Dominance of the genus Polaromonas in the microbial ecology of an Intermittently Aerated Sequencing Batch Reactor (IASBR) treating dairy processing wastewater under varying aeration rates.

In this Research Communication we investigate potential correlations between key bacterial groups and nutrient removal efficiency in an Intermittently Aerated Sequencing Batch Reactor (IASBR) treating synthetic dairy processing wastewater. Reactor aeration rates of 0·6 and 0·4 litre per minute (LPM) were applied to an 8 l laboratory scale system and the relative impacts on IASBR microbial community structure and orthophosphate (PO4-P) and ammonium (NH4-N) removal efficiencies compared. Aeration at 0·6 LPM over several sludge retention times (SRTs) resulted in approximately 92% removal efficiencies for both PO4-P and NH4-N. Biomass samples subjected to next-generation sequencing (NGS), 16S rRNA profiling revealed a concomitant enrichment of Polaromonas under 0·6 LPM conditions, up to ~50% relative abundance within the reactor biomass. The subsequent shift in reactor aeration to 0·4 LPM, over a period of 3 SRTs, resulted in markedly reduced nutrient removal efficiencies for PO4-P (50%) and NH4-N (45%). An 85·7% reduction in the genus level relative abundance of Polaromonas was observed under 0·4 LPM aeration conditions over the same period.

DairyWater: striving for sustainability within the dairy processing industry in the Republic of Ireland.

This Review describes the objectives and methodology of the DairyWater project as it aims to aid the Irish dairy processing industry in achieving sustainability as it expands. With the abolition of European milk quotas in March 2015, the Republic of Ireland saw a surge in milk production. The DairyWater project was established in anticipation of this expansion of the Irish dairy sector in order to develop innovative solutions for the efficient management of water consumption, wastewater treatment and the resulting energy use within the country's dairy processing industry. Therefore, the project can be divided into three main thematic areas: dairy wastewater treatment technologies and microbial analysis, water re-use and rainwater harvesting and environmental assessment. In order to ensure the project remains as relevant as possible to the industry, a project advisory board containing key industry stakeholders has been established. To date, a number of large scale studies, using data obtained directly from the Irish dairy industry, have been performed. Additionally, pilot-scale wastewater treatment (intermittently aerated sequencing batch reactor) and tertiary treatment (flow-through pulsed ultraviolet system) technologies have been demonstrated within the project. Further details on selected aspects of the project are discussed in greater detail in the subsequent cluster of research communications.

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

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).