Applying scientific thinkingin the service of society

Water and Sanitation

Low carbon cities meeting 04 – 06 October 2010

Findings • The eThekwini Municipality buys bulk potable water from

Umgeni Water• Potable water is from dams to treatment plants to

reserviors and then onwards to consumers through gravity and pumping

• Central and sub-urban regions – waterborne sewerage system

• Outer west, rural areas and informal settlements – onsite sewage disposal

• Total of 461, 267 kl of wastewater is treated daily by the city’s 26 wastewater treatment works

Figure: Wastewater treatment works in eThekwini municipal area

Water Demand Management

• There will be substantial growth in housing and development associated with the Dube Tradeport, which will increase water demand

• Existing backlog: 63,000 households, need water and sanitation

• Water demand management (WDM) aims to reduce the quantity of non-revenue water.

• Currently, 37% of water is lost(due to illegal connections and leakages)

• Aim to reduce it to 20%

Forecasted water demand for eThekwini

Scenario A: No further WC/WDM measures Scenario A1: Scenario A with waste management over 5 years

Carbon footprint of the system• Main factor contributing to carbon emissions – electricity

demand • 0.10 kWh (0.14 kg CO2e) / kL of potable water

• 0.14 kWh (0.15 kg CO2e) / kL of wastewater

Figure: Contribution of various water processes to global warming

Water and sanitation projects

Urine diverter toilet

• Urine diverter toilets• 80 000 urine diverter toilets

have been rolled out. • Waterless, sludge is used as

fertiliser• Community empowerment • Project roll-out focuses on

empowering people. Contractors must train people from the community to do the labour

Water and sanitation projects (cont.)

Water re-use for industry• Durban is the first city in South Africa to introduce the first

private water recycling project. The recycling plant can treat up to 47.5 million litres of water per day

• It provides 2nd class water to Mondi and SAPREF, at a lower tariff in comparison to potable water.

Membrane Technology • A pilot project is being run of this technology, which is a low

cost treatment works, using gravity membranes to treat waste water. The pilot project aims to understand the capabilities of the decentralised wastewater treatment (DEWAT) system for municipal water borne sanitation.

Western Aqueduct Pipeline• Western Aqueduct is the largest water infrastructure project

undertaken by the eThekwini Municipality • The project aims to increase the capacity of water to the region• The potential of implementing hydro-turbine generation

projects in the Western Aqueduct Pipeline, is being investigated. • The project is expected to initially generate 4 MW per station,

which can potentially increase to 8 – 10 MW.

Mini Hydro • Plans are underway to install mini hydros at inlets of reservoirs.

The electricity generation capacity of a mini hydro is from 100 kW – 500 kW

Water and sanitation projects (cont.)

Wind turbines / solar turbines • 6 wind turbines are currently being produced to pump water and to abstract water

from boreholes Oil from Algae • A biodiesel project is also planned for two to three years time to transform algae

from maturation ponds at the city’s wastewater treatment plants to biodiesel and other products,

Rainwater HarvestingRecognised as a climate change adaptation strategy. A 3000 – 5000 l tank is fitted next to a household.

Figure: Rainwater Harvesting Tank

Water and sanitation projects (cont.)

The use of effluent and sludge for agriculture • Final effluent is pumped into JoJo Tanks and are distributed to people for

agricultural purposes. • The sludge is also composted and distributed to farmers, which is used as

fertiliser.

Electricity from methane gas • A prefeasibility study has also looked at the use of sludge to generate

electricity. The process will involve the use of a digester, which would destruct the methane and generate electricity, which will be supplied to the grid

Agri – tube The agri-tube was developed to allow people to plant their own food in areas where space is limited for example in informal settlements.

Draft recommendations • The municipality has been very active in

minimising impacts • Increase supply of recycled water - option to

supply industries close to waste water treatment plants with recycled water

• Water distribution losses are high and must be addressed

• Promote on-site sanitation (uses less energy) • Fast-track wastewater to energy initiatives

Applying scientific thinkingin the service of society