[compost_tea] More on Chlorine

From: Ted Peterson <ted.peterson_at_tcsn.net>
Date: Mon, 3 May 2004 16:37:02 -0700

Folks:

Here is some supporting material for Elaine's statement about how chlorine =
works. In another email, I sent some info about pathogen resistence to chl=
orine. Here is the info. For those railing aginst chlorine/chloramine in =
our drinking water, it does have some positive effect. Of course, as with =
everything, it comes with a price. It's the ol' "Monkey's Paw" principal a=
t work.

Note down at the bottom that the recommendation for certain protozoa that s=
how resistence to chlorine is filtration. All my water is double flitered.=
  One filter is on the house in general and one for drinking water only. T=
hese filters are for particulates and taste. They are charcoal based. Now=
 this is kind of weird because I have to be careful that I don't overfilter=
 or over process; we need some of those microbes and I don't think that "of=
f the shelf" filtration really can identify a pathogen from a benificial. =
RO is always an answer but everyone I know who has RO on their home water s=
upply is sick all the time. It appears that too much disinfection is as ba=
d as too little.

Here's the info:

Although chlorine's value has been known for nearly a century, the mechanis=
m by which the compound kills or inactivates microorganisms is not clearly =
understood. The bulk of chlorine disinfection research, conducted from the =
1940s to the 1970s, focused on bacteria. Though limited, this work gave ris=
e to some speculation. Researchers postulated that chlorine, which exists i=
n water as hypochlorite and hypochlorous acid, reacts with biomolecules in =
the bacterial cell to destroy the organism.
Further work led to the so-called "multiple hit" theory of chlorine inactiv=
ation. It asserted that bacterial death probably results from chlorine atta=
cking a variety of bacterial molecules or targets, including enzymes, nucle=
ic acids and membrane lipids.

Early research efforts focused on how chlorine attacks enzymes. The disinfe=
ctant was able to inactivate extracts of various enzymes because it is high=
ly reactive with sulfur-containing and aromatic amino acids. But it had no =
effect on cytoplasmic enzymes, suggesting that it might not reach biomolecu=
les within the bacterium. Thus, researchers redirected their attention to t=
he molecules on the surface of the bacterial cell.

A new hypothesis proclaimed that perhaps chlorine acted by attacking the ba=
cterial cell wall. Proponents of this idea suggested that chlorine exposure=
 might destroy the cell wall--by altering it physically, chemically and bio=
chemically--and so terminate the cell's vital functions, killing the microo=
rganism.

A possible sequence of events during chlorination would be:

a.. disruption of the cell wall barrier by reactions of chlorine with targe=
t sites on the cell surface
a.. release of vital cellular constituents from the cell
a.. termination of membrane-associated functions
a.. termination of cellular functions within the cell.


Here is some other info about virus, protozoa and chlorine:

Certain waterborne viruses, such as enteric viruses and hepatitis A, may be=
 even more tolerant to chlorine disinfection than some bacterial species. B=
ut the means by which chlorine inactivates viruses is not well understood.=
 

In recent years, the parasitic protozoans Cryptosporidium parvum and Giardi=
a lamblia have emerged as formidable waterborne pathogens. These protozoa a=
re remarkably resistant to chlorine disinfection and consequently, present =
a great challenge to the water industry and health officials, who are respo=
nsible for providing safe drinking water to the public. Currently, filtrati=
on is the most effective process for removing these protozoa from drinking =
water. To fully protect the public, however, effective disinfection methods=
 must be developed.




Received on Mon May 03 2004 - 22:22:41 EDT

This archive was generated by hypermail 2.3.0 : Tue Feb 07 2012 - 14:15:15 EST