Influence of hydraulic and organic load on the anaerobic-aerobic dairy wastewater treatment characteristics

Abstract

The performance of the anaerobic-aerobic sequencing labscale reactors for the treatment of a milk processing wastewater was studied. The wastewater flow rate was varied from 78.0 to 149.0 ml•h-1 and organic matter content from 3.8 to 6.8 g COD∙dm-3. This corresponded to the change of dilution rate from 0.4 to 0.8 day-1 and organic loading rate from 1.4 to 2.8 g COD•dm-3•day-1. An increase of hydraulic load reduced the treatment efficiency at the first anaerobic stage from 44.4 to 29.7%, but it was compensated at the aerobic treatment stage. Increasing the organic loading rate improved the treatment efficiency at the anaerobic stage from 44.4 to 54.2%. It was shown that spatial separation of anaerobic stage onto two phases increases the treatment efficiency in anaerobic stage and in whole (85.8 and 98.7%) in comparison to non-separation mode (45.5 and 73.9%, respectively). The correlation analysis of the organic loading rate L, organic consumption rate P and dilution rate D on the treatment efficiency E allowed to obtain the equations can be used for mathematical optimization of the process.