An innovative trial using tiny bacteria to de-sludge effluent ponds will save South Taranaki ratepayers millions of dollars.
In a New Zealand first, the South Taranaki District Council has been trialling adding a special species of bacteria to the Hawera effluent pond.
Council operations and projects manager Viv Eyberg said the scheme had been a success and would save ratepayers about $3.7 million over the next four years.
Mr Eyberg said tests had shown 22 per cent of the sludge had been removed in nine months.
"To date, the biological trial has cost $164,000, with the final cost of total removal estimated to be $646,000," he said.
About 85,000 cubic metres of sludge need to be removed and under conventional methods it could cost up $4 million.
"Calculating the amount of sludge reduced is not an exact science, however we have conservatively calculated a 22 per cent reduction, which is about 18,700 cubic metres."
Mr Eyberg said the operation was all natural.
"The process basically involves putting bacteria which produce enzymes, called exoenzymes, into the wastewater pond.
"These exoenzymes help break the organic waste in the pond down into a soluble form which can then be more easily consumed by the bacteria."
Council chief executive Craig Stevenson said the project had exceeded his expectations and would be rolled out to all effluent ponds run by the council.
"The potential savings from not having to extract, dry and bury the sludge are too attractive to pass up," he said.
"Nationally, beneficial re-use or responsible disposal of bio-solids is a big issue and it's great to see council is at the forefront of an innovative solution."
Mr Stevenson said a number of other councils had also inquired about the project as it "had the potential to save the local government sector tens of millions of dollars".
Exactly what micro-organisms are being used is a secret of Parklink who tout themselves as "specialists in harvesting nature's most powerful biological forces".
- © Fairfax NZ News
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