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| |  Posted 5/29/2007 1:52:13 PM | |
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| Recently We have had to start feeding an excessive amount of liquid cl2 into our reclaim water line. At present we are feeding about 240 gallons per day but we are only getting 3 to 4 parts per million when we do our cl2 testing. This is about160 gallons more than normal. Just before our reclaim system is our denite filters that 90% methanol is fed into and our Trojan UV System. Is this methanol or UV System affecting the cl2 in any way.
davis |
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| | | Posted 5/29/2007 7:57:29 PM | |
| Supreme Being
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| | Where are you taking the sample for chlorine testing. At the end of the chlorine contact tank? Before or after methanol? Before or after UV? After all of these? |
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| | | Posted 5/30/2007 8:59:53 AM | |
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| My sample is taken after methanol injection in the denite filters and uv disinfection. Samples are taken for cl2 just after cl2 injection and sampled again approximately 7 miles down our reclaim water line.
davis |
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| | | Posted 5/30/2007 1:00:23 PM | |
| Supreme Being
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| I can envision two possible culprits in the requirement to feed excessive chlorine: nitrite and methanol. If the nitification is incomplete, you will produce nitrite and certainly get a significant chlorine demand. The other possibility is excess methanol feed. I'd look at those two parameters first. If you can rule those out, we can look further at other possible causes of the high chlorine demand.
David |
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| | | Posted 5/30/2007 1:29:55 PM | |
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| If methanol was the case would we not see a change in effluent BOD.
davis |
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| | | Posted 5/30/2007 2:11:09 PM | |
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Supreme Being
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| | Bacteria that use methanol to denitrify need acclimation to get working. I don't know if your BOD seed would be able to rapidly degrade methanol. Soluble COD or TOC would be a better check for excess methanol and quicker. |
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| | | Posted 8/2/2007 10:48:43 PM | |
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| | I suggest that you measure the ammonia-N and nitrite-N (not nitrate) in the effluent at the dosing point. 5 mg/L of chlorine is needed for every mg/L of nitrite-N. Also you will probably notice that your ammonia is below the nitirite concentration. This phenomena is called nitrite lock. It can occur due to insufficient alkalinity in your nitirification process (alkalinity < 80 mg/L or easier to spot by pH < 6.4). Not sure if denitration filters can only partially denitrify. Increased ammonia above the level of nitrite, or elimination of nitrite is necessary to stabilise the process and good mixing at the chlorine dosing point essential. I imagine it is summer at your plant. This leads to higher nitrification nitrifying ammonia and reducing NH3-N and producing nitrite. Ammonia has a stabilising effect on chlorine and in its absence the free chlorine may react with color in the effluent. This could be an alternative conern if nitrite is absent. Regards Grant H, Melbourne Aust |
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