desposal by dilution
DESCRIPTION
desposal by dilutionTRANSCRIPT
DISPOSAL BY DILUTION
introduction
The study of the sources of disposal is
important, because the amount of
treatment required to be given to
sewage depends very much upon the
source of disposal.
Disposal By DilutionThis process where the treated sewage
or the effluent from the sewage
treatment plant is discharged into a river
stream.
The discharged sewage, in due course of
time is purified by what is known as self
purification process of natural waters
Disposal of sewage effluentsDilution i.e. disposal in water ; and
Effluent Irrigation or Broad Irrigation or Sewage
Farming i.e. disposal on land
{Disposal by dilution is common of these two}
Conditions favoring Disposal By DilutionWhen sewage comparatively fresh(4 - 5 hrs. old),
and free from floating and settle able solids.When the diluting water (i.e. the source of
disposal ) has a high dissolved oxygen (D.O) content.
Where diluting waters are not used for the purpose of navigation on the down stream from the point of sewage disposal
When the out fall sewer of the city or the treatment plant is situated near some natural waters having large volumes
The bureau of Indian Standards
(BIS),previously known as Indian
Standard Institution (ISI), has there for
laid don it’s guiding standards for
sewage effluents ,vide IS 4764 -
1973,and for industrial effluents vide IS
:2490-1974 as shown in the table
Bureau of Indian Standards
Standards of Dilution Based on Royal commission Report
Dilution Factor Standards of purification required
Above 500 No treatment is required .Raw sewage can be directly discharged into the volume of dilution water
Between 300 to 500 Primary treatment such as plain sedimentation should be given to the sewage
Between 150 to 300 Treatments such a sedimentation, screening and essentially chemical precipitation are required
Less than 150 Complete thorough treatment should be given to sewage
Dilution in Rivers and self Purification of Natural Streams
The automatic purification of
polluted water by dilution.
sedimentation, oxidation-reduction
in sunlight, etc in due course is
called Self Purification Phenomenon
BIS STANDARD FOR DISCHARGE OF SEWAGE AND INDUSTRIAL EFFLUENT IN SURFACE WATER SOURCE
AND PUBLIC SEWERS:
GENARAL STANDARDS FOR DISCHARGE OF ENVIRONMENT POLLUTANT FROM EFFLUENT INTO SURFACE WATER SOURCE,
PUBLIC SEWERS, AND MARINE COASTS UNDER ENVIRONMENT(PROTECTION) RULE, 1986
Natural Forces of PurificationPhysical Forces
Dilution and dispersion
Sedimentation
Sunlight
Chemical Forces
Oxidation(bio)
Reduction
Dilution and dispersionWhen the putrescible organic matter is discharged
into a large volume of water contained in the river
stream, it gets rapidly dispersed and diluted . this
results in diminishing conc. of organic matter
When sewage of concentration Cs flows at a rate
Qs in to a river stream with conc. Cr flowing at rate Qr
Cs Qs + Cr Qr = C ( Qs+Qr)
SedimentationThe settle able solids, if present in
sewage effluents ,will settle down
into the bed of river, near the outfall
of sewage.
SunlightThe sunlight has a bleaching and
stabilizing effect of bacteria .It also helps
Certain micro – organisms to derive
energy, and it’s called photo synthesis
OXIDATION
THE OXIDATION IS A ORGANIC MATTER
PRESENT SEWAGE EFFLUENT, WILL START
AS SOON AS THE SEWAGE OUTFALL INTO
THE RIVER WATER CONTAINING DISSOLVED
OXYGEN
REDUCTION
REDUCTION OCCURS DUE TO HYDROLYSISOF
ORGANIC MATTER SETTLED AT THE BOTTOM
EITHER CHMICALLY OR BIOLOGICALLY.
ANAEROBIC BACTERIA WILL HELP IN
SPLITTING THE COMPLEX ORGANIC
CONSTIUTUENT OF SEWAGE INTO LIQUID
AND GASES, AND THUS PAVING THE WAY FOR
THEIR ULTIMATE STABILIZATION BY
OXYDATION.