Coffee processing wastewater treatment: a critical review on current treatment technologies with a proposed alternative

Coffee is globally the second largest most traded commodity after petroleum, and this has facilitated many countries to grow and produce coffee in commercial quantity. The production processes uses large volume of water which comes out as contaminated water. The presence of toxic chemicals like tannins, phenolic and alkaloids inhibits biological degradation. Microbial processes break down the organic substances released into water bodies slowly, using up the oxygen from the water (COD). As demand for oxygen needed to break down organic waste in a wastewater begins to exceed supply, a decrease in oxygen needed to combine with chemicals (COD) slowly creates anaerobic condition. The review looks at few of the current methods (physicochemical and biological) used in coffee wastewater management, their advantages and disadvantages including, high cost implication, complex operation and more time consumption among others; furthermore, the review suggests ion exchange technique as a better alternative based on its capacity to act as both an ion exchanger and absorber.