Hastings Wastewater an Update of This Remarkable ‘win-win’ No Sludge Wastewater Treatment Solution That Challenged Conventional Practice

Almost three years on from commissioning, the unique $30M domestic wastewater treatment approach developed by Hastings District Council (HDC) and consultants MWH has proven itself to be leading-edge, technically-robust, cost-effective and culturally-acceptable. An innovative “no sludge” solution was adopted that has resulted in a paradigm shift in wastewater planning and treatment in New Zealand. Unlike many other municipal wastewater treatment plants which traditionally use primary and secondary treatment incorporating clarifiers the project team designed a modified Biological Trickling Filter (BTF) process without clarifiers. This natural biological treatment process incorporates a low organic loaded BTF which sees the wastewater fine screened before trickling through two 10m depth of randomly packed plastic media in 37m diameter tanks. This process transforms the human waste into biomass, carbon dioxide and water which is then discharged through a Papatuanuku (rock lined) channel to spiritually cleanse the treated human waste before disposal via a 2.75km long offshore ocean outfall. The innovative arrangement meets tangata whenua aspirations, complies with resource consent conditions and eliminates the requirement for any sludge treatment and disposal. This paradigm shift solution is a first for New Zealand and probably internationally. Maori cultural acceptance, plant robustness, low energy use and the avoidance of having to treat and dispose of sludge are significant advantages of this unique approach which has, following Hastings lead, also been successfully implemented by the Gisborne District Council and the soon to be constructed wastewater treatment plant for the Napier City Council.