Performance Optimisation of a Modular Rice Milling System for Rural Agro-Processing Centres in Ebonyi State

This study optimises the performance of a modular rice milling system designed for rural agro-processing centres in Ebonyi State, South East Nigeria. Ebonyi State is one of Nigeria's leading rice-producing states, but the majority of paddy rice is milled at urban facilities, imposing high transportation costs on farmers and reducing miller capacity utilisation. Modular rural rice milling systems that can be configured from standardised component units offer a potentially more cost-effective alternative for rural milling centres. This study assembles and evaluates a modular milling system comprising a de-stoner, rubber roll husker, aspirator, and friction whitener in a pilot rice milling centre at Afikpo, and optimises key operating parameters including husker roll gap, whitener operating pressure, and throughput rate for maximum head rice recovery. Response surface methodology with a central composite design investigates parameter interactions. Head rice recovery, degree of milling, whiteness index, milled rice colour, and specific energy consumption are assessed at each design point. Findings reveal that head rice recovery is maximised at 72.4 percent using an optimised combination of 1.0 millimetre roll gap, 1.2 kilograms per centimetre squared whitener pressure, and 800 kilogram per hour throughput rate. Specific energy consumption at the optimal point is 38 kilowatt-hours per tonne of paddy, competitive with urban mill performance. The modular system investment cost is estimated at 4.2 million naira for a 1-tonne per hour capacity. The study recommends the optimised modular milling system for rural processing centre development in Ebonyi State.

Keywords: rice milling, modular system, head rice recovery, Ebonyi State, agro-processing.