Application of Rice Husk as Water Treatment Agent and Soil Conditioner

Aims: Rice husk was chemically treated to be used as bio sorbent for removal of humic substances from peat swamp runoff. The spent bio sorbent was then applied as soil conditioner for enhancing plant growth.
Study Design: Randomized Complete Block Design.
Place and Duration of Study: Universiti Malaysia Sarawak, between September 2012 and August 2013.
Methodology: Rice husk was chemically treated with sodium hydroxide and citric acid. The treated rice husk was subjected to peat swamp leachate to absorb humic substances. It was then applied to grow Brassica juncea var. rugosa L. in six different treatments, each with six replicates, using Randomized Complete Block Design.
Results: Fourier Transform Infrared spectra of rice husk were characterized by major absorption bands attributable to lignocellulosic compounds. The treatment process primarily removed lignin and hemicellulose increasing the binding sites for adsorption. An average of 60-70% of humic content was removed from peat swamp runoff, determined based on the absorbance at 465 nm. The humic-loaded biosorbent was applied to grow Brassica juncearugosa L. under six different treatments to examine its effectiveness in enhancing plant growth. These include planting media only (sand and topsoil at a ratio of 3:2), [planting media + fertilizer], [planting media + humic-modified rice husk + fertilizer], [planting media + modified rice husk + fertilizer], [planting media + raw rice husk], [planting media + raw rice husk + fertilizer]. Results showed that plants grown in humic-loaded modified rice husk in combination with fertilizer exhibited significant growth improvement followed by those grown in raw rice husk and fertilizer. Others were relatively less promising suggesting that humic fortified biomass may function as soil conditioner in improving nutrient uptake.
Conclusion: The application of rice husk for water treatment and agriculture is an economically sustainable and environmental friendly approach.