A research project in NUI Galway is efficiently and effectively treating wastewater effluent from dairy processors using biological, nanomaterial-based and disinfection techniques, writes Dr William Finnegan
Chem

 

Author: Dr William Finnegan, College of Engineering & Informatics and the Ryan Institute, NUI Galway

The abolishment of milk quotas in 2015 is expected to result in a 50% increase in milk production in Ireland by 2020. This increase in the volume of milk being processed, along with stringent measures on emissions from the industry and growing commercial drive for operational efficiencies, is driving the need for innovative technological and operational solutions within the dairy processing industry.

In this context DairyWater, a new multi-stakeholder research project, is developing innovative solutions for the efficient management of water consumption, wastewater treatment and the resulting energy use within the country’s dairy-processing industry. This project has the potential to position Ireland at the forefront of European, or indeed international, research in this sector.

It strives to make the Irish dairy-processing industry more efficient and environmentally sustainable by reducing carbon footprints, energy and water use. This will, in turn, stimulate job creation and lead to greater potential for exports and increased international competitiveness for Irish products.

DairyWater is led by Prof Xinmin Zhan from the Department of Civil Engineering at the College of Engineering and Informatics and the Ryan Institute at the National University of Ireland Galway (NUI Galway). The project also involves leading research groups at University College Cork (UCC), Trinity College Dublin, Athlone Institute of Technology and Teagasc.

New Picture

NUI Galway DairyWater research team (l-r): Dr Eoghan Clifford, Dr William Finnegan, Emma Tarpey, Kelly Fitzhenry, Dr Jamie Goggins and Prof Xinmin Zhan

The primary goal of the study is to efficiently and effectively treat wastewater effluent from dairy-processing plants using a range of innovative biological, nanometerial-based and disinfection technologies. In parallel, the efficient use of water (and resulting energy costs) within the plants is also being explored. The four-year project has received €1 million funding from the Department of Agriculture, Food and the Marine (further details can be found at: www.dairywater.ie).

Ireland’s dairy industry


Milk production in Europe

Ireland is one of Europe’s largest producers of cow’s milk, with an annual production of over 5,500 million litres. Currently, dairy ingredients and products comprise almost 30% of the Irish food and drink export market and, in 2013, dairy ingredients and products surpassed €3 billion for the first time. This export market is expected to increase due to the abolition of milk quotas and increasing international food demands.

In 2009, the average electrical and thermal energy demand was reported to be 451.9 and 2364 kWh/tonne of product and average water consumption was 14.9 m3/tonne of product within the Irish dairy-processing industry. So, for example, a 400g block of cheese has an energy demand of approximately 0.33 kWh, which is the equivalent of leaving a 40-watt bulb on for approximately eight hours. Similarly, a pound of butter (454g) has an energy demand of approximately 0.165 kWh, which is the equivalent of leaving a 40-watt bulb on for over four hours.

In Australia, 1.5 litres of fresh water is used for every litre of milk processed, while in Ireland, water consumption is approximately 66% higher than this, which indicates that there is plenty of scope for improving the efficient use of water within this sector. Energy and water use, along with water consumption, greatly influence the growth and competitiveness of this industry and will need to be reduced over the coming years.

The project can be divided into three main research areas:

  1. Dairy wastewater treatment technologies;
  2. Water re-use and rainwater harvesting; and
  3. Environmental life-cycle assessment (LCA).
  • Dairy wastewater treatment technologies

One of the most central aspects of the project is the development of novel technologies for the treatment of dairy wastewaters. When dealing with wastewater from dairy processing plants, the most problematic nutrients are nitrogen and phosphorous. The intermittently aerated sequencing batch reactor (IASBR) technology, which was developed at NUI Galway, will be investigated as previous studies dealing with pig-production facilities have shown it has the potential provide an economical solution for nutrient removal.

Initially, laboratory-scale experiments will be performed in order to determine the effectiveness of the technology in the dairy-processing sector. Following this, a pilot-scale onsite system will be constructed at a selected dairy-processing plant. This will give a greater insight into the performance of the IASBR technology at a more commercial scale.

The shift of the microbial ecological structure in laboratory-scale and pilot-scale IASBRs will be determined through molecular microbial ecology studies performed at the UCC Environmental Research Institute, using advanced pyrosequencing techniques. This will aid in the development of bioreactor sampling regimes to obtain representative samples from established reactors and establishment of relevant sample storage and processing protocols. Additionally, this will give a greater understanding of the unique nutrient removal mechanisms of the IASBR technology, which will aid in significant increases of efficiencies in reactor design and operation, improve nutrient removal rates while decreasing costs and energy usage.

The use of nano-materials to improve the efficiency of wastewater treatment processes in this sector has not previously been well explored. DairyWater, at the Centre for Research on Adaptive Nanostructures and Nano-devices (CRANN) in Trinity College Dublin, will develop novel and low cost nano-materials that can greatly enhance treatment performance while reducing energy and operational costs.

With the application of nano-materials within many engineering sectors, this could be one of the major leaps in the development of new and innovative engineered systems in the water and wastewater sectors. The effectiveness of the nano-material technology will be evaluated in both laboratory-scale reactors and full-scale systems.

New Picture

Arrabawn dairy-processing facility wastewater treatment plant, Nenagh, Co Tipperary

  • Water re-use and rainwater harvesting

Along with the effective treatment of dairy wastewaters, a study into the efficient use of water within dairy-processing plants is also being addressed within the project. This aspect will also include assessing the feasibility of utilising rainwater harvesting systems within the plants. In consultation with the advisory board, the existing and future challenges of industry are established.

Laboratory-scale systems will be investigated and will initially comprise filtration technologies, pathogen removal technologies and barrier-type systems. The pathogen removal technologies are innovative pulsed UV systems, developed by Athlone IT and NUI Galway, which are designed to perform secondary treatment of the dairy wastewaters. The innovative technologies explored will be trialled at both laboratory-scale and at a demonstration site to accurately quantify their effectiveness.

  • Environmental life-cycle assessment

Using the data obtained from the various dairy-processing plants, an environmental life-cycle assessment of dairy products manufactured within Ireland will be performed. This will methodically assess the industry from a lifecycle water usage, energy usage and greenhouse gas-emissions perspective. Along with performing an assessment of Irish dairy products, an assessment of individual plants and the potential positive impact of novel technologies investigated in this project will be carried out. From these analyses, the true carbon footprint of dairy products from the greenhouse gas emission perspective can be estimated, which takes into account the global warming potentials (GWPs) of various greenhouse gases.

Industry stakeholders


The project team is working closely with leading industry stakeholders. A project advisory board includes leading members of the dairy processing industry (Arrabawn, Aurivo, Carbery, Dairygold, Glanbia and Lakeland) and Government-funded bodies (Enterprise Ireland, the Environmental Protection Agency and Teagasc). The industry partners will provide data and facilitate pilot-scale activities during the project; thus enabling potential commercial benefits of this research to be realised.

DairyWater has the potential to position Ireland at the forefront of European, or indeed international, research in this sector. The project strives to make the Irish dairy processing industry more efficient and environmentally sustainable, which will lead to greater potential for exports and increased international competitiveness for Irish products, along with stimulating job creation.

For further details and to follow the progress of the project, log onto the DairyWater website or follow the project on twitter: @dairywater.

WilliamFinneganDr William Finnegan BE (Civil) PhD MIEI is a post-doctoral researcher in the College of Engineering and Informatics at NUI Galway. His research interests span a number of civil engineering subjects, including computational fluid dynamics modelling, experimental investigation of hydraulic systems and environmental lifecycle assessment. Finnegan completed his PhD study in 2013, which focused on the wave-structure interaction of offshore wave energy converters. At present, he is exploring the use of lifecycle assessment to examine the environmental impacts of the Irish dairy processing industry.

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  Author: Dr William Finnegan, College of Engineering & Informatics and the Ryan Institute, NUI Galway The abolishment of milk quotas in 2015 is expected to result in a 50% increase in milk production in Ireland by 2020. This increase in the volume of milk being processed, along with stringent measures...