Three reactors, ordinary, greenhouse, and solar, were constructed and tested to compare their impacts on
the composting of municipal sewage sludge. Greenhouse and solar reactors were designed to evaluate the
use of solar energy in sludge composting, including their effects on temperature and compost quality.
After 40 days of composting, it was found that the solar reactor could provide more stable heat for the
composting process. The average temperature of the solar reactor was higher than that of the other
two systems, and only the solar reactor could maintain the temperature above 55 C for more than 3 days.
Composting with the solar reactor resulted in 31.3% decrease in the total organic carbon, increased the
germination index to 91%, decreased the total nitrogen loss, and produced a good effect on pot
experiments.