WATER TREATMENT IN MALAYSIA

HOW WATER IS TREATED BEFORE WE GET WATER SUPPLY

• Water Intake
  A river gate consisting of motorised gates controls the river level. From the river, raw water is channeled to the floating boom and a coarse screen which traps floating debris. The water then flows through a rotating band screen which traps smaller debris and sediments settle into sand hoppers built into the floor of the intake channel. Accumulated sediment is pumped out regularly with sand ejectors. The raw water then flows to the raw water pumps.
  
  
  
  
• Raw water pumps
  From here, the water is pumped to the treatment plant through a water pipe.
 

• Aerator                                                                                                                                                                 The raw water enters the aerator which is designed to create sufficient  turbulence to achieve a dissolved oxygen content of 80% saturation at ambient temperature. Pre-lime and a primary coagulant, poly aluminium chloride (PACI) are added.

 

• Mixing chamber
  The raw water flows to a flash mixing chamber where a flocculent aid (polyelectrolyte) is added. The polymer enhances floc formation for easier removal in the clarification process.

• Clarifiers
  Clarifiers perform the function of floc concentration, collection and discharge. Settled water overflows into collection channels for onward flow to the filters.

• Filters                                                                                                                                                             Rapid gravity sand filters remove fine particles which are not settled in  the  clarification process. Clarified water is filtered through a sand filter media to trap unsettled particles.

• Fluoridation
  The filtered water is collected at the filtered water channel where sodium silicofluoride is added and the filtered water then flows to a clear water tank.
  
  
• Disinfection and pH correction 
  In the clear water tank, chlorine is added for disinfection and tests are carried out to ensure the treated water is free from pathogenic organisms. Hydrated lime is added for pH correction. 

• The clear water tank                                                                                                                                        The tank provides sufficient contact time for the disinfection and conditioning chemicals to work on the water as part of the treatment process.
  

• Treated water pumps
  Treated water is pumped to the balancing reservoir for offtake by the state water supply distribution company.

• Balancing reservoir
  Treated water stored here is gravitated to smaller service reservoirs which cater to the needs of the consumers. A custody transfer flowmeter records the volume of water supplied to the distribution company.

• Water quality monitoring
  Treated water quality is tested in the plant laboratory to ensure that water passing through the plant is always clean and safe for consumption. An independent external testing laboratory is also engaged to ensure water quality compliance.

• Supervisory Control and Data Acquisition (SCADA)
  The SCADA system allows all functions of the plant to be automated and monitored from the control room.

• Sludge lagoons                                                                                                                              Sludge lagoons are  for the storage and drying of sludge. The lagoons are used in rotation. As one lagoon is filled, it is isolated for drying and wet sludge is channeled into an adjacent lagoon. Dried sludge is removed for disposal as a land fill at sludge depository.   

 

 

SEWAGE TREATMENT PLANT

       

Malaysians generate about six million tons of sewage every year. As about 98% of Malaysia’s fresh water supply comes from surface water, proper sewage treatment is important. Raw surface water becomes contaminated as a result of excessive and indiscriminate discharge of waste water directly from households or factories into drains or rivers with minimal or no treatment. This reduces the usability of the water for ordinary purposes. In some cases, it results in a public health hazard through poisoning or the spread of diseases.

There are round 8,000 public sewage treatment plants, 500 network pumping stations, 17,000 kilometers of underground sewerage pipes and half a million household septic tanks connected to the sewers. The government also encourages private companies to build waste water management systems in response to the increasing demand for a better and effective sanitation services.

In Malaysia extensive use has been made of primary treatment systems such as communal septic tanks and imhoff tanks and unreliable low cost secondary systems such as oxidation ponds. In addition, large urban areas utilize Individual Septic Tanks (IST). It is estimated that there are over one million individual septic tanks in Malaysia.

The Indah Water Konsortium (IWK) has been taking charge of Malaysia’s sewage management since 1994, and has built for the country one of the most effective sewerage management systems in the developing world. The system boasts of around 8,000 public sewage treatment plants, 500 network pumping stations, 14,500 kilometers of underground sewerage pipes and half a million household septic tanks connected to the sewers. In Malaysia, 38% of public sewage treatment plants in the country are mechanical plants. These plants operate using mechanical equipment that accelerates sewage break down.

Table 1 : Public Sewage Treatment Plants in Malaysia  

No.	Types of Sewage Treatment Plant	As At Dec 2008	Population Equivalent
1	Imhoff Tank	760	557,752
2	Oxidation Ponds	436	1,824,403
3	Mechanical Plants	4,026	15,099,139
4	Network Pump Stations	668	3,558,108
	TOTAL	5,890	21,039,402

COMMUNAL SEPTIC TANK

3,635

433,573

 

The trend will be moving towards "mechanical plants" such as Extended Aeration (EA), Oxidation Ditch (OD), Rotating Biological Contactors (RBC), Sequenced Batch Reactors (SBR) and Trickling Filters. Careful management of this change will ensure the future of Malaysia's public sewerage systems.