CE 333: Environmental Engineering II

Fall 2023 Semester

Level-3, Term II

Lecture-1: Introduction to Sanitation

Md.Yasin
Assistant Professor
Department of Civil Engineering
Ahsanullah University of Science and Technology (AUST)

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 To be covered:

• Classification of Wastes
• Definition of Sanitation
• Relationship between Sanitation and Health/ Disease
• Classification of Sanitation Systems

Md.Yasin, Asst. Professor, Department of Civil Engineering

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Textbook:
 • Water Supply and Sanitation (Rural and Low-income urban
communities) ___M. Feroze Ahmed
___Md.Mujibur Rahman

Md.Yasin, Asst. Professor, Department of Civil Engineering

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Classification of Wastes
Human Waste or Human Excreta: refers to only human feces and urine. Also
known as “night soil” when collected without dilution in large volumes of water.
 Municipal sewage/ wastewater: Liquid waste conveyed by sewer and may include
domestic and industrial discharge as well as storm water, groundwater infiltration
and inflow.

Domestic/ sanitary sewage: Liquid waste with originates in sanitary

conveniences, e.g., water closets, urinals, baths, sinks, etc. of dwellings,
commercial facilities and institutions in a community. Sometimes it is also referred
to as sanitary sewage.

Md.Yasin, Asst. Professor, Department of Civil Engineering

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Classification of Wastes (contd.)

Black water: Wastewater containing human waste (fecal matter, urine), i.e., toilet
wastewater. It contains pathogens and must be treated before releasing into
 environment.

Sullage or Greywater: Water coming from domestic equipment other than toilets
(e.g., bathtubs, showers, sinks, washing machines). It is often separated from
“black water” to reduce the amount of water that gets heavily polluted.

Separation of black water and greywater nowadays happens with all ecological/
smart buildings. Greywater could be reused for different purposes (other than
potable use) after primary treatment.

Md.Yasin, Asst. Professor, Department of Civil Engineering

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Classification of Wastes (contd.)

Industrial Wastes: Liquid discharges from different industrial processes such as

 manufacturing and food processing.

Storm water: Surface runoff immediately and after rainfall, which enters sewers
through inlets. Strom water is usually not very polluted, and could be carried
though open drains/ channels and disposed of in rivers/ streams/ khals.

Solid waste: Includes all materials which are normally solid and are discarded as
useless or unwanted.

Md.Yasin, Asst. Professor, Department of Civil Engineering

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Some Important Terms

Faecal sludge: Sludge removed from all kinds of on-site sanitation systems such as
 septic tanks, pit latrines, community multiple pit system, etc.

Faecal Sludge Management (FSM): Also known as septage management, FSM

includes the various technologies and mechanisms for collection, transportation,
treatment and disposal of sludge produced by septic tanks, pit latrines, and
wastewater treatment plants.

Septage: Faecal sludge (settled solids, scum and liquid) that accumulates in septic
tanks.

Md.Yasin, Asst. Professor, Department of Civil Engineering

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Some Important Terms

 Sewage Sludge: Sludge generated at the sewage treatment plants as a result of
sewage digestion process is termed as sewage sludge. Sewage sludge is often
more problematic than faecal sludge from household toilet facilities because it
contains contaminants from industrial wastewaters.

Desludging: This refers to the process of cleaning or removing the accumulated

sludge/ septage from a septic tank, pit latrine or wastewater treatment facility.

Biosolids: This usually refers to treated faecal sludge or by-product of the

treatment of domestic sewage in a sewage treatment plant. Biosolids consist
primarily of digested organic matter and dead microbes and can be used as
organic fertilizer or soil conditioner.

Md.Yasin, Asst. Professor, Department of Civil Engineering

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Sanitation
 “Sanitation” may be defined as the science and practice of effecting healthful and
hygienic conditions, and involves the study and use of hygienic measures, such as:

• Safe and reliable water supply

• Proper disposal of all “human waste”
• Proper drainage of wastewater
• Prompt removal of all solid waste

WHO includes food sanitation, rainwater drainage, solid waste disposal and
atmospheric pollution under sanitation.

However, the term “sanitation” commonly refers to disposal of “human waste /

wastewater”.

Md.Yasin, Asst. Professor, Department of Civil Engineering

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Sanitation and Disease

 • Proper sanitation can control many “human waste/ excreta” related diseases.
• Important to have clear understanding of such diseases and their
“transmission routes”.
• Excreta-related diseases are caused by disease producing microorganisms,
called “pathogens”.

Common diseases caused by pathogens:

• Bacteria: Cholera, Bacillary dysentry, typhoid, and para-typhoid

• Viruses: Hepatitis, Poliomylitis, Diarrhea
• Protozoa: Amebic dysentry, Giardiasis
• Helminths: Schistosomiasis (bilharzia or snail fever)

Md.Yasin, Asst. Professor, Department of Civil Engineering

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Sanitation and Disease

 Classification of Excreta-Related Diseases:

❖ Excreted Infections (Direct Transmission of Pathogens): Cholera, Typhoid

Direct Transmision
Infected Excreta New Infections

❖ Vector Transmited Diseases : Schistosomiasis

Infected Excreta Vector Breeding New Infections

Insects (Flies,Mosquito),
Cockroach,Rat, Animals (Cow,Pig),Snails

Md.Yasin, Asst. Professor, Department of Civil Engineering

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Sanitation and Disease
“Fecal-Oral” Transmission Route of Diseases

Md.Yasin, Asst. Professor, Department of Civil Engineering

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Sanitation and Disease

Effect of “Sanitation” on Disease Transmission

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Sanitation and Disease

Interrelationship among water, sanitation, hygiene education and health
 WaSH or WASH:
Water, Sanitation and Hygiene

Md.Yasin, Asst. Professor, Department of Civil Engineering

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Sanitation and
Disease

Important issues for controlling excreta-related diseases:

 • Sanitation is clearly the most important intervention required for the control of
excreta related diseases.
• Also important is improved personal, domestic and peri-domestic hygiene,
through improved water supplies and improved housing.
• Animal excreta control and effective sullage and solid waste disposal must also
be addressed to control all categories of excreta related diseases.

Md.Yasin, Asst. Professor, Department of Civil Engineering

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Sanitation: Commonly Used Terms

Total Sanitation: Refers to total sanitary condition for healthy living. Therefore
includes:
 • Hygienic latrine facilities;
• Proper management of solid waste; and
• Proper disposal of household wastewater
100% Sanitation: At the very least, the term “100% sanitation” include all of the
following:

• No open defecation;
• Hygienic latrines available to all;
• Use of hygienic latrines by all;
• Proper maintenance of latrines for continual use; and
• Improved hygiene practice
Md.Yasin, Asst. Professor, Department of Civil Engineering
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Classification of Sanitation Systems

 1. On-site Sanitation System:
When the wastes are collected, treated
and
disposed of at or close to the point of
generation.

Example:
Pit latrines (rural, urban slum)
Septic Tank System (urban)

Md.Yasin, Asst. Professor, Department of Civil Engineering

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Septic Tank System (urban)

Md.Yasin, Asst. Professor, Department of Civil Engineering
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On-site Sanitation System

Basic Principle:
 • Liquids infiltrate into soil (infiltration capacity of soil, and location of groundwater
table important issues)
• Solids are retained (confined) and digested

Features:
• Designed to dispose of human waste only
• Wastewater from other sources (kitchen, washing, bathing) has to be disposed
separately
• Suitable for sparsely settled rural areas with low population density, and low
water consumption
• Not feasible in areas with: (a) high population density, (b) low infiltration capacity
of soil

Md.Yasin, Asst. Professor, Department of Civil Engineering

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2. Off-site Sanitation System:

 When the wastes are collected and transported to somewhere else for treatment
and disposal.
Example: Conventional sewerage system; Small-bore Sewerage System (SBS);

Bucket latrines Md.Yasin,

Asst. Professor, Department of Civil Engineering
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Off-site Sanitation System

Features:
 • Collection and transportation of waste through a sewer system requires that the
waste be diluted by water.
• Hence piped water supply is essential
• Most satisfactory system of waste disposal, provided sufficient funds are available
for its construction and maintenance.
• Because of high cost, preferable to introduce gradually; where possible existing
sanitation system (e.g., septic tank system) should be upgraded and improved (e.g.,
SBS system utilizing existing septic tank system; will be discussed later in the
course)

Md.Yasin, Asst. Professor, Department of Civil Engineering

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 Sanitation systems may be classified further into:

(a) Dry Sanitation System: No water is used for the dilution of waste. Applied in
areas with no piped water supply.

Example: Pit latrines (rural, on-site), Bucket latrines (urban, off-site)

(a) Wet Sanitation System: Waste is diluted with flushes of water (to carry it
away from the point of generation).

Example: Septic tank system (on-site), conventional sewerage system (off-site)

Md.Yasin, Asst. Professor, Department of Civil Engineering

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 Sanitation systems may be classified further into:

(i) Permeable System: Allows infiltration of liquid portion of waste into soil.
Example: Pit latrines
(i) Confined System: Does not allow infiltration of liquid portion of waste into soil.
Example: Septic tank (not septic tank system, which also includes a soakage pit)

Md.Yasin, Asst. Professor, Department of Civil Engineering

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Most important factor affecting suitability of sanitation system:
• Level of Water Supply:
– Pit latrines would not be appropriate with piped water supply
– Water borne system (e.g., conventional sewerage system) is not feasible with
bucket-carried or hand pump water supply

• Population Density:
– On site system are more appropriate for low-density rural settings, and low
density urban areas
– Off-site systems are suitable for high density urban centers

Md.Yasin, Asst. Professor, Department of Civil Engineering

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Sanitation System in Bangladesh

Rural Areas (without piped water supply)
❑Pit latrines

❑Pour-flush latrines

❑Hanging latrines/ open defecation (still practiced)

Urban Areas
❑Septic tank system

❑Conventional/ water-borne sewerage system (only in Dhaka, coverage

estimates about 20%)
❑Direct connection to storm drainage system (with or without septic tank)
 and surface drains
❑Slum/ low income areas: Pit latrines/ Hanging latrines/ Open defecation

❑Decentralized wastewater treatment systems (DWATS): pilot scale

application in some slums
Md.Yasin, Asst. Professor, Department of Civil Engineering
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