Comparison of lime and alum as oily sludge conditioners

1997 ◽  
Vol 36 (12) ◽  
pp. 117-124 ◽  
Author(s):  
Tay Joo Hwa ◽  
S. Jeyaseelan
Keyword(s):  
Specific Resistance ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Oily Sludge ◽  
Sludge Dewatering ◽  
Capillary Suction ◽  
Sludge Cake ◽  
Solids Content ◽  
Optimum Chemical

Chemical conditioning improves sludge dewatering. Choice of chemical conditioners is very much dependent on the characteristics of the sludges and the type of dewatering devices. Lime, alum, ferric chloride and polyelectrolytes are commonly used chemical conditioners. Anaerobic digested sludge samples collected from a sewage treatment plant with different oil contents varying from 1.8% to 8.0% by weight have been examined in the laboratory to find out their specific resistance, capillary suction time and filter yield. Lime and alum were used separately as conditioners. Different dosages of conditioner varying from 2% to 12% by weight were used to determine the optimum chemical dosage for varying oil contents. Lime dosages of about 6% were found to yield favourable characteristics. Addition of alum decreases the specific resistances and capillary suction times of oily sludges rapidly up to 4% dosages. Alum dosages beyond 4% only increase the solids content in the sludge cake and increase the sludge volume to be handled. A correlation between CST and specific resistance to filtration was established. CST can be measured easily and quickly in the laboratories. Using the CST and the correlation a quick prediction on dewaterability can be established.

Conditioning of oily sludges with municipal solid wastes incinerator fly ash

1997 ◽  
Vol 35 (8) ◽  
pp. 231-238 ◽  
Author(s):  
Tay Joo Hwa ◽  
S. Jeyaseelan
Keyword(s):  
Heavy Metals ◽  
Fly Ash ◽  
Specific Resistance ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Solid Wastes ◽  
Municipal Solid Wastes ◽  
Capillary Suction ◽  
Optimum Dosage

Conditioning of sludges improves dewatering characteristics and reduces the quantity of sludge to be handled. Anaerobic digested sludge collected from a sewage treatment plant contained 1.8% to 8% oil. The increase of specific resistance and capillary suction time (CST) with increasing oil content observed in these samples indicates the interference of oil in dewatering. It has been found that addition of municipal solid wastes incinerator fly ash decreases the specific resistances and capillary suction times of oily sludges rapidly up to 3% dosage. Beyond 3% fly ash, the decrease is less significant and the solids content in the sludge cake increases. This optimum dosage remains the same for sludges with varying oil contents from 1.8% to 12%. The total suspended solids of filtrate decreases with fly ash dosage but the toxic concentrations of heavy metals increases considerably. However at the optimum dosage of 3%, concentrations of heavy metals are within the limits for discharging into the sewers. The correlations of CST with the dewatering characteristics such as specific resistance, filter yield and corrected filter yield are established. These correlations can be used to obtain a quick prediction on dewaterability.

Toxicity assays and their evaluation on organic polymer flocculants used for municipal sludge dewatering

1998 ◽  
Vol 38 (7) ◽  
pp. 207-215 ◽  
Author(s):  
H. Takigami ◽  
N. Taniguchi ◽  
Y. Shimizu ◽  
S. Matsui
Keyword(s):  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Algal Growth ◽  
Pilot Scale ◽  
Organic Polymer ◽  
Municipal Sludge ◽  
Sludge Dewatering ◽  
Algal Toxicity ◽  
Reproduction Tests

The toxicity of organic polymer flocculants used for the dewatering of municipal sludge was evaluated by using two different toxicity assays: the Closterium ehrenbergii algal toxicity test and the Bacillus subtilis rec-assay. The algal toxicity of the effluents from a pilot-scale sewage treatment plant was investigated with and without the addition of a flocculant (0, 0.05, 0.10 and 0.20 mg/L). No clear evidence on the toxicity caused by the flocculant was observed on both asexual and sexual reproduction tests of C. ehrenbergii. It was also found that the algal growth inhibition of various types of flocculants (i.e., cationic, anionic, amphoionic and non-ionic) was in the order of 1 to 20 mg/L, which was mainly due to a molecular weight (MW) fraction of greater than 100,000. The results of the B. subtilis rec-assay for these flocculants indicated that eight out of ten cationic flocculants caused the direct DNA damage with LC50 =0.1 to 10 mg/L. One of the genotoxic flocculants was also fractionated into their components by MW. The experimental results showed that the lethal effects were mainly contributed by the polymer fraction of MW greater than 100,000, although the genotoxicity was not detected in that fraction. Therefore, the detected genotoxicity of the flocculants could be caused by the combined effects of various components, such as polymers, oligomers, monomers and additives.

Control of Heavy Metals and Organochlorines Using the Oil from Sludge Process

1990 ◽  
Vol 22 (12) ◽  
pp. 249-258 ◽  
Author(s):  
T. R. Bridle ◽  
I. Hammerton ◽  
C. K. Hertle
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Control Mechanisms ◽  
Sludge Dewatering ◽  
Water Board ◽  
Unit Operations ◽  
Set Up

A four month pilot plant program, evaluating all unit operations comprising an integrated Oil from Sludge (OFS) plant has been successfully completed for the Sydney Water Board. The unit operations of sludge dewatering, drying and conversion to oil in the patented OFS reactor system were set up at the Malabar Sewage Treatment Plant in Sydney. Pilot testing of the char combustor was conducted off site. Extensive heavy metal and organochlorine monitoring across each unit operation has revealed the following information. There is no loss of contaminants across the dewatering and drying operations. With the exception of arsenic and mercury, all heavy metals fed to the OFS reactor are retained in the char. Greater than 75% of PCB's and 85% of HCB present in sludge are destroyed in the OFS reactor. Greater than 99.7% of the heavy metals fed to the fluid bed combustor are retained in the ash (with exception of mercury, which reported 3% in the flue gas). The FBC ash is classified non-hazardous, using the Toxic Characteristic Leaching Procedure.No organochlorines were detected in the dryer or FBC off-gases. The OFS technology offers decoupling of heavy metal and organochlorine control mechanisms, thus allowing each to be optimally controlled.

Disinfection, Recontamination and Regrowth of Indicator Bacteria in a Wastewater Sludge Heat Treatment System

1988 ◽  
Vol 20 (11-12) ◽  
pp. 329-335
Author(s):  
Roger S. Fujioka ◽  
Wesley M. Hirano ◽  
Philip C. Loh
Keyword(s):  
Heat Treatment ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Wastewater Sludge ◽  
Indicator Bacteria ◽  
Primary Sludge ◽  
Heat Treated ◽  
Sludge Cake ◽  
High Concentrations

The largest sewage treatment plant in Hawaii produces 25,400 kg/day of primary sludge that is heat-treated (190°C) under 330 psig for 3 0 min. Although this treatment should result in a sterilized sludge product, the final sludge cake often contains high concentrations of fecal-borne indicator bacteria. The heat-treatment process was shown to disinfect the sludge of indicator bacteria. However, post contamination of the heat-treated sludge by raw sludge and by chlorinated primary effluent and the regrowth of indicator bacteria in the sludge storage tanks resulted in the presence of indicator bacteria in the sludge cake.

Full-Scale Experience with Sludge Treatment at the Vienna Sewage Works

1989 ◽  
Vol 21 (10-11) ◽  
pp. 1447-1451 ◽  
Author(s):  
Peter Thomas Ruggenthaler
Keyword(s):  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Full Scale ◽  
Fluidised Bed ◽  
Test Results ◽  
Sludge Treatment ◽  
Treatment And Disposal ◽  
Solids Content

The sewage treatment plant at Simmering, Vienna, has been operating since June 1980, together with the ‘EbS' plant for sludge treatment and disposal. This latter consisted of centrifuges, grinder dryers and fluidised bed incineration but due to difficulties with the grinder dryers it has never operated efficiently. Accordingly trials have been done using improved centrifuges and filter presses to increase the dry solids content of the cake fed to the incinerators without using the grinder dryers. It was found that all systems tried were an improvement on the existing but that the best result was achieved using a Centripress on preheated sludge conditioned by polyelectrolyte. The plant was converted to this system in 1987 and results of full-scale operation as well as test results are given in the paper.

Sludge dewatering using centrifuge with thermal/polymer conditioning

2001 ◽  
Vol 44 (10) ◽  
pp. 321-325 ◽  
Author(s):  
C.F. Lin ◽  
Y. Shien
Keyword(s):  
Water Treatment ◽  
Thermal Treatment ◽  
Specific Resistance ◽  
Treatment Plant ◽  
Water Treatment Plant ◽  
Sludge Dewatering ◽  
Capillary Suction ◽  
Temperature Changes ◽  
Biological Sludge ◽  
Sludge Particle

Sludge dewatering is preceded by a conditioning operation to enhance water removal efficiency. In the conditioning operation, chemical coagulants or polymers are added to promote sludge particle aggregation for easier dewatering. In this study, an alternative conditioning method for sludge thermal treatment at temperatures up to 80°C was extensively investigated. Dewatering characteristics such as sludge capillary suction time and specific resistance to filtration, sludge viscosity and concentration of solid cakes were examined thoroughly. A good correlation between capillary suction time and specific resistance to filtration was established for sludges from water treatment, but not for biological sludge. Cationic polymer exhibits the best enhancement on sludge moisture removal. The sludge rheogram varies from 60 to 5 cP as temperature changes from 20 to 80°C for sludges from water treatment plant. The dewatering ability of sludge can be greatly enhanced by thermal treatment in conjunction with the use of polymers.

Automation and Optimisation of Centrifuge Sludge Dewatering

1989 ◽  
Vol 21 (10-11) ◽  
pp. 1319-1324 ◽  
Author(s):  
Gunter Schrank ◽  
Clive Murren
Keyword(s):  
Continuous Measurement ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Effective Control ◽  
Excess Sludge ◽  
Chemical Additives ◽  
Sludge Dewatering ◽  
Sludge Thickening ◽  
Very High

The dehydration of sewage treatment plant sludges has become one of the major problems in the treatment of waste Water. Very high costs, especially those of flocculation additives, increasingly call for optimisation of this phase of the process. Taking the dewatering of sludge by centrifugation as an example, two different approaches can be considered: mechanical excess sludge thickening without the use of additives and the dehydration of sewage sludge with use of chemical additives. A prerequisite of any automation is the reliable acquisition of data of the parameters required for control. Continuous measurement of the concentration of suspended solids in the sludge that is to be dewatered, of sludge flow and of the turbidity of the clear phase (centrate) leaving the centrifuge, make it possible to design several methods of effective control.

scholarly journals Stability Analysis of Mechanical Sludge Dewatering Machine Frame Based on Numerical Simulation

2022 ◽  
Vol 2152 (1) ◽  
pp. 012047
Author(s):  
Li Chen
Keyword(s):  
Equivalent Stress ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Normal Operation ◽  
Motor Speed ◽  
Sludge Dewatering ◽  
Element Analysis ◽  
Operation Conditions ◽  
Interference Frequency

Abstract Sludge is the inevitable product of sewage treatment plant and sewage treatment. Before sludge treatment, dewatering is generally required. Mechanical sludge dewatering machine is a common sludge dewatering equipment. Due to the complex operation conditions, the stability of sludge dewatering machine frame directly affects its reliability. In this paper, a mechanical sludge dewatering machine frame as the research object, based on ANSYS Workbench finite element analysis platform, static analysis and modal analysis. The analysis results show that: under normal working conditions, the maximum variable of the frame is 0.07mm, which can effectively ensure the normal operation of the sludge dewatering machine; the equivalent stress is 4.22Mpa, which is far less than the Xu Yong stress of the material; the vibration of the first two modes of the frame is relatively concentrated, and the corresponding motor speed under the interference frequency is 1241.4-1595.4r/min, which should be avoided in the use process.

Influence of Microwave and Ultrasound on Sludge Dewaterability

2014 ◽  
Vol 955-959 ◽  
pp. 2074-2079 ◽  
Author(s):  
Cui Hong Zhou ◽  
Ying Ling ◽  
Meng Zeng ◽  
Xin Yue Li
Keyword(s):  
Particle Size ◽  
Fractal Dimension ◽  
Moisture Content ◽  
Water Content ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Morphological Characteristics ◽  
Oxygen Demand ◽  
Capillary Suction

Sludge with large production is difficult to be dewatered without any pretreatment. Pretreatment with ultrasound and microwave can adjust the structure of sludge and change the water form, therefore increase the water content which could be dispelled easily. Dewaterability and morphological of sludge from sewage treatment plant including microwave and ultrasound were studied. Capillary Suction Time (CST), viscosity, Settle Volume (SV), water content, Chemical Oxygen Demand (COD), Zeta potential and morphological characteristics were tested. After microwave modification, the particle size of sludge ranged from 33.55μm to 28.98μm, and fractal dimension was about 2.8. Microscopic image analysis showed that the particle of sludge became coarse. After ultrasound modification, the particle size of sludge ranged from 33.55μm to 9.44μm, fractal dimension was about 2.9. Thus, the smaller particles were observed after ultrasound. The gray associate degree coefficient of viscosity and moisture content is the bigest. Through the analysis of dewatering characteristics of sludge and water content, a model which contributes to predict moisture content of sludge online was established.

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