Mainstream partial nitritation/anammox with integrated fixed-film activated sludge: Combined aeration and floc retention time control strategies limit nitrate production

2020 ◽  
Vol 314 ◽  
pp. 123711 ◽  
Author(s):  
Dries Seuntjens ◽  
Jose M. Carvajal Arroyo ◽  
Michiel Van Tendeloo ◽  
Ioanna Chatzigiannidou ◽  
Janet Molina ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Retention Time ◽  
Control Strategies ◽  
Partial Nitritation ◽  
Time Control ◽  
Nitrate Production ◽  
Fixed Film

scholarly journals Efficiency of the work of almond shells as biological carriers in activated sludge aeration tanks: كفاءة عمل قشور اللوز كحوامل بيولوجية في أحواض التهوية بالحمأة المنشطة

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Raghad Salim Al-Shalabi, Naeima Ajib, Mahmoud Fattamah
Keyword(s):  
Activated Sludge ◽  
Removal Efficiency ◽  
Retention Time ◽  
Suspended Solids ◽  
Hydraulic Retention Time ◽  
Aeration Tank ◽  
Sludge Treatment ◽  
Mixed Liquor ◽  
Conventional Activated Sludge ◽  
Fixed Film

Based on the interest in environmentally friendly materials for wastewater treatment, this research is aimed at evaluating the efficiency of almond shells work as biological carriers in activated sludge aeration tanks, known as the integrated fixed-film activated sludge treatment, a hybrid tank with attached growth and suspended growth is obtained. Almond shells were placed at 7% of the size of the aeration tank throughout the experiment period for about 4 months with a number of indicators such as hydraulic retention time and mixed liquor suspended solids. Two sets of experiments were performed, the first group with a constant hydraulic retention time ( HRT= 4 hours), and mixed liquor suspended solids was changed (500-1000-2000-3000 mg/ L), with the best removal efficiency at MLSS = 2000 mg/ l, by 91.3% and 92.1% for COD and SS respectively. The optimal MLSS concentration was adopted for the second group of experiments where HRT was increased to 5 and 6 hours. As a result, the best chain was found to be MLSS = 2000 mg/ l and HRT = 5 hours, with a removal efficiency of 93.4% and 93.9% for COD and SS respectively. As a result, the rate of return activated sludge was reduced from 100% to 60% and the rate of inflow into the aeration tank was increased due to the reduction HRT from 6 hours to 5 hours compared to conventional activated sludge treatment.

The Impact of a Chemostat Discharge Containing Oil Degrading Bacteria on the Biological Kinetics of a Refinery Activated Sludge Process

1988 ◽  
Vol 20 (11-12) ◽  
pp. 131-136 ◽  
Author(s):  
A. D. Wong ◽  
C. D. Goldsmith
Keyword(s):  
Activated Sludge ◽  
Retention Time ◽  
Waste Treatment ◽  
Treatment Plant ◽  
Utilization Rate ◽  
Activated Sludge Process ◽  
Kinetic Evaluation ◽  
Degrading Bacteria ◽  
Waste Treatment Plant ◽  
The Impact

The effect of discharging specific oil degrading bacteria from a chemostat to a refinery activated sludge process was determined biokinetically. Plant data for the kinetic evaluation of the waste treatment plant was collected before and during treatment. During treatment, the 500 gallon chemostatic growth chamber was operated on an eight hour hydraulic retention time, at a neutral pH, and was fed a mixture of refinery wastewater and simple sugars. The biokinetic constants k (days−1), Ks (mg/L), and K (L/mg-day) were determined before and after treatment by Monod and Lineweaver-Burk plots. Solids discharged and effluent organic concentrations were also evaluated against the mean cell retention time (MCRT). The maximum utilization rate, k, was found to increase from 0.47 to 0.95 days−1 during the operation of the chemostat. Subsequently, Ks increased from 141 to 556 mg/L. Effluent solids were shown to increase slightly with treatment. However, this was acceptable due to the polishing pond and the benefit of increased ability to accept shock loads of oily wastewater. The reason for the increased suspended solids in the effluent was most likely due to the continual addition of bacteria in exponential growth that were capable of responding to excess substrate. The effect of the chemostatic addition of specific microbial inocula to the refinery waste treatment plant has been to improve the overall organic removal capacity along with subsequent gains in plant stability.

Improved Oxygen Dissolution Control for Oxygen Activated Sludge

1988 ◽  
Vol 20 (4-5) ◽  
pp. 101-108 ◽  
Author(s):  
R. C. Clifft ◽  
M. T. Garrett
Keyword(s):  
Activated Sludge ◽  
Control Method ◽  
Control Strategies ◽  
Cost Savings ◽  
Utilization Efficiency ◽  
Oxygen Production ◽  
Oxygen Utilization ◽  
Potential Cost ◽  
Oxygen Dissolution ◽  
The City

Now that oxygen production facilities can be controlled to match the requirements of the dissolution system, improved oxygen dissolution control can result in significant cost savings for oxygen activated sludge plants. This paper examines the potential cost savings of the vacuum exhaust control (VEC) strategy for the City of Houston, Texas 69th Street Treatment Complex. The VEC strategy involves operating a closed-tank reactor slightly below atmospheric pressure and using an exhaust apparatus to remove gas from the last stage of the reactor. Computer simulations for one carbonaceous reactor at the 69th Street Complex are presented for the VEC and conventional control strategies. At 80% of design loading the VEC strategy was found to provide an oxygen utilization efficiency of 94.9% as compared to 77.0% for the conventional control method. At design capacity the oxygen utilization efficiency for VEC and conventional control was found to be 92.3% and 79.5%, respectively. Based on the expected turn-down capability of Houston's oxygen production faciilities, the simulations indicate that the VEC strategy will more than double the possible cost savings of the conventional control method.

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