Programme:

13:30                     Depart Spier by coach

14:30                     Arrive at the V&A Waterfront – check in on the ferry

15:00                     Ferry departs for Robben Island

15:30                     Ferry arrives at Robben Island

                                1 x hour tour of the plant

                                1 x hour tour of the prison

18:00                     Depart from Robben Island

18:30                     Arrive at the V&A Waterfront

                              Depart by coach to return to Spier

19:30                     Arrive at Spier

ROBBEN ISLAND

The Robben Island Seawater Reverse Osmosis plant has a long history, with the first plant installed during the early 1990’s. In 2003, due to tests of the product water revealing unacceptably high conductivities, an urgent refurbishment of the plant was undertaken by Malutsa, for the Department of Public Works, to ensure compliance with SABS and WHO standard guidelines for potable water.

In order to comply, the following was done: (1) Pretreatment consisting of flocculation, anthracite filters, dual media filtration, anti-scalant addition and cartridge filtration was included in the refurbishment to ensure the feedwater quality fed to the membranes. (2) A complete membrane replacement and reconfiguration of the stainless steel piping to the vessels was done, in order to ensure consistent, acceptable water quality. (3) A clean water flush and CIP facility was piped into the system to allow frequent cleaning of the membranes.

The upgrade was designed to be capable of consistently producing 400m³/d of potable water to specified quality, with a maximum capability of producing 500m³ of permeate per day (20,8m3/h) @ 25 degrees C at a recovery rate of about 50 %. The seawater reverse osmosis membranes used are capable of reducing the TDS of the feedwater to SABS 241 standards in one stage and this achievement was realized at commissioning in September 2004 and maintained by Malutsa for the first 10 months of the RI SWRO plant’s refurbished life. With feed water conductivities at 58,000 S/cm and a product water quality of <800 S/cm, potable water was supplied to the Robben Island mains at 430 m³/day with 98.7% of the salt being rejected by the membranes.

Currently the plant is being operated by a sub-contractor to the Department of Public Works for the Robben Island Museum.

Refreshments and light snacks will be provided.

NOTE:  This tour is weather dependent – if the seas are too rough, the ferries will not go to Robben Island.

Programme:

13:30                     Depart Spier by coach

14:00                     Arrive at Zandvliet

                              Tour of plant

15:30                     Depart from Zandvliet

16:00                     Arrive at Spier

ZANDVLIET WASTEWATER TREATMENT WORKS

The Zandvliet Wastewater Treatment Works (WWTW) was originally commissioned in 1988 with a design treatment capacity of 40 Ml/d. The selected activated sludge process was based on a design with a Modified Ludzack-Ettinger (MLE) configuration.

Between 2002 and 2004 minor upgrades in the form of larger aerators, additional secondary settling tanks and sludge dewatering equipment increased the potential operational capacity to approximately 54 Ml/d.

The Zandvliet WWTW is located in a high growth area and projects such as the N2 Gateway housing project necessitated that further treatment capacity was urgently required.

Tenders for the construction of an additional 18 Ml/d treatment works were awarded in 2006. The selected activated sludge process was based on a design with a UCT configuration together with a side stream membrane bioreactor (MBR).

The activated sludge reactor consists of a glass fused to steel circular tank with an inner tank diameter of 37,6m,  an outer tank diameter of 49,5m and a side wall depth of 5,65m providing a volume of approximately 10000m³ .

The Zenon MBR system was selected and utilises the ZeeWeed ZW500D hollow fibre membranes. The MBR system consists of 6 trains each with 5 cassettes rendering a total membrane area of 41712 m². This design allows for the treatment of peak flows of up to 35Ml/d for periods of between 4-6 hours. The raw sewage entering the plant is screened by means of 1mm mesh Brackett and Green screens.

Due to the specific design of the existing activated sludge works it was possible to incorporate into the design of the MBR plant an automated control mechanism whereby the flow to the MBR plant will be maintained at a constant flow of 18Ml/d and only treat peak flows when the peak design capacity of 90Ml/d of the existing plant is exceeded.

The MBR plant was recently commissioned and is presently completing its 30 day operational acceptance period.

Refreshments will be provided.

Programme:

13:30                     Depart the Spier Conference Centre on foot

14:00                     Arrive at the plant

                              Tour of plant

15:00                     Return to conference centre

SPIER ENVIRONMENTALLY FRIENDLY WASTEWATER TREATMENT PLANT

BACKGROUND

Spier used the Biolytix system to convert organic and human waste into a reusable resource. In 2006 we discovered that Biolytix was not treating the wastewater to the legal requirements for re-use. Research showed it was more effective for small-scale requirements, but that Spier needed a new way to treat wastewater from all its businesses.

CHALLENGE

We needed to find a sustainable long-term option to solve our wastewater issues in an environmentally-friendly way, overhaul all existing systems and centralise our treatment facillities.

SOLUTION

A biological effluent treatment plant was created that uses a bioreactor, coupled with aerobic bacteria, to cleanse the water. An Archimedes Screw compacts the solid waste, separates the matter and removes the solids for collection. The liquid remnants are moved into an open tank where aerobic bacteria continue the process.

This bioreactor, which is an open-air tank divided into four sections, accepts water into the first tank, and subsequently forces the water into each of the remaining tanks in an anti-clockwise direction. The aeration pumps switch off between 3am and 7am, allowing the bacteria and waste to settle at the bottom. The cleaner water is skimmed from the top and moved through pipes that irrigate an oval-shaped reed bed. This reed bed is ideal for the natural growth of bacteria, which continue the breakdown process as the water seeps into the soil.

CONCLUSION

It would take Eerste Rivier 350 kilometres to purify what our innovative wastewater treatment plant can do in one day. The techniques used combine science, art and healing to create a cyclic system of cleansing and replenishment on the Spier estate.