A Comparative Study of Floc and Sludge of Leachate under Different Types of Coagulants

2015 ◽  
Vol 802 ◽  
pp. 406-411 ◽  
Author(s):  
Nur Shaylinda Mohd Zin ◽  
Hamidi Abdul Aziz ◽  
Mohd Nordin Adlan ◽  
Azlan Ariffin ◽  
Mohd Suffian Yusoff ◽  
...  
Keyword(s):  
Ferric Chloride ◽  
Volume Index ◽  
Sludge Volume Index ◽  
Sludge Formation ◽  
Sludge Characteristics ◽  
Floc Size ◽  
Different Types ◽  
Tapioca Flour ◽  
Sludge Settling ◽  
Composite Coagulant

This study compared the floc and sludge formed during the coagulation of leachate by different types of coagulants. The coagulants tested in this study were Ferric chloride (FC), pre-hydrolyzed iron (PHI), dual coagulant (PHI+TF(tapioca flour)), and composite coagulant (pre mix of PHI and TF (PHITF)). The floc and sludge were characterized by measuring the sludge volume index (SVI), sludge velocity (SV), and floc size. Results showed that the hierarchy for SVI, SV, and floc size were FC>PHI>PHI+TF>PHITF, PHITF>PHI+TF>PHI>FC, and PHI+TF>PHITF>PHI>FC, respectively. PHITF demonstrated the lowest SVI and the shortest sludge settling time among the tested coagulants. PHI+TF produced the largest floc size. The addition of TF in PHI as a composite and dual coagulant significantly improved the floc and sludge characteristics. PHITF improved the floc and sludge formation of partially stabilized leachate.This study compared the floc and sludge formed during the coagulation of leachate by different types of coagulants. The coagulants tested in this study were Ferric chloride (FC), pre-hydrolyzed iron (PHI), dual coagulant (PHI+TF(tapioca flour)), and composite coagulant (pre mix of PHI and TF (PHITF)). The floc and sludge were characterized by measuring the sludge volume index (SVI), sludge velocity (SV), and floc size. Results showed that the hierarchy for SVI, SV, and floc size were FC>PHI>PHI+TF>PHITF, PHITF>PHI+TF>PHI>FC, and PHI+TF>PHITF>PHI>FC, respectively. PHITF demonstrated the lowest SVI and the shortest sludge settling time among the tested coagulants. PHI+TF produced the largest floc size. The addition of TF in PHI as a composite and dual coagulant significantly improved the floc and sludge characteristics. PHITF improved the floc and sludge formation of partially stabilized leachate.

Effects of sludge settling characteristics in the BNR system

2000 ◽  
Vol 42 (3-4) ◽  
pp. 283-288 ◽  
Author(s):  
Z. Yun ◽  
W. Yo ◽  
Y. Yi ◽  
S. Choi ◽  
E. Choi ◽  
...  
Keyword(s):  
Settling Tank ◽  
Volume Index ◽  
Anoxic Zone ◽  
Sludge Volume Index ◽  
Analytical Accuracy ◽  
Fast Settling ◽  
Sludge Settling ◽  
Extracellular Polymer ◽  
Sludge Settleability ◽  
Settling Characteristics

Although the BNR system design assumes no sludge settling problems in the final settling tank, the fluctuation of daily loading and up to 40% of anaerobiosis in the BNR system would be considerable factors in determining the sludge settleability. The sludge volume index (SVI) is a classical parameter to examine the sludge settleability but it has a limited value to evaluate the overall settling characteristics. The extracellular polymer (ECP) content in sludge has long been considered as an indicator of biological flocculation in activated sludge process, but the skepticism on analytical accuracy limits the usage in settling study. This study focused on evaluating the BNR system performance related to the sludge settling characteristics under the controlled laboratory environment. A 5-stage BNR system (anaerobic-anoxic-3 stage oxic) was operated with the HRTs from 3.9 to 7.6 hours. In order to determine the sludge settling properties, both SVI and ECP content were monitored. The ECP contents in the sludge sample were measured by the slime-washing step followed by high-G centrifugation and sonication. The gel-electrophoresis was used to detect the DNA in the sonicated samples to determine the intracellular polymer contamination. It has been found that the anaerobiosis in the anaerobic and anoxic zone that consisted of 37% of reactor volume could not deteriorate the sludge settling properties even at the HRT of 3.9 hours. The SVI values of sludge taken from the reactor with the HRT of 7.2 hours averaged to less than 50 mL/gr. It was postulated that a fast settling sludge in the BNR system could not always ensure production of clear effluent. The sludge with very low SVI might not achieve a complete biological flocculation potential. In addition, the degree of denitrification in the BNR system could be related to the sludge settleability.

Settling Characteristics of Activated Sludge in Danish Treatment Plants with Biological Nutrient Removal

1994 ◽  
Vol 29 (7) ◽  
pp. 157-165 ◽  
Author(s):  
Gert Holm Kristensen ◽  
Per Elberg Jørgensen ◽  
Per Halkjær Nielsen
Keyword(s):  
Activated Sludge ◽  
Nutrient Removal ◽  
Volume Index ◽  
Biological Nutrient Removal ◽  
Sludge Volume Index ◽  
Filamentous Microorganisms ◽  
Best Parameter ◽  
One Year ◽  
Sludge Settling ◽  
Settling Characteristics

In 1989-91, a study was performed to investigate the settling characteristics of activated sludge in Danish treatment plants with biological nutrient removal. The study included three screening series on 38 treatment plants. Furthermore, the study included investigations during one year on seasonal variations in sludge settling characteristics at three treatment plants. The screening investigations were performed in November 1989 and May and September, 1990. Results showed that in the May-screening, 35-45% of the plants had a filament index of 2-2.5 or above, corresponding to a sludge volume index above 150 ml/g. When comparing data for diluted and non-diluted sludge volume indices, a SVI value of 150 ml/g seemed parallel to a DSVI of 110 ml/g. In the November- and September-screenings, some 30% of the plants had activated sludge showing a filament index in or above the critical area. Dominating filamentous microorganisms were found to be (in decreasing order): Microthrix parvicella, Type 0041, Type 021N, Type 0092, Type 0914, and Type 1851. A distinct variation over the year in sludge settling characteristics was found for the three plants. Sludge settling characteristics improved during summer, and deteriorated during winter. For activated sludge with a high content of filamentous microorganisms, the best parameter to follow the variations in sludge settling properties was the filament number. If the activated sludge concentration, the MLSS, varied significantly, the specific filament number was to be applied.

Improvement of the intersection method for the quantification of filamentous organisms: basis and practice for bulking and foaming bioindication purposes

2016 ◽  
Vol 74 (6) ◽  
pp. 1274-1282 ◽  
Author(s):  
Humbert Salvadó
Keyword(s):  
Wastewater Treatment Plants ◽  
Two Dimensions ◽  
Volume Index ◽  
Filament Length ◽  
Improved Method ◽  
Sludge Volume Index ◽  
Filamentous Microorganisms ◽  
Different Types ◽  
Intersection Method ◽  
The Impact

Bulking and foaming phenomena in activated sludge wastewater treatment plants are in most cases related to the abundance of filamentous microorganisms. Quantifying these microorganisms should be a preliminary stage in their control. In this paper, the simplicity of quantifying them based on the intersection method is demonstrated, by redescribing the theory and applying a new improved protocol; new data of interest are also provided. The improved method allows us to use it with stained smears, including epifluorescence techniques. The error that could be made, when considering the distribution of filamentous bacteria in fresh microscope preparations in two dimensions rather than three is negligible. The effect of the different types of filamentous microorganisms on the settleability was also studied. The effect of the total extended filament length on the sludge settleability was shown to depend on the type of filamentous organism and how it aggregates. When these groups of filamentous organisms are found in small aggregations and there is an increase in the number of filamentous organisms, the sludge volume index (SVI) increases proportionally to the filament length. However, when aggregation increases, the impact on the SVI is significantly lower.

Estimation of suspended solids concentrations in activated sludge settling tanks

1997 ◽  
Vol 35 (8) ◽  
pp. 127-135 ◽  
Author(s):  
Youngchul Kim ◽  
Wesley O. Pipes ◽  
Paul-Gene Chung
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Marked Effect ◽  
Treatment Plant ◽  
Accurate Method ◽  
Volume Index ◽  
Sludge Volume Index ◽  
Solids Concentration ◽  
Exponential Decrease ◽  
Sludge Settling

This is a report of a field study based on data from an activated sludge process in a wastewater treatment plant in Chester, Pennsylvania, USA. The objective was to develop an accurate method for estimation of the average suspended solids concentration (SSB) of the layer of sludge in the settling tanks (the “sludge blanket”). Plant operators estimated SSB by averaging the mixed liquor suspended solids (Sm) and the return sludge suspended solids (Su) concentrations. Measurement of SSB showed that averaging Sm and Su frequently overestimated SSB by a large amount. A different relationship between SSB and parameters which are normally measured for operational purposes was developed. The parameters are Su, the overflow rates and data from the sludge volume index (SVI) measurement. It was found that an increasing overflow rate will result in an exponential decrease in the ratio of SSB to Su. Also, the SVI has a marked effect on the ratio of SSB to Su and thus on the amount of suspended solids which can be stored in the settling tanks. The proposed estimation equation was found to be statistically superior to estimation by averaging the Sm and Su.

Effects of water characteristics on granular sludge formation in a USB reactor for denitrification of drinking water

1994 ◽  
Vol 30 (9) ◽  
pp. 141-147 ◽  
Author(s):  
S. Tarre ◽  
R. Armon ◽  
G. Shelef ◽  
M. Green
Keyword(s):  
Mineral Content ◽  
Granular Sludge ◽  
Hard Water ◽  
Volume Index ◽  
Mineralization Process ◽  
Sludge Volume Index ◽  
Sludge Formation ◽  
Water Characteristics ◽  
Water Chemical Composition ◽  
Influent Water

The effects of water chemical composition on granular sludge formation in a denitrifying USB reactor was studied. The mineral fraction and sludge volume index (SVI) of the granular sludge in the reactor were found to be closely related to the composition of the influent water. Groundwater and simulated ‘hard’ water produced granules with good settling characteristics and high reactor VSS concentrations. Sludge granules from the reactor fed with surface water, which had lower concentrations of calcium and alkalinity, had a low mineral content and high SVI values resulting in biomass washout and reactor instability. The mineralization process, as expressed by the sludge's ash content (mainly CaCO3), is due to an increase in the pH and alkalinity during denitrification thereby changing the reactor's precipitation potential.

Use of image analysis and rheological studies for the control of settleability of filamentous bacteria: application in SBR reactor

2001 ◽  
Vol 43 (3) ◽  
pp. 27-33 ◽  
Author(s):  
C. Dagot ◽  
M. N. Pons ◽  
M. Casellas ◽  
G. Guibaud ◽  
P. Dollet ◽  
...  
Keyword(s):  
Image Analysis ◽  
Sequencing Batch Reactor ◽  
Batch Reactor ◽  
Automated Image Analysis ◽  
Volume Index ◽  
Filamentous Bacteria ◽  
Sludge Volume Index ◽  
Floc Size ◽  
First Results

To monitor the ability of flocs to settle in Sequencing Batch Reactor sludge, two methods were tested during two operation cycles. Firstly, an automated image analysis procedure has been tested to quantify the floc size and the length and number of filaments. Secondly, rheological measurements (Bingham viscosity and shear stress) have been used to characterise the dispersion of the sludge which can reflect the cohesive strength of aggregates and so the influence of filamentous bacteria on rheological properties. These results were compared with settling parameters such as Sludge Volume Index or settling velocity. Correlations between the measured parameters with image analysis and parameters such as Sludge Volume Index have been obtained. If it is more difficult to analyze rheological results, it seems however that the thixotropy and the Bingham viscosity distinguish poor settlement owing to some filamentous bulking. The first results are promising, although they require confirmation in the long term.

Monitoring activated sludge settling properties using image analysis

2004 ◽  
Vol 50 (7) ◽  
pp. 281-285 ◽  
Author(s):  
R. Jenné ◽  
E.N. Banadda ◽  
I.Y. Smets ◽  
J.F. Van Impe
Keyword(s):  
Image Analysis ◽  
Activated Sludge ◽  
Volume Index ◽  
Filament Length ◽  
Sludge Volume Index ◽  
Filamentous Bulking ◽  
Sludge Properties ◽  
Fully Automatic ◽  
The One ◽  
Sludge Settling

The goal of this study is to develop a monitoring system for activated sludge properties, as this is an essential tool in the battle against filamentous bulking. A fully automatic image analysis procedure for recognising and characterising flocs and filaments in activated sludge images has been optimised and subsequently used to monitor activated sludge properties in a lab-scale installation. The results of two experiments indicate that the image information correlates well with the Sludge Volume Index. It is shown that, at the onset of filamentous bulking, there is an increase in total filament length on the one hand, and a change in floc shape on the other hand.

Study of filamentous bacteria by image analysis and relation with settleability

2002 ◽  
Vol 46 (1-2) ◽  
pp. 363-369 ◽  
Author(s):  
M. da Motta ◽  
M.N. Pons ◽  
N. Roche
Keyword(s):  
Image Analysis ◽  
Wastewater Treatment ◽  
Settling Velocity ◽  
Treatment Plant ◽  
Volume Index ◽  
Morphological Parameters ◽  
Filamentous Bacteria ◽  
Sludge Volume Index ◽  
Floc Size ◽  
Different Temperatures

An automated procedure for the characterisation by image analysis of the morphology of activated sludge has been used to monitor the biomass in a pilot wastewater treatment plant during two runs inoculated with a different sludge and operated at two different temperatures. The bulking events were easily detected by image analysis. Correlations were found between settleability properties (Sludge Volume Index and settling velocity) and the morphological parameters (filament total length, filament number and floc size).

Settling Properties of Activated Sludge Related to Floc Structure

1984 ◽  
Vol 16 (10-11) ◽  
pp. 55-67 ◽  
Author(s):  
L Eriksson ◽  
A.-M Härdin
Keyword(s):  
Activated Sludge ◽  
Volume Index ◽  
Sludge Volume Index ◽  
Extracellular Polymers ◽  
Filtration Resistance ◽  
Floc Structure ◽  
Floc Strength ◽  
The Difference ◽  
Sludge Settling ◽  
Floc Model

When characterizing sludge settling by means of sludge volume index and stirred sludge volume index it has been found that the former is normally higher, but that the difference varies greatly for different sludges. It was found to depend on difference in shape of the flocs. Spherical flocs give small differences and elongated flocs give large ones. Although both indices were positively correlated to the total length of filamentous organisms the differences were not. A general floc model is proposed on the basis of these findings together with colloid chemical considerations and measurements of floc strength, filtration resistance and amount of extracellular polymers. According to this model young flocs are of the elongated type, while flocs from a stable system are round. Sludge bulking is a consequence of stiff noncompressible flocs which may be due to high amounts of dissolved polymers, but most likely to filamentous organisms fixed in a network by binding polymers within the flocs. The amount of filaments inside the flocs is probably proportional to the amount outside which for that reason is correlated to the settling indices.

Sign in / Sign up

Export Citation Format

Share Document