Characterization of Local Mill Rice Husk Charcoal and Its Effect on Compost Properties

Theeba, Scientist and biochar researcher at MARDI, has previously provided access to the following research paper on Rice Husk Char. I am re-posting this final version for submission to the IBI bibliography. The RHC was not assessed under IBI product certification guidelines but it does appear to meet the "Test Category A - Basic Utility Properties" for Class 3 biochar. The product has a long history of local use as cost effective growing medium. A search on this website for 'rice' will provide links to many previous posts related to the subject of RHC.

The commercialisation of compost products based around this research is under investigation by MARDI.

Abstract

"Rice Husk Charcoal (RHC) is a by-product of rice processing mills which can be found in very large quantities in these mills. This industrial waste is largely unutilized, causing environmental pollution especially in the state of Kelantan. In order to increase its utilization, RHC was characterized and investigated for its potential in enhancing the composting process. Physico-chemical properties of RHC such as pH, nutrient content, ash content, CEC, adsorption kinetics, surface area, functional groups, surface structure and pore sizes were studied. The composting treatments were carried out by mixing 4% (wt/wt) and 6% (wt/wt) RHC with organic substrates and with no RHC amended as control. Parameters such as daily temperature, CO fux, nutrient content, pH, moisture and total microbial count were measured during the composting process. Results showed that RHC is a highly alkaline material (pH 8.9) with a carbon content of 16% (wt/wt dry basis), CEC of 17cmol kg-1 soil, BET surface area of 401 mg g-1 and a methylene blue adsorption capacity of 38.8 mg g-1. The presence of C=O carboxyl-C, ketones and ester, aliphatic C=H, C=C benzene ring and C-H aromatic hydrogen suggests that RHC mainly comprises amorphous char, a random mixture of thermally altered molecules and aromatic polycondensates.The addition of RHC to organic matter accelerated the composting process through higher decomposition rates due to higher microbial population at the thermophilic stage with RHC acting as a bulking agent, as well as higher moisture and nutrient retention during composting. N losses were found to be lower with RHC composting
Rice Husk Charcoal (RHC) is a by-product of rice processing mills which can be found in very large quantities in these mills. This industrial waste is largely unutilized, causing environmental pollution especially in the state of Kelantan. In order to increase its utilization, RHC was characterized and investigated for its potential in enhancing the composting process. Physico-chemical properties of RHC such as pH, nutrient content, ash content, CEC, adsorption kinetics, surface area, functional groups, surface structure and pore sizes were studied. The composting treatments were carried out by mixing 4% (wt/wt) and 6% (wt/wt) RHC with organic substrates and with no RHC amended as control. Parameters such as daily temperature, CO fux, nutrient content, pH, moisture and total microbial count were measured during the composting process. Results showed that RHC is a highly alkaline material (pH 8.9) with a carbon content of 16% (wt/wt dry basis), CEC of 17cmol kg-1 soil, BET surface area of 401 mg g-1 and a methylene blue adsorption capacity of 38.8 mg g-1. The presence of C=O carboxyl-C, ketones and ester, aliphatic C=H, C=C benzene ring and C-H aromatic hydrogen suggests that RHC mainly comprises amorphous char, a random mixture of thermally altered molecules and aromatic polycondensates.The addition of RHC to organic matter accelerated the composting process through higher decomposition rates due to higher microbial population at the thermophilic stage with RHC acting as a bulking agent, as well as higher moisture and nutrient retention during composting. N losses were found to be lower with RHC composting."

https://www.dropbox.com/s/4y0ycvbzqpo6w6b/Theeba.pdf