Coffee Wastewater Solution

Coffee wastewater solution

There are two different methods which can be used to process the coffee cherries: the dry mill and the wet mill. The water use at the wet mills is diverse in both quantity and purpose.

30% of the water is utilized for the de‐pulping process and 70% for the washing of the fermented grains. From this 70%, 20% is used for eliminating the decomposed mucilage and the remaining 50% is very clean wastewater that is used to finish cleaning and selecting the grains.

Coffee wastewater contains large concentrations of sugars, cellulose, caffeine and pectic substances.
Coffee Cherry
Water de-pulping Water from washing
Proteines  8.9% Pectic substances  23.4%
Tannins  10.0% Sugars  54.2%
Chlorogenic acid  14.5% Cellulose  20.4%
Caffeine  22.0%    
Sugars  45.3%    
Table 1. Characterization of coffee wastewater
Parameter Total average (mg/L) De‐pulping water (mg/L) Water from washing (mg/L)
Total suspended solids 7 000 – 10 900 13 200 2 900
pH 4-5 4-5 4-5
BOD5 10000-13000 1000-9000 1000-4000
COD 18000-23000 2000-14000 850-10000

The effluent from the unit was being treated in the Effluent Treatment Plant (ETP) and the discharge was being gardening towards water conservation, As corporate policy there was a requirement to reduce effluent loads through wastewater recovery for recycle/reuse.

Parameters Unit Effluent (Input to RO) Permeate (RO Output)
Flow (recovery rate 66%) cum/day 500 330
pH - 6.8-7.2 6.5
Total Dissolved Solids ppm 800-1000 100
Chemical Oxygen Demand ppm 220 10
Biochemical Oxygen Demand ppm 80 -
Silica ppm 10 <1
Total Suspended Solids ppm 100 0
Chlorides ppm 70 <10
Sulphates ppm <50 <10