Effects of storage on water treatment plant sludges
<p>The effects of in-basin storage of sludge on the iron, manganese, and TOC removal of water treatment plant (WTP) clarifiers and on the dewatering characteristics of sludge were examined. The use of chlorine dioxide as a preoxidant to retard observed detrimental effects was also investigated...
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Virginia Tech
2014
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| Online Access: | http://hdl.handle.net/10919/45542 http://scholar.lib.vt.edu/theses/available/etd-11092012-040020/ |
| Summary: | <p>The effects of in-basin storage of sludge on the iron, manganese, and
TOC removal of water treatment plant (WTP) clarifiers and on the dewatering
characteristics of sludge were examined. The use of chlorine
dioxide as a preoxidant to retard observed detrimental effects was also
investigated.</p>
<p>Sludge samples that were stored over a period of 120 days were found
to release up to ten times the original supernatant concentration of iron
and manganese from the sludge into the overlying supernatant liquor when
sludge redox potential values decreased below +100 mV. Organic carbon
also increased in the supernatant but to a lesser extent. Sludge dewatering
characteristics as measured by specific resistance and capillary
suction time were found to improve when sludge redox potential readings
remained over 100 mV but varied greatly when readings were below this
level.</p>
<p>Field monitoring and sampling of the clarifiers at Lee Hall WTP and
Harwood's Mill WTP from April to July showed that the removal efficiencies
of the clarifiers was not related to in-basin sludge storage. This conflicted
with a later portion of the study and was thought to be due to
the lack of standardized sampling techniques.</p>
<p>The final phase of the investigation dealt with the use of chlorine
dioxide to retard the negative effects of in-basin storage of sludge.
Sludge accumulation in clarifiers resulted in decreased iron and
manganese removal efficiencies when chlorine dioxide was not used. Addition
of chlorine dioxide improved the iron and manganese removal efficiencies
of the clarifiers. Sludge dewatering characteristics were found
to improve with the use of chlorine dioxide as a preoxidant.</p> === Master of Science |
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