1. Chapter 31 Water and Waste Treatment

2. Consequences of Water Pollution Disease Epidemics  Early 1800’s - industrial revolution Outbreaks of typhoid fever, cholera, TB & dysentery  1842 - Edwin Chadwick  1965 - Riverside, California 16,000 cases of Salmonellosis (70 serious, 3 deaths) Unusual because pathogen out numbered coliform indicator (E. coli)

3. Consequences of Water Pollution  1993 - Milwaukee, Wisconsin 400,000 cases of cryptosporidium  1998 74 athletics from triathlons in Wisconsin and Illinois with evidence of infection three (3) hospitalized  Leptospirosis - waterbirne disease  July 2000 10 cases of hemolytic-uremic syndrome (HUS) caused by E. coli. Came from contaminated ice

4. Consequences of Water Pollution Acid-Rain Trash Littered Beaches, Dead Fish Unsightly, foul-smelling odors Accelerated Eutrophication

10. Consequences of Water Pollution Two (2) Important Micro Factors  Pollution problems caused by pathogenic bacteria  Pollution leading to Eutrophication Most Commonly Added Material to Aquatic Environment  Treated Sewage High in Nutrients & Phosphates

12. Myth vs. Fact Streams, lakes and oceans are natural waste disposal units - WRONG Most naturally occurring substances can be recycled, but systems can be overwhelmed Microbial degradation is 10-100 times slower in oceans

13. Waste Water Treatment Definitions  Mineralization (Stabilization) Conversion by microorganisms or organic materials into inorganic materials  Biochemical Oxygen Demand (BOD) Oxygen consuming property of a wastewater sample Roughly proportional to the amount of degradable organic material present in water sample Effective treatment decreases the BOD of sewage

14. Waste Water Treatment Definitions  Aerobic Treatment Microbial oxidation of organic compounds to yield CO 2 and inorganic nitrogen-containing nutrients for plants  Anaerobic Decomposition Similar except anaerobic microbes ferment organic compounds Products of fermentation utilized through aerobic respiration

15. Waste Water Treatment Definitions con’t  Anaerobic Decomposition, Methanogens are Important Transforming small products from other bacteria into CO 2 and CH 4 (methane) In presence of hydrogen, remaining CO 2 can be metabolized by photosynthetic organisms and plants CH4 can be discarded, conserved for fuel (perspective 33.1), or oxidized to CO 2 by methane- oxidizing bacteria

16. Waste Water Treatment Consumption in U.S.  Every day the average American uses: 150 gallons of water 4 lbs. of food 19 lbs. of fossil fuels  Converted into: 120 gallon sewage 5 lbs. Trash 2 lbs. Air pollutants

17. Municipal Waste Water Treatment Primary Treatment  Removal of large objects and much of the particulate matter through the physical processes of screening and sedimentation  Sedimentation Tanks ALUM often added to aid in sedimentation Water held 90 minutes to 2 hours Effluent water is sent to secondary treatment

18. Municipal Waste Water Treatment Suspended solids settling to the bottle form a mass called raw primary biosolids (formerly Sludge) Biosolids are sent to an anaerobic digester or incinerated

19. Waste Water Treatment Anaerobic Digesters  Biosolids from primary sedimentation tanks Utilize Anaerobic Decomposition Following decomposition final Biosolids – commonly burned to ash Lime is recovered and recycled if used is process

20. Municipal Waste Water Treatment Secondary Treatment  Designed to stabilize most of the organic material in sewage and reduce the BOD of the sewage. Removes about 85% of organic matter  A biological process Effluent from primary treatment is pumped to a trickling filter system then/or to an aeration tank for further stabilization.

21. Municipal Waste Water Treatment Activated Biosolids Process (formerly Aerated Activated Sludge Process)  Sewage serves as a nutrient source for mixed populations of aerobic organisms.  Aerated to increase the oxygen levels  End result - a small increase in microbial mass and a decrease in degradable organic material  Aerated activated sludge now called activated biosolids

22. Municipal Waste Water Treatment Secondary Treatment  Effluent from secondary treatment moves on to tertiary treatment process  Sludge moved to activated sludge digester or incinerated

23. Waste Water Treatment Trickling Filters  Sewage is sprayed over a bed of coarse to fine gravel and sand (3 to 6 feet deep) Newer systems may use interlocking pieces of corrugated plastic or other synthetic material  A film of organisms comprised of fungi, algae, cyanobacteria and some protozoa cover the gravel and sand.  Organisms aerobically stabilize the waste  Can be used individually or as part of a large system

24. Municipal Waste Water Treatment Tertiary Treatment  Chemical precipitation of phosphates and biological removal of nitrates Lime added to coagulate and precipitate phosphate containing particles - allowed to settle out in a clarification tank. Certain bacteria may be used to reduce nitrates (NO 3 - ) to N 2 or Gaseous ammonia in water may be removed by passing water through a stripping tower

25. Municipal Waste Water Treatment Tertiary Treatment  Water then passes through a series of activated carbon filter units Removes detergents, pesticides and other toxic materials

26. Municipal Waste Water Treatment Chlorination  Final step in waste water treatment processes Can kill more than 99% of the harmful bacteria in effluent. Municipal treatment  Primary - chlorination  Primary/Secondary - chlorination  Primary/Secondary/Tertiary - chlorination

27. Municipal Waste Water Treatment  Many states now require the removal of excess chlorine before discharging to receiving waters by a process called dechlorination. Accomplished with granulated activated carbon filtration Alternatives to chlorination include ultraviolet light or ozonation

29. Small Scale Waste Water Treatment Lagooning  Sewage channeled into a series of small ponds (lagoons) Remains in each lagoon for several hours to several days or more Sedimentation occurs and waste materials are stabilized by both aerobic and anaerobic processes. Pathogens are usually eliminated by competition

30. Small Scale Waste Water Treatment Septic Tanks (Anaerobic)  Sewage is collected in a large tank where solids settle to the bottom and are stabilized anaerobically  Liquid outflow is run through a distribution box then out to a drainage field (finger system)  Liquid filters down through a gravel base and then into the surrounding soil  Works well in theory

32. Small Scale Waste Water Treatment Septic Tanks – Anaerobic –Possible Problems Washing machines are leading cause of septic system failure Clay soil types decrease effectiveness Toxic materials in the waste water decrease effectiveness Need to periodically reseed septic tank with appropriate bacteria Pathogens can sometimes survive process

33. Small Scale Waste Water Treatment Septic Tanks – Aerobic –Pretreatment May include a traditional septic tank, a primary settling compartment or a trash trap (screening) To reduce greases, oils, toilet paper and other solids. Optional on various systems

34. Small Scale Waste Water Treatment –Aerobic Treatment Units Main function is to collect and treat household wastewater Suspended Growth Units –Main compartment called an aeration chamber. –Air mixed with wastewater (wastewater mixture called mixed liquor). –Some units have a secondary settling chamber or clarifier. Sediment returns to the aeration chamber as bacterial seed for growth of organisms.

35. Small Scale Waste Water Treatment Attached Growth Units –Treat wastewater by taking a surface made of material bacteria can attached to, then exposing surface alternately to wastewater then air. –Requires a pretreatment component. –Example: trickling filter. Final Treatment and Disposal –Includes chlorination or discharge to a soil absorption field, sand filter or evapotranspiration bed (drip irrigation).

37. Small Scale Waste Water Treatment Septic Tanks – Aerobic –Limitations Regulatory regulations High cost Maintenance requirements –Aerobic units are required to have two (2) year manufacturer maintenance service and renewal options.

38. Small Scale Waste Water Treatment Septic Tanks – Aerobic –Do’s and Don’ts Maintain service contract Avoid water overloading Don’t allow anyone to drive over or park on system Don’t use harmful chemicals Avoid using garbage disposal Do not dispose of coffee grounds, kitty litter, fat or grease down drains

39. Small Scale Waste Water Treatment Artificial Wetlands  Sewage pumped into initial pond  Heavy material settles to the bottom where it undergoes anaerobic digestion (stabilization), water in the pond is aerated to promote aerobic stabilization of organic materials  The length of time the water stays in the pond is dependent on the design of the system

40. Small Scale Waste Water Treatment Artifical Wetlands  Water is pumped from the pond into a marsh where additional stabilization takes place  From the marsh water flows into another pond where algae can transform harmful nutrients  The water then flows into a meadow where remaining pollutants can be trapped, water flows from the meadow into area ground or surface waters

41. Treated Waste Residue Problems Receiving waters can be changed if insufficient treatment has taken place causing increased BOD & temperature, pH changes, or introduction of toxic materials Biosolids (Sludge) - if burned produces polluting gases; can only be used as a fertilizer if no toxic compounds are present

42. Water Treatment (Purification) Sedimentation  Addition of either (alum) aluminum sulfate or iron sulfate to cause flocculation to occur Flocculation  Forms jelly like masses of coagulated material - Flocs  Water remains in sedimentation tank for 1 - 10 hrs.  Water flows from sedimentation tank to filtration process

43. Water Treatment Filtration (2 Types of Filters)  Slow Sand Filters Fine particles of sand, several feet deep Schmutzdecke (dirty) layer forms within system to aid in trapping organisms Can purify ~ 3 million gallons/acre/day When system efficiency decreases sand has to be replaced

44. Water Treatment Filtration (2 types)  Rapid Sand Filters Coarse gravel to fine sand No dirty layer Rate of filtration is over 200 million gal/acre/day Easily cleaned by backwashing Both filter types are effective at removing ~99% of microorganisms present in the water

45. Water Treatment Chlorination  Normally use Chlorine gas Water held in storage tanks for 90 minutes to several hours.  Free residual chlorine 0.2-1.0ppm (0.5ppm)  Favored in U.S. because residual chlorine will kill organisms entering system following treatment  Can check safety level based on residuals

46. Water Treatment Chlorination  Can react with naturally occurring or pollution related organic materials to form chlorinated hydrocarbons Can avoid problem by reducing organic material found in water  Granulated active carbon filters can be used to remove chlorinated hydrocarbon compounds

47. Water Treatment Ozonation  Ozone acts as an oxidizing agent to kill bacteria and inactivate viruses Can also destroy some hydrocarbon compounds by oxidation Leaves no undesirable taste or odor Removes color  Safety check requires an 18 hour delay before water is pumped out to communities

48. Water Treatment Ozonation  Used in several European cities  Used by many bottled water companies in the U.S. but few cities.

49. Water Testing Membrane Filter Technique  100ml water sample  passed through a membrane filter cellulose acetate or polycarbonate  Filter placed on appropriate medium & incubated for 24 hours  Count colonies - calculate number of bacteria in original sample

50. Water Testing Most Probable Number Technique (MPN)  Presumptive Test Inoculate water in 10ml, 1ml and 0.1ml amounts into lactose broth tubes Incubate 24 hours, interpret for (+) gas Use MPN table to determine number of coliform bacteria present in sample  This number is used to determine if water is safe to drink, swim in, etc.  It does not detect total number of bacteria in the water

54. Water Testing Most Probable Number (MPN)  Confirmed Test Transfer sample from (+) gas lactose tube to EMB plate Incubate 24 hours If coliform colonies form (+)  Completed Test Select an isolated colony from EMB plate and inoculate a lactose broth tube Incubate & check for gas production

55. Solid Waste Treatment The U.S. creates more than 150 million tons of solid waste material per year Solid Waste Sanitary Landfills  Each days waste is covered with a layer of dirt  When landfill becomes full it is generally made into a meadow area  Concept is to have the land used for recreational purposes and then later as construction sites

56. Solid Waste Treatment Sanitary Landfills - Disadvantages  Limited number of sites available  Organic content degraded slowly anaerobically can take 50 years or more  Methane gas is a by-product, can be explosive  Heavy metals and pesticides leach into surrounding groundwater

57. Solid Waste Treatment Some cities are beginning to charge based on the size of trash container picked up Recycling is becoming more and more important

58. Solid Waste Treatment Backyard and Commercial Composting  Involves mixing garden debris with organic kitchen wastes (excluding meats & fats)  Requires periodic mixing to maintain even temperature (best temp range 100-150 o F)

59. Solid Waste Treatment  Will reduce the bulk by 2/3s over a period of several months  Pathogens are killed but beneficial thermophils survive

60. Bioremediation Pollutants  Traditionally degraded and removed through natural recycling. Most natural organic compounds can be degraded by one or more species of soil or aquatic organisms Industrially synthesized chemicals slowly degraded or nonbiodegradable  Adds thousands of tons of pesticides, herbicides, detergents and plastics to the environment

61. Bioremediation Pollutants  Biological Magnification Continuing ingestion and reingestion of a compound accumulating in fat resulting in an increasing concentration of the compound as it is passed up the food web.  Example: DDT

62. Bioremediation Changing biodegradability  Herbicides  2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5- trichlorophenoxyacetic acid (2,4,5-T)  Only difference is the additional chlorine atom on 2,4,5-T  When 2,4-D applied to soil it disappears completely in a matter of weeks while 2,4,5-T remains more than one year later  Therefore 2,4-D more biodegradable

63. Bioremediation  Increasing microorganisms will also increase rate of degradation  Raising temperature, maintaining pH near neutral and providing optimal moisture will likely increase the rate of degradation of most materials added to the soil Polychlorinated biphenols (PCBs)  Aromatic molecules  Not biodegradable  Concentrations increasing steadily for several years  Banned in U.S. in 1978  1/3 of the U.S. population is estimated to contain PCBs in concentrations greater than 1 ppm in their tissues Natural Materials – Petroleum Oil

64. Bioremediation Means of Bioremediation  Microorganisms Large scale inoculation of polluted areas or introduction of the necessary degradative capabilities into the natural population of a given area.  Dual cultures of Acinetobacter and Pseudomonas can degrade PCBs