GEORGE TOWN, May 7 — The water treatment residue discharged into Sungai Perai is not hazardous to humans and the aquatic environment, Penang Water Supply Corporation (PBAPP) said today.

PBAPP chief executive officer Datuk Jaseni Maidinsa said the main content of the residue that was discharged from the Sungai Dua Water Treatment Plant (WTP) is residual aluminium resulting from the use of aluminium sulphate or polyaluminium chloride for the coagulation process in conventional water treatment. 

“The Sungai Dua WTP is not the only WTP in Malaysia that discharges WTP residue into rivers,” he said in a statement today. 

Jaseni said the National Water Services Commission (SPAN) estimated that WTPs in Malaysia produced a total of 5,500 metric tonnes of WTP residue per day. 

He pointed out that the non-hazardous nature of WTP residue is proven in other countries where WTP residue is recycled as fill material for children’s playgrounds in Kyoto, Japan; and recycled as fertiliser and building construction material in the Netherlands.

He added that PBAPP has won several awards for completing a research project to produce bricks from WTP residue.

 Jaseni said a study in 2008 revealed that WTP residue is not listed as a “scheduled waste” by environmental management authorities in Canada, the United States and the United Kingdom.

“The Sungai Dua WTP has been operating since 1973,” he said.

 He said in the past 48 years, there has been no reported incident of water contamination in Sungai Perai resulting from the discharge of WTP residue.

“If WTP residue were hazardous to the aquatic environment, there would be no fish in Sungai Perai,” he pointed out.

Jaseni said a national WTP residue management plan is in the works.

He said a parliamentary reply by the Ministry of Water and Environment (KASA) last November stated that WTP residue would eventually be regulated by SPAN under the National Water Services Industry Act 2006 (WSIA).

“KASA stated that it was in the process of amending the WSIA to include WTP residue as being part of the water supply system; and that its regulation would include provisions for the setting up of common facilities to treat, recycle and/or dispose of WTP residue properly in Malaysia,” he said.

He said PBAPP is working closely with KASA, SPAN and the Department of Environment in handling the water treatment plant residue and ensuring the sustainability of Sungai Perai.

Jaseni was responding to concerns raised by an environmental group, Penang Sustainable Natural Heritage Association, that sludge containing heavy metals was released into Sungai Perai from the Sungai Dua WTP.