Affiliations: Chinese Research Academy of Environmental Sciences,
Beijing 100012, China | EVSE-Faculty of Engineering, University of Regina,
Regina, Sask. S4S 0A2, Canada
Abstract: Bio-surfactant is a new type of surfactant that is produced in
microbial metabolism. Adding bio-surfactant during composting process,
especially to those contain some toxic substances, has been proved to be a
promising way. In this study, Strains III (2), a bacterial with high activity
to produce bio-surfactant, were isolated firstly. Following comparison
experiments with and without adding Strains III (2), namely Run 1 and Run R,
were conducted, respectively. The experimental results showed that, by adding
Strains III (2), the surface tension could reduce from 46.5 mN/m to 39.8 mN/m
and the corresponding time to maintain the surface tension under 50 mN/m could
prolong from 60 h to 90 h. The oxygen uptake rate and total accumulated oxygen
consumption with Stains III (2) were both higher than those without Strains III
(2), while the accumulation of H_2S in outlet gas was
reduced to around 50% of Run R. Moreover, two additional experiments were also
carried out to examine the effects of strains coming from different systems.
One is adding Strains III (2) with a dose of 0.4% (Run 2), and the other is
seedling commercial Strains at the same conditions, the composting experiments
showed that: Run 2 was more effective than Run 3, because the commercial
Strains can be suppressed significantly in a complex composting system with
different pH, high temperature and some of metals. The bio-surfactant was also
added into the solid waste, which contained some toxic substances, the
corresponding results showed that the remove rate of Hg and sodium
pentachlorophenolate (PCP-Na) could be improved highly. Thus, the
microenvironment, reactionrate and composting quality could be enhanced
effectively by adding bio-surfactant to the composting process.
Keywords: municipal solid waste, composting, bio-surfactant, composting quality
