Tuesday, November 30, 2010

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.

Monday, November 29, 2010

Septic Tank Design in the United States

My undergraduates are looking at small scale treatment systems this week and here is a very interesting video looking at the design of  aUS septic tank system which gives us an interesting comparison with our own systems here in Ireland.

Sunday, November 28, 2010

Leakage Remains a Challenge for Suppliers

Leakage is the starting point in the conservation of drinking water supplies. In the UK leakage reduction targets are monitored by the Water Services Regulation Authority (Ofwat). However a number of companies have failed their targets for 2009/10 including Yorkshire Water who lost on average 295 million litres a day (ML/d) over this period. The target for 2009/10 was set at 3,275 ML/d for all companies in England and Wales and this was almost achieved with reported loss for the period of 3,280 ML/d. However, the overall trend is still downwards with 8.4 and 34.2% reductions since 2005/6 and 1995/6 respectively. Thames Water still are losing the most via leakage at 670 ML/d with Severn and Trent Water close behind at 495 ML/d, but both within their targets of 685 and 500 ML/d respectively. Where targets are not meet then Ofwat can force companies to invest even more money in achieving leakage reduction. For more information about company leakage and performance in general see Ofwat’s annual report: Service and delivery – performance of the water companies in England and Wales 2009-10: Water today, water tomorrow.

Friday, November 26, 2010

Undergraduates at Leixlip WWTP

We were very lucky to be shown around Leixlp Wastewater Treatment Plant just before it snowed. Our thanks to Tom Sexton and Kildare County Council for making us so welcome.

Tom Sexton explains the odour control system at Leixlip

Outer casing of sludge centrifuge

Rare chance to see inside a
sludge centrifuge

Thursday, November 25, 2010

Asbestos Exposure? Act Now!

The risk from asbestos in drinking water is still under debate, but for all of us in the water industry asbestos is all around us and it is inevitable that many of us will have been exposed to airborne asbestos at some time, especially in the past when awareness was not so acute. MesotheliomaSymptoms.com is an extensive database of information and resources to better understand the symptoms of mesothelioma, as well as asbestosis, and the various aspects of diagnosis, prognosis, treatment, and many other factors of survival.  Symptoms of mesothelioma usually do not appear for 20 to 50 years after asbestos exposure, however those who think they may have been exposed should check out the website.

Wednesday, November 24, 2010

CDP Water Disclosure 2010 Global Report

The Carbon Disclosure Project (CDP) is an independent not-for-profit organization that collates greenhouse gas emissions and climate change strategies of the world’s leading corporate bodies.  They have just published the CDP Water Disclosure 2010 Global Report on line in which water use by leading corporate bodies is listed and explored.

Tuesday, November 23, 2010

Inspecting Septic Tanks

New regulations coming into place next year will require all septic tank systems in Ireland to be inspected.  Here is a interesting video from the US looking at some problems associated with tank assessment.

Monday, November 22, 2010

Fog Collectors in Action

Fog collectors are now widely used in highland and coastal areas where water is sacrce.  This video shows the application of fog collectors in a number of regions.  Their simplicity and low cost make them an ideal water harvesting system.  The leaders in this field are FogQuest  which is a Canadian charity dedicated to planning and implementing water projects for rural communities in developing countries.

Saturday, November 13, 2010

Waste Framework Directive: Public Consultation

Ireland is in the process of bringing the EU Waste Framework Directive (2008/98/EC) into Irish law through the provision of new regulations.  The Department of Environment, Heritage and Local Government are now calling for comments and/or submissions on the draft regulations.  These must be forwarded to Gerry Byrne by 26 November, 2010 as Member States must complete the process by 12 December.  To access the draft regulations use this link.

Thursday, November 11, 2010

Laminar Plate Clarifier Ripple Phenomenon

If you click on the image to get a better view you will notice a ripple effect on the surface of this water treatment up-flow clarifier. The effect is caused by the laminar plates and occurs in different parts of the tank each day.  It is clearly a hydraulic phenomenon but does anyone have a better explanation for this?

Wednesday, November 10, 2010

Metal Variability in Sewage Sludge (Biosolids) to Agriculture Land

Sewage sludge (biosolids) disposed to agricultural land in Ireland need only be analysed once a year if disposed to agricultural land for plants of <100,000 PE according to the Code of Good Practice For the Use of Biosolids in Agriculture published by the Department of the Environment and Local Government in 2008. Metals in Irish sludges have decreased over the past 20 years resulting in their widespread use in agriculture with 76% of the 60,000 t DS produced each year now going to farmland. In a recent study done by Elizabeth Whitney of the Water Technology Research Group, the variability of sludge metal concentrations from 12 wastewater treatments plants was examined every two weeks for up to six months. The sludges showed wide variability as measured by the coefficient of variation (CV) over time with each plant with at least one metal where the CV was >50% over that period. Mean plant CV (and range) of the metals studied were Cr 29.5% (11-91%), Cd 48.0% (3-118%), Cu 73.4% (4-168%), Pb 26.5% (6-115%), Ni 46.5% (6-267%) and Zn 26.7% (6-100%). High CV values were generally indicative of an increasing or decreasing trend. However, on some occasions periods of high metal concentration were recorded indicating an intermittent source. The results show that significant variation in sludge metal concentrations occur over time and that in order to ensure safe disposal to agricultural land, the required certificates issued to farmers containing details of metals in the sludge should be either the actual metal concentrations in sludge applied or at least the upper (90 percentile) limit values based on recent monthly samples in order that correct and safe loading rates can be calculated.

Tuesday, November 9, 2010

Science Spin No. 43 Now Available

Science Spin  is Ireland’s premier science magazine which  provides an independent platform for reporting on science. Coverage extends from astronomy to zoology, and features are written with both general public and specialists in mind. 

It is available as a free download with an excellent support website. Link

Tuesday, November 2, 2010

Weil’s Disease (Leptospirosis)

Olympic rowing champion Andy Holmes died last week after contracting Weil’s disease (leptospirosis).  This tragic news highlights the risk to all those working with water and sewage, and of course those who use inland water for recreation, from this waterborne bacterial disease.  Globally up to 10 million people contract the disease each year, although the number of reported cases of the disease in the British Isles is around 100-150 people annually, with farmers, sewage workers, freshwater ecologists and water sport participants (i.e. canoeists, wind surfers and rowers) all in the high risk category.  Advice on safe working practices for those engaged in freshwater monitoring and research can be found in sections 9.2.3 and 13.6 in Water Technology.  The primary infection route for leptospirosis is through damaged skin. So no matter how minor the damage may be (e.g. scratches, rashes etc.) ensure that the area is covered by an effective waterproof barrier if there is a possibility that the skin will come into contact with water potentially contaminated with rat urine (i.e. almost all surface waters). For more information Link.