21 August 2007
The ESR (Environmental Scientific Research) has given Corrections the thumbs up for its innovative and safe recycling of Wanganui Prison’s sewage water.
For the past two years, recycled water from the prison’s sewage treatment ponds has nourished trees, shrubs and plants grown in the prison’s onsite nursery.
Corrections Assets and Property Construction Manager Crispin Kay says recently completed tests for impurities have shown that the recycling process is working exceptionally well.
“ESR has tested the water for every bug and chemical you can think of and given it a clean bill of health,” Mr Kay says. “No harmful impurities have been found.”
“Water quality aside, we are careful not to use the water on edible plants and to ensure that the watering system is only operated after everyone’s left the nursery at the end of the day.”
Operated by the Corrections Inmate Employment programme, the five-acre nursery specialises in growing natives including kowhai and harakeke.
The nursery used to pump 100 cubic metres of water from the prison’s aquifer daily to water the plants. Two years ago when 140 prison beds were added to the prison, Corrections decided that recycling sewage water for the nursery would be an opportunity to save the aquifer water and reduce the environmental impact of the additional prisoner numbers.
The sewage water is passed through several ponds, filtered, stored and U/V treated before being sprayed through heavy droplet sprinklers designed to stop it blowing away on windy days.
Mr Kay says recycling sewage water is not necessarily an easy route to take - obtaining the required resource consent was a challenge but “support from the local iwi and a favourable response from the public consultation process certainly helped our cause”.
“Because recycling sewage water has not been common in New Zealand, the Department of Health requested that the treatment process met the only available Australian water recycling guideline.”
Mr Kay says Corrections is committed to investigating and building systems that reduce energy consumption and enable it to reduce its environmental impact. Water recycling options at other prisons are being actively considered.
ENDS