Study the factors influencing coir pith drying

Abstract

Coir pith is considered an excellent growing medium due to its water retention capacity, pH and high mineral concentration and therefore, it has a good demand in the horticulture industry. Sri Lanka currently utilizes solar and flash drying to reduce the moisture content of raw coir pith. Quality of the dried coir pith was found to be significantly affected due to the drawbacks in the current drying methods. This study was carried out to identify suitable conditions for coir pith drying, specially the drying temperature. Results indicated that coir pith sample dried at 150°C had the highest water retention capacity of 7.96 (w/w) but, it showed relatively low volume expansion ratio of 2.6 (mm/mm). Volume expansion ratio could be improved up to 3.35 by mixing equal amounts of flash dried and raw coir but, it had the lowest water retention capacity of 7.16 (w/w). Drying at 200 °C gave relatively high volume expansion and water etention capacity compared to drying at other temperatures. This study further revealed that both the volume expansion and the water retention capacities of coir pith bricks had gradually reduced with time.