# Optimization of Dissolved Air Flotation in the Treatment of Coffee Processing Wastewater Using Calcium Chloride

## TL;DR

This study shows that using calcium chloride improves dissolved air flotation for treating coffee wastewater, reducing turbidity and organic matter more effectively.

## Contribution

The study introduces calcium chloride as an effective clarifier and optimizes DAF parameters for coffee processing wastewater treatment.

## Key findings

- Using CaCl2 achieved 65% turbidity and 70% UV254 removal in coffee wastewater treatment.
- Optimal DAF conditions with CaCl2 included 5 bar pressure, 80% recirculation, and 30 min flotation time.
- Without CaCl2, flotation time increased to 36 min for similar performance.

## Abstract

Coffee processing
wastewater (CPW) is characterized by
a high organic
load, low pH, and elevated solids, and its improper disposal can cause
severe environmental impacts. Coagulation-flocculation followed by
dissolved air flotation (DAF) has proven effective for CPW treatment.
This study evaluated CaCl2 as a clarifier and the optimization
of DAF operational parameters using a central composite rotational
design. With CaCl2, removals of 65% turbidity and 70% UV254 were achieved, while treatment without the salt reached
only 40% turbidity and no significant UV254 reduction.
The optimal conditions with CaCl2 were a 5 bar saturation
pressure, an 80% recirculation ratio, and a 30 min flotation time;
without salt, similar pressures and recirculation ratios were obtained,
but the flotation time increased to 36 min. These findings highlight
the role of CaCl2 in enhancing the DAF performance for
CPW treatment.