PART C: Reading Comprehension
Directions: Read the following passage and answer the questions by choosing the best choice (1), (2), (3), or (4). Then mark the correct choice on your answer sheet
Sewage pollution is a global issue, but it is often most severe in regions without suitable sanitation infrastructure. In many developing countries, large volumes of wastewater are discharged untreated into rivers, lakes, and coastal waters due to limited funding, rapid urbanization, and lack of access to modern sewage systems. According to the UN, in some of the world's least developed countries, over 95% of wastewater is released into the environment without any treatment. In India, for example, less than 30% of sewage generated in urban areas is effectively treated, leading to widespread contamination of rivers like the Ganges.
In rural areas without access to the public sewer system, individual properties often rely on septic tanks. These are small-scale systems that separate solids from liquids and allow partial treatment on site. However, without regular maintenance or proper siting, septic tanks can leak pollutants into the surrounding soil and groundwater. After treatment, the leftover sludge from the primary and secondary stages undergoes further treatment to make it safe for disposal or reuse. Depending on the facility, it may be digested, composted, incinerated, used as fertilizer in agriculture, or sent to landfill.