Which of the following is true about composition of waste water?
(A) Suspended solids e.g. Sand, silt and clay - 0.1%
(B) Colloidal material e.g. Faecal matter, bacteria, cloth and paper fibres - 0.1%
(C) Dissolved materials e.g. Nutrients, (Nitrate, Ammonia, Phosphate, Calcium) - 0.1%
(D) All of the above together constitute 0.1% of the waste water

Options

A. A, B, C, D
B. A, B, C
C. B,C
D. D

Answer

To determine which statement is true about the composition of wastewater, we need to analyze each option provided in the question.

**Step 1: Understand the components of wastewater.**
Wastewater typically contains various impurities, which can be categorized into three main types: suspended solids, colloidal materials, and dissolved materials.

**Step 2: Analyze each option.**
- **Option (A)** states that suspended solids (e.g., sand, silt, and clay) constitute 0.1% of wastewater. This is incorrect as the total impurities are not solely represented by this percentage.
- **Option (B)** mentions colloidal materials (e.g., faecal matter, bacteria, cloth, and paper fibers) also constituting 0.1%. Like option A, this is misleading because it does not represent the total composition accurately.
- **Option (C)** refers to dissolved materials (e.g., nutrients such as nitrate, ammonia, phosphate, and calcium) also being 0.1%. This is similarly incorrect for the same reasons as above.
- **Option (D)** states that all of the above together constitute 0.1% of wastewater. This option is correct because the total impurities in wastewater are indeed around 0.1%, which includes the contributions from suspended solids, colloidal materials, and dissolved materials.

**Step 3: Conclusion**
Based on the analysis, the correct answer is **(D)**: All of the above together constitute 0.1% of the wastewater.

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