All sewerage systems from individual septic tanks to the most sophisticated mechanical plants produce sludge. Sludge is an active organic compound which can rapidly turn septic if left untreated. Untreated sludge is a significant environmental and public health hazard.
However, treated stabilised sludge is inert, stable and safe to use. It can be utilised to condition soil or as landfill.
Malaysia produces 3.2 million cubic metres of domestic sludge yearly. However, facilities to treat and dispose of this sludge are limited. Currently, sewage treatment plants with excess capacity are being used to treat septic tank sludge.
By the year 2005, Malaysia will be producing 4.3 million cubic metres of domestic sludge annually. As a result, many new sludge treatment and disposal facilities will be needed to manage the large volume.
One viable solution is to construct sludge lagoons that will serve as sludge holding and treatment facilities. These are ideal for short-term use in urban areas as well as long-term use in semi-rural areas.
However, for long-term use in urban areas, sludge settling tanks and digestors are required, such as at the Pantai Sewage Treatment Plant in Kuala Lumpur.
As an immediate solution, Indah Water is proposing to use existing sewage treatment plants with excess capacity. For a short-term strategy of between two to five years, Indah Water proposes the construction of sludge lagoons, while the long-term strategy would be to construct sludge digestion and mechanical dewatering facilities.
In view of this, land is urgently required for the housing of sludge holding and treatment facilities, so that the desludging of septic tanks and sewage treatment plants may begin on a large scale.
Environmentally-sound sludge management is the cornerstone of Malaysia's new approach to sewerage services. Effective and efficient sludge management will significantly contribute to providing a cleaner and safer Malaysia for future generations.