Presentation on theme: "1 Jim Park, Professor Civil and Environmental Engineering University of Wisconsin-Madison."— Presentation transcript:
1 Jim Park, Professor Civil and Environmental Engineering University of Wisconsin-Madison
2 Treatment Objectives 1980 to 2000 Removal of toxic compounds and nutrients (N & P) Early 1970s to 1980 Based on aesthetic and environmental concerns Began to address nutrient removal Improved treatment efficiency and widespread treatment of wastewater 1900 to early 1970s Removal of suspended and floatable material Treatment of biodegradable organics Elimination of pathogenic organisms 21 st Century Endocrine disrupting chemicals (EDCs) and other synthetic compounds, emerging pathogens, etc.
3 Change of Regulatory Policy Conventional Pollutants (BOD & SS) Conventional Pollutants (BOD & SS) + Specific Toxics (Priority Pollutants) Water Quality-Based Permit Limitations for Toxic Pollutants
4 Water Quality-Based Permit Approach To control pollutants beyond specific toxics based controls Applied where violations of water quality standards are identified or projected Two-phased approach: Chemical specific approach Whole-effluent approach Create a challenge to develop effective and economical techniques for toxics control
5 Minimum National Standards for Secondary Treatment ParametersUnits 30-day ave. conc.7-day ave. conc. BOD 5 mg/L30/45 a 45/65 Suspended solidsmg/L30/45 a 45/65 Hydrogen-ion conc.pH units6~9 b 6~9 b Carbonaceous BOD 5 c mg/L2540 a Average removal 85% b Only enforced if caused by industrial wastewater or by in- plant chemical addition c May be substituted for BOD 5 at the option of the National Pollution Discharge Elimination System (NPDES) permitting authorityNational Pollution Discharge Elimination System
6 Water Quality Parameters Organic matter Biochemical oxygen demand (BOD 5 ) Chemical oxygen demand (COD) Total organic carbon (TOC) Toxic compounds Priority pollutants Fats, oils, and grease Inorganic matter pH, chlorides, alkalinity, nitrogen (total Kjeldahl nitrogen [TKN], ammonia, nitrate, and nitrite), phosphorus, and sulfur Bioassay
7 Bioassay Mysidopsis bahia, female, approx. 6 mm in length Ceriodaphnia dubia Brachionus calyciflorus
8 Typical Composition of Raw Domestic Wastewater Strength WeakMediumStrong Solids, total (TS), mg/L3507201200 Total dissolved (TDS), mg/L250500850 Total suspended (TSS), mg/L100220350 Settleable solids, mg/L51020 BOD 5, mg/L110220400 COD, mg/L2505001000 Nitrogen (total as N), mg/L204085 Organic, mg/L81435 Free ammonia (NH 4 + ), mg/L122550 Nitrite & nitrate, mg/L000 Phosphorus (total as P), mg/L4815 Organic, mg/L135 Inorganic, mg/L3510 Chlorides, mg/L3050100 Sulfate, mg/L203050 Alkalinity, mg/L as CaCO 3 50100200 Grease, mg/L50100150 Total coliform, #/100 mL10 6 ~10 7 10 7 ~10 8 10 7 ~10 9
9 Wastewater Treatment Processes Suspended solids Screening and comminution Grit removal Sedimentation Filtration Flotation Chemical polymer addition Coagulation/sedimentation Natural systems (land treatment) Volatile organics Biological degradation Air stripping Off gas treatment Activated carbon adsorption
10 Biodegradable organics Activated sludge variations Fixed-film reactor: trickling filters Fixed-film reactor: rotating biological contactors Lagoon variations Intermittent sand filtration Physical-chemical systems Natural systems Pathogens Chlorination/hypochlorination Bromine chloride Ozonation UV radiation Natural systems Wastewater Treatment Processes - continued
11 Wastewater Treatment Processes - continued Nitrogen - nutrient Suspended-growth nitrification/denitrification Fixed-film nitrification/denitrification Ammonia stripping Ion exchange Breakpoint chlorination Natural systems Phosphorus - nutrient Metal-salt addition Lime coagulation/sedimentation Biological phosphorus removal Biological-chemical phosphorus removal Natural systems Nitrogen and phosphorus - nutrients Biological nutrient removal
12 Wastewater Treatment Processes - continued Refractory organics Carbon adsorption Tertiary ozonation Natural systems Heavy metals Chemical precipitation Ion exchange Natural systems Dissolved organic solids Ion exchange Reverse osmosis Electrodialysis
13 Electrodialysis Dissolved species are moved away from the feed stream rather than the reverse. Because the quantity of dissolved species in the feed stream is far less than that of the fluid, electrodialysis offers the practical advantage of much higher feed recovery in many applications. Ion permeable membranes
17 Disinfection Pasteurization Long-term storage Dewatering Vacuum filter Centrifuge Belt press filter Filter press Sludge drying beds Lagoons Thermal reduction Multiple hearth incineration Fluidized bed incineration Wet air oxidation Vertical deep well extractor Ultimate disposal Land application Distribution and marketing Landfill Lagooning Chemical fixation Sludge Processing/Disposal Methods
18 Sludge Volume Reduction Example Volume of sludge: 10,000 gallon Solids content: 1% Weight of sludge = 10,000 gal × 8.34 lb/gal × 0.01 = 83.4 lb Thickening & dewatering to 5, 15, 30, and 50% What are the volume reductions at each solids content? What are the costs for hauling at each solids content?
22 Process Selection Needs theoretical knowledge and practical experience Principal elements of process analysis Development of the process flow diagram Establishment of process design criteria and sizing treatment units Preparation of solids balances Evaluation of the hydraulic requirements (hydraulic profile) Site layout considerations Upgrading/expansion of existing facility Compatibility with existing facilities Requires new operational procedures and additional training for proper O&M of new units
23 Activate Sludge Process London Wastewater Treatment Plant
25 Design Considerations Cost - initial and annual O&M costs Order of magnitude estimates for conceptual planning Budget estimates (during preliminary design stage) Definitive estimates derived from detailed quantity takeoffs of completed plans and specifications Environmental - environmental impact statement Equipment availability Personnel requirements Energy and resource requirements
26 Project Management Facilities planning: define problems, identify design year needs (usually > 20 years), define/develop/analyze alternative treatment/disposal systems, select plan, and outline an implementation plan (financial arrangements and schedule) Design: conceptual, preliminary, and final design with field testing for design criterion development Value engineering: intensive review of a project by experts (1/3 and 2/3 of the project schedule) Construction: ease of integration of new facilities into existing sites, clarity of presentation, spec. of high quality materials of construction, timely completion of work, and minimum changes Startup and Operation: O&M manual
29 Hydraulic Profile Graphical representation of the hydraulic grade line through the treatment plant. The vertical scale is intentionally distorted to show the treatment facilities and the elevation of the water suface.
30 Impact of Flowrate and Mass- Loading Factors on Design Rated capacity - average annual daily flowrate Peak hydraulic flowrates - control the size of unit processes and interconnecting conduits Peak process loading rates - control the size of unit processes and support systems Goal - provides a wastewater treatment system that is capable of coping with a wide range of probable wastewater conditions while complying with the overall performance requirements.
31 Typical Design Flowrate and Loading Factors Used for Sizing Flowrate based FactorApplication Peak hourPumping facilities and conduits, bar-rack; grit chambers, sedimentation tanks, and filters; chlorine-contact tanks Max. daySludge pumping system > 1-day max.Screenings and grit storage Max. weekRecord-keeping and reporting Max. monthRecord-keeping and reporting, chemical storage facilities Min. hourTurndown of pumping facilities and low range of plant flowmeter Min. dayInfluent channels to control solids deposition Min. monthMin. number of operating units required during low-flow periods
32 Typical Design Flowrate and Loading Factors Used for Sizing Mass loading based FactorApplication Max. daySelected biological processing units > 1-day max.Sludge-thickening and -dewatering systems Sustained peaksSelected sludge processing units Max. monthSludge storage facilities Min. monthProcess turndown requirements Min. dayTrickling-filter recycle Procedure for selecting design flow rate: Average flowrates based on population projections, industrial flow contributions, and allowances for infiltration/inflow Peak flowrate = Average flowrate Peaking factor
33 Forecasting Design Flowrates Expansion project Population of 15,000, 25,000 resident expected after 20 years plus 1000 visitors per day from a proposed college (assume 15 gal/capita/day) A new industry - ave. = 0.22 Mgal/day, peak = 0.33 Mgal/day for 24 hr operation; present ave. daily flowrate = 1.6 Mgal/day Infiltration/inflow = 25 gal/capita/day at ave. flow and 37.5 gal/capita/day at peak flow occurring during day shift Residential water use in the new home is expected to be 10% less than in the current residences because of the installation of water-saving appliances and fixtures Compute future average, peak, and min. design flowrates. Assume that the ratio of min. to ave. flowrate is 0.35 for residential min. flow rates and the industrial plant is shut down one day a week.
34 Solution 1. Compute the present and future wastewater flowrates a. For present conditions, compute the ave. domestic flowrate excluding infiltration Infiltration: 15,000 25 gal/capita/day=375,000 gal/day Domestic: Total ave. flow - Infiltration = 1,600,000 - 375,000 = 1,225,000 gal/day b. Compute present per capita flowrate Per capita flow rate= 1,225,000 15,000 persons = 81.7 gal/capita/day c. Future conditions: 10% reduction Future flow rate = 81.7 0.9 = 73.5 gal/capita/day Total dry-weather base flow: 120 gal/capita/day [70 + 10 (commercial/small industrial flows) + 40 (infiltration)]
35 2. Compute future ave. flowrate a. Existing residents=1,225,000 GPD b. Future residents = 10,000 73.5 =735,000 GPD c. Day students = 1,000 15 gal/capita/day =15,000 GPD d. Industrial flow (given)=220,000 GPD e. Infiltration = 25,000 25 gal/capita/day =625,000 GPD Total future flow rate = 2,820,000 GPD = 2.82 Mgal/day 3. Compute min. flow rate a. Residential min. flowrate = 0.35 1.6 =0.56 Mgal/day b. Industrial min. flowrate =0 Mgal/day Total min. flow rate= 0.56 Mgal/day Solution - continued
36 4. Compute future peak flow rate a. Peak hourly = 1.975 Mgal/day 3.1=6.12 Mgal/day b. Industrial peak (given)=0.33 Mgal/day c. Infiltration = 25,000 37.5 gal/capita/day 0.94 Mgal/day Total future peak flowrate= 7.39 Mgal/day Solution - continued 3.1
37 Important Factors in Process Selection Process applicability Applicable flow rate Applicable flow variation Influent-wastewater characteristics Inhibiting and unaffected constituents Climatic constrains Reaction kinetics and reactor selection Performance Treatment residuals Sludge processing Environmental constrains Chemical requirements Energy requirements Personnel requirements Operating and maintenance requirements Ancillary processes Reliability Complexity Compatibility Land availability
38 Treatment Efficiency Treatment unitsBODCODSSPOrg-NNH 3 -N Bar racks000000 Grit chambers0~50~50~10000 Primary sedimentation30~4030~4050~6510~2010~200 Activated sludge80~9580~8580~9010~2015~508~15 Trickling filters High rate, rock media65~8060~8060~858~1215~508~15 Super rate, plastic media65~8565~8565~858~1215~508~15 Rotating biological contactors (RBCs)80~8580~8580~8510~2515~508~15 Chlorination000000
39 Typical Design Periods FacilityPlanning period range, yrs Collection systems20~40 Pumping stations Structures20~40 Pumping equipment10~25 Treatment plants Process structures20~40 Process equipment10~20 Hydraulic conduits20~40
40 Secondary Clarifier 40 Final Clarifier Use the upper level for beneficial use
41 Top of the Wastewater Treatment Facility 41 Basket ball court and green area above the final clarifiers