Which of the following statements are correct?

I. The solids that settle down after the primary treatment of sewage form the primary sludge, while the liquid portion is called the effluent.

II. The spent slurry from a biogas plant is utilized as fertilizer.

Which of the above statements are accurate?

I and II

The correct answer is Option (2)- I and II

I. After the primary treatment of sewage, the solids that settle down form the primary sludge, while the liquid portion is referred to as the effluent. During the primary treatment process, large particles and solids are removed from the sewage through processes such as sedimentation and filtration.

II. The spent slurry from a biogas plant, which is the residue left after the production of biogas, can be used as a fertilizer. The slurry is rich in organic matter and nutrients, making it suitable for enhancing soil fertility and promoting plant growth.

These statements highlight important aspects of wastewater treatment and the utilization of byproducts from biogas production. The primary treatment helps separate solids from the wastewater, reducing the organic load, while the spent slurry from biogas plants can be recycled as a valuable resource for agricultural purposes.