Sewage Disposal Systems Treatment and Recycling

Sewage Disposal Systems Treatment and Recycling - ARBU121

1. ARBU 121
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
SEWAGE
DISPOSAL
SYSTEMS
TREATMENT AND
RECYCLING
UNIVERSITY OF SAINT ANTHONY
COLLEGE OF ENGINEERING & ARCHITECTURE
INSTRUCTOR: AR. ALVIRIE CLAIRE A. BERMEJO-UVERO, UAP, RMP, LPT

2. ARBU 121
OVERVIEW
INTRODUCTION
SEWAGE DISPOSAL SYSTEM
SEWAGE TREATMENT
SEPTIC TANK
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS

3. Sewage treatment is the process of
removing contaminants from wastewater
and household sewage.
It includes physical, chemical, and biological
processes to remove physical, chemical and
biological contaminants.
Using advanced technology it is now possible
to re-use sewage effluent for drinking water,
although Singapore is the only country to
implement such technology on a production
scale.
Introduction
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121

4. BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
Sewage is generated
by residential,
institutional,
commercial and
industrial
establishments.
It includes
household waste
liquid from toilets,
baths, showers,
kitchens, sinks and
so forth that is
disposed of via
sewers.

5. In many areas, sewage also includes liquid
waste from industry and commerce. The
separation and draining of household waste
into grey water and black water is becoming
more common in the developed world, with
grey water being permitted to be used for
watering plants or recycled for flushing toilets.
Sewage can be treated close to where the
sewage is created, a decentralized system (in
septic tanks, bio-filters or aerobic treatment
systems), or be collected and transported by a
network of pipes and pump stations to a
municipal treatment plant, a centralized
system.
Introduction
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121

6. SEWAGE
DISPOSAL
SYSTEM

7. Means all interceptor sewers,
storm sewers, sanitary
sewers, combined sanitary
and storm sewers, sewage
treatment plants, and all
other plants, works,
instrumentalities, and
properties used or useful in
connection with the collection,
treatment, and disposal of
sewage and industrial wastes,
and includes a storm water
drain system under the
jurisdiction and control of a
governmental agency.
SEWAGE DISPOSAL
SYSTEM
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121

8. Private Sewage Disposal
System – a septic tank
with the effluent
discharging into a
subsurface disposal field,
seepage pits or of such
other facilities as may be
permitted by the
plumbing code.
PRIVATE SEWAGE
DISPOSAL SYSTEM
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121

9. TYPES OF SEWAGE DISPOSAL SYSTEM
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
a non-watertight lined
excavation in the ground
which receives the discharge
of a sanitary drainage
system or part thereof,
designed to retain the
organic matter and solids
discharging therefrom, but
permitting the liquid to seep
through the bottom and
sides of the cesspool (Sec.
204.5). Cesspools are no
longer acceptable as a
means of sewage disposal.
1. Cesspool

10. TYPES OF SEWAGE DISPOSAL SYSTEM
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
is a concrete
vault
constructed for
the collection of
raw sewage
sealed with a
wooden shelter
(obsolete).
2. Privy

11. TYPES OF SEWAGE DISPOSAL SYSTEM
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
A covered watertight
tank for receiving the
discharge from a building
sewer, separating out the
solid organic matter
which is decomposed
and purified by
anaerobic bacteria, and
allowing the clarified
liquid to discharge for
final disposal.
3. Septic Tank

12. TERMS
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
The liquid waste containing animal or
vegetable matter in suspension or
solution that passes through a sewer.
SEWAGE
A layer of sewage matter that rises to the
surface of the sewage in a septic tank.
SCUM
Sediment that settles out of sewage,
forming a semi-solid mass on the
bottom of a septic tank.
SLUDGE
Liquid sewage that has been treated in a
septic tank or a sewage treatment plant.
EFFLUENT

13. TYPES OF SEWAGE DISPOSAL SYSTEM
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
a loosely lined excavation in
the ground, which receives
the discharge of a septic tank
and designed to permit the
effluent from the septic tank
to seep through pit bottom
and sides (Sec. 220.6).
Each seepage pit shall be
circular in shape and shall
have an excavated diameter
of not less than 2.20 meters.
4. Seepage Pits

14. TYPES OF SEWAGE DISPOSAL SYSTEM
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
Distribution lines shall be
constructed of clay tile laid open
joints, perforated clay pipe,
perforated bituminous fiber pipe,
perforated HDPE pipe, perforated
ABS pipe, perforated PVC pipe, or
other approved materials,
provided that sufficient openings
are available for distribution of the
effluent into the trench area.
Minimum spacing of lines, center-
to-center is 1.80 meters.
5. Disposal Field or
Sanitary Drainfield

15. TYPES OF SEWAGE DISPOSAL SYSTEM
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
Is a public sewer
system, operated and
maintained by the
government consisting
of a sewage treatment
plant that conveys the
raw sewage from
buildings and houses to
a disposal system.
6. Public Sewer Line

16. SEWAGE
TREATMENT

17. STAGES OF TREATMENT
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
Sewage treatment generally involves
four stages, called Preliminary,
Primary, Secondary and Tertiary
treatment.
Pretreatment removes materials that
can be easily collected f rom the raw
sewage before they damage or clog
the pumps a nd sewage lines of
primary treatment clarifiers.
Objects that are commonly removed
during pretreatment include trash,
tree limbs, leaves, branches, and
other large objects .

18. STAGES OF TREATMENT
ARBU 121

19. STAGES OF TREATMENT
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
Screening: bar screen to remove
all large objects like cans, rags,
sticks, plastic packets etc.
carried in the sewage stream
Grit removal: include a sand or
grit channel or chamber , where
the velocity of the incoming
sewage is adjusted to allow the
settlement of sand, grit, stones,
and broken glass.
1. PRELIMINARY TREATMENT

20. BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
Flow equalization: Basins provide a
place to temporarily hold incoming
sewage during plant maintenance.
include provisions for bypass and
cleaning, and aerators as well.
Fat and grease removal: passing
the sewage through a small tank
where skimmers collect the fat and
grease floating on the surface.
STAGES OF TREATMENT
1. PRELIMINARY TREATMENT

21. BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
It consists of temporarily holding the
sewage in a quiescent basin where
heavy solids can settle to the bottom
while oil, grease and lighter solids float
to the surface. The settled and floating
materials are removed and the
remaining liquid may be discharged or
subjected to secondary treatment.
The solids that collect at the bottom of
the tank are called primary sludge and
are pumped from the tank for
treatment elsewhere in the plant.
STAGES OF TREATMENT
2. PRIMARY TREATMENT

22. The sludge which settles in the
sedimentation basin is pumped to the
sludge digesters where a temperature
of 30– 35 C is maintained.
0
This is the optimum temperature for
the anaerobic bacteria (bacteria that
live in an environment that does not
contain oxygen).
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
STAGES OF TREATMENT
2. PRIMARY TREATMENT
The usual length of digestion is 20 –30 days but can be much longer
during winter months. Continual adding of raw sludge is necessary and only
well-digested sludge should be withdrawn, leaving some ripe sludge in
the digester to acclimatize the incoming raw sludge.

23. Drying beds: Digested sludge is placed
on drying beds of sand where the
liquid may evaporate or drain into the
soil. The dried sludge is a porous
humus -like cake which can be used
as a fertilizer base.
Trickling filters: The liquid effluent
from the primary settling tank is
passed to the secondary part of the
system where aerobic decomposition
completes the stabilization. For this
purpose, a trickling filter is used.
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
STAGES OF TREATMENT
2. PRIMARY TREATMENT

24. A trickling filter is a fixed bed, biological filter that
operates under (mostly) aerobic conditions. Pre-
settled wastewater is ‘trickled’ or sprayed over the
filter. As the water migrates through the pores of the
filter, organics are degraded by the biomass covering
the filter material to carbon dioxide and water while
generating new biomass.
The Trickling Filter is filled with a high specific surface-
area material such as rocks, gravel, shredded PVC
bottles, or special pre-formed filter-material. Filter is
usually 1 – 3 m deep but filters packed with lighter
plastic filling can be up to 12 m deep.
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
STAGES OF TREATMENT
2. PRIMARY TREATMENT

25. The bed consists of crushed rock or slag (1– 2 m deep) through which the
sewage is allowed to percolate. The stones become coated with a zoogloeal
film (a jelly- like growth of bacteria, fungi, algae, and protozoa), and air
circulates by convection currents through the bed.
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
STAGES OF TREATMENT
2. PRIMARY TREATMENT

26. It removes dissolved and
suspended biological matter.
Secondary treatment is typically
performed by indigenous, water-
borne micro-organisms in a
managed habitat.
Secondary treatment may require a
separation process to remove the
micro-organisms from the treated
water prior to discharge or tertiary
treatment.
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
STAGES OF TREATMENT
3. SECONDARY TREATMENT

27. Secondary or biological treatment is performed in a tank containing
a "soup" of starved microbes called activated sludge.
These microbes require air to live (they are aerobic organisms) and
thus air is pumped into the tank.
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
STAGES OF TREATMENT
3. SECONDARY TREATMENT

28. During aeration and mixing, the bacteria form
small clusters, or flocs. When the aeration
stops, the mixture is transferred to a
secondary clarifier where the flocs are
allowed to settle out and the effluent moves
on for further treatment or discharge. The
sludge is then recycled back to the aeration
tank, where the process is repeated.
The liquid portion then flows over a wall at
the surface of the settling tank to be
chlorinated and released to a receiving
stream.
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
STAGES OF TREATMENT
3. SECONDARY TREATMENT

29. Tertiary treatment can be
employed to further reduce the
solids and organic content of the
effluent. This treatment can
employ conventional processes
with an increased detention time
to allow for greater removals, or
the operations installed for tertiary
treatment can involve more exotic
and expensive equipment such
as electro dialysis units or ion
exchange columns.
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
STAGES OF TREATMENT
4. TERTIARY TREATMENT

30. In tertiary treatment, emphasis is placed on absorptive processes,
such as the use of activated carbon; more efficient oxidation, as
with ozone; foam separation of impurities; and demineralization
using reverse osmosis or distillation.
Treated water is sometimes disinfected chemically or physically
(for e.g. by lagoons and microfiltration) prior to discharge into a
stream, river, bay, lagoon or wetland, or it can be used for the
irrigation of a green areas or park. If it is sufficiently clean, it can
also be used for groundwater recharge or agricultural purposes.
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
STAGES OF TREATMENT
4. TERTIARY TREATMENT

31. BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
STAGES OF TREATMENT

32. SEPTIC
TANK

33. Septic tanks may be used to serve
small installations where the
effluent can be disposed of
through leaching wells, subsurface
tile systems, or artificial
subsurface filter systems.
When sewage enters a septic
tank an equal volume of liquid is
discharged from the tank. The
primary purpose of the septic tank
is to condition the sewage so that
the discharged liquid will not clog
the disposal system.
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
SEPTIC TANK

34. A septic tank combines two
processes. Sedimentation takes place
in the upper portion of the tank, and
the accumulated solids are digested
by anaerobic decomposition in the
lower portion.
As sewage from a building enters a
septic tank, its rate of flow is reduced
so that the heavier solids sink to the
bottom and the lighter solids
including fats and grease rise to the
surface. These solids are retained in
the tank, and the clarified effluent is
discharged.
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
SEPTIC TANK

35. Further treatment of the effluent,
including the removal of pathogens,
is effected by percolation through
the soil. In order not to disturb the
bacterial action of the septic tank,
disinfectants and bleach must
never be flushed down toilets
connected to septic tanks.
A septic tank servicing an average
size home of five people will need to
be de-sludge every three to five
years.
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
SEPTIC TANK

36. Septic tank capacity should equal a
full days flow plus an allowance of
from 15–25% for sludge capacity.
The minimum desirable size of the
tank is 2000 liters. The tank’s length
should not be less than two or three
times the width; liquid depth should
not be less than 1.2 m for small tanks
and 1.8 m for large tanks.
Manholes should be provided over the
inlet and outlet pipes for observation
and maintenance.
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
SEPTIC TANK

37. The scum layer at the top of the septic
tank contains grease, oils, soap films
and other materials that are lighter than
water. Both aerobic and anaerobic
bacteria are found in the scum layer.
The anaerobic bacteria are the
dominant kind in this layer.
As the bacteria digest the scum at the
top layer of the tank, the digested
wastes from the bacteria become
heavier than water and sink to the
bottom of the septic tank to settle on
the sludge layer.
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
SEPTIC TANK

38. Key components of a Septic Tank
Base: The base is usually constructed of
plain concrete with the thickness of about
100-150 mm. This is the minimum thickness
required to withstand the uplift pressure
when the tank is empty. The base also acts
as a foundation for the side walls. A designer
may also reinforce the base slab in larger
tanks.
Side Walls: The side walls of the septic tank
are made of brick, stone masonry or
concrete. The septic tank must be
watertight. The quality can be assessed
through a water tightness test.
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
SEPTIC TANK

39. Manhole: The manhole provides an
access to the compartments in the
septic tank. The manhole should be made
of medium duty cast iron, with a
minimum dimension of 20 inches or
equivalent and with a removable cover in
each compartment.
Inlet and Outlet: The correct installation
of the inlet and outlet are critical in the
performance of the septic tank.
The wastewater must enter and leave the
tank with minimum disturbance. The
arrangement of inlet and outlet with the
minimum required dimensions as shown.
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
SEPTIC TANK
Arrangement of Inlet and
Outlet with Dimensions

40. Baffle Wall: The baffle wall prevents the scum
from flowing out of the septic tank without
treatment. It also facilitates in the smooth
settling of the sludge. The baffle wall has slots
or openings that allow the sewage to flow
from one compartment to another.
Ventilation: The decomposition of the organic
wastes produce gases and the safe exit of the
gases must be provided in the septic tank. The
simplest option is to install a vent pipe with a
screen on the roof slab of the septic tank.
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
SEPTIC TANK

41. 1. The concrete septic tank is usually
constructed in a regular form to retard the
even flow of the waste to avoid disturbing the
decomposition processes inside the tank.
2. The minimum inside dimension of a septic
tank is 90 cm wide by 150 cm long.
3. For effective decomposition of the organic
materials inside the septic tank, a 120 cm
depth of the liquid content is necessary.
4. The inlet and outlet inverts of the septic
tank shall be long turn sanitary tee. The
inverts are installed in the wall of the tank at
least 120 cm from its bottom floor equally
spaced from both sides.
5. The invert is extended down the liquid of the
tank not more than 30 cm to assure smooth
delivery of the incoming sewage below the
scum line.
PARAMETERS IN
SEPTIC TANK DESIGN
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121

43. 6. The bottom of the digestion chamber
should be sloped to one low point to
gather the settled organic materials into
one mass to favor the propagation of
the anaerobic bacteria.
7. The septic tank should be provided
with a manhole extended a few
centimeters above the surface of the
soil to overcome infiltration of surface
water.
8. The septic tank should be
constructed near the surface of the
ground, because the correction of the
waste depends upon the extent of
oxidation and the existence of
anaerobic bacteria.
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
PARAMETERS IN
SEPTIC TANK DESIGN

44. 1.Septic Tank shall be cleaned before
excessive sludge or scum is allowed to
accumulate and seriously reduce the
settling efficiently.
2.Septic Tank shall be inspected at
least once a year and be cleaned
when the bottom of the scum mat is
within 7.50 (3 inches) of the bottom of
the outlet device or the sludge and
scum has reduced the liquid capacity
by 50% .
3.Tanks shall not be washed or
disinfected after cleaning.
4.Sludge from septic tanks shall be
disposed of by burial or any approved
method.
Maintenance of
Septic Tank
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121

45. THANK YOU
for listening, Future Architect :)
BUILDING UTILITIES 1: PLUMBING AND SANITARY SYSTEMS
ARBU 121
REFERENCES:
REVISED PLUMBING CODE OF THE PHILIPPINES
KOLEKAR, P. (N.D.). SEWAGE DISPOSAL. SLIDESHARE. HTTPS://WWW.SLIDESHARE.NET/SLIDESHOW/SEWAGE-DISPOSAL-249396109/249396109#2
SCRIBD. (N.D.-B). SEWAGE TREATMENT. SCRIBD. HTTPS://WWW.SCRIBD.COM/DOCUMENT/548998400/SEWAGE-TREATMENT
SCRIBD. (N.D.-B). SEWAGE DISPOSAL SYSTEM. SCRIBD. HTTPS://WWW.SCRIBD.COM/DOCUMENT/424983204/SEWAGE-DISPOSAL-SYSTEM
SCRIBD. (N.D.-C). SEWAGE DISPOSAL SYSTEMS, TREATMENTS AND RECYCLING. SCRIBD. HTTPS://WWW.SCRIBD.COM/PRESENTATION/221369500/SEWAGE-DISPOSAL-SYSTEMS-TREATMENTS-AND-RECYCLING
BASHIR, N. (N.D.). WASTE WATER TREATMENT PPT. SLIDESHARE. HTTPS://WWW.SLIDESHARE.NET/SLIDESHOW/WASTE-WATER-TREATMENT-PPT/69779935
SCRIBD. (N.D.-A). 08 DESIGN OF SEPTIC TANK. SCRIBD. HTTPS://WWW.SCRIBD.COM/DOCUMENT/648540543/08-DESIGN-OF-SEPTIC-TANK