Treatment of dairy products processing industrial wastewater by Electro-Coagulation-Flotation (ECF) process
25 December 2016
Background and aims: Dairy industry is one of the important sources of environmental pollution. The present
study set out to investigate the removal percentages of COD and turbidity, as well as changes in the effluent pH by
Electro-Coagulation Flotation (ECF) process during the treatment of dairy effluents.
Materials and methods: Electrochemical coagulation process was applied to treatment of pre-treated highly loaded
real wastewater of a factory producing dairy products in Damavand-Tehran. The experiments were carried out
in an electrochemical cylinder-shaped reactor made of steel (cathode electrode) and aluminum (anode electrode)
connected to each other in a Bipolar-serial (BP-S) way. The influence of initial pH, current intensity, electrolysis
time, and initial electrolyte (NaCl) concentration on the performance of ECF was explored. Owing to the nature of
the study, there were not ethical issues.
Results: The findings revealed that the bulk liquid pH, current intensity and electrolysis time had a considerable
influence on the performance of the reactor. The obtained optimal values were 9, 3 A, and 60 min, respectively. Under
optimal condition, the efficiency of COD and turbidity removal were estimated at 70.9% and 99.08%, respectively.
It was also found that the reactor effluent pH increased by 1.6 units. Moreover, electrical conductivity of solution
did not affect the pollutant removal efficiency in this study. Sludge volume index (SVI) was further estimated to be
Conclusions: The results of the present study indicate that the ECF coupled process can be regarded as an
environment-friendly method in the pre-treatment of dairy effluents. In addition, considering the increase of BOD5/
COD ratio from 0.41 (raw wastewater) to 0.79 (effluent), electrochemical treatment was conceived to enhance the
biodegradability for a biological post-treatment.
Keywords: Dairy wastewater, electro-coagulation flotation, COD, turbidity