Kuala Lumpur:Dried sewage sludge could be recycled by adding it to cement to make concrete, researchers in Malaysia have discovered. Disposing sludge left over from treating sewage water is a major challenge for wastewater plants. Meanwhile, the construction sector seeks economic and ecological cement replacement materials in order to meet an increasing demand for concrete. Researchers from Universiti Teknologi MARA investigated the potential to replace various quantities of cement with processed sewage sludge to create a concrete mixture. The researchers first produced domestic waste sludge powder (DWSP). They dried and burnt wet sludge cake to remove moisture, and then ground and sieved the dried sludge cake to make the sludge powder. Using varying proportions of the powder, ranging from three-fifteen per cent, the researchers mixed the material with cement to produce normal strength and two higher strength grades of concrete. They then compared the domestic waste sludge powder concrete mixture of each proportion with normal concrete in terms of their compressive strength, water absorption, water permeability and permeability to salt. Overall, the researchers found that while domestic waste sludge powder has a potential role in the manufacture of concrete, the performance of the concrete blends tends to decline with increasing concentrations of the powder. The findings were published in the Pertanika Journal of Science and Technology. "Overall, there is potential for using DWSP as a partial cement replacement," the researchers said. "However, more detailed research should be conducted to yield better quality powder," they added.