Population growth rates and levels of urbanisation in the Southeast Asian region have kept pace with the region’s economic development. However, these developments have been accompanied by dwindling surface water resources and excessive exploitation of groundwater reserves across the region. Therefore, government bodies today face the daunting task of delivering adequate quantity of freshwater to every household. The lack of adequate fresh water supply has not only caused inconvenience to citizens but also imposed a negative externality on the environment by way of depleting groundwater reserves.

Today, the surge in demand for assured water supply is forcing most municipal agencies and industrial entities to look beyond conventional sources of freshwater supply. Accordingly, desalination has been identified as a key technology to address the ever-rising water demand and to ease escalating the paucity of water, both in terms of quantity and quality. Some Southeast Asian economies have already deployed desalination plants to reduce reliance on freshwater sources. Singapore has installed two desalination plants with a total capacity of 100 million litres per day (mld). In Indonesia and Thailand, a number of industrial players have set up desalination plants to meet their process water requirements. The Philippines and Vietnamese governments have also set up small-scale desalination units to provide potable water to remote islands and rural areas. However, barring Singapore, the majority of the countries have set up very small capacity plants with limited coverage and scope for expansion.

Given the low penetration rate (of desalination) at present, Southeast Asia offers huge potential for desalination, especially for industrial users such as thermal power plants, steel companies, nuclear power stations and oil refineries.

Technology options

The two basic technologies that are used for desalination plants are membrane based and thermal based. Membrane-based technologies include reverse osmosis (RO) and electrodialysis, and thermal-based technologies include multistage flash evaporation, multi-effect distillation, multistage flash distillation, and multistage vapour compression.

Among all the feasible technology solutions, RO is the most commonly used technology in Southeast Asia. Under RO technology, drinking water is produced by forcing seawater against a semi-permeable membrane, producing pure water on one side and concentrated brine on the other. Under this technology, the total dissolved solids (TDS) count of water produced is normally around 300 parts per million (ppm). According to the World Health Organization’s acceptable standard, the recommended TDS count for drinking water has been fixed between 300 and 500 ppm.

While RO technology dominates the desalination market in Southeast Asia, MED technology is also being used extensively by the industrial segment for simultaneous production of desalinated water and energy. As per industry estimates,  MED technology consumes lesser electricity (2.5-3 units per unit of water) in comparison to  RO technology.

Of late, there has been greater deployment of advanced technologies in the desalination market in Southeast Asia. Most notable among these are ultra-filtration membrane technology and electrochemical desalination module technology. These technologies offer the advantages of high quality treated seawater, reduced energy consumption and limited land requirement.

Current scenario

The desalination market in Southeast Asia is dominated by small-scale desalination plants that employ RO technology to treat water. Singapore is the most active desalination market in the region. The city-state has set up large-scale desalination plants to meet its drinking water requirements. While Indonesia, the Philippines, Thailand and Vietnam have also experienced a tremendous increase in desalination demand due to industrial growth, their markets are largely characterised by small-scale desalination plants that provide potable water to industries and small remote islands.

In other parts of the region, rapid urbanisation and population growth, and the surge in demand for assured water supply is leading to the overutilisation of surface and ground water resources. All these factors are forcing industrial entities and, in some cases, municipal agencies, to look beyond conventional methods, one of these being desalination.

Singapore

Singapore is the most active desalination market in Southeast Asia with a total desalination capacity of 100 mgd. Desalination of seawater has been an important component of Singapore’s long-term strategy for water self-sufficiency. Currently, Singapore meets about 25 per cent of its total water demand through seawater desalination. The proportion is expected to increase to about 30 per cent by 2030.

The city-state’s first desalination plant, the SingSpring desalination plant, was commissioned in September 2005. The plant has a capacity to treat 30 mgd of seawater. SingSpring Pte Limited, a wholly owned subsidiary of Hyflux Limited, constructed the facility under a design-build-own-operate agreement.

Hyflux has also constructed a second desalination plant in Tuas. The plant, which was operationalised in September 2013, produces about 70 mgd of potable water, thus increasing the city-state’s desalination capacity from 30 mgd to 100 mgd. The desalination facility also houses a power plant.

The plant has several distinguishing characteristics that make it more cost efficient in comparison to the SingSpring desalination plant. The Tuaspring plant’s compact design has reduced the footprint per cubic metre by more than 30 per cent as compared to the SingSpring desalination plant. The plant also holds the distinction of having one of the largest pretreatment ultrafiltration membrane facilities (318,000 cubic metres per day) in the world. Further, the plant uses the Hyflux’s advanced Kristal ultrafiltration membrane technology for the pretreatment process, which offers better water quality, ease of operation, lower operating cost, and smaller footprint.

Further, the Public Utilities Board (PUB), Singapore’s national water agency, is setting up a third desalination plant of 30 mgd capacity in Tuas. The plant is being constructed by HSL Constructor and is expected to be completed by 2017. In December 2016, PUB awarded the contract for construction of the fourth desalination plant in Marina East to Keppel Infrastructure Holdings. The plant, with a capacity to desalinate 30 mgd of seawater, is expected to be completed by 2020. Singapore’s fifth desalination plant will be constructed at Jurong Island. Recently, in February 2017, PUB invited requests for proposal to construct the 30 mgd desalination plant from pre-qualified applicants – YTL Power International Bhd, Keppel Infrastructure Holdings Pte Limited, Sembcorp Utilities Pte Limited, and Tuas Power Limited.

Besides, Singapore has also developed a new water treatment technique, known as variable salinity, which involves the integration of the desalination and NEWater treatment processes to convert saline water into potable water. PUB has constructed a medium-scale demonstration plant of 1 mgd capacity at Sungei Tampines.

At the industrial level too, small-scale desalination plants have been constructed by a number of industries to meet their process water requirements. For instance, Senoko Energy Pte Limited has set up a 2,400 cubic metres per day desalination plant at its Senoko power station. Also, YTL PowerSeraya has built a desalination plant that produces 9,000 cubic metres per day for its plant and 1,000 cubic metres per day for domestic needs.

Indonesia

Although approximately 82 per cent of Indonesia’s total population has access to improved sources of water (contamination-free), only about 20 per cent get piped water supply. The remaining population does not have access to safe drinking water sources.

Population growth and groundwater depletion has forced the Indonesian government to actively support desalination projects to meet current water requirements. Apart from low water supply, the country also suffers from low water quality. Due to the shortage of safe drinking water and the continuous decline in quality, about 13 per cent of the population relies on bottled water for meeting their drinking water requirements.

Given Indonesia’s long coastline, desalination is considered one of the most viable water supply alternatives for the country. Over the years, there has been a tremendous increase in desalination demand across Indonesia as a result of the country’s rapid industrial growth. Large industrial players in the country are setting up seawater and brackish water desalination plants for producing high quality process water. Most of the established projects cater to industrial water requirements, primarily for thermal power plants. A significant number of thermal power plant operators in Indonesia have established cogeneration desalination units to meet their requirements.

The majority of these cogeneration desalination plants deploy MED technology to desalinate seawater. Besides, there are smaller facilities too that deploy the MSF process for desalination. Over time, the use of MED technology has increased as it is more energy efficient as compared to MSF.

At the municipal level, a number of small-scale desalination plants have been constructed to provide drinking water to remote areas or islands in the country. These small-scale plants predominantly use RO technology to treat seawater. Most of these plants have a capacity of less than 10 mld.

The Philippines

The Philippines has abundant raw water sources including inland freshwater (rivers, lakes, and groundwater), and marine (bay, coastal, and oceanic waters) sources. However, access to clean and adequate water remains an acute seasonal problem in urban and coastal areas in the Philippines.  In Manila alone, most residents rely on water delivery trucks to provide fresh water for various potable and non-potable uses.

Owing to the country’s long coastline, desalination is considered one of the most viable water supply alternatives. Within the industrial sector, desalination projects have been set up primarily to meet the water requirements of thermal power projects. Like Indonesia, a number of power plants in the Philippines have established cogeneration desalination units. Most of these desalination units use RO technology for seawater desalination.

At the municipal level, both bigger cities such as Manila and Cebu and islands like Bohol and Luzon have set up small- to medium-scale desalination plants to meet their freshwater requirements. The desalination plants set up in Manila and Cebu have capacities in the range of 20-30 mld. On the other hand, the smaller islands have plants with capacity ranging between 300 and 500 cubic metres per day or less.

Thailand

The primary sources of drinking water in Thailand are surface and ground water. However, salinisation is a major concern in the northeast and southern parts of Thailand, particularly along the coast. Salinisation is primarily caused by the intrusion of saline water into aquifers due to excessive groundwater withdrawals.

To address this issue, areas with scarce fresh water are using technologies such as RO to desalinate brackish water and seawater in the coastal zones. The small-scale desalination plants with installed capacities of 1 mgd or less primarily serve small or remote islands. In addition, industries such as power, oil and gas, food and beverage, electrical and electronics have set up medium-scale desalination facilities to meet their freshwater requirements. While the capacity of larger plants is in the range of 10-15 mld, the smaller ones are of less than 500 cubic metre capacity.

Vietnam

Although Vietnam has made rapid progress in improving water supply services over the past decade or so, many parts of the country, especially heavily populated areas, remote rural communities and islands, still face acute water shortage. Given the increased scarcity of fresh water and growing demand for water from the agricultural, industrial and municipal sectors, desalination is considered a viable option for the country.

The demand for desalinated water comes from both industrial and municipal segments. At the municipal level, small-scale desalination plants have been set up to provide freshwater supply to remote islands and rural areas. Most of these plants use RO technology to covert seawater into potable water. Within industry, a number of power plants house desalination units to meet their process water requirements. These desalination plants largely deploy MED technology to treat seawater.

The way forward

The promise of desalination of seawater and brackish water to meet the growing industrial and municipal requirements is slowly beginning to be realised and accepted in the Southeast Asia region. Most countries in the region are augmenting their existing desalination capacities and installing new units to meet future water demand.

The desalination market in the Southeast Asia region is currently placed on a high-growth trajectory. It is gaining prevalence as industries such as power, refineries and chemicals continue to adopt efficient and sustainable desalination technologies for the regular supply of freshwater.

Going forward, with the development of new and more advanced technologies such as ultra-filtration membrane technology, electrochemical desalination module technology and solar desalination, the cost of desalination is expected to decline. However, RO will continue to be the preferred technology route for executing desalination projects in small and remote municipal areas, at least in the short run. That said, desalination can have an adverse impact on the environment through brine discharge. Moreover, it requires large quantities of power. These factors have to be weighed against the benefits of using desalination to provide treated water.