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Freshwater heavily polluted; refining cost surges
Sri Lanka’s freshwater sources are now so polluted that the National Water Supply and Drainage Board (NWSDB) is spending increasingly more money to refine drinking water, the National Audit Office (NAO) and officials said.
The steep cost was owing to high levels of contaminants in the water obtained for treatment, said the NAO report published online. Attention was not paid to standards when discharging wastewater into inland water bodies. Apart from the price of chemicals, the appreciation of the dollar and intensified water usage has raised costs.
With a population of nearly six million, the Western Province generates nearly 1,200mn litres of wastewater a day, the NAO report states. It is disposed into the ocean via the Wellawatta and Madampitiya pumping stations. The “severity of marine environmental pollution” is such that an estimated 438,000 million litres of untreated wastewater is added to the ocean each year through the Western Province alone, it says.
The Rathmalana wastewater treatment plant was opened in 2013 to cater to 408 industries and around 20,000 people. It has a capacity of 17,000 cubic meters. The treated water is discharged just 600m into the sea despite the Marine Pollution Prevention Act mandating that the distance should be at least two kilometese.
Wastewater from Dehiwala-Mt Lavinia, Kolonnawa and 11 institutions outside the territory of Colombo is conveyed to the Colombo Municipal Council system. At the time of the audit, both Wellawatte and Madampitiya treatment plants were “inactive” with raw sewage being discharged directly into the sea.
This situation is now being corrected under an Asian Development Bank-funded project, said a senior CMC official overlooking waste management. He said treatment plants are being set up. The sea outfalls are 1.5km away and sewage is disposed of on the seabed so that it diffuses when it reaches the shore, he explained. The system dates back to colonial times.
But the NAO contests that discharging untreated waste into the environment “absolutely” violates the National Environmental Act and the Marine Pollution Act. Although disposal takes place more than one kilometre away, “there is a risk of the above pathogens entering the beach because of the natural process of the sea”.
It also said the authorities have not regularly tested the quality of marine water and the beach in areas such as Wellawatte and Mutwal outfalls. “The beaches of Wellawatte, Mutwal and specially Galle Face area are used by the general public for entertainment and bathing,” the report states. The CMC has not provided confirmation “that pathogens were not in the marine water or beaches of this area due to discharging untreated sewage into the sea”.
Several hospitals were observed not to have environmental protection licences for their wastewater treatment systems, with the Central Environmental Authority having failed to follow-up.
Highly polluted raw water requires different types of chemicals in higher quantities, says Jayalal Wijesinghe, NWSDB’s Assistant General Manager (Laboratory Services). For instance the cost for chemicals (alone) upstream of Kelani River is Rs 0.95 per cubic meter of water; downstream, it is Rs 1.35.
The ADB has predicted that, as the population in Colombo City has increased to 772,000, domestic demand for water will increase by more than 2.9 million cubic meters/year, representing more than 5% of the water supply currently available to all users.
Turbid (less clear) water requires more refining. The average annual turbidity and nitrate load at Hanwella Bridge was so heavy that the chemical cost per unit production of drinking water in the downstream water supply schemes of Ambatale and Biyagama was drastically higher, Mr Wijesinghe reports.
At the Koduwattuwana treatment plant in the Ampara district, the chemical cost for the production of a cubic meter of water is Rs 3.30 as the raw water contained high algal and cyanobacteria counts owing to excessive nitrate and phosphate levels arising from “excessive use of agrochemicals”.