WATER SUPPLY AND WASTEWATER ENGINEERING RAJA NORAZILLA BT RAJA YUNUS ZUMMY DAHRIA BT MOHAMED BASRI
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WATER SUPPLY & WASTE WATER ENGINEERING is a study of water resources, water characteristics, usage and demand of water supply, raw water treatment process and water distribution system. This course also includes the information on the process in sewage treatment plant, sludge treatment and disposal. It also emphasize on the parameter of drinking water and effluent from sewage treatment plant. 3
CHAPTER 1 WATER RESOURCES AND QUALITY 4
Sourcesof Water Supply Surface water Ground water Streams Lakes River Reservoirs Stored rain water in cisterns Wastewater reclamation Sea water Aquifers. Well Precipitation CHAPTER 1 :WATER RESOURCES AND QUALITY 5
CHAPTER1 :WATER RESOURCESAND QUALITY Water Quality Characteristics Physical Chemical Biological Turbidity Taste & odour temperature Bacteria Protozoa Virus Algae Dissolved solid pH value Dissolved oxygen Hardness Mineral content (Pb, Fe, Mn) Organic matter Nutrient (C, N, P) Fecal coliform & Total coliform Suspended solid Colour 6
SOURCES OF WATER POLLUTION Industrial Municipal Agricultural Natural Stormwater Landfill Sources Examples Industrial sources of water pollution washing and rinsing water, solubilizing water, diluting water, sewage and shower or sink water Municipal sources of water pollution wastewater are feces, urine, paper, food waste, laundry wastewater and sink, shower or bath water. These pollutants are all biological and such can be readily biodegraded. Agricultural sources of water pollution Agricultural wastewater can be of animal or vegetable origin or be from a nutrient, fertilizer, pesticide or herbicide source. Natural sources of water pollution animal, vegetable and soil sources Landfill sources of water pollution surface and underground leachate heavy metals including acid mine drainage Lead, a metal found in natural deposits, is commonly used in household plumbing materials and water service lines. Chapter 1 :Water Resources and Quality 7
CHAPTER 2 USAGE AND DEMAND OF WATER 8
Chapter 2 :Usage and Demand of Water Water Usage Classification Agricultural Public or civic use Industrial Commercial / trade Domestic purposes Losses /wastes 9
Factors Affecting Demand of Water Size of city Characteristics of population Miscellaneous factors Metering Chapter 2 :Usage and Demand of Water 10 Industries and commerce
FORECASTING THEPOPULATION Factors Influence the Population Growth Birth Migration rate Decease rate Chapter 2 :Usage and Demand of Water 11
FORECASTING THEPOPULATION Methods of Forecasting Population Arithmetic Geometric Arithmetic Geometric Incremental Graphical / Curvilinear Zoning Logistic curve / S-curve Ratio / Correlation Chapter 2 :Usage and Demand of Water 12
1. Arithmetic Increase Method ✓ Thismethod isbased on the assumption that the rate of growth is constant. An average increment in the population of the past three or four decades is worked out. ✓ For each successive future decade, this average increment is added. Thismethod gives too low estimate. ✓ Thismethod can be adopted for forecasting populations of large cities which have achieved saturation conditions. Chapter 2 :Usage and Demand of Water Methods of Forecasting Population 13
EXAMPLE Referring to the given data, estimate the population for Behrang Bitara for the year 2020 and 2030 by using Arithmetic Method. (5 marks) Year 1970 1980 1990 2000 2010 Population 29 000 36 000 38 000 42 000 43 000 Chapter 2 :Usage and Demand of Water 14
SOLUTION Chapter 2 :Usage and Demand of Water 15
P2020 P2030 =pn-1 +ka.∆t =P2020 + ka. (2023-2020) =465v00 +(350 x (10)) =50000 persons =pn-1 +ka.∆t =P2010 + ka. (2020-2010) =430v00 +(350 x (10)) =46500 persons 1 decad = 10 years Chapter 2 :Usage and Demand of Water 16
PROBLEM 2.1 Calculate the expected population in 2010, 2020 and 2030 by arithmetic increase method Year 1960 1970 1980 1990 2000 population 55,000 60,000 66,000 75,000 80,000 Answer: P2010 = 86,250 person P2020 = 92,500 person P2030 = 98,750person Chapter 2 :Usage and Demand of Water 17
Methods of Forecasting Population 2. Geometric Increase Method ✓ Thismethod assumes the percentage increase in population from decade to decade as constant, and it gives high results. ✓ The percentage increase gradually drops when the growth of city reaches the saturation point. ✓ The fixation of percentage increase should be done carefully. ✓ Thismethod is useful for expansion and where a constant rate of growth is anticipated. Chapter 2 :Usage and Demand of Water 18
Year 1990 2000 2010 Population 28 000 32 000 42 500 Referring to the given data, estimate the population projection for Taman Wangsa Suria for the year 2030 by using Geometric Increase Method. (CLO1, C2) ((5 marks) EXAMPLE Chapter 2 :Usage and Demand of Water 19
Year Population Nilai kj t1 – 1990 p1 – 28 000 Kj1 =ln (p2/p1) t2 - t1 ln (32 000/28 000) 2000- 1990 = 0.0133 t2– 2000 P2 -32 000 Kj2 =ln (p3/p2 ) t3 - t2 ln (42 500/32 000) 2010- 2000 0.0284 t3– 2010 P3 -42 500 Kj average = (0.0133 + 0.0284)/2 = 0.0208 SOLUTION Chapter 2 :Usage and Demand of Water 20
• lnP2020 =ln pn-1 +kj.∆t ) •P2020 ) • lnP2030 =ln pn-1 +kj.∆t =ln (52 327 ) +0.0208 (2030 –2020 =shift ln (11.07326) •P2030 =64425 peoples Year Population t1 –1990 p1 –28 000 t2–2000 P2 -32 000 t3–2010 P3 -42 500 =ln (42 5v00) +0.0208 (2020 –2010 =shift ln (10.86526) =52 3v 27 peoples 1 decad =10 years Chapter 2 :Usage and Demand of Water 21
PROBLEM2.2 Calculate the expected population in 2010, 2020 and 2030 by geometric increase method Year 1960 1970 1980 1990 2000 population 55,000 60,000 66,000 75,000 80,000 Answer: P2010 = 87,858 person P2020 = 96,488 person P2030 = 105,966person Chapter 2 :Usage and Demand of Water 22
PASS YEAR QUESTION JUN 2019 Chapter 2 :Usage and Demand of Water 23
Chapter 2 :Usage and Demand of Water 24
PROBLEM & SOLUTION • Calculate the expected population in 1990, 2000 and 2010 by arithmetic increase method and geometric increase method. Year 1940 1950 1960 1970 1980 Population 55,000 60,000 66,000 75,000 80,000 Chapter 2 :Usage and Demand of Water 25
Water Demand Forecasting Total population served Percapita consumption Service factor Design factor Additional demand Population served means the total number of persons served by a public water supply that provides water intended for human consumption. For municipalities which serve only the population within their incorporated boundaries, it is the last official U.S. census population (or officially amended census population). A service factor of 0.9 means that the distribution system covers adequately 90%of the area and the population located in that area can get easy access to public water supply The design factor is to equalize the differences from month to-month according to season factors, weather, society's habit, industrial activities, trade and agriculture. such as industrial, army camp, institution of higher learning. Per Capita Demand (q) in litres per day = Total water demand a year (litre) 365 x total population (capita/day) Chapter 2 :Usage and Demand of Water 26
Estimation for Water Demand Chapter 2 :Usage and Demand of Water Design period governed by Useful life based on wear and tear Financial constraints & interest rates Feasibility for addition or expansion Expected population growth & developments WDn =Pn x q x F1 x F2 ……… +Dm WDn =waterdemand at the end of year “n” Pn =projected population at the end of year “n” F1 =service factor at the end of year “n” F2 =design factor at the end of year “n” Formula for water demand estimation 27
Case 1 : Resident Area Only (Houses) • From the data given, WDn =(Pn x q x F1 x F2) +Dm • Pn =population estimation year n • q =water demand • F1 =service factor • F2 =design factor • Dm =additional demand Water Demand for Resident Additional Demand for resident Chapter 2 :Usage and Demand of Water 28
CASE 2 : RESIDENT AREA WITHINDUSRTRIAL / INSTITUTION • From the data given, WDn =(Pn x q x F1 x F2) +Dm • Pn =population estimation year n • q =water demand • Industrial water needs =1 / 3 of the population need • F1 =service factor • F2 =design factor • Dm =additional demand WDn =(P x q x f1 x f2) + %Dm (P x q) +1/3(P x q x f2) +%Dm (1/3 x P x q) Water Demand for Resident Additional Demand for resident Water Demand for Industrial Additional Demand for Industrial Chapter 2 :Usage and Demand of Water 29
The following data obtained from Parcel 7 in 2012. Calculate the water demand in 2017. ◦ Total household ◦ Average household member ◦ Per capita water consumption ◦ Population growth ◦ Industrial water needs ◦ Design factor ◦ Percentage of NRW ◦ Water supply coverage = 6000 = 6 people = 270 L/day = 2.65% per year = 1/3 of the population needs = 2.4 = 15% = 97% Pn = Po(1+r)n ; WDn=Pn x q x F1 x F2 + Dm Answer : WD = 36.87 x 106 L/day Chapter 2 :Usage and Demand of Water 30
PROBLEM 2.4 • The data given are collected from Seksyen 7 Shah Alam in 2015. Estimate the daily water demand if water supply coverage is 95%. Total population =330,200 Water usage per capita =280 L/day Industry water demand =1/3 from requirements of population Design factor =1.5 NRW =15% Chapter 2 :Usage and Demand of Water 31
Chapter 2 :Usage and Demand of Water 32
CHAPTER 3 WATER TREATMENT 33
Chapter 3 :Water Treatment 34
Chapter 3 :Water Treatment 35
WATER QUALITY STANDARDS • The definition of water quality depends on the intended use of the water which may be either human consumption or it may be for industries, irrigation, recreation etc.. • Depending upon the proposed use of water, certain water quality criteria are established and based on these criteria quality standards are specified by health and other regulation agencies. • Different types of water require different level of water purity. • Drinking water requires highest standard of purity where as water of lower quality Chapter 3 :Water Treatment 36
Objectives of Water Treatment To provide final water going into supply with an acceptable quality To provide safe water for human To remove dissolve gasses, taste and odor in water Reasonable cost for treated water Ensure the final water leaving the treatment plant complied with regulation Chapter 3 :Water Treatment 37
Importance of Water Characteristics Physical Chemical Microbiological -The reaction in water -Different are not visible More on appearance of water, colour,turbidity, taste & odour Very important because its relationship to human health Chapter 3 :Water Treatment 38
Chapter 3 :Water Treatment 39
GENERAL WATER TREATMENTPROCESSES Raw Water Bar screen User Disinfection Fluoridation Filtration sedimentation Flocculation coagulation Pre sedimentation Aeration Grit removal Fine screen Water pump Sludge treatment Semisolids Liquid Sludge pH adjustme nt Rapid mixing Clean Water Chapter 3 :Water Treatment Storage Tank 40
removal of any coarse floating objects, weeds, etc. Bar screen assembliesare normally installed at 60° to 80° angle from the horizontal. Prevent pump, pipe and equipment from clogging or damage. Designated to handle relatively large debris, a bar screen consist of a rack of straight steel bars welded at both end to horizontal steel member. Chapter 3 :Water Treatment General Water Treatment Processes BAR SCREEN 41
GENERAL WATER TREATMENT PROCESSES AERATION Spray aerator Diffusion / bubble aerator Coke tray aerator Waterfall / cascade aerator Direct the water upward, vertically or at an inclined angle, in such a manner that the water is broken into small drops. require a large area, cannot be housed readily, an pose an operating problem during freezing weather. Spray aeratorsare usually quite efficient with respectto gas transfer (CO2 removal or O2 addition) and have esthetic value. Installation commonly consistsof fixed nozzle on a pipe grid Thisaeratorallowing the water to flow downwardsover a series of steps orbaffles. Exposure time can be increased by increasing the number of steps, and the area-volume ratio can be improved by adding baffles to produce turbulence. The simplest cascade aerator isa concrete step structure which causes the waterto fall in fairly thin layersfrom one levelto another. Consist of rectangularconcrete tanks in which perforated pipes, porousdiffuser tubes or variouspatented impingement or Spurgerdevices are inserted near the bottom of the aeration basin. On rising through the water, these cause turbulence and provide opportunity for the exchange of volatile materials between the bubbles and the water and between the airand the water at the latter’s surface. It provides a longer aeration time than one of the waterfall type. Consist of a series of trays equipped with slatted, perforated, or wire-mesh bottoms over which water isdistributed and allow to fallto a collection basin at the base. This aerators are frequently housed. Stainless steel,aluminum, root-resistant wood and concrete are examples of durable-corrosion-resistant materials In many tray aerators, coarse media such as coke, stone, or ceramic ballsranging from 2 to 6 in size are placed in the trays to improve the efficiency of gas exchange. Mechanisms Mechanisms Mechanisms Chapter 3 :Water Treatment 42
GENERAL WATER TREATMENT PROCESSES PRE-CHLORINATION /PRE-SEDIMENTATION / RAPID MIXING Pre-chlorination Pre-sedimentation Rapid Mixing can be ac complished within a tank utilizing a vertical shaft mixer the most important physical operation affecting coagulant dose efficiency the process whereby the chemicalsare quickly and uniformly dispersed in the water removal of color and taste and odor-causing compounds prior to lime softening to reduce heavy sediment loads in surface suppliesprior to chemical coagulation to prevent alga growth that can c log up treatment plant component to oxidized iron and manganese Chapter 3 :Water Treatment 43
GENERAL WATER TREATMENT PROCESSES COAGULATION AND FLOCCULATION Coagulants Polymers Sodium aluminate(Al 3+ ) Ferric Chloride Ferric sulfate(Fe3+ ) FerrousSulfate Alum (aluminum sulfate Key pr opertie s of coagulant Trivalent cation:Colloidsmostly found in natural waters are negatively charged; hence a cation is required to neutralize the charged. Insoluble in the neutral pH range: The coagulant that isadded must precipitate out of the solution so that high concentrations of ion are not left in the water. Non-toxic:This requirement is obvious for the production of a safe water Coagulation and flocculation processes Alum added to raw water reacts with the alkalinity naturally present to form jellylike floc particles of aluminum hydroxide,Al(OH)3. 1 2 The positively charged trivalent aluminum ion neutralizes the negatively charged particles of color or turbidity. This occurs within l or 2 seconds after the chemical is added to the water. Within a few seconds, the particles begin to attach to each other to form larger particles. 3 The floc that is first formed consists of mic ro floc that still has a positive charge from the coagulant 4 Finally, the micro floc particles begin to collide and stick together (agglomerate) to form larger, settleable floc particles 5 Chapter 3 :Water Treatment 44
GENERAL WATER TREATMENTPROCESSES SEDIMENTATION AND FLOTATION Flotation Sedimentation Sedimentation removes settleable solids by gravity. Water moves slowly though the sedimentation tank or basin with a minimum of turbulence at entry and exit points with minimum short-circuiting Sludge accumulates at bottom of tank or basin Watermovesslowly though the sedimentation tank or basin with a minimum of turbulence at entry and exit pointswith minimum short-circuiting. the treatment of nutrient-rich reservoir water that may contain heavy algae blooms and for low-turbidity electrolytic floatation, dispersed-air floatation and dissolved air flotation The floatis removed from the surface, and clarified water istaken from the bottom of the floatation tank. Chapter 3 :Water Treatment After sedimentation So the clarified water, with most of the Particles removed, moves on to the filtration step where the finer particles are removed 45
Slow sand filter Rapid sand filter Pressure filter While slow sand filtration systems are reliable and use proven technology, modern plantsgenerally don't employ them, because of the variety of problems associated with the systems. These problems are mostly related to smallpore spaces in fine sand. pressure systems enclose the bed in a cylindrical steel tank and pump the waterthrough the media under pressure. Rapid sand filtersare the most commonly used systems for water supply treatment because of their reliability. pressure filters, as in rapid sand filters, water flows through granular media in a filter bed. This can cause problems with reliability; occasionally solids are forced through the filter along with the effluent the small pores filter effec tively,they also slow down the passage of water. Thisalso meansincreased land usage to house the units.The fine pore spaces clog easily as well, requiring manual scraping to clean the filter Rapid filters contain a layer of carefully sieved silica sand over a bed of graded gravel. The pore openings are often larger than the floc particles to be removed, so rapid filter systems use a combination of techniques to remove suspended solids and particulate matter from influent, including simple straining, adsorption, continued floc culation, and sedimentation. Filter cleaning isaccomplished by daily backwashing Chapter 3 :Water Treatment GENERALWATER TREATMENTPROCESSESFILTRATION 46
GENERAL WATER TREATMENT PROCESSES DISINFECTION Characteristics They must destroy the kinds and numbers of pathogens that may be introduced into water within a practicable period of time over an expectedrange in water temperature They must be neither toxic to humans and domestic animals nor unpalatable or otherwise objectionable in required concentration. They must be dispensable at reasonable cost, safe and easy store, transport, handle and apply. Their strength or concentration in the treated water must be determined easily, quickly and automatically They must meet possible fluctuation in composition, concentration, and condition of the waters or wastewatersto be treated. Chapter 3 :Water Treatment Disinfectant Advantages Disadvantages Application Point Chlorine • Effective for viruses, bacteria and Giardia cysts • Can be used either a primary or secondary disinfectant • Chlorine residual can be easily monitored • Available as a gas, liquid, or solid • May result in potentially harmful by-products (THMs) • Significant safety concerns especially for gas system • May result in precipitation of iron and manganese • Variety of application points • To minimize THM formation, generally added to the end of the treatment process Ozone • Effective for viruses, bacteria and Giardia cysts • Enhances removal of biodegradable organics in slow sand filter • Must be generated on site • Does not produce a stable, long lasting residual • May result in harmful by-products • Low solubility in water • Exhaust gas must be treated to remove ozone • Difficult to measure residual • Prior to rapid mixing step • Should provide adequate time for biodegradation of oxidation products prior to chlorination Ultraviolet Light • Effective against viruses and bacteria • Not effective against Giardia cysts • Limited to groundwater systems not directly influenced by surface water supply • Downstream of sedimentation of filtration process 47
Miscellaneous Water Treatment Techniques Iron and Manganese Removal pH adjustment Water Softening produce detectable taste and odor, red-colored water which may stain clothes, cooking utensils, and plumbing fixtures. found in groundwater, surface waters Then pH is raised to precipitate the CaCO3 ; if necessary, CO3 2- is added to precipitate the noncarbonated hardness. First, any free acids are neutralized softening reactions are regulated by controlling the pH to remove some of the hardness Adjustment of the pH level during treatment may be needed to: - make coagulation more effective - make the oxidation of iron and manganese more effective - make disinfection by chlorine more effective - Reduce its corrosiveness [aggressiveness] before distribution.- the addition of acidic solutions or carbon dioxide to the water the addition of alkaline solutions to the water placing solid alkaline materials (eg, marble or dolomitic material)in contact with the water Blowing air into the water, or spraying water into the air (to drive off carbon dioxide). removed by water softening removal can be enhancing by oxidizing - oxidizing agent can be atmospheric oxygen, chlorine, chlorine dioxide, ozone, permanganate, or any other oxidant Chapter 3 :Water Treatment 48
Chlorine Residual Test Combined Residual Chlorination Free-residual Chlorination Breakpoint Chlorination 3 4 Chapter 3 :Water Treatment the application of chlorine to water in order to produce, with natural or added ammonia, a combined available chlorine residual, and to maintain that residual through part of all of a water-treatment plant or distribution system. Combined available chlorine forms have lower oxidation potential than free available chlorine forms and therefore, are less effective as oxidant. Importance 1 To ensure disinfection occurred completely 2 Chlorine are easily found in various form such as gases, liquid and powder Easy to use because chlorine has high solubility rate Chlorine can kill most of the microorganism that presence in water bodies. 49
Bacteria Test The multiple-tube fermentation technique Membrane filter technique Fecal coliform procedure Presence-absence technique Chapter 3 :Water Treatment a. Selection of sample size: Size of sample will be governed by expected bacterial density. In drinking water analyses,sample size will be limited only by the degree of turbidity or by the non-coliformgrowth on the medium. b. For regulation purposes, 100 mL is the official sample size. An ideal sample volume will yield 20 to 80 coliform colonies and not more than 200colonies of all types on a membrane-filtersurface. c. Analyze drinking waters by filtering 100 to1000 mL, or by filtering replicate smaller sample volumes such as duplicate 50-mL or four replicates of 25-mL portions. Analyze other waters by filtering three different volumes (diluted or undiluted), depending on the expected bacterial density. d. When less than 10 mL of sample (diluted or undiluted) is to be filtered, add approximately 10 mL sterile dilution water to the funnel before filtration or pipet the sample volume into a sterile dilution bottle,then filter the entire dilution. 1.Collect the sample and make any necessary dilutions. 2.Select the appropriate nutrient or culture medium. Dispense the broth into a sterile Petri dish, evenly saturating the absorbent pad. 3.Flame the forceps, and remove the membrane from the sterile package. 4.Place the membrane filter into the funnel assembly. 5.Flame the pouring lip of the sample container and pourthe sample into the funnel. 6.Turn on the vacuum and allow the sample to draw completely through the filter. 7.Rinse funnel with sterile buffered water. Turn on vacuum and allow the liquid to draw completely through the filter. 8.Flame the forceps and remove the membrane filter from the funnel. 9.Place the membrane filter into the prepared Petri dish. 10.Incubate at the proper temperature and for the appropriate time period. 11.Countthe colonies under 10 – 15 X magnification. 12.Confirmthe colonies and report the results. •Sterilize sampling bottle in air oven at 170°C for 1 hour or autoclave at 15psi and allowed to cool. •Pour approx. 20ml sample into sampling bottle and allow sample to stand for 15 minutes. •Wipe medium satchet with rubbing alcohol and flame cutting edge (scissors or nail clipper) for sterilization. •Cut medium sachet and pour into sample bottle. Cap and mix. •Place sample at about 25°C (or room temperature). •Take H2S Bacteria P/A reading at 24 and 48 hours(Black = Positive, Yellow = Negative). 50