Industrial processing of rice husk for environment, energy and economy

Department of Chemical Technology, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata-700 009, India

E-mail : rabin.majumdar@gmail.com, ryte2biswa@rediffmail.com,

              mailid_sm @yahoo.com, pijush_mandal @yahoo.co.in

Manuscript received 6 July 2007, accepted 19 September 2007

An approach for comprehensive and efficient utilization of Rice Husk (RH) integrating the three E's - Environment, Energy and Economy has been outlined based on experimental information. RH can be thermally processed for co-production of metal-impregnated or chemically modified active solid silica-carbon composites with simultaneous recovery of liquid and gaseous by-products accounting for about 80-90% of the biomass with minimum addition to environmental pollution.

The active and amorphous silica-carbon composite solid can be used in systems for removing waterborne and airborne toxic substances like phenol, hexavalent chromium, fluoride and arsenic in water and vapours of acetone, chloroform, benzene and pyridine. Liquid condensate collected during processing is a rich source of various useful organic chemicals. The third bulk co-product, a combustible gas of low calorific value, can supplement the energy requirements of the process.

The spent silicarbons, after use in pollution abatement systems may be suitably formulated and melted into stable glass thus solving one of the major problems of ultimate disposal of toxic-loaded solid wastes generated.

Small industries handling ~60 MT RH annually appear to he just viable. As ancillaries to rice mills they arc likely to prove handsomely rewarding. Projected estimates further indicate that industrial processing in the suggested mode, of only 10% of India's annual RH biomass (~4 Million Metric Tons), has the potential of generating ~200000 employments in ~66000 small decentralised units. The estimated capital investment is in the order of Rs. 6600 crores.