Fine Bubble Aeration Using a High Density Diffuser System

1992 ◽  
Vol 26 (9-11) ◽  
pp. 2437-2440 ◽  
Author(s):  
K. Thatcher
Keyword(s):  
Activated Sludge ◽  
Oxygen Transfer ◽  
Oxygen Demand ◽  
High Density ◽  
Plant Performance ◽  
Energy Usage ◽  
High Quality ◽  
Transfer Rates ◽  
Fine Bubble ◽  
Activated Sludge Processes

Current developments with the activated sludge processes with highly concentrated effluents highlight the requirement to (a) reduce energy usage (b) promote the production of high quality effluent. Having observed the efforts being made to improve plant performance we became aware that current methods had to be improved. It was also noted that a period of stagnation had occurred in the development of effective aeration systems. Improved aeration methods are needed which would allow for oxygen transfer efficiencies to be greater than 2kg/kWh. Such oxygen transfer rates should be continually variable in line with the oxygen demand prevailing at any given time. In our study of activated sludge plants we found that operational and electrical/mechanical maintenance was proving to be time consuming and very costly. With these problems in mind we have designed and developed the Fine Bubble High Density Diffuser System.

Use of microtox tests for screening industrial wastewater toxicity

1996 ◽  
Vol 34 (10) ◽  
pp. 43-50 ◽  
Author(s):  
Oliver J. Hao ◽  
Shin Chien-Jen ◽  
Lin Cheng-Fang ◽  
Jeng Fu-Tien ◽  
Chen Zen-Chyuan
Keyword(s):  
Activated Sludge ◽  
Oxygen Demand ◽  
Industrial Wastes ◽  
Wastewater Management ◽  
Waste Discharge ◽  
Significant Toxicity ◽  
Microtox Toxicity ◽  
Microtox Test ◽  
Activated Sludge Processes ◽  
The Impact

Conventional parameters such as chemical oxygen demand and suspended solids may not detect toxic compounds present in a variety of industrial wastewaters and treated wastes. Thus, the presence of toxicity in many industrial wastes presents a significant impact on biological wastewater treatment, and exerts adverse effects on receiving waters. Because of their easy technique and rapid turnaround results, the Microtox tests were used in this study to pinpoint unusual wastewaters, evaluate the toxicity reduction through activated sludge processes, observe the impact of excessive chemical addition to meet the transparency standard, and measure the impact of waste discharge on one particular receiving water. It was found that the results of Microtox tests were useful for such purposes; i.e., low COD wastes exhibited high Microtox toxicity; some activated sludge processes removed significant toxicity; and some effluents from coagulation/oxidation processes showed an increased toxicity. The application of the Microtox test to wastewater management is discussed.

Oxygen transfer and uptake, nutrient removal, and energy footprint of parallel full-scale IFAS and activated sludge processes

2011 ◽  
Vol 45 (18) ◽  
pp. 5987-5996 ◽  
Author(s):  
Diego Rosso ◽  
Sarah E. Lothman ◽  
Matthew K. Jeung ◽  
Paul Pitt ◽  
W. James Gellner ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Nutrient Removal ◽  
Oxygen Transfer ◽  
Full Scale ◽  
Energy Footprint ◽  
Activated Sludge Processes

scholarly journals Systematic Modeling of Municipal Wastewater Activated Sludge Process and Treatment Plant Capacity Analysis Using GPS-X

2020 ◽  
Vol 12 (19) ◽  
pp. 8182
Author(s):  
Nuhu Dalhat Mu’azu ◽  
Omar Alagha ◽  
Ismail Anil
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Systematic Approach ◽  
Municipal Wastewater ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Plant Performance ◽  
Capacity Analysis ◽  
Activated Sludge Process ◽  
Effluent Quality

Mathematical modeling has become an indispensable tool for sustainable wastewater management, especially for the simulation of complex biochemical processes involved in the activated sludge process (ASP), which requires a substantial amount of data related to wastewater and sludge characteristics as well as process kinetics and stoichiometry. In this study, a systematic approach for calibration of the activated sludge model one (ASM1) model for a real municipal wastewater ASP was undertaken in GPS-X. The developed model was successfully validated while meeting the assumption of the model’s constant stoichiometry and kinetic coefficients for any plant influent compositions. The influences of vital ASP parameters on the treatment plant performance and capacity analysis for meeting local discharge limits were also investigated. Lower influent chemical oxygen demand in mgO2/L (COD) could inhibit effective nitrification and denitrification, while beyond 250 mgO2/L, there is a tendency for effluent quality to breach the regulatory limit. The plant performance can be satisfactory for handling even higher influent volumes up to 60,000 m3/d and organic loading when Total Suspended Solids/Volatile Suspended Solids (VSS/TSS) and particulate COD (XCOD)/VSS are maintained above 0.7 and 1, respectively. The wasted activated sludge (WAS) has more impact on the effluent quality compared to recycle activated sludge (RAS) with significant performance improvement when the WAS was increased from 3000 to 9000 m3/d. Hydraulic retention time (HRT) > 6 h and solids retention time (SRT) < 7 days resulted in better plant performance with the SRT having greater impact compared with HRT. The plant performance could be sustained for a quite appreciable range of COD/5-day Biochemical Oxygen Demand (BOD5 in mgO2/L) ratio, Mixed Liquor Suspended Solid (MLSS) of up to 6000 mg/L, and when BOD5/total nitrogen (TN) and COD/TN are comparatively at higher values. This work demonstrated a systematic approach for estimation of the wastewater treatment plant (WWTP) ASP parameters and the high modeling capabilities of ASM1 in GPS-X when respirometry tests data are lacking.

Relationship between manual air valve positioning, water quality and energy usage in activated sludge processes

2020 ◽  
Vol 173 ◽  
pp. 115537
Author(s):  
Samuel Reifsnyder ◽  
Manel Garrido-Baserba ◽  
Francesca Cecconi ◽  
Larry Wong ◽  
Phil Ackman ◽  
...  
Keyword(s):  
Water Quality ◽  
Activated Sludge ◽  
Energy Usage ◽  
Air Valve ◽  
Activated Sludge Processes

Comparative study of membrane bioreactor (MBR) and activated sludge processes in the treatment of Moroccan domestic wastewater

2018 ◽  
Vol 78 (5) ◽  
pp. 1129-1136 ◽  
Author(s):  
S. Kitanou ◽  
M. Tahri ◽  
B. Bachiri ◽  
M. Mahi ◽  
M. Hafsi ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Membrane Bioreactor ◽  
Ceramic Membrane ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Pilot Scale ◽  
Quality Parameters ◽  
Effluent Quality ◽  
Conventional Activated Sludge ◽  
Activated Sludge Processes

Abstract The study was based on an external pilot-scale membrane bioreactor (MBR) with a ceramic membrane compared to a conventional activated sludge process (ASP) plant. Both systems received their influent from domestic wastewater. The MBR produced an effluent of much better quality than the ASP in terms of total suspended solids (TSS), 5-day biological oxygen demand (BOD5) and chemical oxygen demand (COD), total phosphorus (TP) and total nitrogen (TN). Other effluent quality parameters also indicated substantial differences between the ASP and the MBR. This study leads to the conclusion that in the case of domestic wastewater, MBR treatment leads to excellent effluent quality. Hence, the replacement of ASP by MBR may be justified on the basis of the improved removal of solids, nutrients, and micropollutants. Furthermore, in terms of reuse the high quality of the treated water allows it to be reused for irrigation.

scholarly journals Long-term effect of metal oxide nanoparticles on activated sludge

2016 ◽  
Vol 75 (2) ◽  
pp. 462-473 ◽  
Author(s):  
Baranidharan Sundaram ◽  
Arun Kumar
Keyword(s):  
Metal Oxide ◽  
Activated Sludge ◽  
Metal Ion ◽  
Metal Oxide Nanoparticles ◽  
Oxygen Demand ◽  
Microscopic Analysis ◽  
Antagonistic Effect ◽  
Ion Concentration ◽  
Plant Performance ◽  
Oxide Nanoparticles

This study evaluated the influence of metal oxide nanoparticles (NPs) (Ag2O, TiO2) and their mixture on activated sludge for 180 days. When tested, a mixture of NPs at 1 and 10 mg/L had greater impact than individual NPs, in which maximum reduction in chemical oxygen demand (COD) elimination (76.3%) was observed after 150 days for 1 mg/L (500 mg/L COD concentration) and after 180 days (70.2%) for 10 mg/L (250 mg/L COD concentration). TiO2 had higher inhibition on COD reduction than Ag2O NPs at 1 and 10 mg/L. An antagonistic effect was observed in which the combination of individual NPs had a greater effect than a mixture of NPs. Reduction in COD elimination was found to be dependent on NP type and concentration (p &lt; 0.05). Further, metal ion concentration was higher in sludge than supernatant irrespective of NPs, while microscopic analysis showed the presence of NPs inside activated sludge. Among NPs tested, the concentration of Ti4+ ion was greater in sludge than in the Ag+ ion, thus indicating that TiO2 has a greater affinity than Ag2O NPs. All three factors (NP type, NP concentration, organic concentration) play a significant role in imparting COD removal (p &lt; 0.05). Future studies are required to quantify NP concentration to minimize NP effect on plant performance.

Comparison of Oxygen Transfer Parameters from Four Testing Methods in Three Activated Sludge Processes

2005 ◽  
Vol 40 (2) ◽  
pp. 164-176 ◽  
Author(s):  
Venkatram Mahendraker ◽  
Donald S. Mavinic ◽  
Barry Rabinowitz
Keyword(s):  
Steady State ◽  
Activated Sludge ◽  
Oxygen Transfer ◽  
Power Level ◽  
Process Conditions ◽  
Testing Methods ◽  
State Process ◽  
Transfer Parameters ◽  
American Society ◽  
Activated Sludge Processes

Abstract In this investigation, the mass transfer of oxygen was determined using four different testing methods in three activated sludge processes, as per the guidelines established by the American Society of Civil Engineers (ASCE 1997). The testing methods applied included the steady-state oxygen uptake rate (OUR), the non-steady-state changing power level (CPL), the non-steady-state hydrogen peroxide addition (HPA) and the off-gas methods. The analysis indicated that steady-state OUR and off-gas methods resulted in comparable estimates of oxygen transfer parameters, with somewhat higher variations observed in the data from the off-gas method. The application of HPA and CPL methods produced variable results under the same process conditions and these testing methods affected the process. Based on the comparative evaluation conducted in these controlled experiments, the validity of HPA and CPL tests to measure the oxygen transfer under process conditions is questionable. Overall, the off-gas method appears to be superior, as it does not require steady-state process conditions. However, under suitable conditions the steady-state OUR method may be an economical option to study oxygen transfer under process conditions.

Surface active agents and their influence on oxygen transfer

1996 ◽  
Vol 34 (3-4) ◽  
pp. 249-256 ◽  
Author(s):  
Martin Wagner ◽  
H. Johannes Pöpel
Keyword(s):  
Surface Tension ◽  
Oxygen Transfer ◽  
Pure Water ◽  
Interfacial Area ◽  
Clean Water ◽  
Transfer Rates ◽  
Surface Active Agents ◽  
Fine Bubble ◽  
Different Types ◽  
New Guidelines

Oxygen transfer rates of fine bubble aeration systems in uniform arrangement are reduced down to 40% to 70% in wastewater compared to clean water conditions. Surfactants in wastewater are the main reason for the inferior and therefore uneconomic performance. The influence of different types of surfactants (anionic and nonionic) and of their concentration on oxygen transfer is investigated at various properties of pure water (content of electrolytes, hardness) by means of extensive experiments. The main results of the investigations are:in dependence of the type of surfactant, its concentration and the types of water:– the aeration coefficient kLa decreases (down to 55%)– the specific interfacial area (a) increases (up to 350%)– the oxygen transfer coefficient (kL) decreases (down to 20%)nonionic surfactants reduce the oxygen transfer more strongly than anionic surfactantsat the same surface tension, but different types of surfactant α-values can vary over a range of 0.12. Therefore α-values can not be calculated from surface tension measurementsα-values of approximately 0.55 should be taken for designing fine bubble aeration systemsIn new guidelines for the measurement of oxygen transfer rates, addition of 5 gm−3 of an arbitrary surfactant into clean water to simulate wastewater conditions must be abandoned.

Microbial adaptation, process performance and a suggested control strategy in a pre-denitrifying system with ethanol dosage

1996 ◽  
Vol 34 (1-2) ◽  
pp. 91-99 ◽  
Author(s):  
S. Hallin ◽  
C.-F. Lindberg ◽  
M. Pell ◽  
E. Plaza ◽  
B. Carlsson
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Control Strategy ◽  
Nitrate Concentration ◽  
Bacterial Species ◽  
Pilot Scale ◽  
Plant Performance ◽  
Linear Quadratic ◽  
Microbial Adaptation ◽  
Activated Sludge Processes

Biological nitrogen removal in activated sludge processes is dependent on sufficient supplies of easily metabolized carbon compounds for the denitrifying bacterial population. An external carbon source can increase denitrification rates and compensate for deficiencies in the influent C/N ratio. Plant performance and microbial adaptation were studied in a pre-denitrifying pilot-scale activated sludge plant with and without ethanol. Total nitrogen removal efficiency was 67 and 35% for the ethanol and reference line, respectively. The process responded rapidly to ethanol but one sludge age was necessary for full bacterial adaptation. An initial rapid increase suggests enzyme induction rather than alterations in bacterial species composition. Increased enzyme activity was explained by an increase in turn-over rate of biomass. Low effluent nitrate concentration was a result of the simultaneous use of influent COD and ethanol. Fluctuations in influent COD did not affect denitrification capacity with ethanol. Sludge settling properties were moderately better in the process without ethanol addition. An automatic control strategy for carbon dosage using feedforward from influent carbon and nitrate in the recirculated flow was simulated. Simulations with an adaptive linear quadratic controller demonstrated that the desired nitrate concentration at the end of the anoxic zone could be maintained despite relatively large disturbances.

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