Evaluation of the performance against the design parameters of the unit processes of the Kondawaduwana water treatment plant

Abstract

Eastern Coastal Towns of AmparaDistrict(ECTAD) Water Supply Project has been planned to implement in two phases. The first phase of the project, having capacity of 17,500 t:/day was commissioned in June 2001 The second phase was commissioned in June 2007 and it has a capacity of 72,000m:/day. In phase I the treatment process in the plant consists of Coagulation and Flocculation,Dissolved Air Flotation (DAF), Rapid Sand Filtration, Post Chlorination,ph Correction and Sludge Treatment. The treatment process for the phase II is the same, except for pre- chlorination and addition of powdered activated carbon (PAC)at the flash mixer. The scheme serves the Ampara Township, too. The first recorded water quality issue of coloured water, bad smell and taste were raised by consumers in the year 2004. From 2004, sporadic complaints from consumers were received and steps were taken to flush the pipelines periodically. The regular water quality tests had not revealed the cause for the problem and a series of studies have been carried out and various reports have been submitted. However, the water quality issues still persist. Therefore, four numbers of trials were carried out for collecting the samples to identify the reason for the colour problem with following conditions at the various location of the treatment processes such as the rapid mixing, before DAF,after DAF(floated water), filtered and treated water. > With pre chlori nation and with PAC, > With pre chlori nation and without PAC, > With out pre chllorination and with PAC > With out chlorination without PAC Water samples were collected at various location of the treatment processes like, rapid mixing, before DAF,after DAF(floated water), filtered and treated water. The water samples were tested at NWSDBAmpara,University of Moratuwa and NWSDB central laboratory for parameters such as total iron, dissolved iron, total manganese, dissolved manganese, total organic carbon and chemical oxygen demand. VI