Umgeni Proposed Projects

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4.5 Wastewater Reuse
4.5.1 Background and Existing Infrastructure
The reuse or reclamation of wastewater not only improves the sustainability of water resources, but
is strategically important as it improves the security of supply through the diversification of water
resources. Wastewater is available throughout the year and the supply is consistent.
Umgeni Water currently owns an 18% share in the Durban Wastewater Recycling (DWR) Plant. The
DWR treats domestic sewage to near potable standards for industrial use. The plant has the capacity
to treat approximately 40 Mℓ/day of wastewater.
4.5.2 Proposed Options
Umgeni Water is currently investigating the option of treating wastewater from Darvill Wastewater
Works (WWW) (Section 6.2) to potable standards. The proposal is to return the treated water back
into the distribution system at Umlaas Road (Section 5.2). The water can then be used to augment
the supply to the Western Aqueduct which will serve the high growth areas along the western
corridor of the eThekwini Municipality (Section 5.2). The advantage of this is that water is made
available higher up in the system and can therefore be supplied using gravity. The alternative is
reliant on pumping from Durban Heights WTP to serve these demand centres (Section 5.2).
Supplying the water from the Upper Mgeni System will shed load at Durban Heights WTP, thus
freeing up the works to supply additional water. This scenario does, however, place stress on the
infrastructure of the Upper Mgeni System and this infrastructure will have to be upgraded to cope
with the additional demand (Section 7.4).
4.5.3 Project Progress
A number of studies have been undertaken as part investigations into wastewater reclamation at
Darvill WWW. These include infrastructure and environmental pre-feasibility studies as well as
treatment technology investigations.
The infrastructure study involves the evaluation of two methods of utilising Darvill wastewater to
augment the potable supply. The first, a Direct Reuse option, is designed to treat the Darvill effluent
at a proposed wastewater reclamation plant adjacent to the existing works. The second, an Indirect
Reuse option, is designed to abstract the Darvill effluent from a location downstream of the WWW
on the Msunduzi River. Both options require the water to be pumped to the Umlaas Road node
(Section 5.2) for distribution.
The Indirect Reuse (river abstraction) option will require treatment of the river water abstracted and
therefore the WTP at the Umlaas Road node will need to be re-commissioned for this purpose. Due
to the poor water quality of the Msunduzi River (Section 4.4.4) the WTP may have to be upgraded to
cater for the inclusion of more advanced water treatment technology.
Storage reservoirs, distribution pipelines and the associated infrastructure to pump the treated
water to Umlaas Road WTP are required for both alternatives and preliminary designs and pipeline
routes have been completed. A detailed feasibility study is currently underway that will determine
the most economically feasible alternative.

175
Both the Direct and Indirect Reuse options will reduce the flow in the Msunduzi River by
approximately 60 Mℓ/day which potentially may have an environmental impact on the river and its
users. A specialist environmental study was previously completed to assess the possible impacts of
this reduction in flow on the river. The study revealed that reduction in flow would have no to
limited impact on the ecology of the river, because the flow would be returning to its natural or
“virgin” state. The river habitat and ecosystem would therefore adapt to what it was formally used
to. The discharge from Darvill WWW is a return flow and therefore not part of the natural flow
regime of the river. Social impacts were more difficult to quantify without the undertaking of a full
Environmental Impact Assessment, but were also limited and could be mitigated.
A vital component in the Direct Reuse option is the design of the advanced water treatment
technology process train for the reclamation plant. The treating of wastewater for potable reuse
requires that appropriate technologies are used to ensure the public’s safety at all times. This is
achieved by designing treatment systems that ensure no harmful substances or viruses will pass
through the system. The most effective way of doing this is to design “multiple treatment barriers”.
International experience at NEWater in Singapore and at Goreangab in Windhoek makes use of this
philosophy. These plants also undertook extensive treatment trials using pilot plants to obtain the
best treatment train design.
Umgeni Water is following a similar strategy, and with the cooperation and sponsorship of the
Water Research Commission (WRC), is undertaking a wastewater reclamation pilot plant
investigation. The first stage in the investigation involved the installation of Membrane Bioreactor
(MBR) pilot plants. The MBR’s provided excellent pre-treatment for further advanced treatment
technologies such as Granular Activated Carbon (GAC), Reverse Osmosis and Ultra Violet Irradiation.
Combinations of these advanced treatment technologies are being be tested to ascertain the most
effective “multiple barrier” system (Figure 4.60). These tests will be completed by June 2013 and will
culminate in a WRC report in December 2013. The study will provide the recommended process
train for design purposes. A preliminary design for the reclamation plant can then be undertaken
and costed.
Coupled with the pilot plant investigations is a rigorous water quality monitoring programme. Of
concern when reclaiming wastewater to potable standards are the health and safety aspects,
especially those relating to the presence of Contaminants of Emerging Concern (CEC) in the final
water. CECs represent a range of contaminants that include pesticides, pharmaceuticals and
personal care products. Much attention has been given to particular contaminants that fall under
the banner of Endocrine Disrupting Chemicals (EDCs) such as Estrone, Ethinylestradiol and
Testosterone. Umgeni Water is sampling and analysing for these and other EDCs in the product
water once it has passed through all the treatment technologies. Preliminary results are excellent
and these substances are sufficiently removed for the final water to exceed potable drinking water
standards.

176
Figure 4.60 Preliminary process flow diagram for Darvill Reclamation.

177
4.6 Seawater Desalination
Umgeni Water completed a desalination pre-feasibility study in 2010. The objective of the study was
to investigate the viability of constructing a large scale desalination plant in the eThekwini area as a
possible alternative to the proposed Mkomazi Water Project (Sections 4.4.4 and 5.2). The ultimate
capacity of the plant was set at 450 Mℓ/day (164 million m3
/annum), making it potentially one of the
largest SWRO to ever be built.
The study identified the northern end of the Durban Airport as the optimal site to construct a
seawater reverse osmosis (SWRO) desalination plant. The cost of constructing and operating the
plant was estimated as well as the possible environmental implications.
Few points exist within the water supply infrastructure of eThekwini Municipality that have the
capacity to receive the water from a single point desalination plant producing 450 Mℓ/day of
potable water. Early investigations have also shown that due to the limited space for the pipeline
installation, it is highly likely that a phased implementation of the pipelines will not be feasible
because of these space constraints. At this point it is proposed that about 150 of the 450 Mℓ/day
would be injected into the Wiggins System (Section 5.2) at its WTP whilst the balance is injected into
the Central Aqueducts.
An economic comparison, at a pre-feasibility level of detail, between this desalination plant and the
alternative uMkomazi Water Project, indicated no discernible difference. It is therefore necessary to
undertake more detailed investigations of both options so as to obtain a higher level of accuracy in
their comparison.
In order to understand the required components to be focused on during the detailed investigation
of the desalination option, a workshop was arranged with desalination experts from Australia.
Lessons learnt from this workshop have assisted in planning the feasibility study for the desalination
plant. In particular the recommendations regarding the proposed site and linkages to existing supply
infrastructure will need to be reviewed.
A revised strategy has now been adopted. A detailed feasibility investigation is considering the
option of a 150Mℓ/day plant on both the North Coast and South Coast. The capacity of these plants
is based on the capacity of existing and proposed bulk water supply infrastructure in these areas,
which will be utilised to convey the potable water from the desalination plants to the various
distribution points. Datasets on the various criteria that affect the positioning of a desalination plant
have been sourced and two potential sites have now been identified through a site selection study
undertaken by Umgeni Waters Planning Department (Umgeni Water 2011). These sites are located
on either side (north and south) of the Mgeni Supply Area and would have the ability to sufficiently
augment the Mgeni, South Coast and North Coast Systems in the medium-term with supply to areas
in eThekwini Municipality, Ugu District Municipality and Ilembe District Municipality.

I
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IV
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V
Acknowledgements
Umgeni Water’s comprehensive 2012 Infrastructure Master Plan has been updated and improved to
produce this 2013 version. The concerted effort of the Planning Services Department as a whole in
producing this document is acknowledged and appreciated. Specific contributions by the various
team members deserves acknowledgement: Graham Metcalf (Geohydrologist) for managing the
entire project, updating the groundwater sections and preparing the sections on wastewater,
reclamation and desalination and Alka Ramnath’s (Planner) contribution in assisting with the
management of the project process, writing Section 2 of this report, preparing a number of the maps
and assisting with editing the two volumes, was substantial. Without such valuable input the project
would not have been possible. Mark Scott, Reshina Maharaj and Gavin Subramanian
(Planning Engineers) updated the various components relating to the water supply infrastructure
plans and projects within the North and Central, South and Inland regions respectively. In addition
Vernon Perumal (Planning Engineer) has updated the section on supply to Sisonke District
Municipality. Sandile Sithole (Hydrologist) and Sakhile Hlalukane (Hydrologist), updated the various
sections relating to the water resource regions in Volume I. Mark Summerton (Planning Analyst)
revised the section on climate change. David Stephen (Planning Engineer) once again took on the
onerous task of proofreading the report, and Tatum Donnelly (Administrator) kept the department
functioning smoothly throughout the project.
The 2013 Infrastructure Master Plan was not completed by the abovementioned people without the
valued assistance of numerous other staff members within Umgeni Water. Their contributions are
gratefully acknowledged. Operations Division staff provided assistance in updating and confirming
infrastructure information. The Water and Environment Department kindly provided updated
information on water quality within the various water resource regions in Section 4, and Process
Services supplied the process and treatment details for each of the water treatment plants in
Section 5. Finally, last but not least to the GIS Department; Brent Steyn (GIS Coordinator), Dani
Vather and Sindi Ngubane for updating and re-formatting all of the IMP maps.
Kevin Meier,
PLANNING SERVICES MANAGER

Umgeni Proposed Projects

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