A dairy processor in Ireland producing dry powdered milk required a new effluent treatment plant to support there expansion.

The site had an existing wastewater treatment plant, which needed to be upgraded to treat greater production levels and increased flow rates resulting from an upturn in the dairy sector.

The Challenge

To a design a robust wastewater treatment plant that could not only treat current effluent levels but also the planed increase in production. The new treatment plant was to use the latest proven treatment technology to the enable the plant to exceed EPA treated water specifications.

Hydro was engaged to design, supply, build, install and commission a state of the art waste water treatment plant to achieve two key objectives. Firstly, to meet the EPA’s effluent license requirement and secondly to recycle a percentage of treated water on site to reduce overall carbon footprint to facilitate the use of high quality recycled water within the facility.


The first step was to fully understand the requirements and daily and peak production levels and the organic loadings of their effluent stream. This extended to assessing site requirements for both current and future flow levels and loadings.

Site data was analysed and senior management were consulted regarding design options for the wastewater treatment plant.

Following evaluation of the various technical options and both the current and predicted future production levels, the following treatment steps were proposed; inlet screening, balancing tank, chemical DAF, bio-towers, aeration, de-nitrification, MBR clarification, sludge dewatering and finally UF and RO to produce water of a recyclable quality.

Having gained site approval for the proposed design, Hydro then began building the new treatment plant. The timeframe from design sign-off to plant start-up was 6 months.


The plant was designed, installed and commissioned on time and within budget.

The quality of the effluent produced by the plant enables the client to remain well under EPA stipulated licensing requirement and has provided the facility to use 60% of the treated water for recycling .

Parameters Raw Water After MBR Final  (After RO)
Flow 37 m3 37 m3 37 m3
BOD 1318 mg/l 50 mg/l 0 mg/l
COD 2500 mg/l 250 mg/l 2 mg/l
NH3-N 50 mg 10 mg 1 mg
Nitrogen 100 mg 15 mg 2 mg
Suspended Solids 1200 mg 5 mg 0 mg
Phosphorous 22 mg 0.8 mg 0 mg
Fats, Oils, Greases 50 mg 1 mg 0 mg