............................... Solids loading rate

1998 ◽  
pp. 210-211
Keyword(s):  
Loading Rate ◽  
Solids Loading

scholarly journals Enzymatic Hydrolysis and Simultaneous Saccharification and Fermentation of Soybean Processing Intermediates for the Production of Ethanol and Concentration of Protein and Lipids

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Craig C. Long ◽  
William Gibbons
Keyword(s):  
Loading Rate ◽  
Simultaneous Saccharification And Fermentation ◽  
Solid Loading ◽  
Scheffersomyces Stipitis ◽  
Loading Rates ◽  
Solids Loading ◽  
Commercial Enzymes ◽  
Protein Fiber ◽  
Soybean Processing ◽  
Simultaneous Saccharification

Carbohydrates in soybeans are generally undesirable due to their low digestibility and because they “dilute” more valuable components (proteins, lipids). To remove these carbohydrates and raise the titer of more valuable components, ethanol production was investigated. Commercial enzymes (Novozyme cellulase, β-glucosidase, and pectinase) were added to ground soybeans (SB), soybean meal (SBM), soybean hulls (SH), and soybean white flakes (WF) at a 10% solids loading rate to quantify hydrolyzed glucan. Saccharification resulted in glucan reductions of 28%, 45%, 76%, and 80% (SBM, SB, SH, WF, resp.). Simultaneous saccharification and fermentation (SSF) trials were conducted at 5%, 10%, 15%, and 20% solids loading with Saccharomyces cerevisiae NRRL Y-2034 and Scheffersomyces stipitis NRRL Y-7124, with protein, fiber, and lipids analyzed at SSF 10% solids and saccharification trials. S. cerevisiae and S. stipitis produced ~3–12.5 g/L ethanol and ~2.5–8.6 g/L ethanol, respectively, on SB, SBM, and WF over all solid loading rates. SH resulted in higher ethanol titers for both S. cerevisiae (~9–23 g/L) and S. stipitis (~9.5–14.5 g/L). Protein concentrations decreased by 2.5–10% for the SB, SBM, and WF, but increased by 53%–55% in SH. Oil concentrations increased by ~50% for SB; by ~500%–1300% for the others.

Activated Sludge Settlers: Design and Optimization

1987 ◽  
Vol 19 (3-4) ◽  
pp. 613-623 ◽  
Author(s):  
P F. C. Catunda ◽  
A. C. van Haandel
Keyword(s):  
Activated Sludge ◽  
Surface Area ◽  
Loading Rate ◽  
Operational Cost ◽  
Design And Optimization ◽  
Mixed Liquor ◽  
Solids Loading ◽  
Solids Concentration ◽  
Sludge Thickening ◽  
Sludge Settling

Activated sludge settlers perform two functions simultaneously: clarification and sludge thickening. Depending on the values of the mixed liquor and return sludge concentrations and on the sludge settling characteristics either one of these functions may limit the solids loading rate that can be applied to the settler, which in turn determines the required settler surface area. A method is developed to establish which of the two functions is determinant for the maximum solids loading rate in a particular design situation. Expressions are derived to calculate the required settler surface area for clarification and for thickening. These expressions are based on the experimentally verfied supposition that the zone settling velocity decreases exponentially with increasing suspended solids concentration. A graphical method to determine the optimal mixed liquor and return sludge concentrations for minimum construction and operational cost is presented.

scholarly journals Development of Primary Sludge Control Technology Based on Solids Loading Rate in Sidestream MLE Process

2020 ◽  
Vol 42 (12) ◽  
pp. 623-636
Author(s):  
Shinyo Chang ◽  
Pung Shik Shin ◽  
Hyeon Park ◽  
Yeon-Koo Jeong
Keyword(s):  
Removal Efficiency ◽  
Loading Rate ◽  
Withdrawal Rate ◽  
Stable Operation ◽  
High Concentration ◽  
Nitrogen And Phosphorus ◽  
Primary Sludge ◽  
Solids Loading ◽  
Point Analysis ◽  
Tin Removal

Objectives:By measuring the solids loading rate for the sidestream, it was intended to achieve increased treatment capacity and improved process performance by developing control technologies for primary sludge removal, recirculation, and input.Methods:The pilot plant was manufactured by the primary clarifier+MLE process similar to the full-scale plant and was configured to control the amount of sludge withdrawal based on the inflow solids loading rate. The state point analysis was used to determine removal underflow withdrawal rate and the total underflow withdrawal rate for the primary sludge. The operation was divided into manual withdrawal, automatic withdrawal, automatic withdrawal+recirculation, and automatic withdrawal + input methods. The performance evaluation items for primary sludge control technology were primary sludge concentration and SS removal efficiency for primary and secondary clarifiers. The improvement in the performance of the bioreactor by recirculation and input was judged through the removal efficiency of ammonium nitrogen, TIN (Total Inorganic Nitrogen) and phosphate phosphorus, SNR (Specific Nitrification Rate), and SDNR (Specific Denitrification Rate). The cause of the performance improvement was analyzed by comparing the acetic acid concentration changed by recirculation and the microbial community characteristics.Results and Discussion:The average value of SS monitoring of the sidestream influent was 2.2 (0.7~6.3) g/L and the primary clarifier needed treatment in response to high concentration SS and fluctuations. It is judged that the state point analysis based on the actual settling rate can accurately suggest whether the stable operation of primary sludge removal, recirculation, and input is the possible and specific design and operation standards. The automatic withdrawal that controls the underflow withdrawal rate according to the change of the inflow solids loading rate could stably draw out the high-concentration sludge and maintain the SS removal efficiency. It is believed that stable operation is possible even in the sludge recirculation operation, and the treatment capacity of the primary clarifier can be increased more than two times in a full-scale plant. By recirculation of the primary sludge, the TIN removal efficiency in the bioreactor was improved by 24.2~52.3%, and the phosphate phosphorus removal efficiency was improved by up to 20.1%. The TIN removal efficiency in the bioreactor was improved by 32.6% by the input of primary sludge. VFAs (Volatile Fatty Acids) including acetic acid was produced and the removal efficiency was improved because it was in contact with primary sludge by recirculation and the ratio of major fermentation microorganisms was present at 2.0%. It is determined that 26.4% of the main species of microorganisms treated with nitrogen and phosphorus exist in the sidestream inflow and the removal efficiency was improved by supplying microorganisms through the input of primary sludge.Conclusions:Technology that controls primary sludge removal, recirculation, and input by measuring the solids loading rate for the sidestream is believed to increase the treatment capacity of the primary clarifier and improve the nitrogen and phosphorus removal efficiency of the bioreactor.

scholarly journals Dynamic simulation and optimization of anaerobic digestion processes using MATLAB

2022 ◽  
Author(s):  
Prabakaran G ◽  
Karthik Rajendran
Keyword(s):  
Time Series ◽  
Anaerobic Digestion ◽  
Loading Rate ◽  
Continuous Process ◽  
Simulation And Optimization ◽  
Solids Loading ◽  
Significant Difference ◽  
Fundamental Understanding ◽  
Biomethane Production ◽  
Extensive Experimental Data

Time series-based modeling provides a fundamental understanding of process fluctuations in an anaerobic digestion process. However, such models are scarce in literature. In this work, a dynamic model was developed based on modified Hill’s model using MATLAB, which can predict the biomethane production with time series. This model can predict the biomethane production for both batch and continuous process, across substrates and at diverse conditions such as total solids, loading rate, and days of operation. The deviation between literature and the developed model was less than ±7.6%, which shows the accuracy and robustness of this model. Moreover, statistical analysis showed there was no significant difference between literature and simulation, verifying the null hypothesis. Finding a steady and optimized loading rate was necessary to an industrial perspective, which usually requires an extensive experimental data. With the developed model, a stable and optimal methane yield generating loading rate could be identified at minimal input.

Comparison of the 1D flux theory with a 2D hydrodynamic secondary settling tank model

2004 ◽  
Vol 50 (7) ◽  
pp. 195-204 ◽  
Author(s):  
G.A. Ekama ◽  
P. Marais
Keyword(s):  
Surface Area ◽  
Loading Rate ◽  
Settling Tank ◽  
Full Scale ◽  
Tank Model ◽  
Marked Influence ◽  
Solids Loading ◽  
Small Influence ◽  
Secondary Settling ◽  
Sloping Bottom

The applicability of the 1D idealized flux theory (1DFT) for design of secondary settling tanks (SSTs) is evaluated by comparing its predicted maximum surface overflow (SOR) and solids loading (SLR) rates with that calculated from the 2D hydrodynamic model SettlerCAD using as a basis 35 full scale SST tress tests conducted on different SSTs with diameters from 30 to 45m and 2.25 to 4.1m side water depth, with and without Stamford baffles. From the simulations, a relatively consistent pattern appeared, i.e. that the 1DFT can be used for design but its predicted maximum SLR needs to be reduced by an appropriate flux rating, the magnitude of which depends mainly on SST depth and hydraulic loading rate (HLR). Simulations of the sloping bottom shallow (1.5-2.5 m SWD) Dutch SSTs tested by STOWa and the Watts et al. SST, all with doubled SWDs, and the Darvill new (4.1 m) and old (2.5 m) SSTs with interchanged depths, were run to confirm the sensitivity of the flux rating to depth and HLR. Simulations with and without a Stamford baffle were also done. While the design of the internal features of the SST, such as baffling, have a marked influence on the effluent SS concentration for underloaded SSTs, these features appeared to have only a small influence on the flux rating, i.e. capacity, of the SST. In the meantime until more information is obtained, it would appear that from the simulations so far that the flux rating of 0.80 of the 1DFT maximum SLR recommended by Ekama and Marais remains a reasonable value to apply in the design of full scale SSTs – for deep SSTs (4 m SWD) the flux rating could be increased to 0.85 and for shallow SSTs (2.5 m SWD) decreased to 0.75. It is recommended that (i) while the apparent interrelationship between SST flux rating and depth suggests some optimization of the volume of the SST, that this be avoided and that (ii) the depth of the SST be designed independently of the surface area as is usually the practice and once selected, the appropriate flux rating is applied to the 1DFT estimate of the surface area.

Characterizing shallow secondary clarifier performance where conventional flux theory over-estimates allowable solids loading rate

2016 ◽  
Vol 74 (2) ◽  
pp. 324-332 ◽  
Author(s):  
Glen T. Daigger ◽  
John S. Siczka ◽  
Thomas F. Smith ◽  
David A. Frank ◽  
J. A. McCorquodale
Keyword(s):  
Suspended Solids ◽  
Loading Rate ◽  
Fluid Dynamic ◽  
Flux Analysis ◽  
Stress Tests ◽  
Mixed Liquor ◽  
Cfd Models ◽  
Solids Loading ◽  
Cfd Analyses ◽  
The City

The performance characteristics of relatively shallow (3.3 and 3.7 m sidewater depth in 30.5 m diameter) activated sludge secondary clarifiers were extensively evaluated during a 2-year testing program at the City of Akron Water Reclamation Facility (WRF), Ohio, USA. Testing included hydraulic and solids loading stress tests, and measurement of sludge characteristics (zone settling velocity (ZSV), dispersed and flocculated total suspended solids), and the results were used to calibrate computational fluid dynamic (CFD) models of the various clarifiers tested. The results demonstrated that good performance could be sustained at surface overflow rates in excess of 3 m/h, as long as the clarifier influent mixed liquor suspended solids (MLSS) concentration was controlled to below critical values. The limiting solids loading rate (SLR) was significantly lower than the value predicted by conventional solids flux analysis based on the measured ZSV/MLSS relationship. CFD analysis suggested that this resulted because mixed liquor entering the clarifier was being directed into the settled sludge blanket, diluting it and also creating a ‘thin’ concentration sludge blanket that overlays the thicker concentration sludge blanket typically expected. These results indicate the need to determine the allowable SLR for shallow clarifiers using approaches other than traditional solids flux analysis. A combination of actual testing and CFD analyses are demonstrated here to be effective in doing so.

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