A NOVEL BIOREACTOR SIMULATING COMPOSTING OF MUNICIPAL SOLID-WASTE

A bioreactor (19L) was developed to simulate municipal solid waste com posting. The purpose of the reactor was to provide a test system for e valuating physical changes in newly developed materials that may enter the portion of the waste stream being composted. To minimize variatio n in feed stock, the bioreactor utilized a defined waste mixture consi sting of rabbit chow with alfalfa and shredded newspaper inoculated wi th a 1:1:1 mixture of leaf compost, garden soil, and cow manure. Durin g the first 24 h, the mixture self-heated from 37-degrees-C to 58-degr ees-C. Scanning electron micrographs showed that populations of Bacill us-like bacteria dominated the composting mass. Enzyme activity, total bacterial CFU per gram dry weight, acridine orange direct microscopic counts of bacteria, and cellulose mineralization rates increased init ially and remained high throughout a 28 day incubation period. After 2 8 days, volatile solids had decreased from 88 to 77% of the dry weight , and carbon:nitrogen ratios had decreased from 35 to 14. It was concl uded that under moist, aerobic conditions, simulated solid waste can u ndergo changes comparable to those reported for municipal solid waste in full-scale composting systems. Thus, the reactor is appropriate for testing the fate of potentially compostable materials.