topic 9: sewage disposal system Flashcards
_____ is the final stage of the plumbing process.
disposal phase
_____ is where used water and
water-carried wastes are brought to various disposal units.
disposal phase
____ is a watertight covered receptacle designed constructed to receive the discharge of sewage from a building sewer, separate solids from the liquid, digest organic matter and store the clarified liquids through a period of detention, and allow the clarified liquids to discharge the final disposal.
septic tanks
What are the 3 substances found inside the septic tanks?
- effluent
- sludge
- scum
_____ is the liquid content of sewage.
effluent
_____ is any solid organic matter that are denser than water and settle at the bottom of the septic tank.
sludge
____ is the lighter organic material that rise to the surface of the water.
scum
What are the 2 types of bacteria in septic tank to encourage decomposition?
- aerobic bacteria
- anaerobic bacteria
_____ relies on oxygen to survive.
aerobic bacteria
____ can survive in places without oxygen.
anaerobic bacteria
The very common bacteria/system used here in the Philippines is the _____.
anaerobic system
Aerobic systems have ______, which is a device that supplies oxygen from the outside into the system.
aerator
What are the minimum dimensions of e two-compartment septic tank?
L = 1500 mm
W = 900 mm
D = 1200 mm
What are the 13 parts of the design phase of the septic tank?
- plans
- quality of design
- materials
- compartments
- manholes
- size of pipe inlet and outlet and their vertical legs
- length and location of inlet and outlet
- vent diameter
- air space
- partition
- structure
- capacity
- location
______ should show all dimensions, reinforcing, structural calculations, and such other pertinent data as needed.
plans
______ shall be such as to produce a clarified effluent of acceptable standards and shall provide adequate space for sludge and scum accumulations.
quality of design
_____ specifies that septic tanks should be constructed of durable materials, not subjected to excessive corrosion or decay, shall be watertight.
materials
Septic tanks are made of cement (most common) or prefabricated cast iron.
materials
Septic tanks have a minimum of _____ compartments.
2
_____ is not less than 2/3 capacity of the total capacity of the tank; not less than 2 cu.m. liquid capacity; shall be at least 0.9m width and 1.5m long; liquid depth not less than 0.6m nor more than 1.8m.
first compartment
_____ has a minimum of 1 cu.m. liquid
capacity.
second compartment
Septic tanks having over 6 cu.m. capacity, the secondary compartment should not be less than ______ in length.
1.5m
Maintain a slope of _____ at the bottom of the digestion chamber to collect the sludge and make it easily accessible from the manhole.
1:10
Septic tanks with at least two manholes, _____ in minimum dimension; one over inlet, other over outlet.
508mm
Septic tanks wherever first compartment exceeds ____ in length, an additional manhole required over the baffle wall.
3.7m
______ diameter size not less than the
sewer pipe.
inlet and outlet pipes
Vertical Legs of Inlet and Outlet Pipes - diameter size not less than the sewer pipe nor less than ______.
104.6mm
Length and location of inlet and outlet shall extend _____ above and at least _____ below the water surface.
101.6mm, 304.8mm
Invert of the inlet pipe shall be at a level not less than ______ above the invert of the outlet pipe.
50.8mm
______ is equal to the cross-sectional area of the house sewer.
vent diameter
To facilitate air space in septic tanks, side walls shall extend _____ above the liquid depth.
228.6mm
Air space in septic tanks - Cover of septic tank shall be at least _____ above the back vent openings.
50.8mm
An inverted fitting equivalent in size to the tank inlet, but in no case less than 104.6mm in diameter, shall be installed in
the inlet compartment side of the baffle with the bottom of the fitting placed midway in the depth of the liquid.
partition (between compartments)
____ baffles are prohibited as partition between compartments of septic tanks.
wooden
The structure of a septic tank shall be capable of supporting an earth load of not less than ______.
14.4 kPa
The ______ of the septic tank is determined by the number of bedrooms or apartment units in dwelling occupancies; by the estimated waste/sewage design flow rate for various building occupancies, whichever is greater.
capacity
The capacity of any one septic tank and its drainage system shall also be limited by the _____ in its drainage field.
soil structure classification
The location of the septic tanks should not be located ______ the house.
underneath
The location of the septic tanks should at least be _____ from the water distribution system.
15 m
What are the 3 degrees/grades of wast water?
- grey water
- black water
- storm water
_____ a.k.a. area water is waste water with the exception of human wastes.
grey water
____ is from laundries, wash basics, sinks, tubs, etc.
grey water
____ is water plus solid and liquid human wastes.
black water
____ is rainwater only.
storm water
What are the 2 classifications of sewers?
- storm sewer
- sanitary sewer
_____ are drains that carry surface water run-off.
storm sewer
_____ carries regular sanitary wastes only, terminates in a modern sewage disposal plant for treatments.
sanitary sewer
Sanitary sewers are built at a depth of _____.
3 m
____ are the oldest variety of sewers which carries both storm and sanitary wastes.
combination public sewer
What are the 2 types of sanitary sewer?
- tributary sewer
- intercepting sewer
_____ are termination points of individual units or structures.
tributary sewer
Tributary sewer are usually round-shaped, with diameters between ______ made of vitrified clay or cement pipes; often installed by the curb line, before the street.
0.6 to 1.2 m
____ is normally laid in the Northern or Eastern side of streets with east-west or north-south orientations.
tributary sewer
____ a.k.a. “collecting sewer”. These are termination points of tributary sewers.
intercepting sewers
Intercepting sewer are placed much lower in the ground, from _____meters in
depth.
4 to 30
Intercepting sewers varies in shape but have a diameter or effective opening
ranging from _____ meters.
0.6 to 3.0
_____ are sloped at an angle of 1:50 or 2%.
intercepting sewers
What are the 3 requirements of sewers?
- drainage pipers of all buildings shall be connected to the public sewer. (or private sewage system)
- public sewer may be considered as not available if its is more than 61 meters from any proposed building or exterior drainage facility.
- exception: single family with an existing private sewage system may not be connected to a new public sewer when no hazard, nuisance is evident.
What are the 4 damage to public sewer or private sewage disposal system?
- it is unlawful to discharge any ashes, cinders, solids, rages, flammable, poisonous, explosive liquids or gases, oils, grease, and other things whatsoever which would cause damage to the public sewer or private disposal system.
- no rain, surface or subsurface waters shall discharge into any excreta drainage system.
- no cesspool and septic tank effluents, seepage pit or under drain system shall be connected to the excreta building sewer leading to a public sewer main.
- no commercial food waste grinder shall be connected to a private or public sewage disposal system.
The minimum size of any building sewer shall be determined on the basis of the _____ by such sewer.
total number of fixture units drained
No building sewer shall be smaller than _____ diameter nor less in size than the building drain.
150 mm
In the installation of sewers, building sewers shall be run in practical alignment at a uniform slope of not less than _____ toward the point of disposal.
2% or 21 mm/m
Exception to the installation of sewer: when impractical due to depth of street sewer, structural features or to adverse arrangement of building, to obtain a slope of 2%, sewers ___ and _____ in dia
may have a slope of not less than 1% (10.5 mm/m) and those ____ dia and larger may have a slope of not less than
0.5% (5.3 mm/m).
slope not less than 1% - sewers 102 mm, 152 mm dia
slope not less than 0.5% - 203 mm dia
No building sewer shall be installed less than ____ from the outer face of any building foundation, nor less than ____ below the finish surface of the ground.
0.6 m, 0.3 m
Location of building sewer in relation to other services is shown below.
1. ____ m from any building or structure
2. ____ m from water supply wells
3. ____ m from streams
4. ____ m from domestic supply pipes
5. ____ m from public water main
- 0.60m
- 15.2 m
- 15.2 m
- 0.30 m
- 0.30 m
Building sewer or drainage pipe of clay or materials which are not approved for use within a building shall not be laid in the same trench as water pipes unless:
- the bottom of the water pipe is _____ above the top of the sewer pipe (NPC 1208.1.1).
- the water pipe is placed on a solid shelf excavated at one side of the common trench with a minimum horizontal distance of at least _____ from the sewer or drain pipe (NPC 1208.1.2).
0.3m, 0.3 m
Water pipes crossing sewer or drainage pipe of clay or materials which are not approved for use within a building
shall be laid a minimum of _____ clear above the sewer or drain pipe.
0.3 m
Water pipe joint shall be installed not less than _____ away from sewer line in both directions.
3 meters
_____ are private sewage disposal system common in rural areas for structures with large adjacent open fields.
disposal fields
The ____ of disposal fields are dependent on the required septic tank capacity or
estimated sewage flow rate, whichever is greater, and; the .type of soil found in the excavation.
area
Distance of disposal fields from water table - No excavation for leach bed shall extend within _____ of the
water table.
1.5 m
Filter material in the trenches shall terminate 1.5 m from pit excavation and the pipe extending from such points to the seepage pit shall be watertight.
disposal fields with seepage pit
_____ is a loosely lined excavation in
the ground, which receives the discharge of a septic tank.
seepage pits
_____ is designed to permit effluent to seep through pit bottom and sides.
seepage pits
The ____ of seepage pits are based on the quantity of liquid waste and on the character and porosity of the surrounding soil.
capacity
The size of seepage pits - Circular in shape with excavated diameter of not less than _____ and to be lined with clay or concrete brick.
2.2 m
The brick lining of seepage pits shall have a minimum compressive strength of ____.
17225 kPa
_____ is served through a distribution box or shall be connected in series by means of a watertight connection.
multiple seepage pits
The outlet of multiple seepage pits shall have a vented leg fitting extending ____ below the inlet fitting.
304.8 mm
_____ is a non-watertight lined excavation in the ground which receives the discharge of a sanitary drainage system, designed to retain the organic matter but permitting the liquid to seep through the pit bottom and sides.
cesspools
Temporary expedient pending the construction of a public sewer, so long as it is established that a public sewer will be available in less than ____ and the soil and ground water conditions are favorable.
2 years
What are the 3 conditions on which temporary permits disposal fields?
- pending on the construction of a public sewer, so long as it is established that a public sewer will be availabel in less than 2 years and the soil and ground water conditions are favorable.
- as an overflow facility when installed in conjunction with an existing cesspool.
- as a means of sewage disposal for limited, minor, or temporary uses.
____ are the oldest form of disposal of organic waste.
outside privy
_____ consists of a vault constructed of concrete for the collection of raw sewage and a wooden shelter.
privies
What is the requirement of commercial/industrial special liquid waste disposal?
when liquid wastes containing excessive amounts of grease, garbage, flammable wastes, sand, or other ingredients which may affect the operation of a private sewage disposal system, an interceptor for such waste shall be installed.
Waste from _____ may be discharged to a septic tank or other primary system or into a separate disposal system.
interceptors
What are the 6 features of an STP (Sewage Treatment Plant)?
- an aeration system within the tank
- a submersible mixer to mic the waste
- a sludge wast pump that aids in clarifying
- a decanter
- blowers
- a fully electronic control system
What are the 2 most common types of municipal sewage treatment?
- active sludge process
- trickling filter process
_____ type of municipal sewage treatment cannot be seen in the Philippines.
trickling filter process
_____ involves a series of stations where the raw sewage must pass through.
active sludge process
The active sludge process has ____ phases.
3
____ phase of active sludge process gets rid of heavy materials with the use of three different filter houses.
first phase
____ phase of active sludge process clarifies the effluent.
second phase
____ phase of the active sludge process hardens the sludge and converts it to fertilizers.
third phase
The active sludge process produces water with _____ purity.
99 - 99.5%
What are the 13 steps in the active sludge process?
- grit chamber
- course screen house
- fine screen house
- incinerator
- activated sludge tank
- aeration basin
- clarifier
- power house
- drier house
- liquid extractor house
- chemical house
- warehouse
- vacuum power house
____ a.k.a. ‘Percolating or Sprinkling Filter System’.
trickling filter process
____ requires less mechanical elements and less stages.
trickling filter process
Trickling filter process produces water with _____ purity.
95%
_____ requires a large ground area for its building.
trickling filter process
