Change in Microbial Numbers during Thermophilic Composting of Sewage Sludge with Reference to CO ₂ Evolution Rate

Abstract

Dewatered sewage sludge was composted in a laboratory-scale autothermal reactor in which a constant temperature of 60°C was kept as long as possible by regulating the air feed rate. The change in CO2 evolution rate was measured continuously from the start up through the cessation of composting. The succession of mesophilic bacteria, thermophilic bacteria, and thermophilic actinomycetes was also observed during the composting. Specific CO2 evolution rates of thermophilic bacteria and actinomycetes in the constant-temperature region of 60°C were assessed quantitatively. It was found that the CO2 evolution rate was attributed to thermophilic bacteria at the initial stage of 60°C and to thermophilic actinomycetes at the later stage of 60°C.

Effect of inoculum source on the enrichment of microbial communities on two lignocellulosic bioenergy crops under thermophilic and high-solids conditions

“…While prior work has demonstrated that inoculation of organic matter with targeted degradative microbial communities can alter microbial activity and accelerate decomposition (Nakasaki et al 1985;Ichida et al 2001), little is known regarding the ecological differences that arise from differing compost inocula on a given biomass during enrichment culture. Here, two feedstocks relevant to biofuel production and two compost inocula were used for enrichment culture to gauge their effects on enriched community structure.…”

Characterization of a Bench‐Scale System for Studying the Biodegradation of Organic Solid Wastes

“…Ashbolt and Line (1982) classified laboratory scale vessels into rotating drums and stationary cylinders. Several studies have addressed the performance of each type of vessels (Schulze, 1962;Jeris and Regan, 1973;Suler and Finstein, 1977;Ashbolt and Line, 1982;Sikora et al, 1983;Nakasaki et al, 1985;Hogan et al, 1989;Palmisano et al, 1993). Bach et al (1984) combined the advantages of these two types of vessels and used a mixed isothermal reactor.…”

Effect of Temperature on Composting of Sewage Sludge

“…In our previous papers (7,9), we showed that the reaction rate of composting as measured by the CO2 evolution rate is related to microbial succession, and we estimated the specific activity for thermophilic bacteria and actinomycetes. In this paper, the effect of temperature was investigated by the same procedure as in our previous papers, under controlled environmental conditions.…”

“…The composting temperatures were kept at 50, 60, and 70°C as long as possible by controlling the rate of airflow. The operation of the reactor and the composting procedure were the same as those described in our previous paper (7). Two experimental series of runs were performed.…”

“…Isolation of microorganisms. Media and procedures for the isolation of the microorganisms which are responsible for the degradation of organic matter in compost were the same as described in our previous paper (7). Incubation temperatures were 30°C for mesophilic microorganisms and 60°C for thermophilic microorganisms.…”