This document discusses sewage quality and collection systems. It introduces important terms related to sewage and waste water. There are two main methods for collecting sewage - dry/conservancy systems where waste is manually collected and water carriage systems where waste is transported via pipes and mixed with water. Water carriage systems are preferred as they are more hygienic and do not require manual labor. The document also covers sources of sewage, estimating sewage flow quantities, types of sewer systems based on materials and shapes used, and formulas for designing circular sanitary sewers.

1. ENVIRONMENTAL
ENGINEERING II
UNIT I
SEWAGE QUALITY

2.  NECESSITY OF SANITATION
-Creates harmful bacteria
-Increase BOD
-Creates environmental hazard

3. IMPORTANT TERMS
 Sewer- pipes carrying waste water.
 Sewage- liquid waste originate from a community &
generally conveyed by sewer is called sewage.
 Sullage- waste water from kitchen, wash basin,
bathrooms etc.
 Effluent- an out flowing of water from natural water
body or from manmade structure.

4. TYPES OF SEWAGE
-Domestic sewage
-Industrial sewage
-Sanitary sewage (Domestic & Industrial sewage)
-Storm sewage
-Night soil

5.  COLLECTION OF SEWAGE
- Dry or conservancy system of collection
- Water carriage system of collection
- Dry or conservancy system of collection:-
- In this method, night soil in latrines removed manually &
transported in vehicles to point of disposal.

6.  Advantages
- Initial cost is low
- Total quantity of sewage carried to treatment unit is small.
 Disadvantages
- More unhygienic.
- Labour dependant.
- Difficult to provide side gutters in crowded lanes.

7.  Water carriage system
-night soil gets mixed with sufficient quantity of waste water
in this methods.
 Advantages
- Removal of sewage in covered conduits
- It ensure hygienic conditions.
- No labours are needed to carry out this type of unhealthy
works.

8.  Disadvantages
- High initial cost
- Need regular maintenance
- During monsoon, there is load on treatment and
during summer more water is required.

9.  SEWERAGE SYSTEM
1. The combined system
2. The separate system
3. The partially separate system
 SOURCES OF SEWAGE
-Industrial sources
-Domestic sources
-Public sources
-Ground water infiltration sources
- Storm water sources

10.  FLOW QUANTITY ESTIMATION
- It is essential to find out accurate estimate of the sewage
discharge for the hydraulic design of the sewers.
 VARIATION IN SEWAGE FLOW
POPULATION PEAK FACTOR
UPTO 20,000 3.5
20,000-50,000 2.5
50,000-75,000 2.3
GREATER THAN 75,000 2.0

11.  TYPES OF SEWER BASED ON MATERIAL
- Steel Sewer
- Cast- Iron Sewer
- Concrete Sewer
- Brick Sewer
- Stone Ware Sewer
- Plastic Sewer
- Asbestos cement Sewer

12.  TYPES OF SEWERS BASED ON SHAPE
- Circular Sewer
- Rectangular Sewer
- Semi elliptical Sewer
- Egg shaped Sewer
- Horse shoe Sewer
- U- shaped Sewer
- Parabolic Sewer

13.  DESIGN OF CIRCULAR SANITARY SEWERS
1. Chezy’s Formula
V = C√mi
2. Bazin’s formula
C = 157.6
1.81+ k
√m