scholarly journals Impact of hydraulic retention time on phosphorus removal from wastewater using reactive media

2020 ◽  
Vol 82 (12) ◽  
pp. 2920-2928
Author(s):  
S. Benzing ◽  
F. Couceiro ◽  
S. Barnett ◽  
J. B. Williams ◽  
P. Pearce ◽  
...  
Keyword(s):  
Retention Time ◽  
Hydraulic Retention Time ◽  
Wastewater Treatment Plants ◽  
Appropriate Technology ◽  
Synthetic Wastewater ◽  
Depth Analysis ◽  
The Impact ◽  
Over Time ◽  
P Removal ◽  
Reactive Media

Abstract Phosphorus (P) discharge from wastewater treatment plants into the environment contributes to eutrophication issues. Reactive media filters represent an effective, simple and cost-effective solution to decrease the P content. Previous research used various experimental designs and often synthetic wastewater, making assessment of real-world performance difficult. This study assesses the impact of the hydraulic retention time (HRT) on P removal using real wastewater to refine design criteria for full-scale installations. Four media were compared in column experiments for >200 days. Different HRTs were applied and initially the media achieved low P effluent concentrations of >0.1 mg/L PO4–P, increasing over time. Best P removal was observed for the highest HRT with on average >99%. HRT was seen to be the driving factor for P removal rather than media capacity. Three of the four materials showed pH levels above 12 initially, decreasing over time. Water quality parameters, including organics, solids and metals, were monitored. In-depth analysis confirmed formation of calcium phosphate precipitation on the media's surface. The results suggest the importance of an optimal HRT to achieve high P removal and show that the reactive media application is an appropriate technology for P removal on small sites if the elevated pH is addressed.

Nitrification preservation in activated sludge during curative bulking chlorination

2003 ◽  
Vol 47 (11) ◽  
pp. 85-92 ◽  
Author(s):  
E. Cotteux ◽  
P. Duchene
Keyword(s):  
Activated Sludge ◽  
Pilot Plant ◽  
Wastewater Treatment Plants ◽  
Oxygen Uptake Rate ◽  
Ammonia Concentration ◽  
Synthetic Wastewater ◽  
Biological Wastewater Treatment ◽  
Simple Method ◽  
Method Of Measurement ◽  
The Impact

The bulking that occurs in biological wastewater treatment plants using activated sludge is very often controlled by the injection of sodium hypochlorite into the return activated sludge (RAS) stream. In the present study undertaken at two pilot plants fed with synthetic wastewater, the impact of the pass frequency of the sludge at the chlorine dosing point on the nitrifying flora is analysed. The pass frequency is one for the pilot plant 1 and two for the pilot plant 2. A dose of chlorine of 4.85 ± 0.05 g/kg/MLVSS per day was applied at both pilots. The preservative effect on nitrifying activity of the lowest concentration of chlorine at the dosing point and therefore of the highest pass frequency was evidenced. Among other tools, a simple method of measurement of the oxygen uptake rate enabled us to monitor the effect of chlorination on nitrification before recording an increase in the ammonia concentration in the bulking.

Two-Phase Mesophilic Anaerobic Co-Digestion of Food Waste and Sewage Sludge: Effect of Hydraulic Retention Time

2014 ◽  
Vol 852 ◽  
pp. 789-796 ◽  
Author(s):  
Guo Hua Wang ◽  
Lei Wang ◽  
Xue Jun Tan ◽  
Yi Xian Wang ◽  
Feng Wang
Keyword(s):  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Food Waste ◽  
Retention Time ◽  
Hydraulic Retention Time ◽  
Removal Rate ◽  
Two Phase ◽  
Acidogenic Reactor ◽  
In Series ◽  
The Impact

The impact of hydraulic retention time (HRT) on two-phase mesophilic (35°C) anaerobic co-digestion of food waste and sewage sludge was studied under mixing ratio of 1:1 on the TS basis. Laboratory-scale, two-phase anaerobic digestion systems were employed with each system consisting of an acidogenic reactor and a methanogenic reactor linked in series. For the acidogenic phase, an increase of volatile fatty acid (VFA) concentration was observed as HRT increased from 1d to 5d and the HRT of 5d was recommended for significantly higher VFA production and less propionate percentage, which could provide stable and favourable substrates for the methane reactor. Under acidogenic HRT of 5d, 20d was proved to be the optimum HRT for methanogenic phase with the methane content, methane production rate, methane yield and two-phase VS removal rate reached 71%, 0.7L/(L·d), 0.69L/gVSremoved and 64.7%, respectively. Results verified that the constraints of conventional anaerobic digestion for food waste or sewage sludge separately could be overcome by synergistic effect of co-digestion strategy and two-phase treatment.

scholarly journals Numerical Analysis of Circular Settling Tank

2019 ◽  
Author(s):  
Elahe Chero ◽  
Anahita ghafoorisadatieh ◽  
Hamidreza Zahabi ◽  
Mohammadamin Torabi ◽  
Keivan Bina
Keyword(s):  
Hydraulic Retention Time ◽  
Wastewater Treatment Plants ◽  
Settling Tank ◽  
Discharge Time ◽  
Effluent Quality ◽  
Economic Issues ◽  
Ansys Cfx ◽  
Lower Height ◽  
Volume Method ◽  
The Impact

Abstract. Nowadays, settling tank's removal efficiency is one of the most crucial matter in all Water or Wastewater Treatment Plants (WTPs or WWTPs). The unit can affect a WWTP performance and improve effluent quality provided. In this paper, geometrical aspects of a settling tank were numerically analyzed via tracer curves, finite volume method and Ansys-cfx software in which, baffle depth and diameter of a settling tank were assessed. Firstly, a previous study was similarly remodeled to verify the simulation results. The impact of tank depth variation has been numerically assessed where the outcomes showed that deeper tank could raise discharge time or Hydraulic Retention Time (HRT). Thus, extensive discharge time may result in less polluted effluent degrading more solids. However, the tank should not be considered too deep regarding economic issues. Moreover, the differential effect of baffle height was analyzed and indicated that lower height is more useful to boost HRT. Investigation of tank diameter changes also revealed that wider diameters bring broader HRT.

scholarly journals The Effect of pH And Hydraulic Retention Time On Production Of Volatile Fatty Acids From Primary Sludge Anaerobic Fermentation

2021 ◽  
Author(s):  
Umme Sharmeen Hyder
Keyword(s):  
Fatty Acids ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Hydraulic Retention Time ◽  
Wastewater Treatment Plants ◽  
Anaerobic Fermentation ◽  
Nitrogen And Phosphorus ◽  
Primary Sludge ◽  
Effect Of Ph ◽  
Ph Range

Primary Sludge (PS) from wastewater treatment plants contains high biodegradable organic matter and therefore can be used to produce Volatile Fatty Acids (VFAs). The produced VFAs can be utilized in biological nitrogen and phosphorus removal processes as an external carbon source. The objective of this research was to investigate the effect of pH and hydraulic retention time (HRT) on the production of VFAs from PS through the anaerobic fermentation process. The experiments were conducted in both batch and semi-continuous flow regimes using bench scale fermenters under the mesophilic temperature. The Design of experiments included the HRT of 1 – 3 days and pH range of 4.5 - 11.0 for batch and 4.5 - 6.5 for semi-continuous modes. According to the obtained results, the VFAs production increased with an increase in HRT from 1 to 3 days. For the batch study, the pH range for maximum VFAs yield was pH 6.5 –10.0 achieved at HRT of 3 days. For the semi-continuous study, the maximum amount of VFAs production was observed at a pH of 6.5 and HRT of 3 days.

scholarly journals The Effect of pH And Hydraulic Retention Time On Production Of Volatile Fatty Acids From Primary Sludge Anaerobic Fermentation

2021 ◽  
Author(s):  
Umme Sharmeen Hyder
Keyword(s):  
Fatty Acids ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Hydraulic Retention Time ◽  
Wastewater Treatment Plants ◽  
Anaerobic Fermentation ◽  
Nitrogen And Phosphorus ◽  
Primary Sludge ◽  
Effect Of Ph ◽  
Ph Range

Primary Sludge (PS) from wastewater treatment plants contains high biodegradable organic matter and therefore can be used to produce Volatile Fatty Acids (VFAs). The produced VFAs can be utilized in biological nitrogen and phosphorus removal processes as an external carbon source. The objective of this research was to investigate the effect of pH and hydraulic retention time (HRT) on the production of VFAs from PS through the anaerobic fermentation process. The experiments were conducted in both batch and semi-continuous flow regimes using bench scale fermenters under the mesophilic temperature. The Design of experiments included the HRT of 1 – 3 days and pH range of 4.5 - 11.0 for batch and 4.5 - 6.5 for semi-continuous modes. According to the obtained results, the VFAs production increased with an increase in HRT from 1 to 3 days. For the batch study, the pH range for maximum VFAs yield was pH 6.5 –10.0 achieved at HRT of 3 days. For the semi-continuous study, the maximum amount of VFAs production was observed at a pH of 6.5 and HRT of 3 days.

Treatment of Domestic Strength Wastewater with Anaerobic Hybrid Reactors

1987 ◽  
Vol 22 (3) ◽  
pp. 474-490 ◽  
Author(s):  
R.L. Droste ◽  
S.R. Guiot ◽  
S.S. Gorur ◽  
K.J. Kennedy
Keyword(s):  
Retention Time ◽  
Suspended Solids ◽  
Hydraulic Retention Time ◽  
Oxygen Demand ◽  
Anaerobic Treatment ◽  
Synthetic Wastewater ◽  
Solids Retention Time ◽  
Solids Retention ◽  
Removal Efficiencies ◽  
Hybrid Reactors

Abstract Anaerobic treatment of dilute synthetic wastewater (300-1,000 mg chemical oxygen demand/L using laboratory upflow sludge blanket filter reactors with and without effluent recycle is described. Treatment of dilute synthetic wastewater at hydraulic retention times less than 1 and 2 h in reactors without and with recycle, respectively, resulted in biomass washout as the solids retention time decreased to less than 12 d. Reseeding would be required to operate at these critical hydraulic retention times for extended periods. Treatment of dilute synthetic wastewater at hydraulic retention times between 3-12 h resulted in soluble COD removal efficiencies between 84-95% treating 300 mg COD/L. At a 3 h hydraulic retention time, solids retention time of 80 d and stable reactor biomass concentrations of 25 g volatile suspended solids/L were maintained.

Impact of the Hydraulic Retention Time on the Performance of a Sulfidogenic Bioreactor

2013 ◽  
Vol 825 ◽  
pp. 392-395 ◽  
Author(s):  
Robert Klein ◽  
Michael Schlömann ◽  
Yun Zeng ◽  
Bernd Wacker ◽  
Franz Glombitza ◽  
...  
Keyword(s):  
Microbial Community ◽  
Sulfate Reduction ◽  
Retention Time ◽  
Hydraulic Retention Time ◽  
Reduction Process ◽  
Nucleotide Sequence Analysis ◽  
Rrna Gene ◽  
Mine Waters ◽  
Depth Analysis ◽  
Acidic Mine Water

Treatment of acidic Fe (II)- and sulfate-rich mine waters represents a major problem in many areas of the world. Therefore, a process was developed which utilises naturally occurring sulfate-reducing microorganisms for the elimination of sulfate and of part of the acidity from the acidic mine water. In order to improve the performance of this biological sulfate reduction process an in-depth analysis of the microbial diversity and activity in dependence of the hydraulic retention time (HRT) and other process parameters used to run the bioreactors was undertaken. This comparison demonstrated a positive correlation between shorter HRT and increasing sulfate reduction rates. The improvement in performance with decreasing HRT was paralleled by an increase of the total enzymatic activity (measured as hydrolase activity) of the microbial community and of the biomass (measured as protein concentration) in the bioreactors. A partial taxonomic identification of the microbial community in the bioreactors was achieved via nucleotide sequence analysis of a clone library of PCR-amplified 16S rRNA gene fragments prepared from a sample of the microbial biofilm in the bioreactor. Additionally, the genetic fingerprint technique T-RFLP was used to assess temporal changes of the microbial community in the biofilm within the reactor.

scholarly journals A comparative study of an up-flow aerobic/anoxic sludge fixed film bioreactor and sequencing batch reactor with intermittent aeration in simultaneous nutrients (N, P) removal from synthetic wastewater

2017 ◽  
Vol 76 (5) ◽  
pp. 1044-1058 ◽  
Author(s):  
Amir Mohammad Mansouri ◽  
Ali Akbar Zinatizadeh
Keyword(s):  
Removal Efficiency ◽  
Retention Time ◽  
Sequencing Batch Reactor ◽  
Batch Reactor ◽  
Oxygen Demand ◽  
Synthetic Wastewater ◽  
Intermittent Aeration ◽  
Fixed Film ◽  
Removal Efficiencies ◽  
P Removal

The performance of two bench scale activated sludge reactors with two feeding regimes, continuous fed (an up-flow aerobic/anoxic sludge fixed film (UAASFF) bioreactor) and batch fed (sequencing batch reactor (SBR)) with intermittent aeration, were evaluated for simultaneous nutrients (N, P) removal. Three significant variables (retention/reaction time, chemical oxygen demand (COD): N (nitrogen): P (phosphorus) ratio and aeration time) were selected for modeling, analyzing, and optimizing the process. At high retention time (≥6 h), two bioreactors showed comparable removal efficiencies, but at lower hydraulic retention time, the UAASFF bioreactor showed a better performance with higher nutrient removal efficiency than the SBR. The experimental results indicated that the total Kjeldahl nitrogen removal efficiency in the UAASFF increased from 70.84% to 79.2% when compared to SBR. It was also found that the COD removal efficiencies of both processes were over 87%, and total nitrogen and total phosphorus removal efficiencies were 79.2% and 72.98% in UAASFF, and 71.2% and 68.9% in SBR, respectively.

Upgrading of wastewater treatment plants equipped with rotating biological contactors to nitrification and P removal

2000 ◽  
Vol 41 (1) ◽  
pp. 145-153 ◽  
Author(s):  
O. Nowak
Keyword(s):  
Wastewater Treatment ◽  
Oxygen Concentration ◽  
Phosphorus Removal ◽  
Wastewater Treatment Plants ◽  
Research Work ◽  
Design Parameters ◽  
Different Types ◽  
Rotating Biological Contactors ◽  
The Impact ◽  
P Removal

In the course of a research project on the further use of treatment plants with rotating biological contactors for nitrification and phosphorus removal, full-scale investigations were carried out. From the results design parameters for phosphorus pre-precipitation as well as for secondary and tertiary nitrifying RBCs were derived. Regarding the impact of the oxygen concentration, the alkalinity and the pH, respectively, on nitrifying biofilms, former research work could mostly be confirmed. Concepts for the upgrading of different types of RBC plants are discussed - including cost estimations.

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