अपशिष्ट जल में द्वितीय-चरण जैव-रासायनिक ऑक्सीजन मांग (BOD) को इस नाम से भी जाना जाता है:

Turbidity in water is measured on which standard scale?

Mudball formation in rapid sand filters is the result of:

In a water sample, if 2 mg of platinum cobalt salt is dissolved in 1 litre of distilled water, then the colour produced is equal to: