Sludge health check!!

Pictured Clionadh Williams doing monthly measurements on the gamma probes at the Ringsend Hydrolysis plant, and Glenn Gordon doing daily biogas composition analysis on one the 4 anaerobic digesters.

As we all know regular check-ups at the doctor are key to understanding the health of our digestion system. Also, what food stuff we put into our digestion system, and the rate at which we consume it greatly affects how our digestion system performs. As it with us, as it is with Anaerobic Digesters.

CAW operates the largest municipal sludge treatment facility in Ireland at Ringsend. This consists of 4 large anaerobic digesters which are preceded by a CAMBI-hydrolysis treatment plant. Anaerobic Digestion is a fairly robust process when it is in equilibrium with a stable feed, however, maintaining such equilibrium can sometimes be challenging in wastewater treatment plants where highly variable loads are the order of the day.

Organic overloading leading to pH depression in anaerobic digesters is one of the most common process challenges facing digester operators. This occurs as the growth rates of acid producing bacteria populations are significantly higher than that of methane producing bacteria. In an event when digester organic loading is suddenly increased the acid forming bacteria will thrive on the increasing substrate and production of volatile acids increases, depending on digester alkalinity, this will eventually begin to depress the pH of the digester. So why is this an issue? Well the methane producing bacteria like a stable, and usually relatively high pH. Being quite sensitive to pH change even small changes in organic loading rate can lead to pH changes which greatly inhibit the methane bacteria, creating a process upset which can prove very difficult to recover from.

Therefore understanding digester health through careful monitoring of a number of trends is key to understanding when organic loading rates reach limits that cause digester stress. Daily monitoring of digester pH, temperature and biogas composition is a necessity for high rate digesters. Monitoring of volatile solids destruction, gas conversion rates, volatile acid composition and alkalinity should also be done regularly. Ultimately, a digester is like our own gut, it likes the same feed at the same time every day, but unfortunately reality will often dictate that is not possible, but just make sure you know your limits!


Celtic Anglian Water were the proud sponsor of the 6th annual WWT Water Ireland Conference & Exhibition which took place on 28 March 2017 at the Pillo Hotel Ashbourne.

This annual event brings the region’s major stakeholders together to address the economic, environmental and customer service challenges facing the Irish water sector.

A number of key topics covered which included; A Sustainable Model for the Provision of Water Services in Ireland; Infrastructure Investment, Capital Delivery & Flood Resilience; Sustainable Management of the Water Environment; and Driving Innovation & Efficiency.

Mark Driver, Managing Director of CAW,

"The WWT Ireland conference is a great platform to bring the Irish Water industry together to discuss the challenges and opportunities that we are currently faced with. We were privileged to have our colleague Jim Foster from our sister company Anglian Water who delivered an insight into the innovative methods AW have developed to treat WTW in the eastern counties of England. Dr Foster’s presentation was indeed very topical as it highlighted the raw water quality treatability challenges which Anglian Water have and continue to be presented with, many of these raw water quality challenges  are very similar to those  Irish Water is now facing. There was a particular interest in Dr Fosters presentation on the issues associated with the levels of pesticides now present in raw waters and the seasonal variations in contamination levels, MCPA was singled out by one member of the audience for particular discussion. "

Engineers Week is no waste of time with visit to Ringsend

One of the largest wastewater treatment works in Europe will host a visit of three schools and the Director General of Engineers Ireland, on Friday 10th March as part of Engineers Week (4th to 10th March).

Ringsend Waste Water Treatment Works, serving the greater Dublin City area and managed by Celtic Anglian Water (CAW), is one of the most innovative and technologically advanced works of its kind in Europe. It will host a visit by Caroline Spillane, Director General of Engineers Ireland and three schools from across Ireland, marking the last day of Engineers Week.

The pupils visiting are from St. Michael’s College Junior School in Ailesbury Road, Dublin 4 and are all aged between 10 – 12 years old.

Engineers Ireland is the voice of the engineering profession in Ireland and through its STEPS programme organises Engineers Week – funded as a strategic partner of Science Foundation Ireland’s (SFI) Smart Futures Programme.

Engineers Week is a week-long programme of nationwide events celebrating the world of engineering in Ireland. The aim of the week is to create a positive awareness of and spark enthusiasm about the engineering profession among young people with little or no engineering background.

The three visiting schools will be given an introduction to engineering within the water industry and an insight into how wastewater is treated before being recycled back to our waterways from where is began. Presentations on the day will also include an overview of how 50% of the electrical power required by the treatment process is generated on site from the biogas produced in the sludge digestion process, and how the biosolids byproduct of the treatment process is further processed to produce a nutrient rich organic fertilizer, Biofert, for recycling to agricultural land across the country.

Declan Maguire, Operations Director for CAW said:

“We are delighted to be supporting Engineers Week and promoting engineering as a career choice. As one of the largest and most innovative treatment works in Europe we naturally receive a lot of interest in our site at Ringsend, and as a significant employer of engineers we are always keen to promote and develop the profession.

“We are always happy to assist schools, colleges, and universities who are interested in the Works and gaining a real insight into a number of the engineering disciplines including civil, mechanical, electrical, and chemical. Engineers Week, co-ordinated by Engineers Ireland’s STEPS programme, is a great way to raise the profile of the engineering industry to budding engineers of all ages and we are delighted with the level of interest we have received in the events we are hosting for schools today”

Caroline Spillane, Director General of Engineers Ireland commented:

“Engineers Week is a chance for parents and young people to find out more about the many career opportunities available within the engineering sector and learn about the kind of skills that qualified engineers can build on as they move through their careers.  Engineers Week also highlights how a career in engineering is accessible to all those who have an interest in the sector. There are many misconceptions about the ‘type of person’ who should pursue engineering and during Engineers Week we can show people that the world of engineering is open to everyone - girls, boys, creative thinkers, curious minds, problem-solvers and leaders.

"We are delighted that so many engineering organisations have embraced Engineers Week by hosting local students and creating specially tailored workshops and events to showcase their organisation and profession. By doing so, we have been able to engage with over 58,000 students, parents and teachers nationwide, sparking an enthusiasm for the profession and helping students to explore their future in this exciting subject area,”