A model for the filterability of activated sludge supported by mixed-liquor biochemical data

1986 ◽  
Vol 28 (12) ◽  
pp. 1801-1808 ◽  
Author(s):  
R. A. Novak
Keyword(s):  
Activated Sludge ◽  
Biochemical Data ◽  
Mixed Liquor

Evaluating the treatment performance of a full scale Activated Sludge Plant in Islamabad, Pakistan

2012 ◽  
Vol 7 (1) ◽  
Author(s):  
S. S. Fatima ◽  
S. Jamal Khan
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plant ◽  
Suspended Solids ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Full Scale ◽  
Operational Parameter ◽  
Mixed Liquor ◽  
Treatment Performance

In this study, the performance of wastewater treatment plant located at sector I-9 Islamabad, Pakistan, was evaluated. This full scale domestic wastewater treatment plant is based on conventional activated sludge process. The parameters which were monitored regularly included total suspended solids (TSS), mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids (MLVSS), biological oxygen demand (BOD), and chemical oxygen demand (COD). It was found that the biological degradation efficiency of the plant was below the desired levels in terms of COD and BOD. Also the plant operators were not maintaining consistent sludge retention time (SRT). Abrupt discharge of MLSS through the Surplus Activated sludge (SAS) pump was the main reason for the low MLSS in the aeration tank and consequently low treatment performance. In this study the SRT was optimized based on desired MLSS concentration between 3,000–3,500 mg/L and required performance in terms of BOD, COD and TSS. This study revealed that SRT is a very important operational parameter and its knowledge and correct implementation by the plant operators should be mandatory.

Hydrocycloning Influent, Mixed Liquor or Return Activated Sludge for Best Grit Removal and Sludge Production Reduction

2011 ◽  
Vol 2011 (15) ◽  
pp. 2326-2338
Author(s):  
Majdala Mansour-Geoffrion ◽  
Peter L. Dold ◽  
Dwight Houweling ◽  
Daniel Lamarre ◽  
Alain Gadbois ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Mixed Liquor ◽  
Sludge Production

Dispelling the “Nocardia amarae” myth: a phylogenetic and phenotypic study of mycolic acid-containing actinomycetes isolated from activated sludge foam

2002 ◽  
Vol 46 (1-2) ◽  
pp. 81-90 ◽  
Author(s):  
F.M. Stainsby ◽  
J. Soddell ◽  
R. Seviour ◽  
J. Upton ◽  
M. Goodfellow
Keyword(s):  
Activated Sludge ◽  
16S Rdna ◽  
Mycolic Acid ◽  
Mass Spectrometric ◽  
Morphological Data ◽  
Morphological Properties ◽  
Microscopic Approach ◽  
Nocardia Species ◽  
Mixed Liquor ◽  
Nocardia Amarae

Right-angle branched filaments and rods micromanipulated from activated sludge foam and mixed liquor were identified as putatively novel members of the genera Gordonia, Mycobacterium and Rhodococcus using a combination of chemical, molecular and morphological data. Pyrolysis mass spectrometric analyses of gordoniae isolated in both the present and a previous study revealed pyro-groups, distinct from validly described Gordonia species, which could be equated with those based on morphological properties and 16S rDNA data. Putative gordoniae assigned to one of these groups were found to be closely related to strains currently identified as “Rhodococcus australis”. These strains were also found to have properties consistent with their classification in the genus Gordonia. The results of this study highlight the limitations of the microscopic approach to filament identification and cast further doubt on the view that foaming can be attributed to members of one or a few Nocardia species.

A titration technique for on-line nitrification monitoring in activated sludge

1998 ◽  
Vol 37 (12) ◽  
pp. 103-110 ◽  
Author(s):  
Krist Gernaey ◽  
Herwig Bogaert ◽  
Peter Vanrolleghem ◽  
Alessandro Massone ◽  
Alberto Rozzi ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Treatment Plant ◽  
Estimation Method ◽  
Sample Pretreatment ◽  
Mixed Liquor ◽  
Titration Curves ◽  
N Removal ◽  
Nitrification Kinetics ◽  
On Line ◽  
Simple Slope

A titrimetric method to monitor nitrification was applied on a pilot activated sludge plant for biological N removal. Mixed liquor was sampled from the aerobic compartment of the treatment plant and a titration in-sensor experiment was performed. Interpretation of the cumulative base addition curves resulting from each titration in-sensor experiment was done using both a simple slope extrapolation method and a model-based non-linear parameter estimation method. The NH4+-N concentrations obtained with both methods correlated well with the NH4+-N concentrations measured on the effluent of the pilot plant using an on-line NH4+-N analyser. Contrary to most physical/chemical NH4+-N analysers, no sample pretreatment of the mixed liquor is needed for the measurements. It is shown in detail that interpretation of the titration curves yields information about the nitrification kinetics too, which can be an important advantage for process control purposes.

Nocardia effects in waste activated sludge

1998 ◽  
Vol 38 (2) ◽  
pp. 49-54 ◽  
Author(s):  
Krishna R. Pagilla ◽  
David Jenkins ◽  
Wendell Kido
Keyword(s):  
Activated Sludge ◽  
Foam Stability ◽  
Anaerobic Digester ◽  
Waste Activated Sludge ◽  
Dissolved Air Flotation ◽  
Anaerobic Digesters ◽  
Primary Sludge ◽  
Mixed Liquor ◽  
Dissolved Air ◽  
Batch Foaming

Two effects of Nocardia in waste activated sludge (WAS) were investigated: (i) the influence of WAS in the solids treatment recycle streams on Nocardia persistence in the activated sludge, and (ii) the effect of Nocardia in WAS on anaerobic digester foaming. About 4% of the Nocardia present in the mixed liquor was due to seeding from the WAS solids in the dissolved air flotation thickener recycle stream recycle. Nocardia filaments in WAS at levels of between 104 to 106 intersections/g VSS resulted in Nocardia levels of approximately 104 to 105 intersections/g VSS in anaerobic digesters that treated both WAS and primary sludge. The effect of disinfecting these Nocardia filaments in the WAS with Cl2 was investigated at Cl2 dose ranges of 20-60 mg Cl2/l WAS and 100-200 mg Cl2/l WAS on a lab scale using batch foaming tests to assess success. Chlorination with 20 - 60 mg Cl2/l WAS approximately doubled both sludge foaming potential and foam stability. At Cl2 doses of 100-200 mg Cl2/l WAS, foaming potential was increased almost 10-fold, and foam stability was increased by 2.5 times. These results indicate that chlorination of WAS feed to an anaerobic digester for inactivation of Nocardia should not be practiced.

Effects of phosphorus limitation and temperature on PHA production in activated sludge

2004 ◽  
Vol 50 (8) ◽  
pp. 135-143 ◽  
Author(s):  
S. Chinwetkitvanich ◽  
C.W. Randall ◽  
T. Panswad
Keyword(s):  
Activated Sludge ◽  
Nutrient Limitation ◽  
Growth Phase ◽  
Cycle Time ◽  
Phosphorus Limitation ◽  
Two Stage ◽  
Mixed Liquor ◽  
Pha Production ◽  
Effects Of Temperature ◽  
And Storage

The study was designed to investigate the effects of temperature and phosphorus limitation on polyhydroxyalkanoate (PHA) production and storage by activated sludge biomass. The two-stage operation approach, i.e. a growth phase followed by a nutrient limitation phase, was applied to induce PHA accumulation. The pre-selected temperatures of 10, 20 and 30°C were investigated under phosphorus limitation conditions using three four-litre fully aerobic SBR systems operated at an SRT of 10 days with cycle time and HRT of 6 and 10 hours. PHA production was greater in the 10°C system than in the 20°C and 30°C systems but there was little difference between the two higher temperatures. The maximum PHA fractions of the sludge were 52, 45 and 47%TSS for the three temperatures from low to high, and the maximum PHA concentrations in the mixed liquors were 1,491, 1,294 and 1,260 mg/l, respectively. However, it was observed that very low values of PHA yield per unit COD consumed were obtained, i.e., 0.05, 0.03 and 0.04 mgPHA/mgCODu, for the 10, 20 and 30°C reactors, respectively. This was because all three systems required several days to reach maximum PHA accumulation in their mixed liquor biomasses. It is probable the bacteria still had some stored poly-P in their cells upon initiation of the phosphorus limited influent, and PHA accumulation was delayed until the stored phosphorus was depleted. Also, PHA productivity was reduced by the large amounts of biomass lost from the systems because of sludge bulking.

The Effect of Controlled pH on the Development of Rosette-Forming Bacteria in Axenic Culture and Bulking Activated Sludge

1988 ◽  
Vol 20 (11-12) ◽  
pp. 249-255 ◽  
Author(s):  
R. F. Unz ◽  
T. M. Williams
Keyword(s):  
Activated Sludge ◽  
Biological Treatment ◽  
Periodic Acid ◽  
Axenic Culture ◽  
Morphological Characteristics ◽  
Volume Index ◽  
Manufacturing Facility ◽  
Mixed Liquor ◽  
Correction Technique ◽  
Paper And Pulp

An infestation of a rosette-forming microorganism, with morphological characteristics bearing some resemblance to Eikelboom type 021N and Thiothrix spp., occurred in the activated sludge process of a paper and pulp manufacturing facility during the autumn of 1986. The microorganism could not be eliminated by periodic acid-shocking of the mixed liquor with sulfuric acid, however, exposure of the mixed liquor solids for 10 days at controlled pH (circum pH 5.5) brought almost immediate lowering of the sludge volume index and effluent suspended solids to levels observed in normal operations. The bulking correction technique required no purchase of special chemicals in that the procedure was a mere modification of the liming step normally employed to bring the natural pH of the wastewater (pH 3) to a level suitable for the practice of biological treatment.

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