News for hackers. Stuff that matters.

A comment on LA is dumping millions of plastic balls into its reservoir to tackle the drought. Parent comment

Re:LA is dumping millions of plastic balls into its reservoi... by DanBC on Thursday August 13, 2015 @04:28AM (#10052828)
Was the article edited after you read it?

> And the primary reason for deploying the hollow balls is more to protect the quality of the water rather than to simply stop it evaporating. In the reservoir water, the naturally occurring bromide was mixing with sunlight and chlorine (added to disinfect drinking water) to create dangerous levels of the the carcinogen bromate. Shade balls should stop that harmful chemical reaction from happening at a large scale, and of course by deflecting the Sun's rays, they also keep more of the water in liquid form.

[ Parent | on HN ]
Re:LA is dumping millions of plastic balls into its reservoi... by zz1 on Thursday August 13, 2015 @05:06AM (#10052941)
Well, there is a difference from "we do this" and "we have been mandated to do this", whatever the reason "to do this" might be. I guess that explaining they were forced to cover the reservoir makes me appreciate the solution even more: given an order, they found an intelligent and efficient solution.
[ Parent | on HN ]
Re:LA is dumping millions of plastic balls into its reservoi... by desdiv on Thursday August 13, 2015 @04:37AM (#10052850)
Wouldn't it make more sense to add the chlorine after the water is drawn from the reservoir?

Doesn't that fix the bromate problem at the root?

[ Parent | on HN ]
Re:LA is dumping millions of plastic balls into its reservoi... by PhasmaFelis on Thursday August 13, 2015 @04:47AM (#10052870)
I would guess that having loads of dead algae in your drinking water is not much better than live algae. You want to keep assorted gunk from having a chance to grow in the first place.
[ Parent | on HN ]
Re:LA is dumping millions of plastic balls into its reservoi... by zz1 on Thursday August 13, 2015 @05:15AM (#10052977)
But certainly the water is filtered before reaching homes, considering it rests a long time in a open reservoir. So you could remove the dead algae. Still, they certainly have a "better dead" approach, wanting the reservoir to be a dead pool instead of a living ecosystem where they'd have to monitor what is growing and how dangerous it might be.
[ Parent | on HN ]
Re:LA is dumping millions of plastic balls into its reservoi... by DanBC on Thursday August 13, 2015 @09:12AM (#10053870)
It's interesting to compare different systems. Here's one for a small part of the UK. Our tap water (from thefaucet) is vety high quality.

http://www.thameswater.co.uk/cycles/accessible/water_treatme...

The last stage of the process is to add chlorine to the water.

[ Parent | on HN ]
Re:LA is dumping millions of plastic balls into its reservoi... by rtpg on Thursday August 13, 2015 @04:46AM (#10052863)
Just a guess, but maybe chlorine needs a good amount of time to be effective, and the transit time from reservoir to tap might not be enough
[ Parent | on HN ]
Re:LA is dumping millions of plastic balls into its reservoi... by Zardoz84 on Thursday August 13, 2015 @05:11AM (#10052964)
Why not use ozone to teat the water. It's a better solution that chlorine, even more effective to kill bacteria.
[ Parent | on HN ]
Re:LA is dumping millions of plastic balls into its reservoi... by david_b on Thursday August 13, 2015 @06:07AM (#10053121)
Why not, indeed...

Bromates are formed many different ways in municipal drinking water. The most common is the reaction of ozone and bromide.

Source: https://en.wikipedia.org/wiki/Bromate

[ Parent | on HN ]
Re:LA is dumping millions of plastic balls into its reservoi... by TsiCClawOfLight on Thursday August 13, 2015 @04:47AM (#10052869)
Is there any reason why you guys don't have your reservoirs underground? It seems to me that that would solve a lot of problems.
[ Parent | on HN ]
Re:LA is dumping millions of plastic balls into its reservoi... by rmc on Thursday August 13, 2015 @04:58AM (#10052911)
They're pretty hard to dig. Outside resivour can be made by damming a mountain valley and filling it in.
[ Parent | on HN ]
Re:LA is dumping millions of plastic balls into its reservoi... by zz1 on Thursday August 13, 2015 @05:11AM (#10052965)
They have space, and they conceived this system, like many others, thinking of what was the easiest thing to do, disregarding a low-maintenance approach.
[ Parent | on HN ]