The modern water treatment plant is usually using a combination of physical, chemical and biological process to produce high quality drinking water.
The Ballymore water treatment works locates at Ballymore Eustace, County Kildare. It has last for over 70 years since 1940’s. The water plant can provide 230 mega-liters clean water per day to four regions, including Dublin, Kildare, Dun-Laoghaire and South Dublin. Now the plant is trying to expand its capacity to produce high-quality water to the greater Dublin area in this century.
Our field trip happened on April 14, Wednesday. The objective of this field trip is to lead us a better understanding how the waterworks operates. To combine the witness and knowledge is important for engineers who are willing to work in the water treatment area.
The entire water treatment process includes seven stages, including the flocculation, sedimentation, filtration, disinfection, sludge drying, fluoridation and PH correction.
At the beginning, we visited the manifold building. There were huge pipes through walls to link the raw water into the next water treatment stage. What is worth to mention is the function of gravity. As the Poulaphuca lake is behind a strong dam, the lake itself became a good reservoir. The water in this reservoir goes through the pipework by using the potential energy generated by its gravity. This advantage can save huge electricity of pumping and transferring the water in and out the plant.
Within this process, raw water sample will be collected and delivered into the laboratory for the further tests. These tests may finally help to decide the amount chemicals using in the facility to eliminate or minimize the impurity of the water.
The most impressive thing that I mentioned was that the entire water treatment plant is highly automatized with the help of the computer control system. The income and outcome of any process can be manipulated by the particular software for this facility.
Sedimentation is a magic process in which water is converted much clearer and ‘cleaner’. The sedimentation tanks contain a unique gradient honey structure. This structure aims to increase the surface area which sediment can adsorb. It provides a good efficiency for the sedimentation tanks to separate the flocs and water. To use this kind of structure is probably because of the limitation of the plant size and water supply demand. By seeing the sedimentation tanks, it was quite hard to judge that quantity is large in this process. But the quality is good. At least the water here is without any color.
After the sedimentation process, water will go through filters. The function of filters is to remove the particles and to pre-treat water before disinfection process. In Ballymore Eustace water plant, the layers of the filters are sand and gravel which are normally the layer materials in other water treatment plants. The water quality after passing through the layers can be detected by laser-monitors. These monitors can do the spectral analysis of the filter water to figure out the particle amount. This amount could represent the water quality after the filtration process.
Filtration can be seen as a physical cleaning process. At the same time, disinfection will definitely be seen as the chemical cleaning process. The water from nature before treatment may contain kinds of viruses, bacteria and parasites which may cause illness to human. Hence, to remove these illness potentials is necessary. Chlorine is usually put into water to kill or restrain these biological illness potentials. The efficiency of Chlorine to clean water biologically is acceptable for water treatment and supply industry.
As throwing in chemicals to clean the water, it may also cause new problems. To maximize the result of killing the bacteria, viruses and parasites may cause an over use of chemicals, including chlorine and metal compound. Hence, the compound, which might be hazardous to human health, in the water shall be removed. The saturator is designed to separate these chemical compound out.
The sludge drying bed is to remove enough water from the sludge after the sedimentation and filtration process. The layers of the sludge drying bed are also sand and gravel. Workers will take the sludge out and transport them to the sediment drying machine. The machine will push the water out of the sludge by using very high pressure. Finally, the wet sludge become the dry sediment cake.
Before transporting clean water by pipes to different regions, the PH shall be adjusted above 7, which is alkalescent. The biological engineer in the laboratory mentioned that. Lime is usually the adjustment chemical. The final PH value aims to protect the pipes from being corroded during the transportation.
In this field trip, I have obtained the entire view of the water treatment plant. I came to understand the basic operation, technology standard and regulation of the facility. The real tanks, equipment and management systems help me to clarify the relationship between each process. This field trip is a vivid lecture for me. I believe I have obtained by this trip more than I have realized and expressed in the report.
Thanks for this opportunity.
Thanks for Dr. Purcell and all the staff of the Ballymore Eustace Water Treatment Plant.
