As OASE III PTKIN 2026 entered its third day at UIN Sunan Kalijaga Yogyakarta, many competition categories were still underway. One of them was Ecotheology: Waste and Environmental Management, held in the Theatrical Hall of the Faculty of Social Sciences and Humanities. In this competition, students from eight campuses presented a range of work that links religious values with efforts to address environmental problems.

From the use of palm kernel shells to the treatment of batik waste and the management of ablution (wudu) water, the entries showed how students at State Islamic Higher Education Institutions (PTKIN) can translate environmental concern into designs for materials, technologies, and management systems. The value of human responsibility as a steward of the earth served as the foundation for exploring solutions to problems close to people's daily lives.

The UIN Sulthan Thaha Saifuddin Jambi team, for example, presented ECOPALM ROSTER, an innovation that processes palm kernel shell waste into eco-friendly roster (decorative ventilation) blocks. Meanwhile, students from UIN Sunan Kalijaga Yogyakarta developed Granobara, granules made from rice and bone waste to support sustainable agriculture, grounded in the value of anti-israf, or avoiding wastefulness.

The UIN Ar-Raniry Banda Aceh team turned its attention to kitchen waste with MAZA TECH. This work offers a dual-output grease trap integrated with a dish soap made from senduduk (Indian rhododendron). It was developed to mitigate pollution and support sustainable kitchen waste management based on environmental jurisprudence (fiqh).

Students from UIN Maulana Malik Ibrahim Malang offered a digital approach with MIU-CONNECT, a collaborative platform that integrates an Internet of Things (IoT)-based smart waste scale to support a circular economy for waste management in Islamic boarding schools (pesantren). The UIN Siber Syekh Nurjati Cirebon team presented Berkasih Smart, an integrated artificial intelligence-based system for optimizing waste management and the circular economy.

Two other campuses focused on water use in mosques. Students from UIN Raden Mas Said Surakarta developed ECO-WUDHU GOVERNANCE, a model for managing ablution water based on fiqh al-bi'ah (environmental jurisprudence), using audits of water use and prioritization of water usage in urban mosques.

UIN Sultan Maulana Hasanuddin Banten, meanwhile, proposed Smart Eco-Masjid as a living laboratory for ecotheology. The model combines artificial intelligence and IoT (AIoT), aquaponics, and gamification to support water conservation and the circular economy.

Among these works, the UIN Kiai Ageng Muhammad Besari Ponorogo team started from the problem of batik production waste. With ECO-RETOX, short for Ecotheology for Textile Waste Reduction, they developed a filtration system based on local biomass, linked to a process that turns the used biomass into briquettes.

Batik is both an Indonesian heritage and a livelihood for many people. But sustaining its production also requires attention to the waste it generates. Without proper management, that waste can damage the environment around production sites.

That problem led Indra Tri Rahayu, Rehan Putra Candra, Siti Mas Ayu Miftahurrohmah, Aliyya Safira Kahla, and Elza Cahyaning Maharani to develop ECO-RETOX. They wanted to offer a waste treatment approach that supports batik production while protecting the environment.

"Local biomass is used as the filtration material. After use, the biomass is processed again into briquettes. With this design, we try to extend the usefulness of the materials and reduce what gets thrown away," said Elza, a member of the team.

Another team member, Indra, added that the innovation is tied to the values of khalifah (stewardship) and amanah (trust), anti-fasad (the prohibition against causing corruption or destruction), and anti-israf (the prohibition against wasting resources). As stewards on earth, humans are seen as responsible for sustaining life.

These values became the basis for deciding how the innovation works. The responsibility to protect the environment is carried out through waste treatment, while the effort to avoid waste is realized by finding further uses for the used biomass.

To reach the final presentation, the five students went through material exploration, product trials, and testing. They then compiled the results in a written paper, which was approved for presentation in the competition.

"We will keep refining ECO-RETOX, in terms of both materials and equipment. We also want to develop the device toward a larger, industrial scale. To get there, further development and testing are an important part of our work's journey," said Aliyya.

Through the Ecotheology: Waste and Environmental Management category, these abilities found a place to be presented and examined. Starting from problems close to the community, PTKIN students are pioneering ideas so that the responsibility to care for the earth can be put into practice in how waste is treated, how water is used, and how resources are protected. (humassk)