Manoj Pandey

download Manoj Pandey

of 29

  • date post

    01-Jan-2017
  • Category

    Documents

  • view

    219
  • download

    0

Embed Size (px)

Transcript of Manoj Pandey

  • 2111 2005

    Ponds Manoj Pandey

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Decentralized wastewater treatment

    Constructed wetland

    Infiltration

    Package treeatment

    Pond systems

    STEP/STEG

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Waste Stabilization Ponds Waste stabilisation ponds

    (WSP) are typically man-made basins surrounded by an earthen embankment.

    The first recorded construction of a WSP in the US was at San Antonio, Texas, in 1901.

    The oldest WSP in Europe are probably the Fischteiche, built around 1920 in Munich (Germany).

    Anaerobic pond in Colombia (Ginebra) (IHE, 2003)

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Types of Pond

    Anaerobic

    Facultative

    Maturation (aerobic)

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Anaerobic Ponds

    Pond depth is usually between 3 to 5 meters and the HRT for ponds treating municipal sewage is between 1-3 days (for municipal sewage).

    3-5 m

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Anaerobic Ponds -Treatment Mechanism

    Sedimentation Sedimentation of non-degraded and degraded suspended

    particles

    Biological degradation Biological degradation is due to the anaerobic

    degradation of complex organic material

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Anaerobic ponds- degradation process

    Acetic acid

    Complex organic matter: proteins, carbohydrates, lipids

    Amino acids, sugars and fatty acids

    Volatile Fatty Acids: propionic acid, butyric acid. Alcohols

    Hydrogen

    Methane

    Hydrolysis

    acidogenesis

    acetogenesis

    methanogenesis

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Anaerobic Ponds -Treatment Process

    The rate of anaerobic processes depends highly on temperature, in particular the methanogenic bacteria accelerate their metabolic activity with temperature.

    At higher temperatures BOD is therefore more effectively removed, especially the BOD-dissolved.

    In cold climates anaerobic ponds mainly act as settling ponds

    In case the influent contains sulphate or nitrate, also sulphate reduction and denitrification is occurring.

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Anaerobic Pond Pollutant removal

    BOD removed by sedimentation and anaerobic decomposition

    Ammonia nitrogen removal by volatilization, algal uptake

    Nitrite reach infleunt may get denitrified

    Phosphorus removal is minimal

    Removal of bacterial pathogens in anaerobic ponds is poor (1 log unit faecal coliform reduction)

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Anaerobic Ponds - Odor

    Odour formation from anaerobic ponds is frequently reported.

    One of the main odorous compounds is H2S, the product of sulphate reduction.

    In a well designed and operated anaerobic pond the pH is kept in a range around 7.5. In this range most of the sulphide is present as the bisulphide ion, which has no odour.

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Anaerobic Ponds -Odor

    Odor Reduced By Raising the pH to around 8 by lime addition to prevent

    the formation of odorous H2S.

    Recirculation of final maturation pond effluent to the anaerobic pond. This measure will result in an aerobic top layer, in which sulphide is oxidised to sulphate.

    Reducing the applied organic loading rate by providing extra anaerobic ponds in parallel or by increasing the depth

    Stimulating the establishment of a scum layer on top of the anaerobic pond, for instance by spreading a thin layer of straw on the surface.

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Anaerobic ponds- Design

    Anaerobic ponds are designed on the basis of volumetric organic loading (kgCOD/m3/day).

    Van = Pond volume (m3) A = Surface are (m2) D = Average pond depth (m) BODin = Influent concentration (kgBOD/m3) Q = Flow rate (m3/day)

    = volumetric organic loading rate (kgBOD/m3/day) It is quite common to use pond systems in series of two or three

    modules for a full scale treatment.

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Anaerobic ponds- Design

    Volumetric organic loading v (kg BOD/m3/day) based on minimum month-averaged air temperature (0C)

    Temp < 10 0.10 (40 % removal)

    Temp 10-20 0.02 * Temperature 0.10 (then % remvola is -2* Temperature +20 )

    Temp >20 0.30 (60 % removal)

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Operation and maintenance

    Regular desludging The performance of anaerobic ponds may deteriorate

    when ponds are getting full with sludge.

    The accumulated sludge causes the HRT to decrease and this may prevent complete settling and digestion of particulate matter

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Facultative Pond

    Facultative ponds are the second treatment step in a pond system.

    Depth of pond -1.5 2.5 m deep earthen basin with an embankment slope of 1:3.

    Detention time 5 10 days.

    .

    Aerobic layer

    Anaerobic Layer

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Facultative Pond-Treatment mechanism

    sedimentation and anaerobic digestion.

    Sludge BOD removed -while desludging and anaerobically transformed into methan gas

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Facultative Pond-Treatment mechanism

    The oxygen produced by algal photosynthesis in the top layer is used for the decomposition of organic matter in deeper layers by heterotrophs.

    Symbiotic interrelationship referred to as Algae-Bacteria Symbiosis .

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Facultative Pond Pollutant removal

    BOD removed by sedimentation and aerobic and anaerobic decomposition

    Ammonia nitrogen removal by volatilization (during day time when pH is increase due to production of CO2), algal uptake , ammonification

    Nitrate -denitrified

    Phosphorus removal is minimal

    Removal of bacterial pathogens in anaerobic ponds is poor (1-2 log unit faecal coliform reduction)

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Facultative Ponds- Design

    Design based on organic surface loading rate load o (Kg BOD/ha/day) o = 10 * T (10

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Maturation Pond

    Maturation ponds are the final treatment step in a pond system.

    Depth of pond -1 1.5 m deep earthen basin with an embankment slope of 1:3.

    Detention time minimum 3 days., max 20 days

    .

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Maturation Pond Treatment mechanism

    Introduced to polish or upgrade facultative pond effluents and achieve substantial microbial reductions

    Active algal biomass is maintained throughout the entire depth of the system so that during daytime large amounts of oxygen are produced.

    Further stabilisation of organic matter and nutrient removal is accomplished mainly through aerobic bacteria

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Maturation Ponds Treatment mechanism

    Filtered effluent BOD values range from 20 to 60 mg/l, while TSS levels vary from 30 to 150 mg/l.

    Faecal coliform and virus die-off rates may reach over 3 to 4 log units.

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Ponds- Removal mechanisms of Faecal coliforms

    Adsorption to particles and subsequent sedimentation

    Grazing by other micro-organisms (protozoa)

    (Natural) decay FC deprive of food affected by adverse environmental

    conditions.

    UV radiation absorbed by the DNA molecules thus damaging the DNA molecule and causing cell death

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Maturation Pond - Design

    Designed to remove pathogens. Equation for completely mixed pond

    = No. Of FC in the influent, No./100 ml

    = No. Of FC in the effluent, No./100 ml

    = First order decay coefficient, day-1

    n = maturation pond in series, number

    = retention time, days

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Maturation Pond - Design

    Kd is taken as 2.6 day-1 200C

    Value of Kd can be corrected for other prevailing sewage temperatures.

    Retention time (t) usually 3-20 days

    Depth 1-1.5m

    L/W ratio = 3-10

  • NO

    RW

    EGIAN

    UN

    IVERSITY O

    F LIFE SCIENCES

    Pond Layout

    The basic units in WSP systems are anaerobic, facultative and maturation ponds.

    Anaerobic ponds are put in parallel to provide operational flexibility for sludge removal and distribution of settled solids

    Facultative or maturation ponds are put in series to