ZHAOJian-qiang,ZHANGJu,SHIBing-feng,et al.Discussion on the Value Range of Excess Sludge Decay Coefficient[J].China Water & Wastewater,2022,38(24):53-57.
Discussion on the Value Range of Excess Sludge Decay Coefficient
China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU]
volume:
第38卷
Number:
第24期
Page:
53-57
Column:
Date of publication:
2022-12-17
- Keywords:
- wastewater treatment plants; excess sludge; sludge age; mixed liquor volatile suspended solids (MLVSS); decay coefficient
- Abstract:
- The amount of excess sludge is an important factor in the design and operation of wastewater treatment plants. The formula for calculating the excess sludge quantity in wastewater treatment plants according to sludge yield coefficient, decay coefficient (Kd) and non-biodegradable and inert suspended solids is proposed in Standard for Design of Outdoor Wastewater Engineering (GB 50014-2021). However, the value range of sludge decay coefficient (0.04-0.075 d-1) in this formula cannot adapt to the condition that the influent contains a high concentration of non-biodegradable suspended solids with a long sludge age. Based on the concept of sludge age, the paper introduced the expression of sludge decay coefficient by theoretical derivation, illustrated the essential meaning and influence factors of sludge decay coefficient, and pointed out that decay coefficient was not a constant and its value varied with sludge age and the proportion of non-biodegradable suspended solid cumulative concentration in the reaction tank to the concentration of volatile suspended solids in the mixed liquor. It is proposed that the value of Kd can be judged by the sludge age and the ratio of the concentration of non-biodegradable suspended solids and the concentration of biodegradable organic pollutants in the influent. A Kd value of 0.03 d-1 is appropriate for an engineering example cited in this paper. This research is expected to provide useful help for improving and broadening the application range of the formula.
Last Update:
2022-12-17