Inhibitory Effects of Organic Acids on Bacteria Growth During Food Waste Composting

During the process of food waste composting, organic acids are generated from microbial breakdown of easily degradable substrates. These organic acids could inhibit microbial activities and sequentially reduce the decomposition efficiency. Considerable relationships among pH, organic-acid concentration and microbial activity were observed in this study. In order to systematically investigate inhibitory effects of four organic acids on composting bacteria, multivariate experimental designs were implemented in day 5 and day 9 during the initial stage of composting. Butyric and propionic acids had significant inhibitory effects on the growth of thermophilic bacteria on day 5. The inhibitory effects of organic acids on composting bacteria became significantly milder on day 9. The effects of different pH control amendments to mitigate microbial inhibition were also preliminarily examined. The treatment of NaAc resulted in the largest population of thermophilic bacteria.