Before the sun rose, six ADDU scientists and engineering technicians made their way to Sitangkai, an island off mainland Mindanao, on 12 November 2023. This contingent traveled with six solar panels, a combiner box, batteries, and wires, acrylic boards, pipes, and tubes, as well as steel bars and a four-wheeled steel base.

The ADDU mission was straightforward and sincere: help alleviate water and energy poverty in Sitangkai through solar powered desalination—the process of removing salt from seawater using solar energy, thereby producing clean and potable water for the community.

Water, water everywhere, and not a drop to drink
The Municipality of Sitangkai in the Province of Tawi-Tawi is surrounded by water, but it does not have potable water sources. Drinking water on this island comes in blue gallons or single-use plastic bottles that ride in boats coming from Sandakan in nearby Malaysia or Bongao in Tawi-Tawi. Water is one of the most basic needs of the 12,000-strong Sitangkai community that is headed by Municipal Mayor Hon. Tiblan C. Ahaja.

Houses on stilts over water
Sitangkai is a seaweed farming community that also engages in fishing and trading. It is peopled by Samas, Tausugs, and migrant families, some coming from as far as Cebu. The Sama Dilauts still make oars and nine kinds of boats using traditional tools. They used to live in big boats called lepa, which are related to the Butuan balangay. But these days, like the Sama Dileyas, they erect their houses on stilts over water, park their boats astride wooden stands, and build community using bridges that connect with households and with land masses.

Seawater into drinkable water
One such bridge leads to a Covered Court, which has a gravelly area right next to water. The area is known as Purok 2 of Barangay Datu Baguinda Putih (Datu Putih for short). This is the site that the community chose for the installation of a solar still—a machine that uses solar energy to remove salt from seawater. It purifies seawater and produces desalinated drinking water.

The ADDU team assembled the machine in record time. The base, posts, and panel frame were set up; then the solar panels were fixed, as well as the combiner box. The batteries were put in place, and the wires were connected in a series. The pipes and tubes were attached. Finally, the acrylic harvester was set on top, like a crown. Thus was the Mini Portable Solar Still (MPSS) put together.

This is the way it works: Seawater is pumped into the system. The heat from the sun warms up the water, turning it into vapor. The system condenses it back to water, but this time without the salt.

“The solar panels absorb energy from the sun, which is stored in batteries. At night, the batteries power a heater to warm water up,” chemical engineer Christian Mark Labiano said.

“The MPSS is a 3-kW solar photovoltaic renewable energy system that produces potable water 24/7,” Fr. Antonio M. Basilio, SJ, PhD said. It does its job during the day and all throughout the night.

Basilio leads “Renewable Energy Community Desalination Systems” or RECoDeS, a project undertaken under the aegis of ADDU’s Center for Renewable Energy and Appropriate Technologies (CREATE) and the Mindanao Renewable Energy R&D Center (MREC) with Doris B. Montecastro, PhD and Renyl B. Barroca, PhD. Both CREATE and MREC are under the School of Engineering and Architecture (SEA). Fund support is from the Department of Science and Technology (DOST).

“Inspired by the ADDU Vision and Mission, the RECoDeS team does research that develops appropriate technologies and adapts these to the local context of communities that need services the most,” Basilio added.

Much improved versions
To supply drinking water to the people of Sitangkai, Tawi-Tawi, Basilio’s team improved upon a basic solar still designed by the Universiti Teknologi Petronas (UTP) of Malaysia. The ADDU system was tested and retested at the ADDU Jacinto Campus and on the Island Garden City of Samal. It features significant additions to the UTP design, including a multi-stage cycloidal solar still (MCSS).

“The MCSS increases the condensation rate of water for better collection of potable water,” chemistry faculty and RECoDeS team member Ed Ivan Bardoquillo said. 

“As of last testing, the solar still can produce a 5- to 7.5-liter water yield,” Chemistry Analytical and Research Laboratory (CARL) researcher Joshua Johnn Carballo said. Carballo designed the MCSS, which was 3D printed into existence.

The other RECoDeS team members are SEA technicians and fabricators Zaldy Mendoza, Vicente Surada, Jr., and Darwin Magdugo.

The system that the interdisciplinary team built needs just three things: one, clean seawater to be loaded onto the system; two, sunlight to produce clean drinking water; and three, community members to do maintenance checks while they collect the drinkable water to serve the families on the BARMM island of Sitangkai every day.

Stakeholder training
To ensure that the system serves the community the way it was designed, eleven representatives from the nine Sitangkai barangays were trained to operate, monitor, maintain, and repair the solar still.

Labiano explained the science behind the solar still, and Bardoquillo discussed the still’s parts and functions. Both led the training participants to a demonstration and a question-and-answer session at the site with Carballo and Mendoza.

Giving and receiving
Before the sun went down and the MPSS’s stored solar energy kicked in, the two solar still systems were turned over to Sitangkai Municipal Councilor Hja. Merilyn A. Joe, along with the operation manuals and two spare solar panels.

“Alhamdulillah! Kami po ay nagpapasalamat sa inyo,” Hja. Joe said.

Also present were RECoDeS project partner representatives, Dahlia P. Burias and Abdel-Azeem M. Alsim of the Mindanao State University – Tawi-Tawi College of Technology and Oceanography (MSU-TCTO). 

“The hope is that the desalination systems can contribute to the community drinking water supply, especially to those who can’t afford to buy water regularly,” Labiano said.

Other project partners who extended help to the RECoDeS team are the Philippine Coast Guard Station Central Tawi-Tawi and the Provincial Government of Tawi-Tawi.

Moving forward
The day after system installation, on 13 November 2023, Sitangkai resident and training participant John H. Rasdim collected water from the system, drank it, and confirmed that the system works.

Moving forward, the RECoDeS team is checking into the possibility of producing more stills for other communities that might need help, just like Sitangkai.

ADDU engineering technician and fabricator Zaldy Mendoza connects a wire to one of the breakers inside the combiner box of the ADDU-enhanced Mini Portable Solar Still (MPSS). The new MPSS contains significant additions to the design of the Universiti Teknologi Petronas (UTP) of Malaysia.
ADDU technicians Vicente Surada, Jr. (left) and Darwin Magdugo prepare the wires to connect the batteries to the breakers and then to the inverter in a combiner box. The 3-kW solar PV renewable energy system produces clean potable water from clean seawater round-the-clock.
The ADDU-enhanced solar still deployed in Sitangkai features a multi-stage cycloidal solar still (MCSS). “This device increases the condensation rate of water for better collection of potable water,” chemistry faculty member Ed Ivan Bardoquillo said.
Chemical engineer Christian Mark Labiano explains the science behind the Mini Portable Solar Still (MPSS) that the RECoDeS Team installed at Barangay Datu Baguinda Putih in Sitangkai, Tawi-Tawi. The participants are members of the seaweed farming communities on the BARMM island.
To ensure that the participants have the knowledge and skills to operate, monitor, maintain, and repair the solar stills, Chemistry Department faculty member Ed Ivan Bardoquillo gives a rundown of the system parts and functions.
Participants of the training on Renewable Energy Community Desalination Systems (RECoDeS) mark the end of the session before proceeding to the installation site. Sitangkai technician and trainee John Rasdim (center) holds a PhilStill, a household solar still. Also present are RECoDeS project partner representatives, MSU-TCTO’s Ms. Dahlia P. Burias and Mr. Abdel-Azeem M. Alsim (front row, leftmost).
Team RECoDeS after the system installation in Barangay Datu Baguinda Putih, Sitangkai, Tawi-Tawi. (From left): Zaldy Magnaye, Ed Ivan Bardoquillo, Engr. Christian Mark Labiano, Joshua Johnn Carballo, Darwin Magdugo, and Vicente Surada, Jr. Led by Fr. Antonio M. Basilio, SJ, PhD and supported by Doris B. Montecastro, PhD and Renyl B. Barroca, PhD, this interdisciplinary team is composed of chemistry researchers and faculty members, electricians, fabricators, chemical engineers, and engineering technicians working under ADDU Center for Renewable Energy and Appropriate Technologies (CREATE) and the Mindanao Renewable Energy R&D Center (MREC) with support from the Department of Science and Technology (DOST).
Sitangkai, Tawi-Tawi residents navigate around the municipality on various types of boats. They help bring the acrylic harvester from the pier to the installation site.

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