Mitigation and best practice options

Some simple steps to minimise the effects of wastewater on water quality and mahinga kai.

Some simple steps to minimise the effects of wastewater on water quality and mahinga kai.

The 'New Zealand Waste Strategy' includes a target that all substandard wastewater treatment plants be upgraded, closed, or replaced by the end of 2020. The strategy also aims to have sewage sludge used beneficially or at least treated prior to using it as landfill. The overall aim is to reduce the production of methane (a greenhouse gas) and leachate to ground of surface waters (decreases water quality).

A major focus of the strategy is the creation of a circular process which involves re-use, rather than the historic linear process from use to disposal. This process requires recognition of four key stages in any wastewater management system from source to eventual return to the environment:

  1. managing wastewater at source (including water conservation and recycling)
  2. collection and treatment
  3. re-use of treated wastewater and sludge
  4. re-entry of treated waste into an ecosystem.

Reduce and reuse wastewater - reduce wastewater at the source by improved technologies, e.g., low water washing machines and toilet systems, or using recycled water (greywater) in toilets.

Collect rain water - water reclamation and reuse offers an effective means of conserving our limited high-quality freshwater supplies and reduces the amount of water in waste- and stormwater treatment plants, while helping to meet the ever growing demands for water.

Upgrade waste water treatment - minimise pollution of receiving waterways through effective primary, secondary and tertiary treatment of raw sewage. Change household cleaners to ones that do not damage septic tanks and are easily biodegradable to reduce nutrients getting into systems rather than needing complex and expensive treatment.

Control erosion at discharge - prevent erosion of land or stream bank slopes where discharges are directed. Outfalls should be armoured with rock and riparian planting to minimise erosion.

Dispose of wastewater to land – consider disposal of final wastewater via land based methods such as a drip line irrigation or artificial wetland systems instead of directly to waterways.