An Equalization Control Strategy for Activated Sludge Process Control

Dold, Peter; Buhr, H. O.; Marais, G. V. R.

doi:10.2166/wst.1985.0132

Cited by 4 publications

(4 citation statements)

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“…The issues have been discussed by several workers in the past (for example, Dold et al 1984 andDi Toro 1975) and suggest some sort of predictive model is required for adequate equalization operation. The objective of the work in this paper is to set forth an approach that will provide adequate equalization using a relatively straightforward methodology to equalize high ammonia sidestream returns that could be implemented by operators skilled with the use of spreadsheets.…”

Section: Equation 1: Centrate Tank Outflow (Gpd) = Total Centrate Volmentioning

confidence: 99%

Centrate Equalization – What You Don't Control Can Hurt You

Fevig¹,

Bratby²,

Douville³

et al. 2011

proc water environ fed

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Management of high ammonia dewatering return streams is key for plants that struggle to meet effluent ammonia limits. This paper focuses on approaches to high ammonia sidestream management to reduce the impacts of diurnal ammonia peaks and effluent ammonia excursions. The same principles may be applied to other sidestream sources (e.g., filtrate from a belt filter press), but the examples in this paper are related to centrate. When facility operational constraints or other factors prevent ideal load equalization from being implemented, flow equalization can still help mitigate ammonia excursions. A challenge with equalization basin operation is how to predict the daily outflow volume needed for true equalization. Important aspects of high ammonia sidestream management, such as determining the volume of equalization required, dewatering schedules, tank and pump design, desired outflow control, and the impacts of continuous or "trough-fill" high ammonia sidestream recycle are discussed. Examples from two Colorado wastewater treatment facilities are included to demonstrate these approaches.

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Section: Equation 1: Centrate Tank Outflow (Gpd) = Total Centrate Volmentioning

confidence: 99%

Centrate Equalization – What You Don't Control Can Hurt You

Fevig¹,

Bratby²,

Douville³

et al. 2011

proc water environ fed

View full text Add to dashboard Cite

show abstract

“…The influent flow and load rate patterns are not identical, but there are interrelations between the two. Thus, no constant output value can be expected simultaneously for both parameters over the daily cycle (Dold et al 1984). Also the diurnal cyclic influent flow and load rate patterns are not repeated identically from day to day.…”

Section: Introductionmentioning

confidence: 99%

“…In the past, equalization as a control tool has been underestimated for several reasons. Dold et al (1984) reported that incorrect parameters have been used to assess the effectiveness of equalization, studied plants were operated at short sludge ages (< 3 days) where equalization could demonstrate little benefit, load equalization has not been considered and studied settling tanks were considerably overloaded. In recent years, as effluent standards have become more stringent and BNR process has gained popularity, equalization applications have been under investigation again.…”

Section: Introductionmentioning

confidence: 99%

Flow and Load Equalization Using Primary Clarifiers in a BNR Plant

Mikola¹,

Rautiainen²,

Kiuru³

2007

proc water environ fed

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A full-scale 18 month study at Pihlajaniemi treatment plant in Savonlinna Finland (PE 30 000) investigated the feasibility of using the primary clarifiers for flow and load equalization as well as for volatile fatty acid (VFA) production. The objective was to improve the process performance of the biological nutrient removal (BNR) process and find better use for the old primary clarifiers.Equalization in this study decreased flow rate variations by 38% on an average. During the best months the flow to the biological process was practically constant. Hydrolysis was successful. The VFA concentration increased by 50%. The simultaneous removal of raw sludge did not cause any problems. The use of primary clarifiers for equalization and fermentation influenced the biological process in three ways: It improved the hydraulic control of the process, it equalized the load and conditions in the process and it increased the amount of readily usable organic matter. The transformation of old primary clarifiers for multipurpose primary tanks proved to be economically and technically feasible solution for responding to the requirements of BNR process.

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“…Fluctuations in hydraulic and organic loads cause wastewater treatment plant operating problems such as aeration control, settling tank overloading, etc. Dold et al (1984) emphasised that the flow and load equalisation can demonstrate full benefits only in plants where sludge age is long and the process includes anaerobic, anoxic and aerobic zones. Equalisation will, in this case simplify, or reduce the control requirements within the plant.…”

Section: Introductionmentioning

confidence: 99%

The effect of flow equalisation and prefermentation on the sludge production and sludge characteristics in a BNR plant

Mikola¹,

Rautiainen²,

Kiuru³

2008

Water Science and Technology

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A full-scale study investigated the influence of diurnal flow equalisation and prefermentation on the characteristics of sludge. The diurnal variations in the sludge concentration and the level of sludge blanket in the secondary clarifiers were evened out significantly with the use of an equalization basin. Stable conditions in the aeration basin and in the secondary clarifiers contributed to the improvements in the performance of the BNR plant. A decrease in the waste activated sludge production and an improvement in the settleability were also observed. The low WAS yield was attributed to the low yield COD compounds produced by the prefermentation, longer sludge age and constant conditions obtained by the flow equalisation. Some evidence was found that good settling properties would be related to the amount of suspended solids fed to the biological process as well as to the good performance of the biological process.

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An Equalization Control Strategy for Activated Sludge Process Control

Cited by 4 publications

References 0 publications

Centrate Equalization – What You Don't Control Can Hurt You

Centrate Equalization – What You Don't Control Can Hurt You

Flow and Load Equalization Using Primary Clarifiers in a BNR Plant

The effect of flow equalisation and prefermentation on the sludge production and sludge characteristics in a BNR plant

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