There are several elements, ...

Published January 10, 2020 21:42 by Joseph Cotruvo, President at Joseph Cotruvo & Associates, Water , Environment and Public Health

There are several elements, but the simplest and least expensive is: do not perchlorinate if not necessary, reduce the TOC, chlorinate to microbial standards, then convert residual to chloramine. WHO always says that microbial safety is most important, and it should not be compromised for the purpose of reducing DBPs. I wrote the original THM regulation in 1979, and I wrote a recent paper to the effect that THMs are not carcinogenic in drinking water, and bladder cancer rates have not changed in the US and Canada over 40 years since the THM regulation was in effect. Joe Cotruvo

2 Comments

Joseph:

Thanks for your comment. Puerto Rico where we are located belongs to the EPA Region II. Federal regulations here are to be followed and complied, so looks like we have no option,specially for public systems, until regulations are changed.

We receive 60% of the water from lakes.Water from eutrophic stratified lakes may need chlorination in order to oxidize Mn,Fe and reduce color/taste/smell. So some kind of pre oxidation is usually required.

At the other side of the coin, the system that we describe is a barrier vs bacteria (0.1µ vs 5.0 µ of sand filtration), so less chlorine is needed to kill bugs so conversion to chloramine may not be necessary ; coagulant reduction and enhanced enhanced coagulation capability is another benefit.

Published January 11, 2020 14:59 by CARLOS GONZALEZ, CTO at Carlos Gonzalez

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We all want safe and good quality drinking water for a reasonable price. The THM regulation started the process of serious treatment of drinking water, but some people have gone too far. It has generated a cottage industry of analytical and treatment studies. As my paper showed, it is not clear that there is any adverse effect of THMs. We do know that whatever the water quality entering distribution, it arrives at the tap in poorer shape. Distribution is where we should be spending money.

Published January 13, 2020 15:17 by Joseph Cotruvo, President at Joseph Cotruvo & Associates, Water , Environment and Public Health

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I meant "do not perchlorinate if not necessary"

Published January 10, 2020 21:43 by Joseph Cotruvo, President at Joseph Cotruvo & Associates, Water , Environment and Public Health

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Yes thanks. Multitasking problem!!!

Published January 14, 2020 15:39 by Joseph Cotruvo, President at Joseph Cotruvo & Associates, Water , Environment and Public Health

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I think you meant "prechlorinate" not "perchlorinate". I agree that NOM removal is one of the biggest steps to take to reducing THMs (and many other chlorinated DBPs). Also reduces the expense of chlorination.

Published January 13, 2020 20:02 by Adam Eyring

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