Innovative NZ Aeration System Enhanced Ammonia Removal and WWTP Efficiency

A case study on the Waitomo Village oxidation pond system showed significant improvement in treatment capability by the installation of a surface based horizontal venturi fine diffusion aeration system called the Aquarator. The pond performance was studied using an online water quality monitoring station Inlet and outlet flows were measured and mass loadings computed for COD, CODf, Tss Nitrate and Ammoniacal Nitrogen. Independent laboratory analysed manual samples were utilised to verify the monitoring station data. The Aquarator was deployed for 8 months in the Waitomo oxidation pond system beginning Nov 2015. Prior to 2015 the treatment system had failed compliance (exceeding 10mg/l) on Ammoniacal Nitrogen for 9 years. The Waitomo oxidation pond system was originally refurbished to its existing form in the 1950’s. Due to expansion of tourism operations the systems is now expected to treat up to a peak of 4000 people per day. The system was never designed for that loading.

The study clearly demonstrates a significant removal of ammonia. An increased load treatment capacity within the existing plant footprint is now achievable with compliance. In addition, this field study demonstrates the ability of the Waitomo oxidation pond treatment system to be able to comply with a regional council directive to reduce compliance levels by 30% over the next ten years. In addition, the Aquarator installation can accommodate an increase in tourism growth without having to face an expensive upgrade placing a financial burden on the Waitomo Rate Payer.