Water Treatment Plant

Water treatment Plant at Beladin and Maludam

There are two treatment plants at the building which is an old system and new system treatment. The raw water intake taken from surface water that having highest of color and smell but lowest of turbidity. Two treatment plants working in 24 hours per day. The old treatment system can treat only 31288 liter per Hour (LPH) lower than a new treatment system that enclosure 70,000 m³ per hour. Water treatment plant at Maludam, the raw water pumped (flow rate) in 100,000 m³ per hour.

Screening

Screening is the first element in a treatment plant to allow processing of raw water. The purposes of screening are used to remove wood chips, leaves, aquatic plants and floating impurities and prevent damage of the pump. Actually, to protect the structure downstream against large objects which could create obstructions in some of the facility’s units. It’s easily separate and remove large matter carried along by the raw water, which might negatively affect the efficiency of later treatment procedures. Screening is carried out by a manually cleaned bar screen at the Kampung Beladin treatment plant and also camping Maludam. Based on the Waterwork section, the efficiency of the screening operation depends on the spacing between screen bars:

1. Fine screening: spacing< 10 mm
2. Medium screening: 10mm < spacing <  40 mm
3. Coarse screening: 40mm > spacing

Raw water has many types of impurities such as floating and large suspended solids like paper, rags, plastics and grits. Also, dissolved solid in organics and inorganics, dissolved gases such as hydrogen sulphide, methane and microorganisms such as pathogens, bacteria and viruses. The figure 3.2 shows the example of screening Beladin water treatment plant.

Screening process

  

Chemical Diffusion

The main purpose of chemical diffusion is to produce fineness FLOCS that settle and separated from the water called coagulant processing. Mostly, chemical diffusion is able to remove color, odor and taste of water.

Actually, raw water contains a lot of impurities but in colloid form. Colloid is composed of a mass of clay and organic materials of art. It is not easy to settle under the force of gravity and cannot be separated from the water simply filtered in the usual way.

When chemical diffusion is done by applying certain types of chemicals, called coagulants (Coagulants) in water, the most commonly used are Alum, ACH and Sodium Aluminate. When a coagulant added to water and mixed average it produces a thick, sticky dross and trap suspended material in the water when they settle down to the bottom of the tank. Sediment is able to separate the sticky mass of colloidal quickly. Figure 3.3 illustrate the mixing of chemical dosages and coagulant process. Chemicals that are often used for thickening;

Aluminium (Aluminium Chlorohydrate, ACH),  Soda Ash, Polymer

Coagulant process (mixing of chemical)

                

3.3.6.3 Flocculation

Flocculation is a physical and chemical process which is used for the removal of the visible sediments and material from water which makes it a colloidal solution. It can be done through agitation or by adding flocculating agents.

This process is used when the small-suspended solids having low specific gravity and low settling velocity cannot be separated by sedimentation easily. In wastewater treatment, this usually occurs particularly with particles of less than 50 µm in size. When high concentrations of flocculent particles are present, the creation of velocity gradients in the suspension causes collisions between particles with consequent agglomeration. This natural flocculation process can be enhanced by the application of controlled velocity gradients through hydraulic turbulence or mechanical stirring.  The number of collisions in a suspension is proportional to the velocity gradient.

In the flocculation process, the polymers are used as flocculating agent for the formation of bridges between the flocs such as clumps of bacteria and impurities which form a cluster after using ACH and Soda Ash. These agents (Polymers) get adsorbed on the particles by reacting with positively charged suspension. It is very essential to gently mix the flocculating agent at a slow speed so that small flocs can easily agglomerate into large particles.

Flocculation process

Sediment tank

Sedimentation is basic concept at water treatment plants. Clarification is similar term, which usually refers specifically to the function of sedimentation tank in removing suspended matter form the water to give a clarified effluent. In this water treatment, Sedimentation is commonly used to remove impurities that have been done by coagulation and flocculation process called 'flocs'. Naturally, Sediment tank used earth gravity to settle rapidly all the largest flocs. Besides that, the settlement of flocs called slugde and removed by using backwash process.

Sediment tank (sediment flocs process)

         

 Backwash process

To keep water treatment filters functional, they have to be cleaned periodically to remove particulates. Backwashing is pumping water backwards through the filter media, sometimes including intermittent use of compressed air (blower) during the process. Backwashing is used to preventive maintenance, while the filter media can be reused. The system of backwashing used automated process at Beladin treatment plant (package 2) and package 2 is used manually also at Maludam treatment plant.

Filters should be washed and cleaned from all dirt caught during filtration process. The filtration will be cleans once per days after 24 hours water treatment plants operation. The backwash was taken 30 minutes to wash the filters. Before treatment, the valve should be closed at the filtration and the valve of high level tank backwashing will be opened. Figure 3.6 shows the storage of backwash high level tank at Beladin water treatment plant.

 Backwash water storage

Filtration

The purpose of fitration is to removes suspended particles from water such as turbidity and colloidal material that still remaining after settlement tank process. Actually, some types of bacteria, taste and odor also can removed through filtration because reaction occurs when water passes through the filter. In the filter, up to 99.5% of the suspended solids in the water can be removed, including minerals, floc and microorganisms.

Filtration have 3 types which is slow sand filter, rapid gravity filters and vertical and horizontal pressure filters. Maludam and Beladin water treatment plants was used rapid gravity filters. The filtration is now required for water treatment systems. Filter must reduce turbidity to less than 0.5 NTU. The filtration area at Maludam and Beladin water treatment plant.

Filtration process area

            

       

Filtering process have a several layers of sand and gravel size, while all the impurities that remaining in water will be retained by layers of sand.

Disinfection

Water should be disinfected before it enters the distribution system to ensure that any disease-causing bacteria, viruses, and parasites are destroyed. Chlorine is used because it is very effective disinfectant, and residual concentrations can be maintained to guard against possible biological contamination in the water distribution system. The primary goal of water treatment is to ensure that the water is safe to drink and does not contain any disease-causing microorganisms.

 Disinfection (Chlorine and Soda Ash)

 pH correction

Lime is added to the filtered water to adjust the pH and stabilise the naturally soft water in order to minimise corrosion in the distribution system, and within customers’ plumbing.