Bacterial leaching of metals from sewage sludge

1978 ◽  
Vol 5 (4) ◽  
pp. 305-313 ◽  
Author(s):  
W. Sch�nborn ◽  
H. Hartmann
Keyword(s):  
Sewage Sludge ◽  
Bacterial Leaching

The Effects of Bacterial Leaching on Metal Partitioning in Sewage Sludge

2006 ◽  
Vol 22 (10) ◽  
pp. 1013-1019 ◽  
Author(s):  
Ana T. Lombardi ◽  
Oswaldo Garcia ◽  
Waldenir A. N. Menezes
Keyword(s):  
Sewage Sludge ◽  
Metal Partitioning ◽  
Bacterial Leaching

Fate of indicator organisms in sludge during bacterial leaching of metals

1991 ◽  
Vol 18 (2) ◽  
pp. 237-243 ◽  
Author(s):  
J. G. Henry ◽  
D. Prasad ◽  
W. B. Lohaza
Keyword(s):  
Sewage Sludge ◽  
Suspended Solids ◽  
Agricultural Land ◽  
Thiobacillus Ferrooxidans ◽  
Metal Removal ◽  
Bacterial Pathogens ◽  
Indicator Bacteria ◽  
Bacterial Leaching ◽  
Solids Concentration ◽  
Pathogenic Organisms

Biological extraction (bacterial leaching) of heavy metals from digested sewage sludge has been shown to be a practical means for decontaminating sludge for use on agricultural land. However, it was not known whether pathogenic organisms would survive or be destroyed in the acidic environment necessary for the bacterial leaching process. The purpose of the research reported herein was to assess the effect of bacterial leaching on various bacteria commonly used to indicate the possible presence of pathogenic organisms. Although pathogenic viruses, bacteria, protozoa, and helminths may be present in sludge, this study is concerned only with bacterial pathogens. The concentrations of the four indicator bacteria selected to represent the bacterial pathogens were determined in a series of laboratory bacterial leaching units. Results showed that, although about 80–90% metal removal efficiencies were achieved (at a pH of 4.0, an aeration rate of 100 mL of air per minute per litre of sludge) at a temperature of 20–25 °C, the indicator bacteria were not reduced during bacterial leaching at high suspended solids concentrations. The survival of indicator bacteria was found to be a function of the suspended solids concentration in the leaching units, regardless of the source or type of indicator bacteria. At suspended solids concentrations greater than 10 g/L, the indicator bacteria were able to survive, apparently unaffected by the unfavourable environmental conditions (10 days retention at pH 4.0). Below this suspended solids concentration of 10 g/L, significant reductions of total coliforms, faecal coliforms, and faecal streptococci were achieved. Total heterotrophs did not follow the same trends as the other indicator bacteria. Key words: bacterial leaching, Thiobacillus ferrooxidans, indicator bacteria, enteric pathogens removal, sewage sludge, sludge disposal.

Alternative energy substrates for bacterial leaching of heavy metals from sewage sludge

1992 ◽  
Vol 19 (2) ◽  
pp. 359-360 ◽  
Author(s):  
Denis Couillard ◽  
Shucai Zhu
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Key Words ◽  
Alternative Energy ◽  
Thiobacillus Ferrooxidans ◽  
Bacterial Leaching ◽  
Energy Substrates ◽  
Energy Substrate ◽  
Batch System

Bacterial leaching of heavy metals from sewage sludge with different iron containing compounds as energy substrates was studied in a batch system using a culture of Thiobacillus ferrooxidans. It was proven that spent FeSO4∙7H2O and pyrite met the criteria of an energy substrate and could be substituted for reagent grade FeSO4∙7H2O. This substitution could significantly reduce energy substrate cost: 99% with spent FeSO4∙7H2O and 94% with pyrite. The solid aspect of pyrite compromises its use. Key words: energy substrate, bioleaching, heavy metals, solubilization, Thiobacillus ferrooxidans, sewage sludge.

Coliform inactivation in sludge by copper sulphate

1993 ◽  
Vol 20 (5) ◽  
pp. 814-819 ◽  
Author(s):  
D. Prasad ◽  
J. G. Henry ◽  
A. King
Keyword(s):  
Sewage Sludge ◽  
Copper Sulphate ◽  
Contact Time ◽  
Suspended Solids ◽  
Total Coliform ◽  
Subsequent Treatment ◽  
Land Application ◽  
Coliform Bacteria ◽  
Anaerobic Conditions ◽  
Bacterial Leaching

Studies were conducted to demonstrate the effectiveness of copper sulphate for disinfection of sewage sludge under anaerobic conditions. The effects of suspended solids and copper dosages on the survival of total coliforms in normal (neutral pH) and acidified sludges (pH 2.1–3.8) were studied. Results indicated that disinfection of sewage sludge by copper sulphate was feasible. Under anaerobic conditions, significant reductions (about 99%) of total coliform bacteria in normal sludge were achieved at a dosage of 40 mg Cu/g dry sludge mass, sludge suspended solids of < 3.0%, and a contact time of 24 h. The toxic effect of copper dosage was enhanced and the copper dosage and contact time reduced at lower pH (2.1–3.8). Sludge so treated would be suitable for land application insofar as its bacteriological quality is concerned, provided the high copper concentration could be reduced to acceptable levels. Whether this can be achieved in subsequent treatment of disinfected sludge by bacterial leaching will be determined in a future study. Key words: sludge disinfection, coliforms, copper sulphate, sludge disposal, bacterial leaching.

Bacterial leaching of heavy metals from sewage sludge—Bioreactors comparison

1990 ◽  
Vol 66 (3) ◽  
pp. 237-252 ◽  
Author(s):  
D. Couillard ◽  
G. Mercier
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Bacterial Leaching

Bacterial Leaching of Heavy Metals From Anaerobically Digested Sewage Sludge

1983 ◽  
Vol 18 (1) ◽  
pp. 151-162 ◽  
Author(s):  
L. Wong ◽  
J.G. Henry
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Agricultural Land ◽  
Metal Removal ◽  
Health Hazard ◽  
Dry Weight ◽  
Low Grade ◽  
Bacterial Leaching ◽  
Beneficial Reuse ◽  
Digested Sewage Sludge

Abstract Spreading of sewage sludges on agricultural land is an attractive sludge management option because it combines beneficial reuse and disposal at the same time. However, it is important to reduce the metal content in the sludge in order to minimize the health hazard associated with metal uptake by plants and its subsequent accumulation in the food chain. Treatment of sludge with acid for metal removal is not practical because a large amount of acid is required. Typically 0.5 to 0.8 g of H2SO4/g dry weight of sludge will be required to achieve over 70% removal of cadmium (Cd), zinc (Zn) and nickel (Ni). Lead (Pb) and copper (Cu) are not significantly removed. A biological process called bacterial leaching, which has been used commercially for extracting copper and uranium from low grade ores, was reviewed and its potential for removing heavy metals from anaerobically digested sewage sludge was investigated. Leaching experiments were conducted and the results showed that about 80 to 90% removal of cadmium, zinc and nickel, and 60 to 70% removal of copper were possible. The acid requirement was significantly reduced because only 0.15 g of H2SO4/g dry weight of sludge was needed.

Sign in / Sign up

Export Citation Format

Share Document