Story
The area in front of the Purifying Altar is so heavily contaminated that dedicated purification devices have been set up, but they have since ceased working properly. Gather the necessary repair materials and fix the device.
After completion (spoilers)
"We have been using the very same purifying devices to contain the contamination, but they've been broken." The area in front of the Purifying Altar is so heavily contaminated that dedicated purification devices have been set up, but they have since ceased working properly. You gathered the necessary repair materials and fixed the device. Since it was crafted by Zumion's Priests, you knew it would work effectively.