Coconut husk and processing effects on chemical and physical properties of coconut coir dust

Chemical properties of unprocessed coconut (Cocos nucifera L.) husks varied significantly among 11 sources tested. The pH and electrical conductivities were significantly different among husk sources and ranged from 5.9 to 6.9 and 1.2 to 2.8 mS.cm(-1), respectively. The NH4+, NO3-, Ca, and Mg levels did not differ significantly among hush sources and ranged from 0.2 to 1.8, 0.2 to 0.9, 2.9 to 7.3, and nondetectable to 4.6 mg.kg(-1) respectively. Le, els of P, B, Cu, Fe, Ni, S, Zn, Mn, and Mo were all significantly different among husk sources and ranged from nondetectable levels to 33 ppm. The levels of Na. K, and Cl were significantly different among husk sources and ranged from 23 to 88, 126 to 236, and 304 to 704 ppm, respectively. Coir dust (CD) produced by screening of waste-grade coir through 3-, 6-, or 13-mm mesh screens had significantly different fiber content, bulk densities, total solids, total pore space, air-filled pore space, water-filled pore space, and water-holding capacities as compared with nonscreened waste-grade coir. However, screen size did not significantly affect the physical properties of CD, Neither compression pressure nor moisture level during compression of CD blocks significantly affected rehydration of compressed CD or physical properties of rehydrated CD.