Part 4/8:

The tour moves on to reveal the complex interplay of waste processing systems, beginning with the deep-sea tunnel sewage system. Wastewater, including sewage from various parts of the city, is channeled through elaborate pipelines and eventually processed at specialized facilities. The mention of "dry sludge" and "coffee beans"—possibly a metaphor or a visual analogy—illustrates the immense volume and diverse nature of waste materials processed in Singapore.