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Influence of chemical oxygen demand/total Kjeldahl nitrogen ratio and sludge age on nitrification of nitrogenous wastewater

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Title Influence of chemical oxygen demand/total Kjeldahl nitrogen ratio and sludge age on nitrification of nitrogenous wastewater
 
Creator SHARMA, R
GUPTA, SK
 
Subject growth
kinetics
nitrification
nitrogenous wastewater
nitrifier fraction
nitrifier concentration
nitrification rate
chemical oxygen demand/total kjeldahl nitrogen ratio
sludge age
chemical oxygen demand loadings, and total kjeldahl nitrogen loadings
 
Description Four laboratory-scale biological nitrification units (influent total Kjeldahl nitrogen [TKN] = 1002 to 1062 mg/L) were operated at chemical oxygen demand (COD)/TKN ratios of approximately 0.5, 1.0, 15, and 2.0 and at three different sludge ages of 30, 20, and 10 days to study the influence of COD/TKN, sludge age, COD loading. and TKN loading oil nitrification and nitrifiers. Percent nitrification was found to increase with decreases in COD/TKN and increases in sludge age. The average nitrifier concentration increased from 460 mg/L at a COD/TKN of 2.22 and a sludge age of 10 days to 706 mg/L at a COD/TKN of 0.676 and a sludge age of 30 days. The nitrifier fraction was found to be higher at a lower COD/TKN and lower at a higher COD/TKN. The nitrifier fraction increased with the decrease in sludge age and COD loadings and the increase in TKN loadings. The effect of sludge age on the nitrifier fraction was amplified at a COD/ TKN of approximately 0.5 rather than at approximately 2.0. The nitrification rate (kilograms TKN oxidized per kilograms nitrifiers per day) was shown to be dependent on COD/TKN and sludge age. The activity performed by Nitrobacter was affected at all COD/TKN ratios studied as well as at a sludge age of 10 days. This was manifested by the accumulation of high levels of nitrite-nitrogen in the nitrified effluent. The presence of heterotrophs did not affect nitrification rates and the growth of nitrifiers, which were found to be beneficial. High sludge age and COD loadings resulted in a higher sludge volume index of more than 200 mL/g mixed liquor suspended solids. Microscopic examination showed filamentous structure of sludge under these conditions. It is concluded from the investigations that a sludge age of 30 days and a COD/TKN of approximately 1.0 are optimal to yield maximum nitrification and nitrifier growth rates for treating high-strength nitrogenous wastewater.
 
Publisher WATER ENVIRONMENT FEDERATION
 
Date 2011-09-01T10:26:56Z
2011-12-26T12:59:36Z
2011-12-27T05:52:06Z
2011-09-01T10:26:56Z
2011-12-26T12:59:36Z
2011-12-27T05:52:06Z
2004
 
Type Article
 
Identifier WATER ENVIRONMENT RESEARCH, 76(2), 155-161
1061-4303
http://dx.doi.org/10.2175/106143004X141681
http://dspace.library.iitb.ac.in/xmlui/handle/10054/12750
http://hdl.handle.net/10054/12750
 
Language en