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.

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.

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.

Pilot-Scale Study on Electrosorption Technology for Reclaimed Treatment of Power Plant Industrial Wastewater

2014 ◽  
Vol 997 ◽  
pp. 770-776
Author(s):  
Feng Long Xie ◽  
Jian Jun Shen ◽  
Jiang Liu
Keyword(s):  
Production Rate ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Pilot Scale ◽  
Total Hardness ◽  
Water Production ◽  
Electrode Voltage ◽  
Water Production Rate ◽  
Industrial Sewage

Based on the pilot test, the feasibility of E lectrosorption Technology of industrial sewage treatment plant was studied. The result s show that, when the equipment w ater flow and electrode voltage appropriate, in the sewage plant industrial average conductivity row is 3277μS/cm, 4072μS/cm, averaged desalination rate is 74.8%, averaged water production rate is about 75.5%, average consu mption water of a ton is 2.46kW•H. E lectrosorption technology is g ood removal effect of salinity, chloride and total hardness , and water production rate is high, simple operation, can be used for desalination of industrial recyclin wastewater .

scholarly journals Preliminary Investigation of an Installed Pilot-Scale Biological Nutrient Removal Technology (BNRT) for Sewage Treatment

2021 ◽  
Vol 333 ◽  
pp. 12002
Author(s):  
Regina Damalerio ◽  
Aileen Orbecido ◽  
Michael Angelo Promentilla ◽  
Ramon Christian Eusebio ◽  
Liza Patacsil ◽  
...  
Keyword(s):  
Nutrient Removal ◽  
Preliminary Investigation ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Pilot Scale ◽  
Biological Nutrient Removal ◽  
Nitrogen And Phosphorus ◽  
Removal Technology ◽  
New Treatment

Water utilities, commercial and industrial establishments are required to upgrade or install new treatment systems to comply with the revised effluent standards issued by the Department of Environment and Natural Resources – Environment Management Bureau (DENR – EMB) which now includes removal and monitoring of nutrients (nitrogen and phosphorus components). One solution is to utilize a biological nutrient removal technology (BNRT) system capable of removing nutrients from sewage. The on-going study aims to investigate the performance of the pilot-scale system in the removal of nutrients from sewage. The designed pilot-scale anaerobic-anoxic-oxic (A2O) process with a total hydraulic retention time of 8.37 hrs. was operated in an existing sewage treatment plant (STP). System modification was adapted to ensure continuous operation. Dissolved oxygen (DO) and temperature of each compartment were evaluated after 45 days of system modification. The DO of the anaerobic and oxic compartment remained within the required range, while the internal recycling flowrate and/or aeration must be adjusted to achieve a DO concentration of 0.20 – 0.50 mg/L in the anoxic compartment. The research is financially supported by the Philippine Council for Industry, Energy and Emerging Technology Research and Development of the Department of Science and Technology (PCIEERD Project No. 04176).

scholarly journals Speciation Characteristics and Ecological Risk Assessment of Heavy Metals in Municipal Sludge of Huainan, China

Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6711
Author(s):  
Mu You ◽  
Yunhu Hu ◽  
Yule Yan ◽  
Jie Yao
Keyword(s):  
Heavy Metals ◽  
Risk Assessment ◽  
Ecological Risk ◽  
Risk Index ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Potential Ecological Risk ◽  
Risk Level ◽  
Municipal Sludge

In order to fully understand the morphological characteristics and pollution status of heavy metals in the dewatered sludge of Huainan Municipal sewage treatment plant, the physical and chemical properties were analyzed, and the content and occurrence forms of heavy metals (As, Cu, Zn, Pb, Cd, Cr, and Ni) in the sludge were studied using the geological accumulation method (Igeo), risk assessment coding method (RAC), and potential ecological risk index method to evaluate the ecological risk. The results showed that the municipal sludge in Huainan was rich in nutrients, with good prospects for agricultural utilization. There were differences in the morphological distributions of different heavy metals. The Igeo values for Ni, As, Cr, and Pb were below 0. The results of RAC indicated that the risk level of Cr in sludge was a low risk, and those of other heavy metals were moderate risks. The potential ecological risk of Cd had the highest potential ecological risk, and the other six metals were of low ecological risk. This conclusion can provide basic data and a theoretical reference for the comprehensive utilization of sludge in sewage treatment plants.

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.

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