Feasibility Study: Using Treated Wastewater From Māngere and Rosedale Plants for Sports-fields Irrigation in Auckland

Sarisha Hurrisunker - Auckland Council, University of Auckland

Using treated wastewater to irrigate sports fields and urban parks is a practical solution to water resource scarcity worldwide. In New Zealand, recycled water reuse is not presently supported by regulatory authorities. However, water scarcity due to climate change, population growth, economic growth, and the fundamental need to protect precious natural resources for future generations will likely alter New Zealand’s perception of treated wastewater from garbage to gold. This report assesses the feasibility of using treated wastewater from two of Auckland’s largest wastewater treatment plants in Mangere and Rosedale to irrigate community sports fields, focusing on classifying the treated wastewater according to its physical, chemical, and biological properties in line with local knowledge and international guidelines. All effluent characteristics discussed (BOD, TN, TP, pH, TDS, salinity, sodium adsorption ration, and heavy metals - As, Cd, Cu, Fe, Pb, Mn, Ni, and Zn) are below or within range of the Australian wastewater reuse guidelines recommended values. Faecal coliforms were assessed according to USEPA guidelines and were generally higher than the strictly recommended value of nil detection. Pesticides and herbicides were also discussed, and diuron, terbuthylazine, mecoprop, and triclopyr were detected in both Mangere and Rosedale WWTPs. The future of treated wastewater reuse in NZ rests upon the endorsement by regulatory bodies, consultation with Māori, and a comprehensive recycled water reuse guideline document.