CE 356: Fundamentals of Environmental Engineering - PowerPoint PPT Presentation

1 / 21
About This Presentation
Title:

CE 356: Fundamentals of Environmental Engineering

Description:

CE 356: Fundamentals of Environmental Engineering Wastewater Characteristics Ricardo B. Jacquez Professor, CAGE Department New Mexico State University – PowerPoint PPT presentation

Number of Views:104
Avg rating:3.0/5.0
Slides: 22
Provided by: cagesunN
Learn more at: http://cagesun.nmsu.edu
Category:

less

Transcript and Presenter's Notes

Title: CE 356: Fundamentals of Environmental Engineering


1
CE 356 Fundamentals of Environmental Engineering
  • Wastewater Characteristics
  • Ricardo B. Jacquez
  • Professor, CAGE Department
  • New Mexico State University
  • Teaching Assistant M. T. Myint

2
Learning Objectives
  • Comprehend basic characteristics of domestic
    wastewater (flow rate, BOD, SS) and apply these
    characteristics to a preliminary engineering
    design.
  • Calculate mass loadings within the wastewater
    treatment system for BOD and SS.
  • Calculate and interpret mass balances for
    mixtures of wastewaters.
  • Calculate and interpret population equivalents
    for industrial wastewater.

3
Wastewater Characteristics
  • Sources of Wastewater
  • Physical Characteristics
  • Sewer Crown Corrosion
  • Chemical Characteristics
  • Typical composition of untreated domestic
    wastewater
  • Biological Characteristics
  • Population Equivalents

4
Sources of Wastewater (Major Components)
  • Domestic food, soap and detergents, bathroom
    (fecal and urine), and paper.
  • Commercial bathroom and food from restaurants
    and other stores.
  • Industrial highly variable, dependent on
    industry, controlled by pre-treatment
    regulations.
  • Runoff from streets sand and petroleum and tire
    residues (infiltration, not a direct discharge).

5
Wastewater Characteristics
  • Characteristics are categorized as
  • Physical
  • Chemical
  • Biological
  • Concentrations characterize wastewater as
  • weak, medium, and strong.

6
Physical Characteristics
  • Solids
  • - Total solids residue after evaporating all
    water
  • (50 volatile and 50 fixed)
  • (Volatileorganic. Fixedinorganic
    mg/L)
  • - Suspended solids residue retained on a
    filter
  • (75 volatile and 25 fixed).
  • - Dissolved solids residue passing through a
  • filter (40 volatile and 60 fixed).
  • - Settleable solids residue after one hour
    settling in an
  • Imhoff cone (ml/L) (the indicator of primary
    sludge).

7
(No Transcript)
8
Physical Characteristics cont.
  • Odors Odors are caused by gases produced by
    anaerobic decomposition of wastewater (driven by
    microorganisms and limited oxygen).
  • Aerobic Respiration Organics O2 CO2 H2O
  • Anaerobic Respiration
  • Organics SO4-2 H2S odorous organics
  • Fermentation
  • Organics Reduced Organics odorous organics
  • Electron Acceptor
  • Various odorous compounds result

9
(No Transcript)
10
Sewer Crown Corrosion
  • - OrganicsSO4-2 H2S odorous organics
  • H2S is volatile, rises to the crown of sewer,
    and dissolves in water vapor. Crown is aerobic
    (O2).
  • H2S 2O2 H2SO4 (Bacteria ? sulfuric acid)
  • Crown caves in, expensive prevention and sewer
    maintenance / replacement.

  • water condensation
  • Aerobic

  • H2S 2O2 H2SO4
  • SO-2 H2S
  • Anaerobic

11
SEWAGE
  • Domestic wastewater is the ideal mixture of
    biodegradable nutrients and microorganisms
  • BOD (organics)
  • Nitrogen (N)
  • Phosphorus (P)
  • Miscellaneous Micronutrients (S, Fe, Ca, . . . )
  • Bacteria

12
Chemical Characteristics
  • Organics Predominant biodegradable fraction,
    BOD
  • -Protein -Fats, Oils, and
    Greases
  • -Carbohydrates -Surfactants (detergents)
  • -Urea
  • Priority pollutants
  • Industrial solvents, pesticides, etc.
  • Pre-treatment standards control concentrations to
    trace levels

13
Chemical Characteristics cont.
  • Inorganic Matter
  • Nitrogen from protein and urea.
  • NH2, NH3, NH4 forms ammonia and organics.
  • An essential nutrient for growth of bacteria.
  • Oxygen Demand
  • NH4 2O2 NO3- 2 H H2O

14
Chemical Characteristics cont.
  • Phosphorous phosphate (PO4-3)
  • Inorganic-detergents
  • organic-food and metabolic wastes
  • Trace nutrients S, Fe, Mn, Mg, Ca, K, Zn, Mo,
    etc. . . . . . plentiful

15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18
(No Transcript)
19
(No Transcript)
20
Mass Loading Calculations
  • Mass Conc x Flow Rate
  • mg/L x MGD x 8.34 x 1/24
  • lbs/hr
  • Mass Conc x Flow Rate
  • mg/L x ft3/sec x 0.22
  • lb/hr

21
Mass Balance Calculations
  • Fundamental Law Massin Massout
  • Massin Q1 x Conc1 Q2 x Conc2 (knowns)
  • Massout QT x ConcT
  • (unit constants cancel out)
  • QT Q1 Q2
  • ConcT unknown

22
Biological Characteristics
  • Most microorganisms known to microbiologists
    can be found in domestic wastewater.
  • Bacteria
  • Protozoa
  • Viruses
  • Algae (limited)

23
Population Equivalents
  • 1. Wastewater discharge 100 -120 gpcd
  • - 70 gpcd domestic
  • - 10 gpcd industrial/commercial
  • - 20 to 40 gpcd infiltration
  • 2. Suspended Solids and BOD
  • SS 0.2 lb pcd (without kitchen grinder)
  • SS 0.22 lb pcd (with kitchen grinder)
  • BOD 0.17 lb BOD pcd
  • BOD 0.26 lb BOD pcd (with kitchen grinder)

24
Population Equivalents cont.
25
(No Transcript)
26
Population Equivalents cont.
  • Used to
  • Establish population equivalency of an
    industrial waste.
  • Establish charge for treating industrial waste
    based on BOD or SS rather than flow.

27
(No Transcript)
28
Summary
  • Domestic wastewater is a well balanced, nutrient
    rich medium for bacterial decomposition.
  • After primary treatment, biodegradation is the
    most cost effective secondary treatment.
  • - Effective biodegradation requires
  • BODNP 10051
  • - Domestic wastewater contains 100205.
  • - Organics (BOD) limits N and P reduction.
  • Advanced treatment is required to
  • remove excessive N and P.
Write a Comment
User Comments (0)
About PowerShow.com