Enumeration of potentially pathogenic bacteria from sewage sludges

Abstract

To ascertain the health risks that may be posed by the land application of sewage sludges, a scheme was devised to determine the types and numbers of pathogenic and potentially pathogenic bacteria present in sludges. A processing treatment was adapted to sludge to give a homogenate which yielded the greatest numbers of viable bacteria. Conventional methods were successful in enumerating Klebsiella, Staphylococcus, gram-negative enteric bacteria, and commonly used indicator organisms. Modifications of conventional methods improved the enumeration of Salmonella, Mycobacterium sp., fluorescent Pseudomonas sp., and Clostridium perfringens. However, Shigella methodology yielded only one isolate. Utilizing the proposed scheme, the population densities of these organisms were estimated in three domestic wastewater sludges. In light of these results, the potential impact of land application of sewage sludges is discussed.

Hygienization of Surplus Activated Sludge By Dry Ice

“…2). A potential indicator of the sanitary quality of sewage sludge, which is mentioned in the literature [42] is Clostridium perfringens. There was a gradual elimination of the Clostridium perfringens bacteria caused by the growth of the volume ratio of the sludge to dry ice.…”

Bacterial leaching of toxic metals from municipal sludge: influence of sludge characteristics

“…Fifteenmilliliter samples were withdrawn from the flasks count technique using the S 2 0 3 2 _ synthetic salts agar medium for lessacidophilic (pH 7.0) and acidophilic (pH 4.0) thiobacilli, described by Laishley et al (1988) and Reynolds et al (1981). The plate count technique was carried out according to a mod ified technique of Dudley et al (1980). Samples were obtained after vortex mixing 1 mL of sludge at high speed for 2 minutes with 14 mL of sterile phosphatebuffered saline (0.01 M, pH 7.2), containing approximately 1 g of sterile 45mm diameter glass beads in a 50mL centrifuge tube.…”

“…In both cases, the leaching microflora should be able to grow in the presence of elevated metal concentrations. The re sistance of acidophilic thiobacillizyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA (T. ferrooxidans and T. thiooxidans) to high metal concentration is well known (Brierley and LeRoux, 1978;Ehrlich and Brierley, 1990;Karavaiko et al, 1977;and Lundgren and Silver, 1980). However, the waste water sludge provides an entirely different environment com pared to a mineral residue or mine tailings for thiobacilli growth.…”

Biological HRPs in wastewater

“…Wastewater may contain millions of bacteria per milliliter and is also a potential source of various pathogenic bacteria. Recently, a wide range of pathogenic bacteria, such as Escherichia coli, Clostridium perfringens, Mycobacterium tuberculosis, Legionella pneumophila, Pseudomonas aeruginosa, Shigella flexneri, Salmonella enterica, Vibrio cholera, and Yersinia enterocolitica, have been detected in the wastewater (Cai and Zhang, 2013;Dudley et al, 1980;Stevik et al, 2004). Several reports have summarized pathogenic bacteria commonly detected in wastewater (Table 3.3) (Gerardi, 2006;Gerardi and Zimmerman, 2004).…”