Production of Organic Acids from Kitchen Wastes

Abstract

This study involves (he production of short-chain organic acids from kitchen wastes as intermediates for the production of biodegradable plastics. Flasks, without mixing were used for the anaerobic conversion of the organic fraction of kitchen wastes into short-chain organic acids. The influence of pH, temperature and addition of sludge cake on the rate of organic acids production and yield were evaluated. Fermentations were carried out in an incubator at different temperatures controlled at 30°C, 40°C, 50°C, 60°C and uncontrolled at room temperature The pH was also varied at pH 5, 6. 7, and uncontrolled pH. 1.0 M phosphate buffer was used for pH control, and 1.0 M HCl and I 0 M NaOH were added when necessary. Sludge cake addition enhanced the rate of maximum acids production from 4 days to 1 day. The organic acids produced were maximum at pH 7 and 50°C i.e., 39.84 g/1 on the fourth day of fermentation with a yield of 0.87 g/g soluble COD consumed, and 0.84 g/g TVS. The main organic acid produced was lactic acid (65-85%), with small amounts of acetic (10-30%). propionic (5-10%). and butyric (5-20%) acids. The results of this study showed that kitchen wastes could be fermented to high concentration of organic acids, which could be used as substrates for the production of biodegradable plastics.

Key Words:

• Organic acids
• temperature. pH
• sludge cake

Additional information

Notes on contributors

C. W Loh

Joyce Laing works in the Department of Child and Family Psychiatry, Playfield House, Cupar, Fife, and is a Consultant Art Therapist to Psychiatric Hospitals and Prisons and Chairwoman of the Scottish Society of Art and Psychology.