Design Guide for Community Water Systems - The Water, Sanitation ...

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4.3.4. Design Pressure Drop or Transmembrane Pressure.Design pressure drop or transmembrane pressure is the pressure differentialrange required across the membrane to produce at the design flux for anormal filter run. Large pressure differentials require high influent pressures,increase operating costs, and shorten membrane life. Also, bypass flow frommembrane fiber breakage is proportional to the pressure differential acrossthe membrane. Pretreatment and membrane selection shall be done toprovide the lowest practical design pressure drop.4.3.5. Membrane Fouling.Fouling and scaling characteristics of the source water and design cleaningfrequency shall be considered. Design shall include provisions forminimizing membrane fouling.4.3.5.1. System integrity.System integrity and reliability shall be considered in the design.Multiple membrane arrays, skids or trains shall be provided. Thetreatment system shall be able to meet design maximum designflows while one membrane array, skid or train is isolated formembrane replacement, testing, back washing or cleaning.4.3.5.2. Membrane design.Design shall include piping, valves, fittings and other provisionsfor isolation and easy removal of membrane arrays, skids or trainsand of individual membrane modules for replacement, testing,backwashing and cleaning.4.3.5.3. Direct testing equipment.Equipment for direct testing shall be provided to monitormembrane integrity and to detect and locate defects or breachesthat could allow feed water to bypass membrane filtration. Directtesting equipment shall include but not be limited to equipmentfor bubble testing and conducting pressure or vacuum hold testingof membrane modules.4.3.5.4. Membrane backwashing and air filtration.Provisions for backwashing the membranes shall be provided.Since backwashing is frequent, duplication of equipment isnecessary to assure continuous plant operation. If pressure air isused, the air compressors shall not impart oil into the compressedair. Furthermore, air filtration shall be provided to assure that themembranes are not contaminated with airborne pathogens.Aug. 29, 2003Page 64
4.3.5.5. Chemical cleaning.Equipment and appurtenances necessary for chemical cleaning ofthe membranes shall be provided.4.3.6. Membrane Rating.Membranes rated by pore size can be either nominal or absolute. Nominallyrated membranes must be rated at the size on their particle retention curvewhere the membrane retains 98% of that size particles. Absolute ratedmembranes must retain 100% of particles that are the same size as the poresize rating of the membrane. Specifications shall clearly state whethermembrane pore size is nominal or absolute. Nominal size membranes shallbe followed by additional treatment.4.3.7. Recovery.Recovery is the amount of finished treated water produced from a givenamount of feed water. Design percent recovery should be more than 80%.4.3.8. Membrane Filtration Design.The following shall be addressed in membrane filtration design:a. Redundancy of membrane arrays, skids or trains shall be providedsufficient to meet maximum design flow at the highest expected designpressure drops and lowest expected temperatures of the water to betreated.b. The design shall provide for plugging off and replacing failedmembrane fibers. The necessary equipment, valves, piping andappurtenances shall be provided to easily shut off individual membranemodules and to locate and remove defective fibers;c. The design shall provide for pressure gauges on the influent andeffluent piping to each membrane array, skid or train. Preferably thesepressures should be measured by pressure transducers with digital readouts and continuous recorders. At a minimum, the gauges shall be 4½inchdiameter, liquid filled, sealed gauges correct to within ½ of 1% offull scale;d. Online particle sizing and counting equipment shall be provided on theeffluent piping of each membrane array, skid or train. Turbiditymonitoring equipment shall be provided for on the influent and effluentpiping of the membrane arrays, skids or trains. Continuous recordingequipment shall be provided for turbidity and for the particle counts inthe 2 to 5 micron range. This equipment shall connect with an alarmsystem to warn operators of excessive particle or turbidity breakthrough;ande. Design life of the membranes should be greater than four years.Aug. 29, 2003Page 65
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Design GuideforCommunity Water Syst
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2.18. AUTOMATION. .................
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4.3.11. Waste Disposal. ...........
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CHAPTER 6 -- MINIMUM CONSTRUCTION R
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Maximum Hour Demand -- The amount o
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and deviations are subject to indiv
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(blank)Aug. 29, 2003Page viii
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a. A description of the nature and
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a. Hydrological data, stream flow,
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4. Be conducted under the same oper
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maintaining the new technology and
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1.2.1. Plans shall include:a. Suita
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name, number, effective date, publi
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Page 34 and 35: e. The site will provide all-weathe
Page 36 and 37: chlorine residual by methods in "St
Page 38 and 39: etween them, a six-inch band of con
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Page 46 and 47: a. Regulated recreational activitie
Page 48: e done to determine the degree and
Page 51: 1. Pumping rate;2. Pumping water le
Page 55 and 56: sieve analyses of the water bearing
Page 57 and 58: e circulated in the annular space s
Page 59 and 60: emoved. Therefore, every well shoul
Page 61 and 62: 3.2.6.4. Pitless well units.a. The
Page 63 and 64: SIZE (inches)6 id.8101214 od.161820
Page 65 and 66: Chapter 4 -- Tre atment4.0. General
Page 67 and 68: settling basins shall be not less t
Page 69 and 70: 3. Shall have valves located outsid
Page 71: d. Be automatic. Timers on automati
Page 76 and 77: 2. Uniformity coefficient not great
Page 78 and 79: j. During air scour, the backwash w
Page 80 and 81: . An easily readable meter or flow
Page 84 and 85: 4.3.9. Flow Meters.Totaling rate of
Page 86 and 87: utilized, shall be 1.0 milligrams p
Page 88 and 89: . Removal of precursors prior to ch
Page 90 and 91: 5. Consideration shall be given to
Page 92 and 93: . Pre-treatment requirements. Iron,
Page 94 and 95: t. Housing. Bagged salt and dry bul
Page 96 and 97: 4.7. Iron and Manganese ControlIron
Page 98 and 99: Where phosphate treatment is used,
Page 100 and 101: 3. Series and parallel flow piping
Page 102 and 103: approval of the department before u
Page 104 and 105: contact time must be provided to co
Page 106 and 107: a. Sanitary sewers with the approva
Page 108 and 109: 1. Obtain a letter of approval from
Page 110 and 111: 6. The provisions for the final dis
Page 112 and 113: a. Missouri River or Mississippi Ri
Page 114 and 115: 5.0.3. General equipment design.Gen
Page 116 and 117: minimize chemical dust created by t
Page 118 and 119: 1. At least 30 days of chemical sup
Page 120 and 121: e. Hand pumps shall be provided for
Page 122 and 123: 5.2. Chemicals.5.2.1 Shipping conta
Page 124 and 125: outside atmosphere, above grade and
Page 126 and 127: 5.4.2. Acids.a. Acids shall be kept
Page 128 and 129: 4. Anhydrous ammonia contact with c
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fluoride feed line when a metering
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possibility for overfeed.h. Protect
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caution.d. Where taste and odor con
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e installed to monitor the flow of
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the generator dielectrics. Sufficie
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published by the National Fire Prot
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g. Water from pump gland drainage s
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6.3. Pumps.6.3.1.Pumps shall be siz
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6.4.2.2. Suction lines.Suction line
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cessation of minimum essential serv
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parameters: average winter (Decembe
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a. Overflows shall be sized to perm
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additional shielding to prevent the
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largest pump out of service shall b
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7.1.4. CostsAs part of the final en
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7.4. Hydropneumatic Storage7.4.1. H
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provided on larger tanks as needed
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7.5.2. Fire Suppression Rating Sche
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in areas served by rural water dist
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connected directly to any sewer. Su
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8.6.5. Force mains.There shall be a
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8.11.2. Filling device.A filling de
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