Wangsa Maju WTP (WMWTP) was built with the Dissolved Air Floatation (DAF) system on a fast track basis - within six (6) months, during water crisis in year 1998. The plant abstracts its raw water from Klang Gates Dam and Gombak River and currently supplies its treated water to Wangsa Maju, Keramat AU3, AU4 and AU5, Hulu Klang, Taman Sri Rampai, Taman Setapak Jaya, Taman Desa Setapak and surrounding areas.

Throughout the water treatment stages, the plant is equipped with the following units :

The plant is also known to be one of four (4) WTPs in the country that use the DAF system in water clarification and potable water production.

The principle of floatation is based on the transfer of particles to the surface of a liquid through attachment of micro-bubbles to the particle surfaces. This principle is opposite to the sedimentation process whereby the unwanted particles or flocs in the latter settle to the bottom of the tank and clarified water is collected at the top to undergo further filtration stage.

In the DAF system, size of the micro-bubbles is best maintained at 50 micrometer (microns) in order to increase the contact surface area with the flocs and therefore increase the solid separation efficiency. The particles are then removed as a floating sludge by mechanical skimming units (scrappers), continuously into the Sludge Treatment Plant.

Brief description of DAF system at Wangsa Maju WTP :

Reduced chemical coagulant requirements
In this system, formation of a large settling floc is not required. Small size of flocs would easily attached to the micro-bubbles and float to the surface. With raw water abstracted directly from Klang Gates dam is at very low turbidity level between 2 – 10 NTU, the floc formed is very fluffy. In fact, the coagulant (liquid alum) dosage applied in the plant is slightly lower (within 9 – 14 mg/L) as compared to conventional clarification (18 – 22 mg/L).

Small land area for installation
Land area for WMWTP is very limited with only 14,450 m2 available as it located in a fully developed residential area of Wangsa Maju. Hence, the required space for installation of DAF system can be minimized as a result of the plant operation at high surface loading rates (higher compared to sedimentation process).

The average velocity in DAF stage is in about 10 m/hr as compared to 1 – 1.5 m/hr for the conventional type. Therefore, the shorter hydraulic retention time at the DAF system enables the process plant to be compact and suitable for a limited area. The WMWTP’s clarification process area (coagulation, flocculation & flotation) : 27m X 23m

Higher concentration of sludge solids
The micro-bubbles behave as hydrophobic solids that have more surface area to enhance the agglomeration of flocs in water and theoretically shall increase the total number and concentration of solids, to be discharged into the Sludge Treatment Facility.

Rapid stabilization of the system
Rapid stabilization of clarified water quality upon start-up because of the shorter detention times throughout the process. It takes less than 40 minutes to produce the required level of clarified water upon start-up of the system.

Removal efficiency of small suspended particles
This solid-liquid separating system is more effective in separating light and small suspended solids that can hardly be separated by ordinary air flotation or sedimentation. It was also reported that DAF is a more effective process as compared to a conventional sedimentation for treatment of water containing low-density particles such as algae.

In terms of turbidity and iron removal efficiency, DAF is consistently able to remove almost 83% - 89% of the contaminants. In fact, turbidity and iron in the water is almost completely removed after filtration process.