CUTTING THE CRAP?
Regarding the city discharge into the Manawatu River.
Many systems for treating discharge are available, and from what I can discern, these fundamentals apply to all systems: How long the discharge is treated; the amount of bacterial activity – which in turn depends on aeration and the balance of nutrients.
Increasing these increases the quality of the discharge.
The costs correlate with construction and materials, the cost of the location, and the area required.
New Plymouth is trialling discharge flowing through bark waste. Could this be improved by having columns of bark wrapped in geodesic cloth? The discharge would be pumped in at the top and filter down through the bark nodules.
This would mean ample aeration due to the permeability of the cloth and a slowing of the flow because of the lumpiness of the bark.
The bark provides a porous nodular medium for the bacteria to colonise. Several columns could be arranged closely to save space, and fed from a pump or auger.
With time the columns could be utilised as a fertiliser, and being modular, their replacement wouldn’t interfere with the running of the plant.
These materials would cost much less than conventional materials.
Kevin Wells Palmerston North