The people of Philadelphia in the Western Cape are up in arms about fly infestations and the bad odours that have become part of their lives over the past four years. problem, they say, lies with the sewerage sludge being sprayed onto agricultural land as a natural fertiliser in the Koeberg area.
“Our small town is surrounded by agriculture,” Philadelphia resident Carsten told Farmer’s Weekly. “There are many animals so we realise there will be flies, but the situation we’ve been enduring must end.” The ‘perpetrator’ Phil Stofberg is the man behind the smell. owns the farm and dairy Keert de Koe and sprays 8 000m³ of sludge per month on 2 000ha of land in the Koeberg area.
The sludge is the byproduct left after raw sewerage has been treated in Cape Town’s various sewerage plants. A private company, Hlumani Wasteman, is contracted by the Cape Town Municipality to dispose of the sludge.
It has a private dumping facility, but prefers to use contractors who spray the sludge onto agricultural land in the Koeberg region. “I only started dealing directly with the contractor this year,” said Phil, “because in the past there were problems with the application, outlined certain prerequisites before entering into the contract.” Bad for business But local business owner FB Dippenaar is still not happy. He owns the Swartland Engen Wimpy One-Stop fuel station on the N7 highway. “We invested R1,5 million in these premises last year. Now nobody wants to use our outside seating, as there are too many flies,” he said. “People refuse to stop for fuel because of the smell. It’s an embarrassment for us and we are losing money.”
His wife Elna added that last year the sludge was sprayed on a field right across the road, 200m away from them. F B said he recognises that everyone has a right to do business, but he had to undergo a rigorous environmental impact study before he could open his fuel station, whereas nothing of the sort was done to approve the spraying of the sludge. “The sludge is supposed to be completely covered once it’s ploughed into the soil.
This is not being done as it can be seen on the surface. And nobody seems to monitor how often the same piece of land is sprayed.” he Dippenaars and Deon believe raw sewerage is also being sprayed. They argued that closed trucks – the type used for pumping out drains and bucket system waste from the nearby townships – are regularly seen entering Keert de Koe. But Phil said he works closely with the municipality, which takes soil samples before each application. These are analysed to determine if there is any heavy metal build-up and then coordinates deliveries with Hlumani Wasteman. ime is of the essence, because protocol states that the waste must be underground within 12 hours.
“We try to do it within one to two hours,” Phil explained. “My farm’s soil is poor, but this is changing as I’m building it up with the sludge. I’ve seen a 20% increase in production over the last five years and land that used to be unsuitable for planting is now producing excellent pastures. With the current fertiliser prices, sludge is the way to go for farmers.”
Phil confirms he’s currently investigating the use of effective microorganisms with his spray machine, as this would reduce odours by up to 80%. The pros and cons of sludge Tiennie Stofberg farms on Oliefantskop and also sprays sludge onto his land. “This is fantastic compost and I have been using it for five years now,” he said. Tiennie farms with pasture, oats and wheat and said his crops are flourishing and his cattle are healthy. “All compost stinks. People who think it shouldn’t don’t know anything,” he said. But Nico Stofberg, owner of Vaatjie Farm, doesn’t agree and is another disgruntled voice in the region.
“The Kleine Zoete River drains winter rains from the Koeberg area and joins the Atlantic at Melkbosstrand, a popular surfing spot,” he explained. “It only flows in winter, but during summer, there are pools where my cattle used to drink. The river used to have pristine white shores and indigenous fish. But now my cattle die if they drink there.” Nico had the water tested, and the results confirmed that it contained toxins which made it unsuitable for animals. “We regularly see raw sewerage trucks offload on Keert de Koe. Those trucks don’t transport treated sludge,” Nico said. He pointed out that the people in the Atlantis area are dependant on rain and underground water for personal use.
He believes that the groundwater is being polluted, as the waste does not only consist of human faeces, but also chemicals from drain- and toilet-cleaning products. Nico adds that during the summer, the waste dries out and is blown as a fine dust into water tanks and roof gutters. The local farm school is experiencing health problems and Nico believes this is directly linked to the sludge application. The official standpoint “Since the beginning of the sludge application in June 2003, a total of 540 soil samples were taken and analysed,” confirms Kevin Samson, manager of the City of Cape Town’s Wastewater Department. “Some areas are now undergoing their fourth application and to date, no discernable build-up of heavy metals has been noted.”
According to Kevin, a borehole is being drilled on Keert de Koe and groundwater samples will be taken there as well. Some 532 000m³ of landfill space has been saved since 2003 by spraying the sludge on farmland. Cape Town will produce more sludge as its sewerage plants are upgraded to produce cleaner effluent. It’s vital that only treated and stabilised sludge is applied, said Kevin. Only crops of which the edible portion is above ground, and which are cooked before consumption, can be planted on sludge-treated land.
These include canola, wheat, rye, barley and triticale. In the case of silage, the crop is stored for several months to allow for fermentation of the stalks and for the bacteria to die before they’re consumed, Kevin explained. “If fly and odour problems persist, options include relocation, dosing sludge with a fly deterrent, extra vigilance with the covering of sludge during the ploughing stage, or disposing of it into the contractor’s private landfill,” Kevin said.
Effective microorganisms: the solution?
Effective microorganisms (EMs) were developed in Japan by Dr Teruo Higa for the rehabilitation of soil that was subjected to years of intensive mono-cropping in the 1970s and 1980s. Microorganisms were selected from the three categories found in the environment: aerobic microbes, anaerobic microbes and microbes that can be either aerobic or anaerobic depending on the given situation.
A secret formula is used to produce a liquid that contains a specific ratio of these microbes. This liquid is sold to distributers who then multiply them, using water and molasses, to produce a commercial product, known as Multiplied EMs. According to Michael Fell from Emrosa, the South African EM distributor, the ideal solution to Philadelphia’s problem would be to treat the sludge at the sewerage plant. To date, efforts to sell this idea to the Cape Town Municipality have been unsuccessful. “If Phil were to put a boom spray behind his sludge application machine, there would be an immediate improvement regarding smell, as the aerobic microbes will consume the anaerobic microbes,” said Michael.
“Fly populations will decrease, as the EM microbes will affect the larvae, preventing them from reproducing. If properly treated with EMs, Keert De Koe land will be suitable for root crops, something that is currently prohibited.”
