Tweaking the chemicals in a rotting pit of buttermilk might save Eltham from a stinky summer.
The South Taranaki District Council has enlisted the help of an expert wastewater scientist and yesterday unveiled a plan to combat the stench from millions of litres of curdling buttermilk at the town's wastewater treatment plant.
Earlier this year, Fonterra dumped about three million litres of the milk byproduct, along with another 150,000 litres of milk tainted with drilling wastes, at the plant in an effort to deal with spring's record milk production.
But as the milk broke down those living near the plant had been swamped by a vile smell.
Council engineering group manager Brent Manning said after discussions with a Fonterra expert, they had implemented several changes.
"Instead of using powdered sodium bicarbonate, baking soda, we are switching to a liquid form of caustic soda which will raise the pH levels faster," he said.
The waste will also be dosed with ferric chloride - basically iron salts in liquid form - which will be pumped into the facility at a controlled rate.
"The ferric chloride will help settle the sulphurous compounds which are the primary cause of the odour," he said.
He said they were also using a "more effective deodoriser", hydrogen sulphide gas level and the pH of the liquid waste were being measured daily and rat traps have been placed around the site.
Residents took the council to task earlier this week after the month-long assault on their nostrils.
"Following concerns about the composition of the gas we brought in an expert from Auckland to take a full gas sample," Mr Manning said.
"The sample has been sent to a laboratory in Christchurch for testing and we should have the results of this by Monday."
- © Fairfax NZ News
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