029: Air Nanobubbles in Dairy Processing Wastewater Treatment: Improving Effluent Treatment Efficiency

Introduction

Dairy wastewater consists of milk components such as protein, fat, lactose, and minerals contributing to high biochemical and chemical oxygen demands. Current treatment methods are lengthy, energy-intensive, utilize chemicals, and have inefficiencies in their processes. Therefore, this study aims to investigate the effectiveness of air nanobubbles as a novel and sustainable solution for enhancing the treatment efficiency of dairy wastewater and reducing its environmental impact.

Methods

Air nanobubbles were generated in model dairy wastewater (MDW) and composite dairy industry wastewater (DW) samples using hydrodynamic cavitation for a duration of 10 minutes in both streams. Various physicochemical parameters including dissolved oxygen, redox potential, and conductivity were monitored along with total suspended and dissolved solids, biochemical and chemical oxygen demand for samples with (NB) and without nanobubbles (control).

Results

NB treatment led to a marked increase (p < 0.05) in dissolved oxygen levels, while redox potential decreased significantly (p < 0.05) in both MDW and DW compared to the control samples. Furthermore, enhanced dissolved oxygen levels led to a 10.6% and 5.77%, reduction in biochemical oxygen demand, and the chemical oxygen demand for nanobubble-treated DW samples (p < 0.05), compared to untreated dairy wastewater samples. Also, a 16.6% and 7.2% reduction in total suspended solids (TSS) and turbidity respectively was found with NB treatment for both MDW and DW samples (p < 0.05). Scaling up the nanobubble technology to an industrial wastewater treatment plant for a cheese and whey powder manufacturing company showed similar promising results, with higher dissolved oxygen and lower TSS for NB-treated wastewater samples.

Significance

Overall, these findings suggest that air nanobubbles can substantially enhance the efficacy of dairy wastewater treatment by increasing the oxidation rates and decreasing total suspended solids in the waste streams to improve the effluent discharge quality from dairy processing plants. This paves the way for NB technology to be used in dairy processing wastewater treatment effectively and can potentially replace or supplement traditional aeration systems.

Authors: Fnu Akshit, Shafeeqa Irfan, Muhammed Shijas Vallikkadan, and Maneesha S. Mohan