Specialising in
Grey Water
and
Rainwater Harvesting systems in South Africa .

Drinking water algal bloom poses no medical risk

The City of Cape Town’s Scientific Services Branch has isolated and identified an algal species called Melosira in the water of the Molteno Reservoir, and is assuring the public that it poses no medical risk to public health.

Melosira falls into the class Bacillariophyceae which are diatoms. In drinking water can give the water a grassy or fishy odour

Melosira are commonly found in drinking water reservoirs worldwide. The Melosira species belongs to the family of algae called Bacillariophyceae and is a diatom that forms long filaments. They are known for clogging filters in water systems.

The mechanism of the sudden and unexpected bloom of this species in the reservoir is being carefully examined to determine the causal factors so that appropriate corrective and preventative action can be taken.

Molteno Reservoir is a balancing reservoir situated above the city in Oranjezicht and is supplied by a blend of water from the Theewaterskloof, Wemmershoek, Steenbras and Voëlvlei Dams. The algae have not been detected in the incoming water supply. The water level in the reservoir rises at night when the demand in the city area is low and falls during the day while the peak demands prevail. The reservoir is cleaned annually during low demand periods in winter. Continue reading Drinking water algal bloom poses no medical risk

Lake Tanganyika warming fast

Posted by: Saving Water SA (Cape Town, South Africa) – partnered with Water Rhapsody conservation systems – 17 May 2010

Africa’s Lake Tanganyika has heated up sharply over the past 90 years and is now warmer than at any time for at least 1,500 years, a scientific paper said on Sunday, adding that fish and wildlife are threatened.

The Lake Tanganyika is an over 10 million year old rift-valley lake in East-Africa and the second deepest lake in the world.

The lake, which straddles the border between Tanzania in East Africa and the Democratic Republic of the Congo, is the world’s second largest by volume and its second deepest, the paper says.

Lead scientist on the project Jessica Tierney told Reuters the sharp rise in temperature coincided with rises in human emissions of greenhouse gases seen in the past century, so the study added to evidence that emissions are warming the planet.

The ‘Great Lakes’ such as Tanganyika, Malawi and Kenya’s lake Turkana were formed millions of years ago by the tectonic plate movements that tore Africa’s Great Rift Valley.

Some 10 million people live around Tanganyika and depend upon it for drinking water and food, mostly fish.

Geologists at Rhode Island’s Brown University used carbon dating to measure the age of sediments on the lake floor. They then tested fossilized micro-organisms whose membranes differ at various temperatures to gauge how hot it was at times past.

The results were published in Nature Geoscience on Sunday.

“Lake Tanganyika has experienced unprecedented warming in the last century,” a press release accompanying the paper said. “The warming likely is affecting valuable fish stocks upon which millions of people depend.”

Most climate change studies have focused on the atmosphere, but increasingly scientists are studying the effects on the oceans, seas and lakes, which all absorb a huge amount of heat. Continue reading Lake Tanganyika warming fast

Demolition of Athlone towers to proceed

Posted by: Saving Water SA (Cape Town, South Africa) – partnered with Water Rhapsody conservation systems – 11 April 2010

Three thousand holes need to be drilled into each tower for controlled demolition

Progress towards the demolition of the two Athlone cooling towers is proceeding smoothly, as the City works towards a demolition date around Sunday 30 May 2010.

A professional team, which includes an environmental scientist, was appointed on 10 March by means of a competitive process to oversee the technical, environmental and heritage aspects of the project and to prepare for a safe demolition.

The decision to demolish the two iconic towers follows structural damage to one of the cooling towers during the early hours of Sunday, 14 February 2010, when the stabilising rings around one of the towers became detached and fell to the ground. These rings were fitted as an additional safety and stability measure almost twenty years ago. Consulting structural engineers were immediately appointed to assess the damage and advise the City on what steps should be taken. Their recommendation was that the towers be demolished as soon as possible.

The City accepted the recommendation and has immediately proceeded to plan the demolition process. Continue reading Demolition of Athlone towers to proceed