The solids from the digesters are dried in sludge beds (Figure 1) for about six months. After drying, the sludge is mixed into compost piles (Figure 2) with shrub clippings from Arcata City parks and with Marsh Pennywort that is harvested from the enhancement marshes. The heat in the piles, generated from the microbial degradation, eliminates most remaining pathogens. The compost is spread as fertilizer in city parks.
This page will be expanded by Fall 2008 semester Engineering 115 students.