Brief Report on Twinning PWA This brief report was prepared to assist in targeting the twinning assistance to be agreed upon between PWA Thailand and Ranhill Utilities of Malaysia. The following guideline was given to Ranhill to give assistance to PWA : 1.
Treatment system optimization
PWA wants a crash course on up-to-date water treatment processes â€“ whether itâ€™s optimizing existing systems or introducing new, non-conventional technologies. The reason is that PWA last had technical assistance from UNDP about 12 yrs ago on system design and thus itâ€™s looking for more efficient/effective ways to treat water including upgrades, rerating, etc (rerating is a good process to maximize capacity without heavily investing on major capital works). Key interests are: (a)
How to execute plant performance studies (or audit) and propose improvements in order to rehabilitate malfunctioning parts of a plant; checklists/procedures will be useful for PWA
How to select appropriate treatment processes depending on nature of impurities to be removed; PWA has mentioned algae bloom at raw water intake as a impurity of concern
How to optimize, operate and maintain manual and semi-automated treatment plants including methods to examine unit processes, establish proper quality control, and troubleshoot
Learn basic principles of membrane processes and the capabilities/constraints of using membrane processes in water treatment application
Water quality management improvements
PWA wants to adopt best practices in setting up water quality management systems. Key focus areas include: (a)
How to set-up and efficient and effective monitoring system for water quality in raw water, pre- and post-production, and within distribution network
How to establish sound laboratory practice and water quality information management system (e.g. sampling collection, analysis, reporting, frequency, etc)
METHODOLOGY Ranhill Team, represented by General Manager Operation and Water Quality Manager was given to walk through of the treatment process at Nakorn Nayok treatment plant, Ban Na treatment plant and Ongkarak treatment plant in 2 days. Observation was done on the treatment process and treatment facilities emphasizing on water quality. An audit on how the water quality testing was also carried out. Ranhill Team also gave a presentation to the staff of PWA at the PWA Headquarters and Nakorn Nayork treatment plant on : 1. 2. 3. 4.
Various Treatment process carried in SAJ Holdings Water Quality management carried out in SAJ Holdings How to Audit water quality in treatment plant Water safety Plan
30 PWA Staff from Nakorn Nayok treatment plant, Ban Na treatment plant, Ongkarak treatment plant, Headquarters and Regional office attend the presentation.
OBSERVATION Raw water source for the three treatment plant : Nakorn Nayok Ban Na Ongkarak
- Huay Prue reservoir - Canal 29 - Nakorn Nayok river
And there were no raw water meter found to measure the raw water flow for all treatment plant.
The capacity for the 3 treatment plants is 24000, 3360 and 2400 cu.m/day respectively. The three treatments plant have the same treatment process for flocculation with concrete baffle wall, horizontal type sedimentation tank, filtration with sand as filter media. Aeration process is only at Nakorn Nayok treatment plant and no aeration process at Ban Na and Ongkarak treatment plant. At Nakorn Nayok the aeration process is done by introducing air bubble into a tank of water. The team is not able to identify whether the air bubble is sufficient to ensure the oxidation process is completed. Formation of flocs were good at the beginning of the flocculation tank but the flocs start to break away somewhere in the middle of the flocculation tanks. At the sedimentation tank there are still a lot of light flocs floating along the whole length of the sedimentation tank and plenty of the light flocs were carried over into the filters. The dosing of chemical carried out was not according to the best practice and frequency of testing of raw and treated water quality is very limited. Dosing equipment at Nakorn Nayok treatment are all out of order and dosing is done using temporary system. Lack of equipment for testing water quality and accuracy is questionable. No record of water testing is found at the laboratory. Standard Operating Procedure for work process is also not to be found at the appropriate location.
RECOMMENDATION From the two days observation the Ranhill Team would like to recommend as follows : 1. To install raw water meter to accurately measure the flow into the treatment plant for dosing purposes 2. Dosing of chemicals at the proper location taking into consideration distance between each chemical dosing point and sequence of chemical dosed 3. To install on-line pH meter after lime dosing point to easily obtain the coagulated pH 4. Flocculation tank – to restudy the design to ensure the flow in this process is from rapid, moderate and slow for better floc formation and to avoid breakage of floc (adjustable metal plate as in Nakorn Nayok TP is more appropriate compared to fix concrete baffle wall as in Ban Na and Ongkarak TP) 5. Chemical tanks – each chemical should have at least 2 tanks, 1 running and 1 standby – running use for dosing and standby use for chemical preparation 6. Individual calibration curve for each metering pump to be prepared to ease the control of chemical dosing (to relate the dosage and the stroke of the pump) 7. Clock and bucket test to be carried out systematically to ensure the actual chemical flow for the dosage to get the optimum dosage – to translate the jar test result into operation. 8. Use of hydrometer to ensure the concentration of chemical solution prepared (to get c value)(calibration curve within appropriate range 9. Use of hydrometer to ensure the concentration of chemical solution prepared and calibration curve within appropriate range 10. Pipe carrying lime solution to be flush periodically to avoid clogging of the pipe (preferably to have standby line or motise water)
11. Pipes bringing water raw water, coagulated water, settled water, treated water to the Laboratory for ease of collecting water for testing
12. Jar test to be done daily or when any changes in raw water quality (heavy rainfall) - to get optimum alum dosage 13. To emphasize record keeping for future analysis and decision making 14. To prepare SOP for each individual work process 15. Training of operators to refresh/update knowledge and skill of operators 16. To provide appropriate state-of-art equipment at the treatment lab 17. Calibration of equipment and meter to be done periodically to ensure accuracy 18. Water samples to be taken at a fix and appropriate location so that trends can be develop from data collected 19. Program for water sampling to be established for water quality monitoring purposes (frequency of sampling) 20. Preventative Maintenance for all equipment and installations to be carried out systematically to avoid breakdowns
21. Upgrading of treatment process base on raw water characteristic (if present facility not capable to handle than only look for new technology) 22. Upgrading of treatment facilities such as pumping system, pipelines should be base on proper design
Published on Mar 31, 2010
Published on Mar 31, 2010