WATER TREATMENT PLANT DESIGN PROJECTCE 431 Water Supply Engineering Spring 1998- General:A city of 60,000 population plans to construct a water treatment plant to produce potable water using a design flow of 200 gpcd. The City uses surface water from a nearby lake. Both water quality and water demand vary with season. The typical raw water characteristics are asfollows:Raw Water CharacteristicsCO2 ( mg/l ) 6 Turbidity ( NTU) Ave 20 Max 60Ca++ ( mg/l) 210 TDS ( mg/l) 550Mg ++ ( mg/l ) 30 Color ( CU) Ave 18 Max 60Na+ ( mg/l ) 21Alkalinity ( mg/l as Ca CO3)340SO4-- ( mg/l ) 280Cl - ( mg/l ) 32The requirements for the product water quality Product Water Quality Requirements are as follows:Turbidity ( NTU) 0.2 Sulfate ( mg/l) 250Coliform 1 TDS ( mg/l) 500pH 6.5-8.3 Color ( CU) 5- Scope of Work:I. Budgetary estimate of construction cost and engineering design fee.II. Evaluate and select treatment processes and prepare a preliminary design of the treatment facilities. The preliminary design shall include the following:1. Evaluating given information and developing a schematic flow diagram of the processes.2. A tabulation of the design criteria.3. Design calculations for Modules A through H for unit processes and equipment sizing.4. A summary of preliminary sizes.5. A hydraulic profile.6. A layout and detailed sketch of the facilities.7. Support documents including equipment data sheets, and catalog cut sheets.- Design Requirements:Module A-- Raw Water Intake and Pump StationGiven: Static head 22 ftTotal pipe length 4300 ftTotal minor losses 14 ftNumber of pumps 2 + 1The elevation of the low water level 100.00Design:1. Inlet & discharge pipe sizes ( Inlet velocity < 6 fps and discharge velocity < 8 fps)2. Pump calculation including discharge and TDH 3. Pump & motor selection ( include catalog cut)Module B-- Flash MixGiven: Number of Tanks 2Freeboard 2 ftVertical shaft vaned disc turbine mixer with 4 flat bladesMixing energy ( G) 920 per secondGT 20,000 - 35,000 ( use average value)Impeller diameter 40 to 50% of tank diameter or widthWater temperature is 50o F.Design:1. Tank size2. Impeller type , diameter and rotating speed.Wei23. Mixer motor HP ( Assume overall efficiency is 80%)4. Select a chemical diffuser. Justify your decision.Module C-- FlocculationGiven: Number of rectangular tanks 2The basin for each stage L/W = 3 and water depth = 11 ftFlocculation stages 3 per tankNumber of flocculators 3 per stageDetention time 10 minutes each stageFlocculator type Horizontal shaft with paddles and variable speed drive Mixing Energy ( G) 50, 35 and 20 per second for the 3 stagesDesign:1. Tank volume2. Tank dimensions and baffled wall details3. Flocculator paddle dimensions and details4. Check ratio of paddle area to tank area and tip velocity5. Flocculator motor HP6. Discuss other common alternatives ( exclude proprietary devices), the pros and cons of each alternative.7. Is your design a good selection? Justify your answer.Module D -- SedimentationGiven: Number of rectangular tanks 2Tank L/W ratio 4Surface loading rate 0.93 gpm/sq ftAve depth 14 ftWeir loading rate 13.9 gpm/ftSludge collection Chain and flightSludge quantityApproximately 4% of total flowDesign:1. Tank dimensions 2. Ave horizontal velocity. Check Reynold’s no. and Froude's no. Reshape the tank if there is a problem.3. Detention time4. Sludge withdrawal pumps ( one pump per tank)Wei35. Influent and effluent structures ( hydraulics and details)6. Calculate the tank size reduction if 75% of the tank area is covered with tube modules. The tubes are 2 ft high, 2 inch wide and of 45o inclination.Module E-- FiltersGiven: Conventional gravity filter, square filters, fixed-nozzle typeFilter media anthracite coal and sandNumber of filters 5 operating + 1 spareFilter rate 4 gpm/sq ftAverage backwash cycle every 48 hoursDesign:1.Dimensions and details of filters2.Filter media depth ( inches), effective size ( mm), Uniformity coefficient, Specific gravity.3.Gravel bed depth ( inches), effective sizes ( inches)4.Filter backwash backwash rate ( gpm/sq ft), backwash flow ( gpm), backwash duration ( minutes)5.Filter surface wash rate ( gpm/sq ft) and duration ( minutes)6.Total washwater as a percentage of plant flow7.Elevations for filter HWL, LWL, top of filter media, top of wash water trough, required water elevation in effluent channel for self wash type, effluent weir crest, and HWL inclear well.8.Is the dual media filter a good selection for given conditions? Justify your answers.Module F-- Sludge LagoonGiven: Two earthen basinsStorage period 60 daysDesign: Basin volume and dimensionsModule G -- ChlorinationGiven: Plant effluent free chlorine residual 1 mg/lchlorine demand 0.5 mg/lDesign:1. Chlorine requirement lbs/day2. Chlorination system 3. InjectorWei4Module H-- Chemical facilitiesGiven: Alum dose 50 mg/lAlum feed solution commercial liquid alum ( without dilution)Liquid alum 5.6 lbs / gal solutionPolymer (cationic) dose 1 mg/lCommercial liquid polymer 65-75 lbs/cu ft 80% strength Polymer feed solution 2.5-5% strength Design:1. Chemical consumption ( lbs/day and gal /day)2. Size of day tank for polymer ( Gal and dimensions)3. Feed pump type and capacity ( gpH)Wei5Each student is required to turn in a self-evaluation and a peer evaluation to the instructor at conclusion of the project. The guidelines are shown in section III and an evaluation form is attached.III. GUIDELINE TO PEER- EVALUATIONEach person will be rated in four areas: Preparation, participation, contribution, and leadership.1. PreparationHas the person studied the class material and reading assignments and ready to contribute in a positive manner.2. ParticipationIs the person making a sincere effort to participate in group activities? Is the person a good team player?3. ContributionIs the person knowledgeable on the subject? Has the person made valuable contribution to the project?4. Is this person able to step in and organize an activity when the need arises? Is this person well organized? Is this person an effective leader?Wei6EVALUATIONCourse No.__________________________________Project __________________________________Evaluator Name _____________________________ Date ________________SELF EVALUATION: ( State one's own contribution to the project)PEER EVALUATION: Name Prepa- Parti- Contri- Leader- Total ration cipation bution shipScore