95-190 Magnetrol Environmental Water and Wastewater ... · Challenges:Non-contact measurement is...

E N V I R O N M E N T A L A P P L I C A T I O N S

Level and Flow Controls for Water and Wastewater Treatment

Lift Station Pump Control 4

Chemical Feed Tanks 4

Splitter Box Level 5

Clarifier Level 5

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KEY LEVEL APPLICATION PAGE

Sludge Level 6

Digester Level 6

Water Storage Tanks 7

Filter Tank Level 7

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KEY LEVEL APPLICATION PAGE

Lime Slurry Level 8

Carbon Slurry Level 8

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Open Channel Flow 9

Pump Protection 9

Blower Air Flow 10

Digester Gas Flow 10

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KEY LEVEL APPLICATION PAGE KEY FLOW APPLICATION PAGE Please Note: The instruments recom-mended in this guide are based on fieldexperience with similar applicationsand are included as a general guide tolevel and flow control selection. Be-cause all applications differ, customersshould determine suitability for theirown purposes.

Application: Pre-treated wastewater isbrought up from inlet trunk sewers to groundlevel by centrifugal pumps, where it continueson by gravity flow to subsequent treatment.To maintain a desired level in the headworkswetwell, pump speed is often varied. Pumpsturn on and off automatically according to anoperator selectable sequence.

Challenges: A desired wetwell level reducesthe drop downstream of the influent flumes tominimize turbulence and air entrainment, andeliminates frequent pump cycling associatedwith variable level control. Proper level controlmaintenance in the wells can alleviate pumpsurging, which disrupts settling by causingcurrents and eddies in the clarifier.

LIFT STATION PUMP CONTROL

Application: In both wastewater and watertreatment facilities, a wide array of chemicalsare added from feed tanks for purposes thatinclude water softening, pH adjustment, tasteand odor control, coagulation and sedimenta-tion, scale and corrosion treatment, pathogencontrol, neutralization, and fluoridation.

Challenges: Liquid solution storage andday tanks require stringent level monitoringto ensure ongoing chemical treatment. The na-ture of the chemical, the geometry of the hold-ing vessel, and the presence of mixingsystems or other hardware are factors thatwill help determine the most suitable levelcontrol technology for the application.

CHEMICAL FEED TANKS

4Wastewater: Water Treatment:

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Sewage Pumps

Liquid Storage

� Continuous Level:Echotel® model 344ultrasonic transmitters

INSTRUMENTATIO

N

� Continuous Level:Echotel model 355ultrasonic transmitters

INSTRUMENTATIO

N

� Continuous Level:Eclipse model 705or Horizon model704 guided waveradar transmitters

� Visual Indication:Atlas™ MagneticLevel Indicatorscan be suppliedwith switches ortransmitters

� Continuous Level:Pulsar™ model R95pulse burst radartransmitters

� Continuous Level:Eclipse® model 705or Horizon™ model704 guided waveradar transmitters

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Application: Wastewater treatment facilitieswith a large number of primary clarifiers oftenemploy a concrete tank with chambers andgates known as a splitter box, or distributionbox, to split the influent flow into multiplestreams that are routed into the bank of clari-fiers. A similar device may also be used to splitmixed liquor flows between secondary clarifiers.

Challenges: Level control in the splitter boxeshelps maintain balanced routing of influentwastewater in the primary sedimentationprocess where 50 to 70 percent of the sus-pended solids are removed, and in the second-ary sedimentation process where remainingsuspended solids are removed.

SPLITTER BOX LEVEL

CLARIFIER LEVEL

Application: In small wastewater treatmentfacilities with only one clarifier, it is advanta-geous to know the clarifier’s surface level. Inlarger plants where influent flow is routedthrough a splitter box to many clarifiers,there may be insufficient room inside thesplitter box to accommodate level instru-mentation. In this instance level monitoringof the clarifier will help attain proper loadbalance.

Challenges: Continuous monitoring of theclarifier level will maximize efficient treat-ment flow within primary and secondarysedimentation areas where the majority ofsuspended solids are removed.

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Primary Clarifier

Primary Clarifier Splitter Box

INSTRUMENTATIO

NIN

STRUMENTATIO

N

� Continuous Level:Kotron® models82CE, 804, or 805RF capacitancetransmitters


� Continuous Level:Eclipse model 705 orHorizon model 704guided wave radartransmitters

� Continuous Level:Echotel models 344and 345 ultrasonictransmitters

� Continuous Level:Eclipse model 705guided wave radartransmitters

Application: The principal biological methodsemployed in wastewater treatment for sludgestabilization are aerobic and anaerobic digestion.The former utilizes aerobic bacteria to convertorganic matter and stabilize biosolids while thelatter accomplishes this goal with anaerobic bac-teria working without oxygen. Both processes aremonitored for level within their tanks.

Challenges: The gas-injection and mechanicalstirring systems of anaerobic process, and theaeration systems of aerobic process, createlarge amounts of foam that have traditionallyhampered mechanical level controls. Recent de-velopments in radar technologies have ad-vanced measurement accuracy despite the foamcontent of these digesters.

DIGESTER LEVEL

Application: There are several areas withina wastewater treatment facility where solidssettle and are subsequently removed assludge. These include hoppers, holdingtanks, gravity thickeners, and other sludgecollection systems. Sludge level is moni-tored to control against incomplete dis-charge or dilution of the sludge.

Challenges: Non-contact measurement isoften preferred since sensors are locatedabove the process fluid and beyond directcontact with the sludge. Sensors of contacttechnologies should be single rod types tominimize material buildup—or bridging—that occurs in twin rods configurations.

SLUDGE LEVEL

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Anaerobic Digester

Sludge Concentrator

INSTRUMENTATIO

N


INSTRUMENTATIO

N

� Continuous Level:Pulsar model R95pulse burst radartransmitters




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WATER STORAGE TANKS

Application: Following the clarificationphase of water treatment, pre-filtered waterpasses from an inlet channel and onto a fil-tration bed. As it passes through the bed’smedia—sand or anthracite in depth-filtra-tion types; cloth or synthetic membranes insurface-filtration types—the water iscleansed of its fine-grained suspendedsolids.

Challenges: Filter tank level triggers thebackwash cycle. As solids accumulatewithin the filter, headloss begins to build upand water level increases in the filter tank.A pre-determined tank level indicates thatterminal headloss value has been reached,and that the filter must now be back-washed to remove the suspended solids.

FILTER TANK LEVEL

Application: Storage for reclaimed waterranges from small tanks for potable and servicewater use, to large, open or enclosed, reser-voirs. Large capacity storage—most commonlyin open reservoirs—is necessary for off-linestorage of peak flows, flow-through in-line stor-age, and long term storage of seasonal flowsthat are discharged during alternate seasons.

Challenges: Level monitoring is essential forlarge and small water storage tanks. Controlsare specified according to the size and geome-try of the bulk storage vessel. Level controls inopen atmosphere reservoirs must frequentlywithstand punishing weather conditions.

Reclaimed Water Storage

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Filter Building

INSTRUMENTATIO

NIN

STRUMENTATIO

N




� Continuous Level:Eclipse model 705guided wave radartransmitters withmodel 7X1 flexiblesingle rod probes



CARBON SLURRY LEVEL

Application: Carbon is employed in adsorptionprocesses for the removal of organic, inorganic,and taste and odor control compounds. GranularActivated Carbon (GAC) and Powder ActivatedCarbon (PAC) are two leading adsorption treat-ments, the former utilizing a carbon bed and thelatter employing a contact basin. Carbon slurrytanks require level monitoring.

Challenges: Handling and safety problems areassociated with the fly-away dust and difficult-to-wet characteristics of carbon. As carbon buildupoften chokes mechanical level controls, non-con-tact monitoring technologies are popular. Contactlevel sensing should use single rod probes toavoid media buildup.

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LIME SLURRY LEVEL

Application: In terms of annual tonnage, limeranks first among water treatment chemicals.Lime is used for pH adjustment, phosphateremoval, sludge and biosolids conditioning,and in association with other chemicals forprecipitation. Lime is initially mixed with waterin lime slakers to form a slurry referred to asslake lime. The slake lime is then added toraw water for formulation under carefullycontrolled conditions.

Challenges: Often contained in an agitatedtank, lime slurry is slightly abrasive, and canbe corrosive depending upon the other chem-icals involved. Contact level sensing shoulduse single rod probes to avoid media buildup.

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Lime Tank

Carbon Tank

INSTRUMENTATIO

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INSTRUMENTATIO

N



� Point Level:Thermatel® modelsTD1 and TD2 thermaldispersion switches


Application: Flow measurement is accom-plished by a transmitter programmed to converta level reading into units of volume per time, asliquid passes through a flume or weir in an openchannel. A flume is a specially shaped portion ofthe open channel, with an area or slope that isdifferent from the channel’s slope or area. A weirresembles a dam placed across an open channelpositioned so that liquid can flow over it.

Challenges: Measurement devices are config-ured according to the geometry of the flume orweir. Devices must provide reliable measurementdespite turbulence, solids content, corrosivechemicals, or varying flow velocities and flowdepths. Environmental requirements often man-date the use of a totalizer and data logger.

INFLUENT/EFFLUENT FLOW

Application: A centrifugal pump operating in ano-flow condition will quickly sustain damage.Whether caused by a closed valve or plugged linedownstream, or by cavitation, restricted flow canoverheat the media and cause seal damage. Aflow switch along the pump’s discharge pipingwill shut down the pump when liquid flow dropsbelow the minimum selectable flow rate.

Challenges: Solid state switches provide thehighest level of reliability for pump protectionby offering low flow sensitivity, wide temperatureoperation and high turndown.

PUMP PROTECTION

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Influent Flow

Centrifugal Pump

INSTRUMENTATIO

NIN

STRUMENTATIO

N

� Continuous Flow:Echotel model 355ultrasonic transmitters

� Continuous Flow:Echotel models 344and 345 ultrasonictransmitters

� Flow Alarm:Thermatel modelsTD1 and TD2 thermaldispersion switches

� Flow Alarm:Model F10 vanetype flow switches

� Flow Alarm:Model F50 globevalve type flowswitches


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Application: Air flow measurement is requiredin aerobic digesters and aeration basins. In di-gesters, oxygenation allows microbes to de-compose complex organic compounds.Concrete aeration basins utilize fine or coarsebubble diffusers to aerate the water. In addi-tion to digesters and aeration basins, air flowmonitoring may also include air going to anaerated grit tank, to a flow equalization tank,or to secondary sludge holding tanks.

Challenges: Aeration blower systems mustsupply a wide range of airflows with a relativelynarrow pressure range under varied condi-tions. In addition to detecting the presence orabsence of air flow, the flow switch should beable to detect low-flow conditions.

BLOWER AIR FLOW

Application: In the anaerobic decompositionprocess, organic matter is converted intostable solids and energy-rich gas, mainlymethane (60%) and carbon dioxide (40%). Acombustible hydrocarbon of high fuel value,methane can serve as a fuel for in-plant heatexchangers, blower engines or other systems,marketed to the local industrial community, orburned off.

Challenges: Safe and reliable flow measure-ment is essential in the collection, disposal orre-use of methane gas. Because methane ishighly combustible, flow instrumentation mustbe certified for operation in these hazardouslocations.

DIGESTER GAS FLOW

Aeration Basin

Thermatel on Methane Line

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3IN

STRUMENTATIO

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� Continuous Flow:Thermatel modelsTA1 and TA2 thermaldispersion mass flowtransmitters


INSTRUMENTATIO

N

� Continuous Flow:Thermatel modelsTA1 and TA2 thermaldispersion mass flowtransmitters




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Water treatment professionals know that goodwater originates with the help of level and flow

controls that deliver reliable service in the most de-manding applications. This is why so many rely onlevel and flow controls from Magnetrol Environmental.

Magnetrol’s buoyancy products first entered serv-ice in 1932. Later, we were among the first to applyultrasound, thermal dispersion and other electronictechnologies to water treatment challenges. More re-cently, we pioneered Eclipse Guided Wave Radar andPulsar Pulse Burst Radar to bring customers the lead-ing-edge in control instrumentation.

But what makes Magnetrol Environmental theclear choice for so many water treatment profession-als is the company’s applications engineering skillsand a service network that’s second to none. That’sthe difference between buying an instrument andpartnering with a world class level and flow measure-ment specialist.

Contact your Magnetrol Environmental sales repre-sentative to learn how our level and flow solutions notonly help produce quality water, but can also lower theprofitability threshold of your treatment operation. �

Quality water starts here.

AN INDUSTRY GUIDE TO LEVEL MEASUREMENT AND CONTROL FROM MAGNETROL

Other industry and special application brochures from Magnetrol include:

CORPORATE HEADQUARTERS5300 Belmont Road • Downers Grove, Illinois 60515-4499 USA

Phone: 630-969-4000 • Fax: 630-969-9489magnetrol.com • [email protected]

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Phone: 052 45.11.11 • Fax: 052 45.09.93

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Copyright © 2010 Magnetrol International. All rights reserved. Printed in the USA.

Bulletin: 95-190.3 • Effective: June 2009

PLEASE NOTE: The instruments recommended in these brochures are based on field experience with similar applications andare included as a general guide to level and flow control selection. Because all applications differ, however, customers shoulddetermine suitability for their own purposes.

• Chemical• Flue Gas Desulfurization• Food & Beverage• Interface Level Measurement• Mass Flow Measurement• Nuclear Power• Oil & Gas Field Processing• Petroleum Refining

• Power Generation• Pulp & Paper Mills• Renewable Energy• Steam Generation• Tank Bridle Level Measurement• Understanding Safety Integrity Level (SIL)• Water & Wastewater

95-190 Magnetrol Environmental Water and Wastewater ... · Challenges:Non-contact measurement is...

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Transcript of 95-190 Magnetrol Environmental Water and Wastewater ... · Challenges:Non-contact measurement is...