Dewatering
Headworks : Enniskillen WWTP, Northern Ireland
By Michele LaNoue
Oct 7, 2009 - 10:14:08 PM

Houston, TX -- The town of Enniskillen, located in the county of Fermanagh in Northern Ireland, is situated on a natural island which separates the Upper and Lower sections of Lough Erne (“lough” is Irish for “lake”).  Enniskillen is the largest town in its county and its commercial center.  Its location, historic buildings and lack of modern developments give it a very special and unique atmosphere.

Wastewater treatment in Northern Ireland is the responsibility of Northern Ireland Water (“NI Water”). The original Enniskillen Waste Water Treatment Plant (“WWTP”) was built in the early 1970’s in order to provide preliminary, primary and secondary sewage treatment for a population equivalent to 24,000.  In 2007, a consortium formed by the UK contracting firms Enpure and Lagan initiated the construction of a new plant in the existing site, designed to provide preliminary, primary, secondary and new sludge storage and thickening facilities for a total population equivalent of 35,830 (12.5Ml/day).

In addition to the increase in plant capacity and enhanced treatment capabilities, an important objective with this project was to solve some of the operational problems faced at the old plant.  The problems included constant blockages of pumps and pipelines and also ragging accumulation in the aeration lanes.  All of this was caused by inadequate screening equipment.  These issues would at times affect the performance of the plant’s biological treatment system, resulting in violations of both European Urban Waste Water and Northern Ireland Environmental Consented Standards.  Also, the possible pollution of the Lough Erne may impact on the lake achieving the good quality status by 2015, as required under European Directives.

Being located adjacent to the lake and discharging directly into it, in a region where many people depend on their livelihoods from the tourist industry and particularly in the areas of craft, boating and inland fishing, the reliability of the plant and the quality of its effluent were extremely critical factors in this project.

As part of the preliminary design, the engineers considered utilizing screens with 6mm, “2-directional” circular openings, such as band screens, as the only screening system. Having experienced serious operational and maintenance issues first-hand at some of the local plants with this type of equipment in the past, Mr. Michael McAlary, Regional Operations Manager for NI Water, was interested in finding a better solution to achieve NI Water’s screening capturing requirements, while at the same time having a robust and reliable screen that would withstand the toughest conditions for many years.  After a series of technical meetings and visits to plants where Headworks’ Mahr Bar Screens® were successfully operating for more than 10 years, Northern Ireland Water decided to go ahead with Headworks.

Two Headworks Mahr Bar Screens with 4mm openings were installed and commissioned at the new Enniskillen WTP in March 2009, along with a Headworks dual screw conveying and washing/compacting system.  Each screen, 15ft long by 3.3 ft wide, was designed to handle the maximum design flow of 19 million gallons per day. 

The Headworks 4mm screens have been successfully operating since then, each one performing both coarse screening and fine screening functions all in one.  In discussing the improvement in the new system operations over that of the old plant, Michael McAlary stated that “at this moment all the issues and problems we had with blockages and rag accumulations seem to have been resolved”.  He further stated his pleasure in the efficiency of the capture rate with the new screens, commenting that “the capture rate of the 4mm bar screens is of similar ratio when compared to 6mm 2-directional screens”. 

All of this is possible due to Headworks’ unique combination of robustness, reliability and precision in the design and manufacturing of high-quality screening equipment.
   
“NI Water bought the Headworks screen based not on cost alone but whole life longevity. I wanted a robust and simple-to-maintain screen with a proven track record. For too long I have been purchasing inlet screens and replacing fundamental and critical parts after as short a time as two years, sometimes with delays in receiving these parts. I needed something in a screen that was tough and easy to maintain.  I seem to have received it from Headworks!”
Michael McAlary
Regional Operations Manager
Northern Ireland Water

Source: http://www.headworksusa.com/

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