Dublin Faces Possible Water Shortages

Dublin City Council have issued advanced notice that their reservoirs in the Wicklow mountains are rapidly falling due to a very dry March and April resulting. With little or no water replenishing stocks reserves now stand at 120 days, rather than the usual 178 days normally expected at this time of year. This means that if dry weather continues then restrictions will have to be implemented both in the City and throughout the Greater Dublin area. The cut off point is 80days storage at which restrictions will be put into place. Consumers are asked to conserve supplies, especially in relation to using water for the garden and washing vehicles etc.

Ballymore Eustace Changes to On-Site Electro-Chlorination (OSEC)

Ballymore Eustace Water Treatment Plant supplies 70% of Dublin’s water and is currently being expanded from 250 Ml/d to 318 Ml/d, with a planned peak capacity of 400 Ml/d. Siemens Water Technologies have provided two OSEC systems each be capable of producing 1,000 kg/d of chlorine to replace the use of chlorine gas for chlorination. Both units will operate in tandem producing 24 hours’ worth of chemical during the 8 hour low-tariff energy period.

Siemens electrolyzer unit where brine is
turned into sodium hypochlorite

Water softened to <17 mg/L hardness is used to produce a 2.8% w/w brine solution from stored salt. The brine solution is passed through an electrolyzer (image right) where a current is passed between two electrodes resulting in chlorine gas being produced at the positive electrode (anode) and sodium hydroxide and hydrogen gas at the negative electrode (cathode). The chlorine then reacts with the sodium hydroxide to produce a 0.8% sodium hypochlorite  solution which is stored before added to the finished water for disinfection. Salt usage equates to 3.0-3.5 kg per kg chlorine equivalent. Fifty-seven liters of 0.8% sodium hypochlorite is equivalent to 0.45 kgs of chlorine gas or 3.79 liters of commercial sodium hypochlorite (12%). This results in a much safer and cost effective chlorination system.  Further information on Siemens OSEC technology.

Visit to Ballymore Eustace Water Treatment Plant

Final year students from the Environmental Science course visited Ballymore Eustace Water Treatment Plant this afternoon and were treated to a fantastic tour of the plant.  This also included a sneak preview of the new rapid sand filtration complex.

The plant is undergoing a major upgrade which will increase the output by 26% from 250Mld to 318Mld. Construction of new filters, sedimentation tanks, reservoir, administration and laboratory facilities are well under way with staff currently moving into the new administration building and laboratory.