecal coliforms?
Total coliforms include bacteria that are found in the soil, in water that has been influenced by surface water, and in human or animal waste. Fecal coliforms are the group of the total coliforms that are considered to be present specifically in the gut and feces of warm-blooded animals.
Why is water tested for coliform bacteria rather than for pathogenic bacteria which may be present?
Most pathogens that can contaminate water supplies come from the feces of humans or animals. Testing drinking water for all possible pathogens is complex, time-consuming, and expensive. It is easy and inexpensive to test for coliform bacteria.
Why do water-testing procedures look specifically for coliform bacteria rather than specific pathogens quizlet?
Why do water-testing procedures look specifically for coliform bacteria rather than pathogens? Coliforms are routinely found in feces, survive longer than pathogens and are easy to detect.
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
Where does the trickling filter effluent go?
The trickling filter effluent collects in the underdrain system , then travels to a sedimentation tank called asecondary clarifier. Secondary clarifier (or final clarifier as it is sometimes called) construction is similar in most respects to the primary clarifier, although differences occur in operation that can include detention time, surface settling rate, hydraulic loading, sludge pumping, overflow rate, weir loading, and other details.
What chapter is Trickling Filters?
Along with the online lesson, read Chapter 6: Trickling Filters in your textbook Operation of Wastewater Treatment Plants Volume I.
What is recirculation in a filter?
Recirculation: The return of filter effluent back to the head of the trickling filter. It can level flow variations and assist in solving operational problems, such as ponding, filter flies, and odors.
How deep is a trickling filter?
The primary consideration for media selection is that it be capable of providing the desired film locations for biomass development. Media may be 3 to 20 or more feet in depth, depending on the type of media used and the filter classification. Trickling filters that use ordinary rock are usually only about 3 meters deep. The weight of the rocks causes structural problems, and also requires wide bed construction - in may cases up to 60 feet in diameter. Ligher weight synthetic media allows much greater bed depths.
How does a zoogleal slime work?
The organisms aerobically decompose the solids producing more organisms and stable wastes, which either become part of the zoogleal slime or are discharged back into the wastewater flowing over the media . The wastewater continues through the filter to the underdrain system where it is collected and carried out of the filter. At the same time air flows through the filter (bottom to the top or top to bommtom depending on temperature). Oxygen is transferred from the air to the wastewater and slime to maintain the aerobic conditions. Periodically the slime on the media becomes too heavy and portions will be released. This material known as sloughingsis carried out of the filter with the wastewater flow and is removed in the settling tank following the filter.
What is the moving force in primary treatment?
Gravity is the moving force in primary treatment whereas biological activity is the moving force behind secondary treatment. Secondary treatment includes methods that use biological processes to convert dissolved, suspended, and colloidal organic wastes to more stable solids, which can be either removed by settling or harmlessly discharged to the environment. Biological treatment, sometimes called secondary treatment, provides biochemical oxygen demand (BOD) removal well beyond the levels that primary treatment can achieve, producing an effluent with not more than 30 mg/L BOD5and 30 mg/L total suspended solids to meet Clean Water Act requirements. Trickling filters were the most widely used form of wastewater treatment in the first half of the twentieth century and are still considered a viable treatment alternative due to their low energy and maintenance requirements and their ability to treat variable organic loads and toxic substances.
What is underdrain in a filter?
Filter Underdrain: The open space provided under the media to collect the liquid (wastewater and sloughings) and to allow air to enter the filter. It has a sloped floor to collect the flow to a central channel for removal.
What filter is used in place of activated sludge in secondary sewage treatment?
Trickling filters may be used in place of activated sludge in secondary sewage treatment. T/F
How does recycling help landfills?
Recycling greatly reduces the amount of wastes sent to landfills.
Why do water tests look for coliforms rather than pathogens?
Why do water-testing procedures look for coliforms rather than pathogens? - It is always somewhat dangerous to culture pathogens in a laboratory setting - people in the lab are at risk of contracting serious disease. It is much safer to test for coliforms which simply indicate that humans have been swimming in the water.
What is the purpose of artificial wetlands?
Artificial wetlands provide a habitat for wildlife. Methane is a by-product of anaerobic digestion. Removal of nitrates by microorganisms requires aerobic conditions. Removal of nitrates by microorganisms requires aerobic conditions.
What is the purpose of phosphate removal?
involves the removal of phosphates and sulfur compounds. is done to promote nutrient enrichment. is done to promote growth of photosynthetic organisms. is done to prevent possible overproduction of algae and other organisms . All of the choices are correct.
What happens when a substance clumps in a compost pile?
When suspended material clumps, it sinks and can be easily removed. Antibodies are used bind bacteria into large masses that can be removed by filtration. When suspended material clumps, it sinks and can be easily removed. The compost pile temperature at which pathogens, but not thermophiles, are killed is about 20-30ºC.
What are the pollutants that are combined into clumps?
Pollutants such as lead are combined into clumps using toxic chemicals, for easy removal.