Belgian know-how to come to grips with saline intrusion in Mekong Delta

December 09, 2021 | 10:18
Each year, saline intrusion becomes a larger problem for the Mekong Delta – and it is now reaching critical levels threatening the sustainable development of Vietnam’s food basket. The crisis requires a long-term strategy with a desalination system in place to help replenish exhausted ecological resources. Company Smart Universal Logistics (SUL) is now testing several systems to keep the good water cheap and affordable of the farmers.
Belgian know-how to come to grips with saline intrusion in Mekong Delta
Belgian know-how to come to grips with saline intrusion in Mekong Delta

The saline intrusion would come sooner in the Mekong Delta during this dry season (from November 2021 to early May 2022) and would be worse than in previous years, warned the Department of Water Resources Management under the Ministry of Natural Resources and Environment. Saltwater intrusion is forecast to reach 2015-2016 levels when the water level of the Mekong fell to its lowest since 1926 and the severity of saline intrusion reached a 100-year record.

According to the department, saline intrusion in this dry season would affect 210,000 hectares of rice, orchards, and rice-shrimp fields in the region. At its peak, saltwater intrusion will likely affect 60,000ha of rice fields in the coastal provinces, including 11,900ha in Tien Giang, 12,000ha in Ben Tre, 15,000ha in Tra Vinh, and 20,000ha in Soc Trang.

Meanwhile, 43,300ha of fruit growing areas would be affected, including 3,100ha in Long An, 21,800ha in Tien Giang, 16,000ha in Ben Tre, and 3,400ha in Soc Trang. Around 107,400ha of integrated rice-shrimp fields would be hit in Kien Giang, Ca Mau, Soc Trang, and Bac Lieu. By 2050, it is estimated that agricultural output may decline by 30 per cent, equalling damages of VND12 trillion ($521.74 million) due to desalination.

For the long term, Vietnam is one of the countries suffering from desalination, with 2016 setting a new 100-year record in the severity of salt intrusion for the country. At the time, the water level of the Mekong River had gone down to its lowest level since 1926, leading to the worst drought and salinisation there.

Pioneering desalination

Sounding the red alert over saline intrusion, cities and provinces in the region have been rolling out urgent solutions.

In recent years, the delta, which includes Can Tho city and 12 provinces, built and upgraded saltwater prevention sluices and dams, dredged canals and irrigation works to store more fresh water, and instructed farmers to store irrigation water in ponds and other water containers for use in the dry season.

It also adjusted growing schedules for rice crops such as starting rice crops earlier than normal or switching to drought-resistant crops in saltwater-affected areas in the dry season to avoid the shortage of water for irrigation. The delta also built and upgraded water supply facilities to ensure water supply for households in saltwater-affected areas.

Ben Tre province is eager to implement land clearance and compensation to develop a water management project worth VND6 trillion ($260.87 million). During the 5-year project duration, eight saltwater prevention gates and pumping stations will be built in various districts and Ben Tre town, the provincial capital. The project aims to control salinity on more than 200,000ha and generate freshwater to irrigate about 90 per cent of agricultural land in the province.

However, effectively resolving saline intrusion would require solutions that integrate local green power, and water desalinisation technology which can help not only turn the tide of saltwater intrusion but yield significant savings and promote sustainability.

Such an extensive and tech-enhanced approach would need support from countries with experience and the requisite know-how. Belgian small- and medium-sized enterprises have brought to Vietnam numerous advanced technology solutions and modern management methods to support agricultural restructuring towards sustainability and climate change adaptation. These solutions included remote sensing technology for sustainable land use, wind-powered desalination of water; and smart cold storage.

Coastal areas are often remote from adequate power grids, especially in developing countries. For such areas, Smart Universal Logistics (SUL) and its co-shareholder International Port Engineering and Investment (IPEI) have already developed and built the first desalination plant in Ninh Thuan. This first demonstration plant is extremely useful to analyse the interaction of a (discontinuous) windmill and a (continuous) electro-osmose. Starting from this first installation in Ninh Thuan, new systems of local green power supply are now being studied and tested, in some cases without windmill.

The innovative mobile desalination unit builds on SUL’s 20 years of experience in the port and renewable energy sector. The deployment of such systems of various sizes can provide poor and remote coastal areas with cheap water.

“The most popular desalination method is membrane osmosis, which comes with reasonable high construction, operation, and maintenance costs. The wind-powered water desalination plants are not only more climate-friendly than fuel-driven systems, they also create stable water supply,” said Marc Stordiau, managing director of SUL. “We are willing to help Vietnam identify and seek the most suitable financing sources for the development of such plants.”

To realise this commitment, in September 2020, the Ministry of Agriculture and Rural Development (MARD), the National Institute of Agricultural Planning and Projection, and SUL signed agreements on the implementation of a test water-by-wind unit of 20cu.m a day in the central province of Ninh Thuan, using official development assistance from the Belgian government. The wind-powered water desalination demo plant will be located at An Hai commune of Ninh Phuoc district.

The company is eager to develop the project this December and expects to complete the construction and installation in late February 2022. The demonstration project costs a total of $2 million, $600,000 higher than the initially calculated $1.42 million, with SUL paying approximately $1.2 million.

The demonstration plant includes four parts: an inland waterway barge, a power generation and storage unit, as well as a water production system and a central control unit.

After the trials in Ninh Tuan (whereby 10 farmers will get access to drinking water for themselves and their neighbours) the whole system will be operated by Mekong Plus, a non-governmental organisation supporting poor farmers in the Mekong Delta and Ninh Thuan.

If tests are successful, SUL believes they will be able to effectively address the freshwater shortage created by climate change and saltwater intrusion, providing access to potable water for everyday life and agricultural production in the region.

Besides, this ongoing project in Ninh Thuan, SUL and its shareholder IPEI are using these trials to try to lower the cost of the system and to make it more continuous, in order to keep the OPEX-cost of the membranes as low as possible. The new systems that are now being engineered will produce between 800 and 2000cu.m per day. One of the interesting options is a new European development with a small centrifugal Vortex pump that may replace the windmill and generate more continuity for the electro osmose plant.

“We want to come to the bankable concept for the machine in Vietnam by 2023 so that we could get a European Bank loan to invest in 5-6 larger types of machinery in the coming years. The exact locations will be determined with the help of provincial authorities, with the primary criteria being areas with no access to cheap drinking water mainly populated by poor farmers. The aim of this water project is not to make money but to make people’s daily lives easier,” Stordiau from SUL said.

“Once these green-energy-driven desalination plants are completed and operate stably, the model could be replicated in other regions along Vietnam’s long coastline. They will not only produce enough water for daily life but also to develop sustainable agriculture, the backbone of the Vietnamese economy,” Stordiau explained.

Long-term commitment

Vietnam and Belgium will continue their collaboration on localising green-powered water desalination stations in Vietnam, with about 200 stations installed along the south-central coast and in the Mekong Delta.

This was affirmed at the working visit of a Vietnamese high-level delegation headed by National Assembly Chairman Vuong Dinh Hue to the Kingdom of Belgium. During the visit, Vietnamese Minister of Agriculture and Rural Development Le Minh Hoan worked with local small- and medium-sized enterprises to boost cooperation, training, and technology transfer between the two nations.

“Vietnam encourages Belgian businesses to continue investing in the development of waterborne logistics in the Mekong Delta, utilising Belgian technology to connect the region’s fresh agricultural and seafood products to Cai Mep Port, Belgium’s Antwerp Port, and other major ports worldwide,” the minister said.

Besides, representatives of the MARD and SUL signed an MoU on collaboration in the development of wind-powered water desalination technology. The agreement was signed on the basis of the Ninh Thuan wind-powered water desalination model by the MARD’s National Institute of Agricultural Planning and Projection as part of the Vietnam-Belgium strategic cooperation on agriculture, which began in 2020.

In addition, during the signing event, representatives of T&T Group and SUL also signed an MoU on investment collaboration in the water-from-wind project. The primary goal of the agreement is to research and invest in a green power desalination system in Vietnam, while also surveying the requirements and implementing such green power system in regions afflicted by droughts and seawater intrusion. This is one of the initiatives that exemplify the MARD’s goal of localising and scaling up the green desalination concept in Vietnam.

Conclusions

This green power-driven desalination project is based on locally-produced green electricity with as much as possible continuity:

- Totally green;

- Contribution to the mitigation of impact of climate change;

- Customised to the region’s water demand, water quantity, and natural conditions;

- The technology can be exported worldwide;

- Highly reduced frequency start/stop cycles RO unit increases the lifetime of the membranes;

- Single power management control;

- Reasonable maintenance cost; and

- Comparison of windmill option with other solutions to produce electric power.

By Oanh Nguyen

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