Illangasinghe

Wasantha comes forward to solve problems in water treatment

1
Dr. Wasantha Illangasinghe
Water is a life giving force. Without it, life would not exist. Sources of water are polluted due to industrialization and climate and landscape change.  It is important that we drink water that is cleansed of contaminants in order to stay healthy. It is in this context that water treatment is an important service. It makes water suitable for human consumption. Bacteria, algae, viruses, fungi, harmful solids and minerals are removed via a series of steps in treatment plants before water is pumped out to our homes.                         
1
Supervisor:
Prof. J.M.A. Manatunge

If even one of these steps falter, then the water will not be suitable for consumption. The National Water Supply and Drainage Board (NWSDB) provides a yeoman service, giving us safe water via its treatment plants located countrywide.Our researcher, Wasantha Illangasinghe, says, “as an Engineer at the NSWDB, the interest for my research came from a practical issue at our treatment plants. The solid particles suspended in the water get collected as the raw water passes upwards through a sludge blanket. This clarification process is enhanced by a coagulant. However, the operators faced a challenge in this process, to keep the sludge blanket stable, an essential prerequisite for producing good quality drinking water.  It appeared to be affected by the quality of raw water and fluctuating ambient temperature. My interest in research this particular area came from this conundrum”.

1
Supervisor:
Prof. N. Rathnayake

Wasantha referred literature to identify a parameter that could be used to study the particle structuring of a sludge blanket; her search led to the rather obscure parameter ‘sludge cohesion coefficient (SCC)’ which appeared to give the desired description of the sludge that she was looking for. Using this parameter, together with the quality of water and the ambient temperature, she directed her efforts into finding the cause, and the solution to the problem.

Higher SCC gives a stable and consistent sludge blanket, whereas lower SCC gives a fragile blanket. She further observed that higher surrounding temperatures made the sludge blanket more fragile. Finding the correct coagulant dose to get a stable blanket under varying conditions became Wasantha's main research objective, which she successfully achieved.

2
Schematic of Pulsator Clarifier                     Source: http://www.thewatertreatments.com/

 

Wasantha notes that with these findings, our treatment plants could ensure that solid particles are removed effectively. Further, by keeping to the optimal coagulant concentration, the cost of the treatment process would be minimized. She has further suggested that a new step be introduced to the water treatment process whenever an abnormally high raw water turbidity level is noted, such as during times of heavy rain.

Wasantha is grateful towards both Prof. (Mrs.) Niranjanie Ratnayake and Prof. Jagath Manatunge from the Department of Civil Engineering, University of Moratuwa for their support and guidance during the course of her research. “They are both very knowledgeable and supported me without any reservations”, says Wasantha.

Prof. Mrs. Ratnayake summarizes Wasantha's contribution as, "she was able to provide guidelines to the treatment plant operators on the way the optimum coagulant concentration could be found under different raw water and environmental conditions. Earlier, this was a trial and error process, mainly guided by operators' experience".

Prof. Niranjanie Ratnayake, the first female Professor in any field of Engineering in Sri Lanka, is well known for her helpful approach and as a keen researcher. A Civil Engineering graduate from the University of Peradeniya, she has a Masters in Engineering from the University of Wales, UK and has accumulated a vast amount of experience working with many different local and foreign universities. She is a Past President of the Institution of Engineers, Sri Lanka (IESL). She is the current Chairperson of the National Science and Technology Commission (NASTEC).

Prof. Manatunge is a highly respected multi-disciplinary researcher. His Bachelor’s degree in Civil Engineering is from the University of Moratuwa. He has a Masters degree in Environmental Technology from the Imperial College of Science, Technology & Medicine, UK. His PhD is from Saitama University, Japan. 

Wasantha is from Kekirawa and completed her secondary education at Sri Sangamitta BalikaVidyalaya,  Matale. She obtained her Bachelor’s degree from the Department of Civil of Engineering at the University of Peradeniya. She has a Masters degree in Infrastructure Management from Yokohama National University, Japan.

Wasantha is now the Deputy General Manager for North Western Province at the NWSDB. She hopes that her findings will be useful for water treatment plants all over the world. When asked what her hopes are for the future, she says, “I would like to keep improving the quality of treatment systems in the country”. We hope Wasantha succeeds in achieving her career goals.

An Initiative by MoraMinds                                                                                           1 this post on 1

1
                                 Formation of floc blanket, Kandy South Water Treatment Plant
                                                National Water Supply & Drainage Board