Case Study: Kaipara

Project ID:

Company: Kaipara District Council
Location: Mangawhai, New Zealand
Year: 2009
Description: Tertiary Effluent Filtration

Remove parasitic Helminth
Nematode eggs, reduce turbidity
and TSS

Capacity: 20 m3/hour
Water Source: Municipal effluent

The Problems:

  • Mangawhai is a water-surrounded popular tourist resort, on New Zealand’s east coast.
  • Its population grows considerably during the summer months, and septic tank effluent was causing poor water quality in the harbour.
  • The wastewater contained a high concentration of the parasitic nematode Ascaris spp. The worm infects the blood, lungs, internal organs and can grow up to 35cm in the intestine. The nematode can prove to be fatal. The infectious egg (40 um) must be removed from the wastewater to allow it to be used for irrigation.
Items Existing Values Required Value
TSS (mg/l) 100 <10
Turbidity (NTU) Up to 50 < 5


High None

Technical Solution:

  • AFM® - Activated Media filtration with coagulation, implementing a filter with 1600mm diameter.
  • AFM® filter auto-cleaning with a combination of backwash water and air scouring


Items Existing Values Required Values After Treatment  
TSS 100 <10 <1  
NTU Up to 50 <5 <2  
Helminths High None NIL  

During the period no nematode eggs were detected in the product water from the AFM filters.

Dryden Aqua’s Deliverables: