Recycling Wastewater to Irrigate California Botanical Gardens

A botanical garden in California is looking into recycling wastewater to combat droughts in the region. Descanso Gardens is a 67-Hectare botanical garden located in La Cañada Flintridge, Los Angeles County that has recently experienced a statewide drought and record-high temperatures that caused thousands of plant species to die. This prompted the property managers to seek new sources of water for their land to prevent a repeat of this incident.

So, when the site’s largest septic system began to fail in 2017, they wanted to do more than just find a mere fix for the problem and decided on building a compact sewage treatment plant that is suitable for recycling wastewater that is suitable for irrigation.

The system they chose to use is called a membrane bioreactor (MBR) which combines biological wastewater treatment with ultrafine membrane filtration. It is capable of processing up to 150,000 litres of wastewater per day.

“When our sewer system started to fail, we really saw it as an opportunity to do something better,” said Descanso Executive Director Juliann Rooke. “The new MBR will take water that was not being used and put it right back into the gardens.”

Recycling wastewater in the facility was able to irrigate a 6,000 square metre front entrance garden that replaced the redwoods killed by a severe heatwave a year before.

“They just couldn’t handle the heat,” said Descanso horticulturalist David Bare. “They were never going to be able to recover from that. We got to the point where we thought they were a fire hazard.”

Although many trees were lost, their wood were still put to good use. It was given to other gardens and school groups that use recycled redwood.

Bare also put the lumber through a recycling process called “hügelkultur.” It is a practice where dead and decaying wood is placed into raised beds to create nutrient-rich soil for new plantings. Their hope is that the renewed space will better reflect the horticulture seen inside the gardens.

With their strategy of recycling wastewater through the new treatment plant, they were able to use about 64,000 litres of reclaimed water per day for irrigation. It is expected that the plant would receive wastewater from other septic systems around the area to further augment their water output.

“When Manchester Boddy founded his ranch in the 1930s, he secured water rights in Hall Beckley Canyon, about 5 kilometres away. We’ve had concerns over that water source and the pipes that bring the water to us,” Rooke said. “Now up to 150,000 litres of water that were currently not usable will be treated and used to water the front drive and, eventually, parking lot gardens.”

Places like Descanso Gardens are finding it necessary to look towards renewable sources of water to replenish their scarce supplies for their plants particularly during harsh droughts and extreme heat waves. Wastewater treatment offers a practical and sustainable solution that offers many benefits for businesses and communities which not only saves them money but more importantly, saves the environment.

If you are a municipality in Ontario and in need of a biosolids management solution, please feel free to contact us at 1 (877) 479-1388.


Recycling Wastewater to Irrigate California Botanical Gardens
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