Evaluation of dairy processing wastewater biotreatment in an IASBR system: Aeration rate impacts on performance and microbial ecology

Highlights

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  Dairy processing wastewater biotreatment using IASBR technology is proposed.

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  Minor (0.2 LPM) aeration rate variations heavily influenced efficiency and ecology.

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  Optimal nutrient removal efficiencies (≥92%) achieved under 0.6LPM aeration rate.

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  Comamonadaceae stably enriched in reactor biomass (>80% relative abundance).

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  Comamonadaceae top contributor of nitrogen and phosphorus assimilation genes.

Abstract

Dairy processing generates large volumes of wastewater that require extensive nutrient remediation prior to discharge. Significant commercial opportunities exist therefore for cost-effective biotechnologies capable of achieving this requirement. In this study the authors evaluated the use of intermittently aerated sequencing batch reactors, (IASBRs), as a single-tank biotreatment system for co-removal of COD, nitrogen and phosphorus from synthetic dairy processing wastewater. Variation of the IASBR aeration rates, (0.8, 0.6 and 0.4 L/min), had significant impacts on the respective nutrient removal efficiencies and underlying microbial diversity profiles. Aeration at 0.6 L/min was most effective and resulted in >90% co-removal of orthophosphate and ammonium. 16S rRNA based pyrosequencing of biomass DNA samples revealed the family Comamonadaceae was notably enriched (>80% relative abundance) under these conditions. In silico predictive metabolic modelling also identified Comamonadaceae as the major contributor of several known genes for nitrogen and phosphorus assimilation ( nirK, nosZ, norB, ppK, ppX and phbC).