Extracellular polymers of ozonized waste activated sludge

2001 ◽  
Vol 44 (10) ◽  
pp. 137-142 ◽  
Author(s):  
J.C. Liu ◽  
C.H. Lee ◽  
J.Y. Lai ◽  
K.C. Wang ◽  
Y.C. Hsu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Activated Sludge ◽  
Weight Distribution ◽  
Specific Resistance ◽  
Optimal Dose ◽  
Cationic Polyelectrolyte ◽  
Waste Activated Sludge ◽  
Extracellular Polymers ◽  
Capillary Suction ◽  
Ozone Dose

Effect of ozonation on characteristics of waste activated sludge was investigated in the current study. Concentrations of cell-bound extracellular polymers (washed ECPs) did not change much upon ozonation, whereas the sum of cell-bound and soluble extracellular polymers (unwashed ECPs) increased with increasing ozone dose. Washed ECPs in original sludge as divided by molecular weight distribution was 39% < 1,000 Da (low MW), 30% from 1,000 to 10,000 Da (medium MW), and 31% > 10,000 Da (high MW). It was observed that the low-MW fraction decreased, and the high-MW fraction increased in ozonized sludge. The unwashed ECPs were characterized as 44% in low MW, 30% in medium MW, and 26% in high MW. Both low-MW and medium-MW fractions of unwashed ECPs decreased while high-MW fraction increased in ozonized sludge. The dewaterability of ozonized sludge, assessed by capillary suction time (CST) and specific resistance to filtration (SRF), deteriorated with ozone dose. The optimal dose of cationic polyelectrolyte increased with increasing ozone dose. The production rate and the accumulated amount of methane gas of ozonized sludge were also higher.

Co-conditioning and dewatering of alum sludge and waste activated sludge

2004 ◽  
Vol 50 (9) ◽  
pp. 41-48 ◽  
Author(s):  
J.Y. Lai ◽  
J.C. Liu
Keyword(s):  
Activated Sludge ◽  
Cost Effective ◽  
Management Plan ◽  
Cationic Polyelectrolyte ◽  
Solid Content ◽  
Waste Activated Sludge ◽  
Capillary Suction ◽  
Alum Sludge ◽  
Sludge Dewaterability ◽  
Treatment And Disposal

Co-conditioning and dewatering behaviors of alum sludge and waste activated sludge were investigated. Two different sludges were mixed at various ratios (2:1; 1:1; 1:2; 1:4) for study. Capillary suction time (CST) and specific resistance to filtration (SRF) were utilized to assess sludge dewaterability. Relatively speaking, waste activated sludge, though of higher solid content, was more difficult to be dewatered than alum sludge. It was found that sludge dewaterability and settlability became better with increasing fraction of alum sludge in the mixed sludge. Dosage required of the cationic polyelectrolyte (KP-201C) for dewatering was reduced as well. It is proposed that alum sludge acts as skeleton builder in the mixed sludge, and renders the mixed sludge more incompressible which is beneficial for sludge dewatering. Implications of the results of the study to the sludge management plan for Taipei City that generates both alum sludge and waste activated sludge at significant amount are also discussed. The current sludge treatment and disposal plan in Metropolitan Taipei could be made more cost-effective.

Sludge conditioning by using alumina nanoparticles and polyelectrolyte

2007 ◽  
Vol 56 (8) ◽  
pp. 125-132 ◽  
Author(s):  
Z.S. Wang ◽  
M.T. Hung ◽  
J.C. Liu
Keyword(s):  
Activated Sludge ◽  
Paper Industry ◽  
Cationic Polyelectrolyte ◽  
Alumina Nanoparticles ◽  
Waste Activated Sludge ◽  
Capillary Suction ◽  
Floc Size ◽  
Combined Use ◽  
Retention Aids ◽  
Sludge Conditioning

The combined use of nanoparticle and polyelectrolyte as retention aids in pulp and paper industry tend to give better flocculation (retention) and drainage (dewatering) than conventional polyelectrolyte flocculation. The combined use of alumina nanoparticle and polyelectrolyte in conditioning waste activated sludge was investigated in the current study. Alumina with three different sizes (139.5, 241.7, and 326.4 nm) was utilized in combination with a cationic polyelectrolyte (T3052) of molecular weight of 1.1 × 107 and charge density of 2.1 meq/g. It was found from capillary suction time (CST) and specific resistance to filtration (SRF) measurement that sludge conditioned with alumina/polyelectrolyte showed a better dewaterability than polyelectrolyte alone. In addition, it was found that the better dewaterability was obtained as alumina became smaller. Floc size and fractal dimension of flocs were examined as well. The mechanism of enhanced dewaterability was proposed that alumina nanoparticles became adsorbed onto sludge and positive patches were formed. The electrostatic repulsion made the polyelectrolyte more stretched, and resulted in more effective flocculation and bridging as polyelectrolyte was added. Dosing sequence also affected the conditioning effectiveness. However, the combined use of silica nanoparticles and a cationic polelectrolyte, KP-201C, or alumina nanoparticles and an anionic polyelectrolyte, AP410, did not result in improved dewaterability of waste activated sludge. Possible explanation was discussed. Preliminary results show that some in-depth work is needed regarding the introduction of nanoparticles in sludge conditioning.

The role of blending in polymer conditioning of waste activated sludge

2001 ◽  
Vol 44 (6) ◽  
pp. 63-66 ◽  
Author(s):  
A. Erdinçler; ◽  
S. Koseoǧly ◽  
T. Onay
Keyword(s):  
Molecular Weight ◽  
Activated Sludge ◽  
Waste Activated Sludge ◽  
Capillary Suction ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer ◽  
Biological Polymers ◽  
Time Periods ◽  
Control Samples

This paper presents the results of an investigation on the role of blending in sludge polymer conditioning by evaluating the polymer consumption, and measuring the capillary suction time of waste activated sludge samples blended for different time periods. All of the sludge samples, including non-blended control samples, were conditioned by a cationic high molecular weight polymer in desired concentrations. The protein concentrations of the sludge samples increased as a biological confirmation of cell disruption or desorption of some part of biological polymers present in sludge. Blending decreased the critical polymer dosages required to condition the waste activated sludge samples depending on the blending time applied to the samples.

Extracellular polymeric substances and dewaterability of waste activated sludge during anaerobic digestion

2014 ◽  
Vol 70 (9) ◽  
pp. 1555-1560 ◽  
Author(s):  
Fenxia Ye ◽  
Xinwen Liu ◽  
Ying Li
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Extracellular Polymeric Substance ◽  
Extracellular Polymeric Substances ◽  
Waste Activated Sludge ◽  
Sludge Dewatering ◽  
Capillary Suction ◽  
Relationship Analysis ◽  
The Relationship ◽  
Insight Into

Anaerobic digestion of waste activated sludge was conducted to gain insight into the mechanisms underlying change in sludge dewaterability during its anaerobic digestion. Unexpectedly, the results indicated that sludge dewatering properties measured by capillary suction time only deteriorated after 10 days of anaerobic digestion, after which dewaterability recovered and remained stable. The loosely bound extracellular polymeric substance (LB-EPS) content increased three-fold after 20 days of anaerobic digestion, and did not change significantly during the remaining 30 days. The tightly bound EPS (TB-EPS) content reduced slightly after 20 days of anaerobic digestion, and stabilized during the last 30 days. Polysaccharides (PS) and proteins (PN) content in LB-EPS increased after 10 days of anaerobic digestion. However, PS and PN contents in TB-EPS decreased slightly. The relationship analysis showed that only LB-EPS correlated with dewaterability of the sludge during anaerobic digestion.

scholarly journals Enhancing Phosphorus Recovery and Dewaterability of Waste Activated Sludge for Combined Effect of Thermally Activated Peroxydisulfate and Struvite Precipitation

2021 ◽  
Vol 13 (17) ◽  
pp. 9700
Author(s):  
Zicong Liao ◽  
Yongyou Hu ◽  
Yuancai Chen ◽  
Jianhua Cheng
Keyword(s):  
Activated Sludge ◽  
Extracellular Polymeric Substances ◽  
Phosphorus Recovery ◽  
Waste Activated Sludge ◽  
Optimal Conditions ◽  
Capillary Suction ◽  
Radical Oxidation ◽  
Thermally Activated ◽  
Struvite Precipitation ◽  
The Cost

Phosphorus is a nonrenewable and irreplaceable limited resource, and over 90% of phosphorus in influenttransfers into sludge in wastewater treatment plants. In this study, thermally activated peroxydisulfate (TAP) treatment was combined with struvite precipitation to enhance waste activated sludge (WAS) dewaterability and phosphorus recovery. TAP simultaneously enhanced dewaterability and solubilization of WAS. The optimal conditions of TAP treatment were PDS dosage 2.0 mmol/g TSS, 80 °C, pH 4.0~7.0 and 40 min, which enhanced dewaterability (capillary suction time (CST) from 94.2 s to 28.5 s) and solubilization (PO43−-P 177.71 mg/L, NH4+-N 287.22 mg/L and SCOD 10754 mg/L). Radical oxidation disintegrated tightly bound extracellular polymeric substances (TB-EPS) and further released bound water. The acidification effect neutralized the negative surface charge of colloid particles. Compared with thermal hydrolysis, TAP effectively promoted the release of PO43−, NH4+ and SCOD. Cation exchange removed most Ca and Al of the TAP treated supernatant. The optimal conditions of struvite precipitation were Mg/P 1.4 and pH 10.0, which achieved phosphorus recovery of 95.06% and struvite purity of 94.94%. The income obtained by struvite adequately covers the cost of struvite precipitation and the cost of WAS treatment is acceptable.

Enhancement of Waste Activated Sludge Dewaterability by Potassium Ferrate Pretreatment

2014 ◽  
Vol 1073-1076 ◽  
pp. 937-940 ◽  
Author(s):  
Xiao Rong Kang ◽  
Ya Li Liu
Keyword(s):  
Activated Sludge ◽  
Optimal Dose ◽  
Soluble Proteins ◽  
Waste Activated Sludge ◽  
Potassium Ferrate ◽  
Sludge Dewatering ◽  
Cationic Polyacrylamide ◽  
Floc Structure ◽  
Sludge Dewaterability

Potassium ferrate was used to enhance sludge dewatering and the mechanism was studied. Sludge floc structure was effectively destroyed by potassium ferrate, and the soluble COD, proteins and polysaccharides increased with the increase of potassium ferrate. The optimal dose for sludge disintegration was 100 mg/gSS, and the corresponding maximal SCOD, soluble proteins and polysaccharides concentrations were 2455, 800 and 145 mg/L, respectively. Sludge dewaterability was enhanced significantly with cationic polyacrylamide (C-PAM) application, and the SRF decreased to 0.72×1010m/kg from 50.12×1010m/kg. This study indicated that the potassium ferrate pretreatment was helpful for enhancing sludge dewaterability and reducing the coagulant dose.

scholarly journals Process Optimization of Waste Activated Sludge in Anaerobic Digestion and Biogas Production by Electrochemical Pre-Treatment Using Ruthenium Oxide Coated Titanium Electrodes

2021 ◽  
Vol 13 (9) ◽  
pp. 4874
Author(s):  
Gan Chin Heng ◽  
Mohamed Hasnain Isa ◽  
Serene Sow Mun Lock ◽  
Choon Aun Ng
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Chemical Oxygen Demand ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Ruthenium Oxide ◽  
Parameters Optimization ◽  
Waste Activated Sludge ◽  
Capillary Suction ◽  
Pre Treatment

Anaerobic digestion (AD) appears to be a popular unit operation in wastewater treatment plant to treat waste activated sludge (WAS) and the produced methane gas can be harvested as renewable energy. However, WAS could inhibit hydrolysis stage during AD and hence pre-treatment is required to overcome the issue. This paper aimed to study the effect of electrochemical pre-treatment (EP) towards efficiency of AD using titanium coated with ruthenium oxide (Ti/RuO2) electrodes. The investigation has been carried out using in-house laboratory batch-scale mesophilic anaerobic digester, mixed under manipulation of important operating parameters. Optimization was performed on EP using response surface methodology and central composite design to maximize sludge disintegration and dewaterability. By operating at optimal conditions (pH 11.65, total solids 22,000 mg/L, electrolysis time 35 min, current density 6 mA/cm2, and 1000 mg/L of sodium chloride), the pre-treated WAS in terms of mixed liquor volatile suspended solids (MLVSS) removal, soluble chemical oxygen demand (sCOD), capillary suction time (CST) reduction, and extracellular polymeric substance (EPS) were 38%, 4800 mg/L (increased from 935 mg/L), 33%, and 218 mg/L, respectively. Following AD, the volatile solids (VS) removal and chemical oxygen demand (COD) removal by EP were enhanced from 40.7% and 54.7% to 47.2% and 61.5%, respectively, at steady-state. The biogas produced from control and electrochemical pre-treated WAS were in the ranges of 0.12 to 0.17 and 0.2 to 0.24 m3/kg VSfed, respectively, and the volume of biogas produced was 44–67% over the control. Based on the results obtained, suitability of EP for WAS prior to AD was confirmed.

Effect of centrifugation on the removal of extracellular polymers and physical properties of activated sludge

1994 ◽  
Vol 30 (8) ◽  
pp. 117-127 ◽  
Author(s):  
F. Dilek Sanin ◽  
P. Aarne Vesilind
Keyword(s):  
Activated Sludge ◽  
Physical Properties ◽  
Inorganic Materials ◽  
Extracellular Polymers ◽  
Capillary Suction ◽  
The Past ◽  
Main Components ◽  
The Relationship ◽  
Flocculated Suspension ◽  
Extracellular Polymer

Activated sludge is a flocculated suspension of living and dead microorganisms enmeshed together in a polymer matrix along with some organic and inorganic materials. Extracellular polymers, main components of which are the polysaccharides, proteins, and nucleic acids, act as a protective barrier to the living microbial community, and give the floc its integrity and rigidity. These polymers have been found to affect the dewatering and settling characteristics of activated sludge. Even though they were studied considerably in the past there is not a complete understanding of the relationship between the amount of polymer and changes in the physical properties of sludge. The purpose of this research is to observe the effects of centrifugal force on the extraction of the extracellular polymers from an activated sludge and to correlate the amount of polymer extracted to the subsequent physical properties of the sludge. Centrifugal forces of 2000, 5000, 8000, 11,000, 14,000, and 16,500 G were tested for their effects on the amount of extracellular polymer collected, as well as the final properties of sludge like viscosity, filterability, compactability and supernatant turbidity. Results were evaluated in comparison to those of an uncentrifuged control waste activated sludge. Removal of extracellular polymers seems to affect the viscosity of activated sludge. Filterability, as measured by the capillary suction time instrument, was affected by the extraction of polymers to a great degree. Results of the independent tests correlated well with each other and with the amount of polymers extracted. Results of this study have important implications on sludge pumping and dewatering.

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