Wastewater collection technologies (onsite and
conventional)and Treatment technologies (primary,
secondary and tertiary treatment)
Module One and Two
Dr. Maha Halalsheh & Dr. Mohammad Duqqah
Learning objectives
Sewage management:
A Strategy
Pollution Treat and Dispose
Prevention re-use ‘self
purification’
The 3 - Stage Strategic Approach
Gravity collection systems Conventional
collection system
Solids-free
collection system
Simplified
collection system
Conventional wastewater collection system
Advantages Disadvantages
Convenient systems and High investment costs
no attention is needed
by households or users
Abundant experience in
such systems exist in the
region
System is mostly in line Minimum velocity is
with existing national required to flush solids.
codes and standards Accordingly, minimum
slope should be provided
to maintain the
minimum velocity
Requires less Leakages may pose high
maintenance as risk for contamination as
compared to other compared to other
gravity systems systems
Solids-free wastewater collection system
Advantages Disadvantages
Cost savings might be 30 to 50% Space has to be provided for the
as compared to conventional interceptor tank at each
sewer system household. Additionally, access to
the interceptor must also be
provided
No need for continuous Regular de-sludging is crucial for
downward slope and accordingly the a well operated system
the pipes might be installed at
shallow depths
Inspection manholes are not Needs high public awareness as
required public are involved in the
operation and maintenance of
the system
Less environmental risks in case In many cases in the region,
of leaks codes and standards still need to
be developed for such systems
Reduction on the treatment Lack of regional experience in
costs since solids are removed such systems
upstream
Simplified wastewater collection system
Advantages Disadvantages
Shallow depth and flatter Toilets need to be flushed
gradients as compared to with sufficient amount of
conventional systems water to provide flushing
for the system
Pipes are smaller and Grease and grit traps
cheaper as compared to need to be installed at
conventional sewer each household and
system regularly maintained.
Accordingly, community
involvement is crucial
Higher maintenance
requirements as
compared to
conventional system
No sufficient experience
exists so far in the region
regarding such systems
Wastewater treatment
Preliminary treatment Screening
Preliminary treatment Grit removal Unit
Primary treatment sedimentation tank
The purpose is to remove readily
settleable solids and floating materials.
Efficiently designed and operated
primary sedimentation tank removes
50-70% of TSS and 24-40% of the
BOD.
The tank can be rectangular or circular
and equipped with scrapers at the
bottom to remove collect sludge at the
sludge hopper. The clarifier is also
equipped with scum removal
mechanism.
Aerobic Biological processes
Suspended growth Attached growth
Heterotrophic bacteria degrades the organic material and are found
in suspended or attached systems.
Activated Sludge system
Trickling filter system
Rotating biological contactors
Anaerobic treatment
Up Flow anaerobic sludge blanket
Anaerobic treatment
Anaerobic Baffled reactor
Anaerobic treatment: Septic tank
1895, England
Donald Cameron Septic
Tank
Natural Systems
Waste stabilization ponds
Natural Systems
Constructed wetlands
How do we
select the
treatment
system?
Some important factors that must be considered
when selecting unit operations and processes
1. Process Past experience, data from full scale plants, published
applicability data and from pilot plant studies. If new conditions are
encountered, pilot plant studies are essential.
2. Applicable flow
range Example: stabilization ponds are not suitable for
extremely large flow rates in highly populated areas.
3. Influent Affect the type of the process to be used. The
wastewater presence of inhibiting constituents may limit the
characteristics application of biological treatment systems.
4. Climatic Temperature affects the rate of reaction for most
conditions biological and chemical processes.
Some important factors that must be considered
when selecting unit operations and processes
5. Process Reactor sizing is based on the governing
sizing based on reaction kinetics and kinetic coefficients. Data
reaction kinetics on kinetics are obtained experimentally. Data on
or process loading rates are based also on kinetics but can
loading criteria be obtained from pilot studies.
6. Performance Needed effluent quality is important in
determining the required treatment system.
7. Sludge Are there constraints that would make sludge
production and processing and disposal infeasible or
processing expensive.
8. Environmental conditions such as prevailing
Environmental wind direction and proximity to residential areas
constraints may restrict the application of some processes.
Proximity to water bodies may require removal
of some constituents such as nutrients.
Some important factors that must be
considered when selecting unit operations
and processes
9. Chemical What effects might the addition of chemicals have on
requirements or any the characteristics of sludge and what is the cost of the
other resources chemicals.
requirements.
Energy requirements and future energy cost must be
10. Energy known for cost effective treatment systems.
requirements
11. Personnel How many do need for operating the systems and do
requirements they have the skills.
12. Flexibility Can the unit operation be modified when needed to
meet future requirements.
Sustainability criteria for comparing different
options
Please refer to the excel sheets
Outputs of the module
Questions