Microbial disinfection capacity of municipal solid waste (MSW) composting

Abstract

The disinfection capacity of a municipal solid waste (MSW) composting plant (Siloda) has been evaluated. In spring and summer, MSW was followed during the composting process from raw material to mature compost and long-term storage (1 year). Ascaris eggs, Salmonella, Shigella, total streptococci, faecal streptococci, total coliforms, faecal coliforms and Escherichia coli were studied. Disinfection was successful in terms of a decrease in faecal contamination indicators and disappearance of faecal pathogens. Faecal coliform concentration in raw waste reached 2.1 x 10(8) cfu g-1 dry weight in spring (CI 95%:5.2 x 10(7)-3.4 x 10(8)) and 7.2 x 10(8) cfu g-1 dry weight (1 x 10(8)-1.7 x 10(9)) in summer, and fell to less than 100 cfu g-1 dry weight within 20 d. Faecal streptococci concentrations reached 8.7 x 10(8) cfu g-1 dry weight (3.7 x 10(8)-1.3 x 10(9)) in spring and 2.0 x 10(9)cfu g-1 dry weight (5.6 x 10(8)-3.4 x 10(9)) in summer, and fell to 8.7 x 10(4) cfu g-1 dry weight (6.9 x 10(4)-1.0 x 10(5)). No seasonal pattern of contamination, mainly of animal origin, was observed. Microbiological quality of finished compost depends on the storage conditions. Therefore, the storage stage should be viewed as part of the composting process. Monitoring disinfection capacity of MSW composting needs to combine several microbial populations.

Isolation and Characterization of Bacteria and Fungi Associated With Biodegradation of Municipal Solid Wastes in Abakaliki Metropolis, Nigeria

“…During degradation, the organic acids that have evolved from the process would depress the pH from the original levels [23,24]. The pH values obtained in this study are in agreement with the levels reported by Baffa et al [25] and Deportes et al [26]. The increase in acidity of degrading substrate would also favour the activity of fungi resulting in the release of simpler nutrient that enhances bacterial proliferation.…”

Enhanced stabilisation of municipal solid waste in bioreactor landfills

“…The reduction of total and faecal coliforms (Fig. 4a), 99% and 100% respectively, was inline with the results of reported by Déportes et al (1998) and Vanotti et al (2005) who used disinfection techniques for liquid swine manure. The normal factors for die-off of coliforms in solid waste (high temperature, extreme alkaline pH (pH>11) and high EC) as described by Watson-Craik et al (1992) and Boost & Poon (1998) were not significantly influential in this experiment.…”

Fate of non O157 Shiga toxigenic Escherichia coli in composted cattle manure

“…Although the elimination of pathogens by composting has been well documented (Deportes et al, 1998;Tiquia et al, 2002;Larney et al, 2003), composting times and temperatures required to achieve elimination or reduction of the number of E. coli vary widely. Turner (2002) demonstrated inactivation of E. coli in farmyard manure, pig feces, and cereal straw already after 2h at 55 o C. In contrast, Lau and Ingham (2001) reported that E. coli could be cultured from bovine manure kept for 19 weeks at 21 o C. In the present study, E. coli could be cultured at every condition tested after up to 120 days, however the non-O157 STEC-stx2-gene strains were not found after 30 days, indicating that competition among the bacteria associated with the temperature seem to be very important aspects.…”