Experimental Data-Based Modeling and Techno-Economic Assessment of Scaling-Up ZnCl2-Activated Carbon Columns Derived from Spent Coffee Grounds for Herbicide Removal in Water Treatment Plants

Herbicides such as bentazon, diuron, and linuron are chemical compounds widely used in agriculture. This study uses previously published experimental adsorption data for bentazon, diuron, and linuron to inform process modeling and presents an industrial-scale application of ZnCl2-activated carbon derived from spent coffee grounds. The results showed that the herbicide properties varied linearly with increasing temperature, except for linuron. The adsorbent reached saturation after approximately 1250 s. Regeneration cycles were 5 for bentazon and diuron, and 5 for linuron. The simulated design considered eight parallel adsorption-bed systems for a nominal population of 100,000 inhabitants. The techno-economic assessment indicates an estimated annualized cost of US$ 1.300 million for the proposed tertiary adsorption system, including annualized capital and operating expenditures, a value within the range of conventional project designs that promote a circular economy for spent coffee grounds. The scale-up and economic results are preliminary and remain subject to uncertainties in adsorption capacity, breakthrough behavior, and adsorbent regeneration.