RISING SLUDGE IN SECONDARY SETTLERS DUE TO DENITRIFICATION

被引:45
作者
HENZE, M
DUPONT, R
GRAU, P
DELASOTA, A
机构
[1] CONSORCIO AGUAS GRAN BILBAO, BILBAO, SPAIN
[2] PRAGUE INST CHEM TECHNOL, DEPT WATER TECHNOL & ENVIRONM ENGN, CS-16628 PRAGUE 6, CZECHOSLOVAKIA
关键词
RISING SLUDGE; NITRIFICATION; DENITRIFICATION; SECONDARY SETTLERS; NITROGEN GAS; SUSPENDED SOLIDS;
D O I
10.1016/0043-1354(93)90080-2
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
High suspended solids concentrations in settler effluents can be caused by rising sludge, which is the effect of flotation of solids by nitrogen gas resulting from biological denitrification. Many factors influence the nitrogen gas bubble evolution. The most important factor is the rate of biological denitrification. Factors like nitrogen gas solubility and oxygen concentration in settler influent only play a minor role. The hydraulic retention time in the bottom part of the settler is, for all practical purposes, so high that sufficient nitrogen gas will be generated at temperatures above 20-degrees-C, if the nitrate content in the influent to the settler is above the critical one. For temperatures around 20-degrees-C the critical nitrate-nitrogen concentration is 6-8 g NO3--N/m3. The best measure in order to avoid rising sludge is to denitrify the wastewater in the treatment process ahead of the settler.
引用
收藏
页码:231 / 236
页数:6
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