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Lecture 4. Community Wastewater Treatment Management
The Islamic University of Gaza- Environmental
Engineering Department
Wastewater Management- EENV 6306
By
Husam Al-Najar
Scope of Application
On-Site
Rural - Municipal
Urban - Municipal
Industrial
Decentralized wastewater systems collect, treat, and reuse or dispose of
wastewater at or near its point of generation.
It include systems that treat wastewater from individual homes or buildings as
well as cluster systems that treat wastewater from groups of two or more
houses.
Unlike centralized urban wastewater treatment systems, decentralized systems
treat wastewater close to the source, typically using small pipes for collecting
small volumes of domestic wastewater.
Most cost-effective option especially in rural areas and hilly terrain.
Cost-effectiveness depends on a number of factors like population size and
density, topography, distance to an existing centralized system
Introduction
Advantages of Decentralized Wastewater Treatment
Often more affordable for small communities
Achieves high removal rates for most pollutants
Less hydrological impact
Can be integrated into a flexible wastewater system
Can be used as a tool to manage development
Reduce sewer networks
Involve local labour and material available
Construct what requires low maintenance and no energy
Generate water and nutrients for irrigation in agriculture and food-
garden
Requires greater awareness and participation of homeowners
Less familiar to engineers
Funding challenges
Lack of management structures
Fragmented regulatory structure
Disadvantages of Decentralized Wastewater Treatment
Potential threat to ground water quality
Can be harder to document treatment effectiveness
No dilution benefit
Risk of failure concentrate
Barriers to Implementation
Lack of Knowledge and Public Misperception
Homeowners and developers think that houses with centralized
systems will carry higher property values and have greater acceptance
Legislative and Regulatory Constraints
Lack of Management Programs
Liability and Engineering Fees
Unwillingness of homeowners and developers to accept the liability
associated with unfamiliar treatment systems
Financial Barriers
The funding agencies generally do not assist privately owned systems.
Five Management Models for community wastewater
Treatments
Model 1 - Homeowner Awareness
Individual OSSF owned and operated by homeowners
Use in areas of low environmental sensitivity
Treatment technologies limited to conventional systems
Maintenance reminder notification
Model 2 - Maintenance Contract
Homeowner system ownership
Professional maintenance
Complex OSSF design such as ATU
Licensed technicians provide proper and timely maintenance
Individual contracts with individual homeowners
Model 3 – Operating Permits
Annual permit renewal to assure system performance
Suitable for increased environmentally sensitive areas
Performance based designs with management controls similar to Model 2
Individually owned OSSF systems
Model 4 – Responsible Management Entity Operation and Maintenance
Decentralized systems
May be combined with individual OSSF systems
Highly reliable operation and maintenance
Water quality and sensitive environmental areas
Operating permits are issued to the RME instead of individual homeowners
Model 5 – Responsible Management Entity Ownership
Suitable for decentralized systems
Not suitable for individual OSSF’s
Systems are owned, operated and maintained by the RME
Removes property owners from responsibility for the system
Greatest assurance of system performance in the most sensitive of environments
Functions of RME Districts
Notification
Asset Inventory
Certification
System design and installation
Monitoring
Plan review & construction inspection
Reporting
Operation and Maintenance
Education
Inspections
Successful RME Attributes
Financial capacity Governance capacity Technical capacity Managerial capacity
Well defined mission,
objectives and goals
Sufficient political will
exists
Preexisting laws
sufficient to grant the
RME authority to
accomplish it’s mission,
objectives and goals
Operation outside
traditional health
department paradigm
Big picture focus and
NOT micromanagement
Set fees and price
structure
Biological
unit
processes
Chemical
unit
processes
Mechanical
unit
processes
Component
uniformity
System type
and
compatibility
A paid manager
Effective and timely
collection
enforcement
Strong board,
annual performance
reviews
Use generally
accepted accounting
principles and good
record keeping
Strong team of
professional
consultants
Long term and
contingency plans
Long-term financial planning
Sufficient cash flow to be self-sufficient
Establish reasonable and sustainable monthly charges
Independent financial oversight
Funds escrowed monthly for replacement cost
Annual audit and performance review
Recommendations for RME’s
Existing development using existing treatment systems – Model 3
Existing development using new treatment systems – Model 4
New development using new treatment systems – Model 5
START
Define Service
Area
Determine number of
Connections
Sufficient political will exist
Existing laws in place to
provide sufficient legal
authority to the new
RME
Petition for RME creation
and authorities
Develop mission
objective &Goals
RME Startup
STOP
Select RME legal structure
Develop required technical, managerial
and financial capacity
Develop short and long term plans and
Contingencies
This chart makes certain
assumptions regarding the
service area and system size,
age and type
Continue
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On site treatment systems configurations and
technique
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