Table 11 Simple cost analysis for laboratory scale produced RAAC

Sample collection

80 ETB, half-day work for one labour worker

Raw material drying

0, used sun-dried Rumex abyssinicus

Size reduction

2.29 ETB, KWh = 1.223 ETB, the grinding machine utilizes 0.75 KWh per hour, takes 0.5 to 3 min to grind 50 g of the Rumex abyssinicus, 780 g of Rumex abyssinicus end up with 314 g of activated carbon, which means 2.5 kg of the raw material was required to produce 1 kg of activated carbon, 2.5 h was used to finish grinding the RM, that means (0.75 KWh * 2.5 h)/h = 1.875 KWh * 1.223ETB = 2.29ETB

Chemical activation

Cost of 88% phosphoric acid in Ethiopia per liter is 800ETB, diluted to 50% phosphoric acid solution for application due to high moisture uptake of the raw material, the specific gravity of 50% phosphoric acid = 1.334 kg/L and 600 ETB used per kg. Hence, to impregnate 2.5 kg of raw Rumex abyssinicus sample needed 2.5 kg * 3 * 600 ETB = 4500ETB

Thermal activation

Furnace energy consumption 26 KWh per day, for 2 h of activation 2.167 KWh * 1.223ETB/KWh = 2.65 ETB

Neutralization

Distilled water was used for neutralization, approximately 10 ETB

Drying of activated carbon

0.75 KWh/h * 8 * 1.23 ETB = 7.38 ETB