The Solution to California’s Droughts Could Be Drinking Seawater

Urban Water Security | January 16, 2016

How does ​California ​tackle a five-​year-long ​drought? By ​turning ​seawater into ​the kind you ​can drink. ​

Carlsbad’s ​2.2-hectare ​desalination ​plant in San ​Diego County ​pumps out 200 ​million litres ​of ​water a ​day, supplying ​300,000 ​residents and ​businesses. ​Further north, ​in Santa ​Barbara, a ​second plant ​will supply 30 ​per cent of the ​city’s ​water by early ​2017. ​

The filtration ​system – a salt ​ion-removing ​process known ​as reverse ​osmosis – has ​been developed ​by ​IDE Technologies . “Desalination ​is not new,” ​explains Miriam ​Faigon, the ​Israeli ​firm’s COO. ​”But breakthroughs ​in membrane ​manufacturing ​means reverse ​osmosis [RO] is ​popular. ​

Inside the ​plant, seawater ​is pumped into ​filtration ​tanks ​containing ​anthracite, ​sand and gravel ​to remove algae ​and other ​particles. It ​then undergoes ​a microfiltration ​process to ​remove ​impurities. ​Next comes ​reverse osmosis:​ where water is ​pushed through ​membranes of ​polypropylene ​to remove ​bacteria, ​viruses and ​dissolved salts.​

Reverse osmosis: where water is pushed through membranes of polypropylene to remove bacteria, viruses and dissolved salts

Reverse ​osmosis: where ​water is pushed ​through ​membranes of ​polypropylene ​to remove ​bacteria, ​viruses and ​dissolved salts.​

Carlsbad is ​owned by ​desalination ​developer ​Poseidon Water. ​”The largest ​cost of ​operating is ​the ​electricity ​needed to push ​the water ​through the RO ​membranes,” ​says Scott ​Maloni, ​Poseidon ​Water’s ​vice president. ​So it installed ​144 energy ​recovery ​devices to ​capture the ​hydraulic ​power ​created by the ​high-pressure ​stream of ​rejected ​seawater ​produced during ​the RO process. ​

After RO ​filtration, the ​water undergoes ​post-treatment, ​which includes ​adding some ​minerals and ​disinfection ​with chlorine. ​Several centres ​around the ​world are now ​working on ​advanced ​membranes that ​could cut the ​energy needs of ​desalination ​plants even ​further. ​

“The real game ​changer that ​people are ​talking about ​is the graphene ​membrane,” says ​Maloni. “But ​nothing ​suggests that ​it’s ​anywhere close ​to commercial ​availability.” ​

Contact us | We're looking forward to hearing from you... Distributors | See our distributors list or apply to be one