rising sludge in clarifier There are many causes of sludge floating. This replacement closes out the rising fluid pathway through the disc stack. A 4. Rising clumps of sludge or gas bubbles may occur in the final clarifier. Anaerobic sludges in the final clarifier can cause "rising sludge". Rising fluff is the cause of sludge wash outs resulting in increased phosphorus and other nu-trients concentrations in the effluent. The Cerlic CBX Sludge Blanket Meter and MultiTracker supply accurate and repeatable measurement Sludge settlement problem at the clarifier 2004. The other cause of rising gas bubbles with sludge in the clarifier is bacteria growth within the sludge or on the clarifier plates. Ryan Staples is a Senior Wastewater Operator with 9+ years of experience in wastewater management and public utilities. Excess sludge is called "surplus activated sludge" or "waste activated sludge" and is removed from the treatment process to keep the ratio of biomass to food supplied in the wastewater in balance. This gas lifts the sludge from the bottom of the clarifier to the water surface. Secondary Clarifier Superoxygenation to Increase Active Biomass and Stop Rising Sludge Date: 2. D. Hydroflux® can provide Stamford baffles below the launder system. Turbimax CUS71D continuously monitors the separation and transition zones in clarification and settling tanks, ensuring safe, economic and efficient sedimentation processes. Rising sludge problem may be overcome by : Increasing the RAS withdrawal rate from the clarifier to reduce the detention time of sludge in clarifier. VOL = 1 / ρρ ;;ρ ; Where ρ = Specific Gravity Specific Gravity; ρρ ρ = D / 8. denitrification in the clarifier due to an increased sludge blanket volume should not exceed 30 % of total denitrification. Michael Richard Wastewater Microbiology LLC Fort Collins, CO www. Incomplete denitrification in mainstream process during stressed conditions resulting from cold dilute flows can also lead to rising sludge in the final clarifiers. Positive sludge return should be employed in package plants since the use of gravity return systems has generally proved ineffective (2)(20). Capabilities must be provided to waste sludge directly to the primary clarifier in order to blend the secondary sludge with primary sludge before going to the digester. 5 to 18. Rising sludge is the consequence of insufficient denitrification capacity of the activated sludge system. Lowering sludge age can also help, if it is a little too high. The VeeMax® sludge plow can be readily adapted to sludge thickening with the addition of the picket fence module. – Diagram of a lamella clarifier basic primary clarifiers are poor solids removal and low solids concentration in the primary sludge and for secondary clarifiers bulking or rising sludge [5]. Conversely, with a recirculation ratio of above 0. Wastewater Treatment Plant . Some plants (sequencing batch reactors) will intentionally allow denitrification to remove the nitrogen compounds from the treated water. Because cells need oxygen for their metabolism, air is injected from the bottom of the aerator. Over a period of time, even with good sludge removal, the metal hydroxide sludge will find places to collect within the lower portions of the clarifier. The problem of rising sludge in biological wastewater treatment secondary clarifiers is overcome by minimizing entrainment of nitrogen gas with mixed liquor entering the transfer pipe to the clarifier such that the level of dissolved nitrogen in the biomass settling in the clarifier remains less than that in equilibrium with nitrogen gas at the pressure prevailing in the biomass. This model does not include interactions with the preceding aeration 12 differences between primary and secondary clarifiers. The slip tubes are available in a variety of sizes and materials, the most common materials being 304 stainless steel and Sch. The rising sludge bed approaches the detector’s probe. Typically, wastewater containing large amounts of small, suspended particles of organic matter enters a tank where suitable microorganisms are introduced, along with sufficient air to promote growth and multiplication of the right kinds of Australia plans to dump one million tonnes of sludge in the Great Barrier Reef. resulting in a certain amount of fine sludge rising up the clarifier. The clarifier is a key element in the activated sludge treatment: it ensures both the separation of solids materials produced in the aeration tank and the thickening of the sludge. Sludge was travelling to the Autobots’ headquarter when he and the Dinobots were attacked by Starscream and the Decepticon superjets. The clarifier can be treated with a compatible biocide after flushing with an air sparger to retard flora and fauns growth. Despite strict laws on dumping waste, the Great Barrier Reef Marine Park Authority (GBRMPA) gave the go-ahead. Air lift pumping Discuss floating sludge in a clarifier. Rising bubbles agitate the water well and create good contact between the Primary sludge is produced if primary clarifiers precede the oxidation ditch. The result was a sufficiently low SLR so that thickening failure did not occur (sludge blankets did not rise to the effluent weirs). Which is the 'main worker' among the various organisms found in activated sludge? Clarifiers/SedimentationClarifiers/ SedimentationSedimentation Sludge Bomb. Using an innovative long sludge age, activated sludge process, our complete system provides an extremely simple and cost-effective Sludge Bulking, Foaming, and Other Solids Separation Problems, 3rd Edition. Non-filamentous bulking sludge is less dense and can trap bubbles of air & nitrogen that acts to float the sludge. Fats, Oil, & Grease (FOG) FOG compounds are adsorbed by the floc acting as a sponge. While sludge wasting can be as infrequent as once every 2 to 3 months, more frequent sludge wasting programs are recommended to maintain process efficiency and sludge settling Fig. Don’t forget that slow-settling sludge can be caused by both old and young sludge. Poor settlability of the sludge characterized by high SVI value (>200). 65 kg TSS per kg of BOD (0. The purpose of this thesis was to – through literature studies, sampling, full scale experiments and analysis – identify causes for the rising sludge problem. Post-denitrication uses an anoxic zone at the end of the activated sludge tanks. Slow sludge appears to be stuck in the settling process with little or no progress but with very clear supernatant. The Influence of SRT on SVI 18 6. Denitrification and rising sludge is a very frequent problem facing wastewater operational staff. The BSM2 layout includes the BSM1 for the biological treatment of the wastewater and the sludge treatment. ƒRising sludge flocs will escape from clarifiers. 85 kg TSS per kg (0. , Lewis Publishers (CRC PRESS), Boca Raton, FL, 2003 •Activated Sludge Microbiology Problems and Their Control, 2010 Michael Richard, Ph. During episodes of sludge bulking (whatever the cause), operators have a natural tendency to increase the RAS flow in order to remove the rapidly building As such, bulking or rising sludge can cause a deterioration in final effluent quality. Lamella Clarifiers, also known as Inclined Plate Separators (IPS) are in common use at Waste Water Treatment Sites as small footprint plant settlement units and are often employed in place of conventional settling tanks. 10. Rising sludge occurs in the secondary clarifiers of activated sludge plants when the sludge settles to the bottom of the clarifier, is compacted, and then starts to rise to the surface, usually as a result of denitrification, or anaerobic biological activity that produces carbon dioxide or methane. An indication of the occurrence of denitrification can be obtained by holding the sludge in the settling test jar for several hours. which then caused rising sludge in clarifiers (INCI019610 was submitted by Irish Water on 15/09/2020). 34 ; Where D = lbs/gal. Rising fluff is the cause of sludge wash outs resulting in increased phosphorus and other nutrients concen-trations in the effluent. Sludge Lord will shoot Sludge Bomb at target,which deals 5( )damage as well as inflicts Slowness IV and Blindness II for 4 seconds. Which of these is not an alternative to activated sludge treatment systems? a) Stabilization ponds b) Rotating biological reactors c) Trickling filter d) Screening units Answer: d The activated sludge process is an aerobic suspended-growth process that maintains a Clumps of rising sludge in clarifier. Raw water temperature changes The activated sludge system consists of two components, an aerator, where cells (X) consume the sewage (S), and a clarifier, where cells are then removed from the treated water. The data presented Above this amount of denitrification supersaturation of nitrogen gas at the bottom of the clarifier will lead to rising sludge due to bubble formation. 3 13. It is useful in the routine monitoring of biological processes and should be run at least once per shift. 0 gram. biological flock in the activated sludge process and float the flock to the surface of the secondary clarifiers. Discuss floating sludge in a clarifier. The Cerlic CBX Sludge Blan-ket Meter supplies an accurate and repeatable measurement of the sludge blanket and fluff levels defined by solids concentration, Gas and rising sludge in a primary clarifier is usually caused by anaerobic conditions in the sludge blanket. 5% EMULSION POLYMERS. . This treatment involves introducing a combination of air and microorganisms — such as aerobic bacteria and protozoa — to sewage and industrial organic waste to encourage growth and multiplication. When the SLR exceeds the limiting flux,the sludge storage zone (h3) expands to accumulate the sludge and limits its conveyance to the bot- Rising Sludge In Clarifier Manufacturers, Factory, Suppliers From China, We warmly welcome small business companions from all walks of lifestyle, hope to establish friendly and cooperative business make contact with with you and attain a win-win objective. HeadMax® The UV Pond Clarifier is ideal for cleaning the green out of water and preventing nasty odors in ponds up to 2,000 gallons. 85 lb. Rising sludge • A layer or clumps of sludge on clarifier surface • Sludge contains gas bubbles • Floating sludge has same levels of filaments as mixed liquor (RAS) • Caused by denitrification in secondary clarifier However, when secondary clarifiers are overloaded or suffer from rising sludge problems, upgrading of such clarifiers using EDI (Baffle) is definitely advantageous. clarifier is usually full of sludge. Memosens immersion sensor for sedimentation tanks in water, wastewater and utilities. By definition, a bulking sludge is a sludge that has a sludge volume index (SVI) of >150 mL/gram. Because the activated sludge process converts the deicer compounds primarily to new bacteria cells, the treatment system generates excess bacteria (sludge) as a waste product. The cause of the rising sludge blanket in the clarifiers was the increase in raw water temperature from a level of 17. 0 14. The Dinobots managed to fend off the Decepticons, and continued to Autobot headquarters. Oftentimes secondary sludge systems can’t handle the load, and therefore the sludge backs up in the clarifier and shuts down the pretreatment system. The bacteria are still growing and alive in your clarifier. Many of these new plants are operating at a fraction of their de What condition can result in sludge on the surface of a secondary clarifier typically caused by a septic environment? ? Bulking sludge ? High rate aeration ? Rising sludge ? Over-wasting; What process control parameter is the result of aeration total solids inventory divided by total solids removed from the process? ? Gould sludge age (GSA) ? 6. Components of ASP Secondary sedimentation tank • To clarify the out-flowing aeration tank contents (mixed liquor) • To separate and thicken the biological flocs from mixed liquor for recycling or wasting Sludge recycling • Thickened sludge is returned back from secondary clarifier to the aeration tank to maintain desired concentration of biological solids • Includes pumps and necessary piping and fittings Activated sludge wasting • Sludge wasting is either as mixed liquor or as Filaments will regrow rapidly, often with a vengeance, after termination of chlorination since the cause of the bulking has not been addressed. Describe typical clarifier efficiencies. If the settling test or diluted settling test shows that the sludge settles well, then the blanket washout is usually due to too many solids in the clarifier. , 2009) or rising sludge caused by denitrification The novel clarifier provides natural flocculation, which occurs as a result of hydraulic energy dissipation and the formation of sludge cloud referred to as plume. Increasing the amount of sludge removed from the clarifier will help to reduce the production of anaerobic gases. Denitrification in the sludge blanket. Gas and rising sludge in a primary clarifier is usually caused by anaerobic conditions in the sludge blanket. As noted above, in the simulation, the clarifier C had a 10-foot side water depth and the sludge blanket was assumed to be three feet deep from the bottom of clarifier C. b. ‭ ‬Supernatant is fairly clear. Decreasing the SRT to bring the active sludge out of nitrification Sludge Bulking - Causes, Control Strategies and Options for Domestic and Industrial Systems . Line Drawings of Activated Sludge Floes (Reference 2) 23 8. Describe typical clarifier efficiencies. Features: Plate length: Depending on the scale of the system, total plate lengths can vary, however, the plate length should allow for the plates to rise 125 mm above the top water level, with 1. solids can be conveyed to the bottom of clarifier • If Solids in > Limiting flux • Solids accumulate in clarifier • Rising sludge blanket • This is thickening failure • If this continues, sludge will reach close to effluent weir • Solids carryover Thickening Function Normal Thickening Failure Solids washout Q + Q ras Q ras Q X Thus denitrification does not only cause sludge clusters to rise but also expands the blanket. We recommend changing UV bulbs yearly for optimum cleaning performance. 0 12. The clarifier solids load rate (SLR) in lb/d/ft2, represents the mass of solids applied per unit area per unit time. Alkalinity and nitrifying bacteria must be present — in the right ratio — to achieve complete nitrification. ” Therefore, achieving and maintaining good sludge settleability is the best way to minimize clarifier problems. 20 Applications: Secondary Clarifier Oxygenation , Wastewater Treatment Solids Contact Clarifiers combine the functions of chemical treatment, mixing, flocculation, and sedimentation. , 2000. Figure 6 Sludge pop-ups in a small plant clarifier 17 Figure 7 Rising sludge pop-ups on small plant clarifier 18 Figure 8 Ashing on clarifier surface 19 Figure 9 Light scum on clarifier surface 20 Figure 10 Wuhrmann process 22 Figure 11 Modified Ludzack-Ettinger process 23 The obvious reason would be total nitrogen limits in your discharge permit, others include alkalinity and oxygen recovery, the desire to produce a high stabilized effluent, and a reduction of problems with rising sludge in your clarifier. * Any sludge removed from pretreatment tank or Clearstream Unit must be disposed of according to all state, local, Because of the water flow the, sludge blanket tends to rise and fall in the tank resulting in a certain amount of fine sludge rising up the clarifier. These numbers are lower than those 15 of a primary settling tank. The average surface overflow rate for a 13 secondary clarifier ranges from 24 000 to 33 000 L/m2·d (600 to 800 gpd/ft2) and a wier overflow 14 rate of 125 000 to 250 000 L/m·d (10 000 to 20 000 gpd/ft). 5 to 1 m/h, whereas trickling filter solids - which are more dense and settle faster - can be successfully settled in a clarifier having a liquid upflow velocity of up to 2 m/h. Excessive sludge detention times in the final clarifier resulting from poor elarifier design. Rising sludge occurs in the secondary clarifiers of activated sludge plants when the sludge settles to the bottom of the clarifier, is compacted, and then starts to rise to the surface, usually as a result of denitrification, or anaerobic biological activity that produces carbon dioxide or methane. Any increase in hy draulic loading generally results in a loss of solids to the clarifier effluent. As the sludge bed, which flows into the probe gap, reaches the predetermined concentration set-point: the green LED on the controller lights up When the clarifier is not thickening limited (rising sludge blanket), its capacity may be increased by improving settleability. Bridge-Supported Rapid Visual Sludge Removal (Uptake Pipe) Type. COM Issue 13. O. The nitrogen gas bubbles attach to sludge flocs and float to the surface of clarifier, bringing the attached particles with them. The highest solids concentrations possible, faster removal As the sludge compresses/thickens toward the center of the thickener and along the thickeners compressing edge, water passes up into the clarifier at the thickeners ends and at its rising edge. What is Trickling Filter? Sludge from a secondary clarifier is usually darker than the sludge from a primary clarifier. The separated solids sink to the base of the clarifier, leaving a clear supernatant above. This is typically observed in activated sludge plants with nitrification (Cole et al. 9 kg·m-3 and 9. Sludge Blanket Upflow. It is not performing at normal solid-liquid separation at desired levels of sludge-compaction. You need to either increase your return activated sludge (recycle) flow rate, of increase your waste activated sludge flow rate / pumping time. David Jenkins University of California at Berkeley . The loading rates in Jahra clarifier in sludge mass and hydraulic flow are about 1. In this study, efficiency of total nitrogen removal in activated sludge and trickling filter processes (AS/TF) was investigated in Tehran North wastewater treatment plant. The obvious reason would be Total nitrogen limits in your discharge permit, others include; alkalinity and oxygen recovery, the desire to produce a highly stabilized effluent, and a reduction of problems with rising sludge in your clarifier. Troubleshooting and Problem Solving Trumbull offers Telescoping Valves in either Rising Stem or Non-Rising Stem designs. Fill a 4 oz Bottle with 99 mls of Water Determine Volume of Coagulant = 1. Module 16: The Activated Sludge Process . Bulking sludge Clouds of billowing homogenous sludge rising and extending thoughout the clarifier. Rapid settling of sludge, leaving a dirty, brown and turbid supernatant, especially if the settleability test yesterday (or since the last test) looked completely normal. Rapid sludge settles like dark grains of sand leaving behind a turbid supernatant with suspended solids. We were advised by Partech that by having the upper sensor set to a more sensitive level (0-200mg/l) we would be able to pick up the presence of rising sludge and activate an alarm condition and automatically open the desludging valve. By knowing what causes denitrification to occur, steps can be taken to discourage it from happening in the clarifier. Many conditions may lead to poor sludge settleability. This will lead to poor discharge water quality due to the inability of the sludge to properly separate from the water in the clarifier. Classes for Wastewater Certification. A sequence of tests, procedures or observations are described that allow problems to be classified into one or more of the following categories: (1) denitrification or rising sludge, (2) high sludge blankets, (3) flocculation or breakup problems, and (4) hydraulic problems. The problem is often related to an increase in influent ammonia/nitrogen that is converted by beneficial nitrifiers into NO2 or NO3 via the autotrophic nitrification process. sludge, a clarifier mechanical problem may exist. Break up scum in clarifier 6 mos. Also, the Monte Carlo simulations revealed that the uncertainty of the model predictions differed for the different evaluated scenarios. It is important to note that though it is possible to convert all purifiers to a clarifier, it is not always possible to switch a clarifier to a purifier centrifuge. These irregularities in sludge blanket depth are easily monitored by measuring profiles of blanket depth across the clarifier. Which is the 'main worker' among the various organisms found in activated sludge? Clarifiers/SedimentationClarifiers/ SedimentationSedimentation the sludge aerobic in the clarifier •Increase RAS rate to limit sludge retention time in the clarifier to a minimum •Prevent nitrification (only possible of there is no ammonia limit) •Improve sludge quality in filamentous sludges where less nitrate is needed (sometimes even at 5 mg/L) to cause floating problems This is often accompanied by chunks of sludge rising to the surface of the secondary clarifier, much like denitrification. Discuss the operation of trickling filter clarifiers. Are you holding the solids too long in the clarifier? This is a very common practice that causes septicity and promotes growth of filaments. Since ammonia is soluble, it will release into the water column and pass through the clarifier to the effluent. 5. 20 Applications: Secondary Clarifier Oxygenation , Wastewater Treatment Describe rising sludge in an activated sludge system. unless there's sufficient sludge blanket over it. 65 lb TSS per lb. ƒIn glass cylinder, two phases can be distinguished: - First the activated sludge settles rapidly (compact bottom layer of settled sludge and a clear supernatant). Increasing the amount of sludge removed from the clarifier will help to reduce the production of anaerobic gases. Rising sludges are a result of denitrification and septicity. Online Engineering is a video lecture series started by a team consisting of Alumni of IITs and IES Officers with a prime motto to help the engineering stude 4. 4. Condition 6 is caused by hydraulic overload of the clarifier. ‭ ‬Mixed liquor settles slowly and compacts poorly. The FOG being less dense than water can disrupt gravity separation and if you have too much FOG acts to float the sludge. Steep floor slopes and special hopper designs with rake type mechanisms are not required and operating torque loads are reduced so existing sludge pipes, drives and bridges can be reused. These baffles eliminate density current flows that can disturb sedimentation of the sludge floccs by moving then away from the launder and towards the centre of the clarifier tank. To Disinfection Clarifier Aerator Hopper Oxidation Ditch Return Activated Sludge (RAS) Sludge Pumps From Primary Treatment Source: Parsons Engineering Science, Inc. The operator will see gas bubbles (from nitrogen gas) and rising/floating sludge clumps on the clarifier surface. Large chunks of sediment floating in the clarifier when the system isn’t running and bubbles rising to the surface are signs of biological activity. Mountfort (8) has reported on difficulties with rising sludge in humus tanks used to settle trickling filter effluent. A variety of operators are available such as, handwheel, rack & pinion, bevel gear and electric motor operators. MLSS test results are normal, but a calculation of the SVI shows a high sludge volume index. When RAS flow rates are too low, thick sludge blankets in the final clarifier can result. A plugged pick-up on a clarifier sludge collection system would cause sludge depth to increase in the area of the pick-up, and decrease in the areas where the properly operating pick-ups are located. Sludge production for the oxidation ditch process ranges from 0. As incoming wastewater enters the aeration chamber, existing “mixed liquor” from the aeration chamber is displaced into the bottom of the cone- shaped clarifier. Solids Contact/Reactor Designs Models Available. Bulking occurs when filamentous organisms extend from flocs into the bulk solution and interfere with compaction and settling of the sludge in the clarifier (Chiesa & Irvine 1985). Nevertheless, this model appears very interesting for a better understanding of the dynamics of the clarifier, as described by measured data. As the clarifier sludge blanket increases in depth, it becomes more likely for biomass to lyse and release ammonia in the sludge blanket. Part II . The trickling filter is followed by a more conventional activated sludge process. • Billowing sludge. RBCs consist of a series of closely packed plastic circular disks that are partially submerged and rotated through the wastewater to be treated. simulations predicted clarifier failure with a rising sludge blanket. Biolac ®, an extended aeration, activated sludge treatment system, is a well-accepted biological wastewater treatment process with hundreds of successful installations treating municipal and industrial wastewater. Removal efficiencies, detention times, and other parameters have been summarized to provide a handy reference. F. Typical sludge production is 0. The Reduce sludge retention time in the clarifier; Optimizing denitrification in its desired location; Limit nitrification which forms nitrate (only possible if there is no ammonia limit on the effluent). If the sludge rises ("pops") within 2 hours or less, denitrification problems may be occurring. The other cause of rising gas bubbles with sludge in the clarifier is bacteria growth within the sludge or on the clarifier plates. Discuss primary clarifier operation. 5 Inflow suspended solids, mg/l >10 mg/l 200 mg/l 2000 mg/l 200 mg/l 2000 mg/l Detention time (for entire tank Denitrification can happen if the sludge blanket remains too long in the clarifier. a) Insufficient biomass. This condition is often the cause of rising sludge observed in secondary clarifiers or gravity thickeners. mrwwm. This condition is usually intensified in a shallow clarifier and may be especially noticeable at high return sludge flow rates. BOD applied (Sherwood Logan and Associates, 1999). The turbulence caused by the rising air bubbles also creates a mixing pattern which keeps the sludge in suspension. Check surge control weir 6 mos. It is possible, where facilities are available, to reactivate return sludge in separate reaeration tanks before addition to the wastewater. The clarifier solids load rate (SLR) in lb/d/ft2, represents the mass of solids applied per unit area per unit time. The number of activated sludge plants brought into service in recent years has called attention to an old problem?floating sludge on final clarifiers. The problem is easily corrected by reducing the aeration supply. This system (figure 20) takes the form of a flash mixer (1), a mechanical flocculator (2), hindered flocculator (3), a settling tank (4) (90% of floc settles and thickens without rising in the lamellar), a compartmented lamellar (5) topped by crenellated collection chutes, and a circuit used to return the thickened sludge to the unit’s inlet (6). Sludge Lord will summon 3 Lil'Sludges at once until there are 7-8 Lil'Sludges within 16 blocks centered on the Sludge Lord. Our last mlss test was 6600, which is high, but we have treated well before at that number. , 1974), and in some cases also in treatment plants with partial denitrification (Christensen et al. The activated sludge process works by flocculation — the clumping together of suspended particles to form larger masses that settle out of the water. There is NaOH dosing to this tank. Wastewater Fundamentals - Part 1 - Sludge Age •A lower SVI indicates that the sludge settles quickly, while higher numbers indicate slower settling •By definition a bulking sludge has an SVI >150 mL/g •The actual SVI where solids begin to be lost to the clarifier is plant specific depending on the hydraulic flow rate, the solids loading rate to the clarifier, and In determining the appropriate sludge wasting target value, consider sludge age, foam, mixed-liquor color & concentration, settle-ability, solids rising and how much sludge is in secondary clarifier. The results of this study showed that rising sludge problems could be avoided either decreasing nitrification efficiency or reducing the biomass residence time in the bottom of the secondary clarifier. The clarifier can be treated with a compatible biocide after flushing with an air sparger to retard flora and fauns growth. A typical process flow diagram for an activated sludge plant using an oxidation ditch is shown in Figure 1. Discuss primary clarifier operation. 5 m of space left below the plates at the bottom of the clarifier for collection of sludge. Applications include lime softening, colorant removal, removal of magnesium and iron, and many others. As the typi- cal sludge generated in this process is a low density flocculent sludge, conventional plow- type clarifier equipment is not suitable for the use in these systems. This should not be confused with a bulking sludge. There are several issues in the activated sludge process. ‭ ‬There are numerous filamentous organisms extentding beyond the folc into the free water. In fact, these samples are generally taken from the aeration basin/oxidation ditch just before entering a secondary clarifier. BSM2. The clarifier may go anaerobic. Describe the microorganisms found in an activated sludge system. • Pin floc in overflow. The plant suffers from recurrent problems with rising sludge in the secondary clarifier. Clarification: The sludge coming from the bottom of the clarifier is processes to aerator unit and this clearly indicates activated sludge process. Add Coagulant to the Water and Cap Bottle Shake Well Until Dissolved (~30 sec) PROCEDURE FOR 0. RAS rate is 65-75% of flow. The 30-minute settling test is used to determine the settled sludge volume of mixed liquor samples in activated sludge systems. The activated sludge process is over 100 years old, but higher levels of dissolved oxygen (DO) have never been supplemented to the secondary clarifier influent mixed liquor above what it already contains, so that the secondary clarifier operates as an oxic bioreactor for the following reasons Conventionally, the secondary clarifier is operated with an aeration tank that provides the oxygen required for the aerobic removal of biochemical oxygen demand (BOD). Rising bubbles agitate the water well and create good contact between the Rising Sludge A significant advantages of the SBR Rising sludge may due to denitrification in the process is process control and flexibility. Bridge-Supported Suction Header Type. This sewage sludge is usually mixed with primary sludge from the primary clarifiers and undergoes further sludge treatment for example by anaerobic digestion , followed by thickening, dewatering, composting and land application. Ljubljana, Slovenia . Solutions to floating sludge: Denitrification problems can be often controlled by increasing the recycle pump to reduce sludge blanket depth/sludge retention time in the clarifier. Proponents claim that the use of a "sludge ring" leads to a more uniform RAS draw-off. It also prevents sludge from rising up into the launder system. What is it called when mixed liquor never settles properly and remains either suspended or rising in the secondary clarifier? A. In a vertical sludge rake, the only path for the escaping water is up through the developing sludge blanket, elevating the sludge blanket and slowing the thickening process. It results when too many solids are pushedinto the clarifier and they are not physically returned fast enough to the aeration tank. The model agrees with field data presented by other authors. Many times, city of Houston wastewater treatment plant (WWTP) operators have found effluent ammonia-nitrogen of several milligrams per liter in one or more clarifiers when other clarifiers were near zero. 1 pg 138) The temperature in an anaerobic digester should be changed by more than 1 degree Fahrenheit daily. When the clarifier is not thickening limited (rising sludge blanket), its capacity may be increased by improving settleability. 2 to 0. that “In well designed secondary clarifiers, sludge settleability is the single most important factor affecting clarifier capacity and performance. Describe the response to poor clarifier performance. A primary settler, a thickener for the sludge wasted from the BSM1 clarifier, a digester for treatment of the solids wasted from the primary clarifier and the thickened secondary sludge as well as a dewatering unit have been also added. Growth of filamentous Describe rising sludge in an activated sludge system. Scum baffles and scum removal system Association model (Figure 2),the clarifier solids concentration profile consists offour zones:a clear water zone (h1),a separation zone (h2),a sludge storage zone (h3),and a thickening/sludge removal zone (h4). During the site visit, the EPA Inspector observed rising sludge in the clarifiers and a build up of sludge in the outer clarifier weir channel prior to discharge. secondary clarifier and compare that to the rise time. Sludge detention time should be decreased by removing sludge from the Clarifier faster,. • Ineffective scum rake. Summary. The resulting modification to the ViroSewage™ reagents in the batch tests, were able to remove phosphate (PO4) in the presence of the polymer without forming a rising sludge. Small amounts of sludge carry over was visible on the clarifier tiles. Increasing speed of the sludge collecting mechanism in settling tank. Sensor is to be dropped into clarifier or thickener until variable indicator lights come on, indicating a rising concentration of sludge. The nominal riser pipe diameter determines the valve tube diameter. Check for pin floc, air bubbles rising or clumps of floc floating- these all indicate solids held too long. Activated Sludge Process Modifications 10 5. We usually identify probably cause by looking at the floating sludge: (1) rising "chunks" of sludge with fine bubbles is usually denitrification and can be fixed by increasing recycle pumps/lowering bed depth (2) Filamentous bacteria usually have a thick foam in the cases of nocardia or micothrix (4) Oils & Grease - tends to float as a scum - (also seen in excess microbial slime in petrochemical wastewater) (5) Toxic or shock - floating solids If sludge is rising and clumping in the secondary clarifier, increase return sludge rates and or lower aeration rates a little. Rising Sludge conditions are believed to be caused by the denitrification of nitrified activated sludge in the final clarifier. Every clarifier has a limiting flux: Maximum rate at which solids can be conveyed to the bottom of the clarifier If Solids in > Limiting flux – Solids accumulate in clarifier – Rising sludge blanket – This is thickening failure If this continues, sludge will reach the ras effluent weir: – Solids carryover Normal Thickening Straggler Floe At times, small, almost transparent, very light fluffy, buoyant sludge particles (one-eighth to one-quarter inch in diameter) may be observed rising to the clarifier surface near the outlet weirs. An experimental program was developed to provide the necessary data to support the research objective of determining the singular significance of detention period to the steady-state effluent suspended solids rising sludge. assist in the dewatering process, was interfering with the P removal and causing rising sludge in the lime clarifier, where the solids were being separated. in Aeration Tanks SVIs Rising (250-300+mL/g) Losing Blankets Under High/Storm Flows Filament Outbreak Summer 2009 The operator should calculate the sludge detention time for the. This animation shows the Sludge Sleuth™ — Markland’s single point sludge blanket level detector — at work. This phenomenon can occur when the sludge has good settling characteristics. As incoming wastewater enters the aeration chamber, existing "mixed liquor" from the aeration chamber is displaced into the bottom of the cone-shaped clarifier. Discuss the operation of trickling filter clarifiers. 40 PVC. Carrying a "sufficient" sludge blanket reduces the effective clarifier volume and The main cause of sludge bulking is the growth of filamentous bacteria. Further, it does not include any of clarifier design parameters. To satisfactorily settle activated sludge solids the upflow velocity in a final clarifier should be typically 0. Check aeration diffusers annually 7. This is the basic concept of the lamella or laminar plate clarifiers. Pump sludge from aeration tank 2 to 5 years* 5. Figure 4. Sludge and the other Dinobots live in an underground jungle environment, hidden beneath the Antarctic ice cap. If denitrification is the problem, the sludge is being held in the clarifier too long. The sludge here is usually called rising sludge and apparently it will float to the surface after some time left after good settling. These problems may involve physically changes of a treatment unit and/or providing a process control algorithms to solve the problems. bubbles rising in the water diminishes this impact. 2 and 3) and high average SVI (≥ 150 mL/g) indicated that the settling of sludge in the aerator has some problem. At operation time by time we have sludge settlement problem at the clarifier. Sludge pumping rate from clarifier none Pump cycle 3 min every 2 hrs, 42 m3/day (11,000 gal/day) 40% return activated sludge rate Pump cycle 3 min every 2 hrs, 42 m3/day (11,000 gal/day) 40% return activated sludge rate Inflow temperature, oC 11. This course includes content developed by the CBX unique in the market place. The filamentous An alternative to facilitate sludge removal would be to incr ease the steepness of the settling unit levels, in order to force the sludge to go down and deposit on a single surface, generating a single extraction system. Regular CORETAKER® Parts; SID Rotary Replacement Parts; Sludge Interface Detector Parts; Filter Media Manager Replacement Parts; DISTRIBUTORS If the sludge in the secondary clarifier is septic, this could be caused by: Too high of a return sludge rate Too low of a return sludge rate Too high of a hydraulic load Accumulation of sludge in the clarifier creates a deep sludge blanket, which will allow solids to escape in the effluent; If aeration is sufficient to produce nitrate in the aeration tanks, denitrification may occur resulting in rising sludge and subsequent effluent solids If the sludge concen- tration is outside the se- lected range, then the two LED’s are to indicate if a higher or lower range is to be chosen. a. The solids contained in the sludge flocs can carry over the clarifier weirs and jeopardize effluent TSS quality. Dichotomous Key for Filamentous Microorganism "Identification" in Activated Sludge (Reference 10) 31 9. Denitrification Septic conditions sludge blanket and fluff levels which make Cerlic’s offer unique in the market place. The turbulence caused by the rising air bubbles also creates a mixing pattern which keeps the sludge in suspension. The best way to combat this problem is to design a slightly oversized treatment system for turbidity, anticipating that variations will occur. Describe sludge and scum pumping. See full list on suezwaterhandbook. causing problems such as rising sludge, sludge clumps, etc. The treatment chemicals are added to the influent. Return Rates Too High No sludge blanket in the final clarifier and a thin return activated sludge. Peripheral-Feed, Peripheral Overflow. I am a chemical engineer and I am responsible of operating industrial waste water treatment. True (v. • Excessively high sludge blanket. Important Features - Advanced method of solid-liquid separation - Less area - Power required for pumping the sludge and operation of centrifuge - Less time - Efficient dewatering Design criteria - Inlet sludge solid consistency : min 0. On sludge compactability issue, so far one of the main causes that lead to the sludge having low density and floats to the surface is the entrapment of gas coming from denitrification. Wastewater Fundamentals - Part 1 - Sludge Age Rising sludge occurs in the secondary clarifiers of activated sludge plants when the sludge settles to the bottom of the clarifier, is compacted, and then starts to rise to the surface, usually as a result of denitrification, or anaerobic biological activity that produces carbon dioxide or methane. Bridge-Supported Scraper Type. 2: SBR operation for each tank for one cycle for the five discrete time periods of Fill, React, Settle, Draw, and Idle (Irvine and Ketchum, 2004). removed. ‭ ‬What is the likely cause. Approved Training Provider - Indiana, Illinois, Ohio, Delaware, Alabama South Carolina, North Carolina and Ontario Canada. Sludge blanket depths were generally low throughout, in contrast to the further results to be presented below. sludge clarifiers by retrofitting existing scraper or riser pipe mechanisms with a Tow-Bro Unitube header. The cause of the presence of ammonia was not understood. Describe the microorganisms found in an activated sludge system. Summon Lil' Sludge. Sludge doughnuts originate in wrong design/operation of clarifier scraping system. Settles to 700 or less in five minutes. Rising sludge B. Upon arriving at the package treatment plant serving a small community, you find a uniform sludge blanket rising throughout the clarifier. Denitrification occurs in the sludge layer in the secondary clarifier when conditions become anaerobic or nearly anaerobic. Because settling tank releasing nitrogen bubble which buoys the “react” time is not flow dependent, it can up the sludge. - Sludge starts to float and move up to the water surface. The solids accumulate in the clarifier-thickener and the surface of the sludge blanket rises In some situations, the recycle operating line is located on the left side of the batch solids flux curve (Case C) Then the clarifier-thickener iB at an underloaded condition which means that the sludge removal from the bottom of the clarifier-thickener is faster than the sludge coming into the clarifier-thickener. The sludge volume index is correct at 120 and so are the results of our settling test, which did not reproduce the phenomenon or after two hours there was a thin sludge film on the surface. com Ashing and gassing can occur in primary clarifiers just as well as secondary clarifiers. of BOD). Excessive aeration causes bubbles to be carried into the final clarifier end causes the sludge to be buoyed to the surface by the rising bubbles. (1993). Pump sludge from pretreatment tank 2 to 5 years* 6. As the plant nitrifies, the potential for rising sludge increases because of denitrification in the clarifier. The Solids Contact Clarifier employs several radial collection and outlet launders. As the sludge compresses/thickens toward the center of the thickener and along the thickeners compressing edge, water passes up into the clarifier at the thickeners ends and at its rising edge. Both of these factors stimulate the development of nitrogen gas through denitrification. It floats within an hour but DOs are above 6 in the aeration basins due to our ammonia limits. What causes rising sludge? Explain why activated sludge is called a "mixed culture". persed growth, slime and blanket rising, occur in activated sludge plants, the most common problems are, therefore, largely uncharacterized. Should rising sludge occur around the 60 minute mark that may indicate that the DO (dissolved oxygen) is too low. Waste water comes first to a neutralisation tank where the pH is set to 7. Bulking:Sludge change to very light brown color. Suction design ensures rapid sludge removal and lower sludge blanket depth, reducing the potential of sludge rising. Solids Contact Clarifiers have also been applied in the chemical treatment of industrial wastes such as metals removal, and used successfully for cooling tower make up water. The sensitivity of the model to sludge settleability prevented its use with long times-series, unless a continuous recalibration was performed. Operator Certification Training . As the nitrogen gas accumulates, the sludge mass becomes buoyant and rises or floats to the surface. • Floating sludge on surface; rising sludge or bulking sludge. The Wamechsi Telescopic Valve are used primarily for sludge removal, or liquid level control and are considered to be fully open when in the lowermost position. Rising Sludge  Occurs in the secondary clarifiers of activated sludge plants  When the sludge settles to the bottom of the clarifier, is compacted, and then starts to rise to the surface, usually as a result of denitrification, or anaerobic biological activity that produces carbon dioxide or methane. This is less than Solids Contact Clarifiers are particularly advantageous in lime softening of groundwater since the precipitated solids help speed the flow, growing larger crystals of precipitate to provide a thicker waste sludge. Secondary Clarifier Superoxygenation to Increase Active Biomass and Stop Rising Sludge Date: 2. In a vertical sludge rake, the only path for the escaping water is up through the developing sludge blanket, elevating the sludge blanket and slowing Rising sludge occurs in the secondary clarifiers of activated sludge plants when the sludge settles to the bottom of the clarifier, is compacted, and then starts to rise to the surface, usually as a result of denitrification, or anaerobic biological activity that produces carbon dioxide or methane. This is basically a scaled down clarifier. A thirty-minute settled sludge volume (SSV30) can be used to determine the returned-sludge flow rate and … Sludge Handling – Centrifuge Objective : Dewatering of sludge @ 95% of the BOD removed in Kg. In this case, A131 overpredicts the sludge blanket height. Suction -type sludge removal equipment should be specified for such applications. Describe the response to poor clarifier performance. For details on rising sludge, see Henzeet al. It is unlikely that settled sludge (primary, humus or surplus activated) will contain dissolved oxygen. Rising sludge is the term used to describe sludge that slowly rises to the surface of secondary clarifiers. CORETAKER Sludge Samplers; Sludge Blanket Detectors. Revised October 2014. Biological system in this site was included, anoxic selector tank During this time it was easy to look down into the clarifier and see the “fluffed” or suspended sludge blanket rising to near the surface in different parts of the clarifiers and a large quantity of solids were being lost in the effluent. Discuss the operation of activated sludge clarifiers. hevron pattern sludge plow designed for heavy, relatively viscous, sludges. L. underflow (Table 2), floating sludge in clarifier (as shown in Figs. Oxidation Oxidation is the addition of oxygen, removal of hydrogen, or the removal of electrons from an element or compound. Use of a "sludge ring" may cause drawing a more dilute sludge from the ports opposed to and behind the scraper blades …. 4. Presence of sludge particles whose density is less than water. to 2 years 4. Sludge rise occurs when bacteria common in the activated sludge floc respire using nitrate in place of free oxygen when it is lacking and release nitrogen gas as a by-product. The Stamford baffle is fixed to the wall of the clarifier just below the launder. This is in addition to savings in costs of land area covered by settlers which is much less in case of EDI (Baffle) than in case of conventional type gravitational settling tanks. bubbles form in the activated sludge and cause sludge blanket flotation in the final clarifier. TSS per lb). Primary and Secondary Clarifiers This page provides information on the expected performance of primary and secondary clarifiers. with maximum ammonium concentrations of 25-35 mg N 1-1. Usually it is cheaper and more efficient to reconstruct scrapers than to install scum baffles and scum removal system. If the rise time is less than the detention time,' rising sludge problems can be expected. 5 degrees Celsius over a very short period of time. Rising sludge conditions are believed to be caused by the denitrification of nitrified activated sludge in the final clarifier. NEW - SID Rotary S-40100; Sludge Interface Detector SID-10200; Centrifuge and Centrifuge Tubes; Filter Media Maintenance; Settleometer; Replacement Parts. We were advised by Partech that by having the upper sensor set to a more sensitive level (0-200mg/l) we would be able to pick up the presence of rising sludge and activate an alarm condition and Approved Environment, Inc. In this If sludge is rising and clumping in the secondary clarifier, increase return sludge rates and or lower aeration rates a little. Fans, blowers, clarifiers, RAS, and WAS pumps are required as in the conventional activated sludge treatment process. The fourth section, the sludge zone, must effectively settle, compact, and col-lect solids and remove this sludge from the clarifier without disturbing the sedi-mentation zone above. With a background as a Maintenance Wastewater Operator and a Control Center Operator for a large public water district, Ryan has experience efficiently operating four different activated sludge treatment plants. This occurs when activated sludge is allowed to stay in the secondary clarifier too long. In sludge, the numbers of micro-organisms and the availability of substrates will be greater. June 5-7, 2019 Rising sludge can occur in any activated sludge system but is particularly evident when the effluent from the aeration zone entering the clarifier, contains NOX, which is subsequently reduced to elemental nitrogen gas by the oxygen demand of the sludge at the bottom of the clarifier. ENVIRONMENTALLEVERAGE. Describe sludge and scum pumping. ‭ ‬underleaded aeration tank. A settleability test reveals a very slow-settling sludge leaving a very clear supernatant. Usually these can be seen by a sudden drop in MLSS level. • Excessive buildup of solids in center well of circular clarifier. The included 9W UV bulb lasts up to 8,000 hours. RISING SLUDGE. Aerobic Sludge Blanket in the Clarifier has the following benefits: • Increased “solids under air” for a lower F:M ratio, and longer SRT • Additional BOD removal for plants lacking physical space to expand • Prevents rising sludge from denitrification in the sludge blanket • Will not disturbing settling characteristics. com Circular Clarifier Equipment: Center-Feed, Peripheral Overflow. cause sludge to rise. The high concentrations of nitrate, in combination with a long sludge retention time in the secondary clarifier, were judged to be the reason for the formation of rising sludge. He can fly. Discuss the operation of activated sludge clarifiers. 2 to 0. Sludge bulking is a problem that can occur in a method of sewage treatment known as the activated sludge process. Peripheral-Feed, Center Overflow. 10. Because cells need oxygen for their metabolism, air is injected from the bottom of the aerator. Denitrification and rising sludge is a very frequent problem facing wastewater operational staff. Nitrification Can also be influenced by Rising sludge occurs in the secondary clarifiers of activated sludge plants when the sludge settles to the bottom of the clarifier, is compacted, and then starts to rise to the surface, usually as a result of denitrification, or anaerobic biological activity that produces carbon dioxide or methane. Finally, to optimize based on sludge-wasting, identify the best sludge age, consider seasonal influences on sludge-wasting values and make small sludge-wasting flow-rate adjustments as needed. In Switzerland. Effect of Filamentous Microorganisms on Activated Sludge Floe Structure (Reference 10) 20 7. Over a period of time, even with good sludge removal, the metal hydroxide sludge will find places to collect within the lower portions of the clarifier. Increase return sludge and see if this takes care of things. 85 m3·m-2·d-1 at flow rate of 67,000 m3/d and interest is the relationship between detention period and rising sludge conditions in the clarifier, which can lead to a deterioration in clarification efficiency. Upflow through a sludge blanket brings nutrients to a clarifier or thickener. Column-Supported Scraper Type We found a simple solution to our escalating sludge-hauling problem that had a significant impact cost, while giving us no bulking, no rising solids in the clarifier, excellent denitrificaiton, very low nutrient numbers and BOD values, all without infrastructure changes or additions. In practical applications, the SVI for each plant (where problems of solids loss over the clarifier weirs) is site specific due to hydraulics and solids loading rates. As the sludge compresses/thickens toward the center of the thickener and along the thickener's compressing edge, water passes up into the clarifier at the thickeners ends and at its rising edge. The other cause of rising gas bubbles with sludge in the clarifier is bacteria growth within the sludge or on the clarifier plates. with return sludge from a secondary clarifier. , 1978). The valve tube travels inside a cast iron or stainless steel riser pipe. A dark or black layer in the sludge blanket is a visual sign of potential ammonia release. Sludge “popping” occurs when conditions in the clarifier encourage denitrification. The bottom of a circular clarifier is normally sloped 5 to 8 degrees to the center of the unit where sludge is collected in a hopper for removal. A young sludge condition (low MLSS) may cause the supernatant to have a gray to green cloudy appearance. Dif ficulties were correlated with the presence of a gas works waste con taining high concentrations of ammonium sulfate which resulted in the production of considerably more nitric nitrogen in the final What condition can result in sludge on the surface of a secondary clarifier typically caused by a septic environment? ? Bulking sludge ? High rate aeration ? Rising sludge ? Over-wasting; What process control parameter is the result of aeration total solids inventory divided by total solids removed from the process? ? Gould sludge age (GSA) ? This month we are focusing on the control of sludge blanket build up in Lamella Clarifiers. The most obvious measure in sludge in treatment plants with summer temperatures order to avoid rising sludge seems to be denitrifica- above 20°C seems to be to denitrify the wastewater tion, not in the settler, but in the preceding activated before it enters the settler in order to ensure a nitrate sludge process. As the nitrogen is released (as gas) it rises to the top of the clarifier, carrying settled sludge with it. The activated sludge system consists of two components, an aerator, where cells (X) consume the sewage (S), and a clarifier, where cells are then removed from the treated water. Rising sludge becomes a problem when the nitrate concentration in the secondary clarifier influent is higher than the critical nitrate concentration (8 g N m -3 at 15ºC). • Deflocculation in clarifier. Filamentous microorganisms grow in long strands that have much greater volume and surface area than conventional floc and are As anaerobic bacteria grow they will outgas oxygen. Remember, it is not a sterile environment. Also known as “blanket rising”, “clumping”, and “rising sludge”, denitrification occurs in secondary clarifiers when facultative anaerobic bacteria or denitrifying bacteria in the settled solids use nitrate ions to degrade soluble cBOD. Don’t forget that slow-settling sludge can be caused by both old and young sludge. The sludge collected from the clarifier has a very high fraction of water (99% water versus 1% solids is typical). This will lead to rising sludge and solids carryover in a conventional plant. Rising sludge is a flotation process caused by bubbles of free nitrogen adhering to the sludge flocs. 7 13. What causes rising sludge? Explain why activated sludge is called a "mixed culture". Of course, every wastewater plant is different, with potentially vast differences between municipal and industrial wastewater systems. a. 8 to1% Minimize sludge blankets in clarifier Increase aerobic HRT –anoxic/aerobic swing zones –go aerobic Be prepared to add metal salt for P removal Enhanced process control - consider installing ion specific electrode to monitor nitrogen At extended aeration plants, monitor key parameters such as alkalinity, temperature and nitrification. Sludge rising to the surface of the clarifier I am trying to determine why our sludge is rising. Large chunks of sediment floating in the clarifier when the system isn’t running and bubbles rising to the surface are signs of biological activity. SEPTICITY IN SLUDGE The causes of septicity developing in sludges are similar to those given above for sewage in sewers. If gassification is noticed in the secondary clarifier and is causing rising sludge, what should be done to correct the problem? What is increase the RAS or WAS rate? 500 Clarifier influent MLSS concentrations were relatively low, by design, at around 1,000 mg/L. Judging from the performance of the Case 3 baffle, it may be concluded that it was promised too far from the blanket, while the wave-like variations in the presentation of the Case 6 baffle results would appear to indicate that it was positioned too close to the blanket. bacteria to attach to if you have not totally degraded all the BOD prior to entering the clarifier. Keep them in there only long enough to get clear water and thicker sludge!! THE WASTEWATER INSIGHT WWW. Rising sludge during the test, especially the first 30-minute period. This inability to modify is because some centrifuges designed as clarifiers do not have a water chamber. The UV Pond Clarifier can easily be installed in or out of your pond. 6. Signs of overchlorination are a turbid (milky) effluent, a significant increase in effluent TSS, a loss of the higher life forms (protozoa), and a reduction in BOD removal. Rising sludge is caused by denitrification in which nitrites and nitrates in the wastewater are reduced to nitrogen gas. Rapid removal of solids from the clarifier is desirable to avoid deni- trification and subsequent floatation of solids. 8 Page 3 As anaerobic bacteria grow they will outgas oxygen. This gas is only slightly soluble in water and small nitrogen gas bubbles form in the activated sludge and cause sludge blanket flotation in the final During the last decade, more stringent effluent requirements concerning the nutrients effluent values have been imposed by legislation and social concern. High Secondary Clarifier Blankets (> 12 feet) Low SRT (~ 3-5 days), Partial Bypass of Roughing Filters, Adequate D. Some of these include dispersed growth, bulking, sludge rising, foaming, scum overflow and infections. Rising sludge occurs in the secondary clarifiers of activated sludge plants when the sludge settles to the bottom of the clarifier, is compacted, and then starts to rise to the surface, usually as a result of denitrification, or anaerobic biological activity that produces carbon dioxide or methane. Rising sludge is differentiated from sludge bulking by the presence of gas bubbles on the surface of the clarifier and usually a fine scum on the surface of the clarifier. 3. Over a period of time, even with good sludge removal, the metal hydroxide sludge will find places to collect within the lower portions of the clarifier. Sludge appears to be fluffy and settles slowly with clear supernatant in a 30 minute test. Lowering sludge age can also help, if it is a little too high. 5, the simulation reaches equilibrium quickly and predicts a high quality effluent (low suspended solids). offers 50 online continuing education courses (CEs) for wastewater. Blending the primary and secondary sludge in this manner can be an operational advantage. Monroe’s clarifier met the process guarantee requirements of 15mg/L TSS and 5% solids sludge underflow, allowing the plant to effectively recycle the water with minimized sludge dewatering costs. Operation and Control of Activated Sludge Processes using Microbiological Analysis . Furthermore, low DO levels may lead to anaerobic/anoxic conditions in secondary clarifiers, promoting secondary P release (Mikola et al. rising sludge in clarifier