Explanation: The presence of iron in water is usually indicated by the colour of water. This is usually brown in colour. In some cases, this is usually reddish brown in colour.

Explanation: The Iron is removed by oxidation. The iron is usually present as a ferrous compound. This is usually oxidized to ferric compounds and is precipitated out.

Explanation: The safe limit for iron in water is 0.3 ppm. Excessive iron in drinking water can lead to digestive problems. This can cause nausea, vomiting etc.

Explanation: The safe limit for manganese in drinking water is 0.05 ppm. According to EPA, manganese concentration is not a concern unless and until it is 10 times the safe limit concentration. Presence of manganese can be found by an impairing colour, odour and taste to the water.

Explanation: The method used to delay the precipitation of oxidized manganese and iron is adding phosphate. This is effective when the water contains less than 0.3 ppm of iron. This is also effective when the water contains less than 0.1ppm of manganese.

Explanation: 0.14 ppm is required to oxidize 1 ppm of iron. Ferrous compounds are oxidized to ferric compounds. This is then precipitated out.

Explanation: 0.27 ppm is required to oxidize 1 ppm of iron. Manganese can be oxidized by chloride. This can also be oxidized by permanganate.

Explanation: Activated carbon is not used in the removal of arsenic. Activated alumina is one of the methods to remove arsenic. Green sand and coagulation by Iron hydroxide is also one method to remove arsenic.

Explanation: The most expensive method to remove arsenic is green sand. The total cost includes capital cost. This total cost also includes operational and maintenance cost and waste disposal cost.

Explanation: Tehonoarz is the most efficient method to remove arsenic. Activated alumina is the second most efficient method to remove arsenic. Green sand is the least efficient method to remove arsenic.