A REDUCED-ORDER ODE–PDE MODEL FOR THE ACTIVATED SLUDGE PROCESS IN WASTEWATER TREATMENT: CLASSIFICATION AND STABILITY OF STEADY STATES

2013 ◽  
Vol 23 (03) ◽  
pp. 369-405 ◽  
Author(s):  
STEFAN DIEHL ◽  
SEBASTIAN FARÅS
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Hyperbolic Conservation Laws ◽  
Wastewater Treatment Plants ◽  
Coupled System ◽  
Steady States ◽  
Activated Sludge Process ◽  
Hyperbolic Conservation ◽  
Flux Function ◽  
Sedimentation Tank

Most wastewater treatment plants contain an activated sludge process, which consists of a biological reactor and a sedimentation tank. The purpose is to reduce the incoming organic material and dissolved nutrients (the substrate). This is done in the biological reactor where micro-organisms (the biomass) decompose the substrate. The biomass is then separated from the water in the sedimentation tank under continuous in- and outflows. One of the outflows is recirculated to the reactor. The governing mathematical model describes the concentration of substrate and biomass as functions of time for the biological reactor, and as functions of time and depth for the sedimentation tank. This gives rise to a system of two ODEs for the reactor coupled with two spatially one-dimensional PDEs for the sedimentation tank. The main mathematical difficulty lies in the nonlinear PDE modeling the continuous sedimentation of the biomass. Previous analyses of models of the activated sludge process have included excessively simplifying assumptions on the sedimentation process. In this paper, results for nonlinear hyperbolic conservation laws with spatially discontinuous flux function are used to obtain a classification of the steady states for the coupled system. Their stability to disturbances are investigated and some phenomena are demonstrated by a numerical simulation.

Controlling Activated Sludge Process Using EFOR

1992 ◽  
Vol 26 (3-4) ◽  
pp. 783-790
Author(s):  
J. Pedersen
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Simulation Program ◽  
Activated Sludge Process ◽  
Activated Sludge Model

A newly developed simulation program, based on the Activated Sludge Model No. 1, has been investigated for its controlling abilities. The program is capable of simulating most of the control types which have been applied to wastewater treatment plants. The program was tested on a nitrifying and a denitrifying treatment plant. The results showed that the model makes good simulations of the applied controls.

Removal Characteristics of Human Antibiotics during Wastewater Treatment in Japan

2006 ◽  
Vol 1 (3) ◽  
Author(s):  
Y. Kobayashi ◽  
M. Yasojima ◽  
K. Komori ◽  
Y. Suzuki ◽  
H. Tanaka
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Treatment Method ◽  
Batch Experiment ◽  
Aqueous Environment ◽  
Activated Sludge Process ◽  
Conventional Activated Sludge ◽  
Conventional Activated Sludge Process

Pharmaceuticals resident in sewage and in the aqueous environment has begun to attract attention. The objectives of this research were to clarify the behaviour of selected human antibiotics in wastewater treatment plants, namely levofloxacin (LVFX), clarithromycin (CAM) and azithromycin (AZM) which are much used in Japan. The concentrations in raw influent of LVFX, CAM, AZM were respectively 425~981ng/L, 340~573ng/L, ND(<190 ng/L)~371ng/L. The averages of removal ratio were about 50 % for all selected antibiotics. It was suggested that selected antibiotics was not too much removed in the conventional creature processing like the conventional activated sludge process. The remarkable removals in activated sludge tank using high class treatment method were confirmed about all selected antibiotics. The rise of the concentrations of CAM and AZM was confirmed after the addition of chemical coagulants in one wastewater treatment plant. From the result of batch experiment with activated sludge, it was suggested that LVFX and AZM were removed from water mainly by the absorption to activated sludge. Also, in batch experiment with chemical coagulants, it was suggested that LVFX was removed from water and CAM, AZM were eluted a little in water by adding sulphuric acid band.

The limits and ultimate possibilities of technology of the activated sludge process

2008 ◽  
Vol 58 (8) ◽  
pp. 1671-1677 ◽  
Author(s):  
A. F. van Nieuwenhuijzen ◽  
A. G. N. van Bentem ◽  
A. Buunnen ◽  
B. A. Reitsma ◽  
C. A. Uijterlinde
Keyword(s):  
Wastewater Treatment ◽  
The Netherlands ◽  
Activated Sludge ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Treatment Method ◽  
Activated Sludge Process ◽  
Municipal Wastewater Treatment ◽  
Nitrogen And Phosphorus ◽  
Activated Sludge Processes

The (low loaded) biological nutrient removing activated sludge process is the generally accepted and applied municipal wastewater treatment method in the Netherlands. The hydraulical and biological flexibility, robustness and cost efficiency of the process for advanced removal of nutrients like nitrogen and phosphorus without (too much) chemicals results in a wide application of the activated sludge process within Dutch waterboards. Presumably, wastewater treatment plants will have to contribute to the improvement of the quality of the receiving surface waters by producing cleaner effluent. In this perspective, the Dutch research organisation STOWA initiated a research project entitled “The Boundaries of the Activated Sludge Process” to investigate the possibilities and limitations of activated sludge processes to improve the effluent quality. It is concluded that the activated sludge process as applied and operated at WWTP's in the Netherlands has the potential to perform even better than the current effluent discharge standards (10 mg Ntotal/l and 1 mg Ptotal/l). Reaching the B-quality effluent (<5mg Ntotal/l and <0.3 mg Ptotal/l) will be possible at almost all WWTPs without major adjustments under the conditions that:   the sludge load is below 0.06 kg BOD/kg TSS.d   the internal recirculation is above 20   the BOD/N ratio of the influent is above 3. Complying with the A-quality effluent (<2.2 Ntotal/l and <0.15 mg Ptotal/l) seems to be difficult (but not impossible) and requires more attention and insight into the activated sludge process. Optimisation measures to reach the A-quality effluent are more thorough and are mostly only achievable by additional construction works (addition of activated sludge volume, increasing recirculation capacity, etc.). It is furthermore concluded that the static HSA-results are comparable to the dynamic ASM-results. So, for fast determinations of the limits of technology of different activated sludge processes static modelling seems to by sufficient.

Occurrence of Cryptosporidium in Japan and counter-measures in wastewater treatment plants

2001 ◽  
Vol 43 (12) ◽  
pp. 183-186 ◽  
Author(s):  
M. Suwa ◽  
Y. Suzuki
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Treated Wastewater ◽  
Activated Sludge Process ◽  
Counter Measures ◽  
Low Levels

The outbreak of cryptosporidiosis in Ogose in 1996 forced the wastewater treatment authorities to rethink the level of contamination by Cryptosporidium of wastewater and waters in the watersheds and counter-measures in wastewater treatment plants. A survey of Cryptosporidium concentrations in wastewater and treated wastewater conducted nationwide showed relatively low levels. Also, evaluation of wastewater treatment showed a 2 log oocyst removal with an activated sludge process and an additional 1 log removal with coagulant dosing.

scholarly journals Technological characteristics of reject waters from aerobic sludge stabilization in small and medium-sized wastewater treatment plants with biological nutrient removal

2020 ◽  
Author(s):  
Zbigniew Mucha ◽  
Jerzy Mikosz
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Biological Nutrient Removal ◽  
Activated Sludge Process ◽  
Sludge Stabilization ◽  
Aerobic Stabilization ◽  
Multi Phase ◽  
The Impact ◽  
Aerobic Sludge

Abstract Most studies on the impact of reject waters recycled from sludge processing in the multi-phase activated sludge process focus on anaerobic sludge treatment in large wastewater treatment plants, leaving apart the processes of aerobic sludge stabilization often used in smaller facilities in rural and suburban areas. The article presents the results of tests carried out in three small and medium-sized wastewater treatment plants with biological removal of biogenic compounds that use aerobic stabilization to process sludge. The research concerned the quantity and quality of reject waters generated in the process of aerobic stabilization and dewatering of sewage sludge and their impact on the multi-phase activated sludge process. The results showed that the average volume of generated reject waters ranged from 3.2 to 5% of the incoming wastewater volume. The average share of organic compounds and total nitrogen loads contained in reject waters did not usually exceed 5–10% of the loads in raw wastewater but reached almost 50% in the case of total phosphorus. Studies indicated that the composition of the supernatant from aerobic stabilization is strongly dependent on the course of the process. The best quality was obtained for cyclic operation of the aerobic stabilization tank with 16 h of aeration and 8 h of settling. The results also showed the negative impact of sudden discharges of reject waters from sludge processing to a multi-phase biological reactor, which can be reduced by using an appropriate equalization tank and pretreatment of the side stream to reduce the recirculation of phosphorus.

Small Wastewater Treatment Plants in Norway

1990 ◽  
Vol 22 (3-4) ◽  
pp. 33-40
Author(s):  
H. Ødegaard ◽  
R. Storhaug
Keyword(s):  
Wastewater Treatment ◽  
Particulate Matter ◽  
Activated Sludge ◽  
Pollution Control ◽  
Chemical Treatment ◽  
Wastewater Treatment Plants ◽  
Septic Tank ◽  
Activated Sludge Process ◽  
Waste Sludge ◽  
Control Authority

About 70 % of the total number of advanced (biological, chemical or biological/chemical) wastewater treatment plants in Norway are small (100 - 2000 PE). More than half of the small plants (55 %) are based on biological/chemical treatment. Simultaneous precipitation and post precipitation based on the activated sludge process is dominating even if systems based on biofilm processes are gaining more and more popularity. The State Pollution Control Authority has made recommendations on design of small wastewater treatment plants. Two systems are recommended; one based on a low loaded activated sludge process with querning of particulate matter as pretreatment and with a separate waste sludge holding tank, and one based on a low loaded biofilm system (biofilter, RBC, etc.) with a large septic tank serving both as pretreatment and waste sludge holding tank.

Biosensor-based control of nitrification inhibitor in municipal wastewater treatment plants

2006 ◽  
Vol 53 (4-5) ◽  
pp. 357-366 ◽  
Author(s):  
Y. Okayasu ◽  
H. Tanaka ◽  
T. Inui ◽  
Y. Tanaka
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Nitrification Inhibitor ◽  
Nitrifying Bacteria ◽  
Activated Sludge Process ◽  
Municipal Wastewater Treatment ◽  
Municipal Wastewater Treatment Plants ◽  
The Impact

The effect of potassium cyanide (KCN) on nitrification processes in municipal wastewater treatment plants was studied by batch nitrification tests, which indicated that nitrification processes tend to be inhibited at a lower KCN concentration than the present discharge standard to sewerage. The experiment of the biosensor using nitrifying bacteria was also conducted for continuous monitoring of nitrification inhibitor in influent wastewater, and demonstrated that the biosensor can detect KCN at as low as EC10 of the abovementioned batch nitrification test. Moreover, to determine the effectiveness of application of the biosensor to avoid the impact of KCN due to an accidental spillage in a sewerage system, KCN was intentionally injected into the experimental models of activated sludge process equipped both with and without the biosensor. The model with the biosensor that could detect KCN could divert the wastewater including KCN to a refuge tank, which resulted in the avoidance of upset of the activated sludge process. On the other hand, the model without the biosensor was upset in the nitrification process due to KCN. Such differences demonstrate the effectiveness of the biosensor applied to countermeasures of an accidental spillage of toxic chemicals to avoid upset of nitrification in municipal wastewater treatment plants.

DESIGN PLANNING WASTEWATER TREATMENT PLANT OF NATA DE COCO INDUSTRY WITH THE ACTIVATED SLUDGE PROCESS

2016 ◽  
Vol 9 (2) ◽  
Author(s):  
Dinda Rita K. Hartaja ◽  
Imam Setiadi
Keyword(s):  
Waste Water ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Waste Water Treatment ◽  
Treatment Plant ◽  
Water Treatment Plant ◽  
Appropriate Technology ◽  
Waste Water Treatment Plant ◽  
Activated Sludge Process ◽  
High Level

Generally, wastewater of nata de coco industry contains suspended solids and COD were high, ranging from 90,000 mg / l. The high level of of the wastewater pollutants, resulting in nata de coco industry can not be directly disposed of its wastewater into the environment agency. Appropriate technology required in order to process the waste water so that the treated water can meet the environmental quality standards that are allowed. Designing the waste water treatment plant that is suitable and efficient for treating industrial wastewater nata de coco is the activated sludge process. Wastewater treatment using activated sludge process of conventional (standard) generally consists of initial sedimentation, aeration and final sedimentation.Keywords : Activated Sludge, Design, IPAL

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