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Published on July 30, 2007

After a year under construction, a Bt528-million state-of-the-art desalination plant using reverse osmosis (RO) technology was completed in Karon earlier this year by project contractor REQ Water Services.

After initial testing, however, it quickly became apparent that the local power grid was incapable of consistently supplying the power needed for the plant to run at full capacity.

Now the largest desalination plant in Thailand, the facility was built under a 20-year, build-and-operate contract with the Phuket Provincial Water Supply (PPWS), which agreed to buy 12,000 cubic metres of potable water daily from the plant at about Bt40/cubic metre.

Disruptions in the power supply to the RO plant, however, have left it incapable of producing the 12,000 square metres promised to the PPWS by REQ, which now faces fines for failure to meet the terms of reference (TOR) of its contract.

The most the plant has produced is about 9,000sqm per day, most of which is piped to the PPWS supply in Kata-Karon. Smaller volumes, 1,000-2,000sqm per day, are piped over the hill to Patong, another area that faces chronic water shortages all year round.

REQ general manager Jaturong Saduangkarn said the system in Karon consisted of a series of 24 pumps designed to bring the seawater to the very high pressures needed to force it through semi-permeable membranes. The heart of the RO process, these membranes are contained in hundreds of tubes that essentially serve as filters, allowing fresh water to pass through while restricting the passage of solutes.

Of the water treated, about 40 per cent emerges as pure water. The remainder is pumped back into Karon Bay through an effluent pipe that discharges about one kilometre offshore.

Jaturong said the plant had received the necessary permits to discharge effluent into the sea off the popular tourist beach and that subsequent studies of the area around the discharge point found no deleterious effects on the environment or water quality. But it should be noted that in countries such as the US the highly saline RO plant effluent is classified as industrial waste.

Working at full capacity, the Karon plant is designed to produce 500 square metres of fresh water per hour, or 12,000sqm a day. For the plant to run continuously, however, it needs a constant 380-volt electric supply.

Jaturong said the plant's power requirements were on the same scale as those of an entire district. Since operation began at the plant, REQ has been paying electric bills of "Bt1 million, Bt2 million or even Bt3 million in some months".

Although the company faces possible fines for breach of contract, REQ argues that instabilities in the power supply are a matter "beyond its control". When asked what measures the authorities planned to take for its failure to comply with TOR requirements, he said the case would need to be reviewed by the provincial government.

While the plant is currently the largest of its type in Thailand, an RO plant with double its production capacity is planned to go on line in Rayong province in two or three years, he said. That plant will have its own electricity-generating plant, he added.

PPEA head Suthep Jitseree said that after being informed about the power-supply problems his agency wrote to REQ advising it to install hi-tech imported timing devices.

As for the quality of the water being produced at the plant, PPWS manager Sayan Wareearoonroj confirmed it had been passed as potable.

While declining to answer how much REQ would be paid for the fresh water it produced while failing to fulfil the amount specified by the TOR in the contract, Sayan said that if the volume of RO water was insufficient to meet demand, it could be supplemented from other sources.

The problems facing the RO plant were discussed by Phuket Governor Niran Kalayanamit during a May 1 meeting he chaired at Phuket Provincial Hall.

The province intends to fine REQ for falling short of its production goal, he said. He did not specify the amount.

Sompratch Saowakhon,

Stephen Fein

Phuket Gazette

Phuket