The department has ordered the Penang Water Supply Corporation (PBA) to immediately address the issue, as alum sludge is a scheduled waste.

This comes after local green group Lekas raised a red flag over “teh tarik” coloured water being pumped out from PBA’s treatment plant north of Butterworth into a tributary of Sungai Perai. The plant draws its water from Sungai Muda.

Lekas claimed that the activity had polluted the tributary and affected agriculture along the main river on the mainland.

Alum sludge is a by-product of aluminium sulphate or polyaluminium chloride used in water treatment plants, which is used in the coagulation process. It later leaves the plant as residual aluminium or alum sludge.

PBA has claimed that the residual aluminium discharged from the plant is non-toxic and shows no characteristics of scheduled waste.

In a statement today, Penang DoE director Sharifah Zakiah Syed Sahab said PBA was told to immediately carry out scheduled waste and effluent management to mitigate the issue.

She said PBA could not stop the water treatment plant right away, as it supplies water to 85% of the state and has since proposed short and long-term measures to address waste and effluent management.

Sharifah said alum sludge, categorised as SW204 scheduled waste, has to be managed or disposed according to prescribed methods.

“The department is also of the view that the issue of cost is unreasonable because the same situation and cost are also borne by other industries in Malaysia.

“In this case, the cost of waste and wastewater disposal management should be taken into account in the overall operating costs so that the production of clean water is carried out sustainably and in accordance with the provisions of the law.

“The same principle is applied by other industries in Malaysia so that premises comply with all requirements under the Environmental Quality Act 1974 and the quality of the environment is not compromised,” she said.