CHEMICAL COMPOSITS

It indicates the state of sewage decomposition, its strength and type of treatment needed. Fresh sewage is little alkaline, but stale sewage is acidic in nature. Sewage water contains 0.08 to 0.1 %  of solids matter by weight. Solids may be suspended, dissolved and settle-able. which settle when sewage is allowed to remain undisturbed for a period of two hours.

Estimation  of 1,000 kg  sewage contains 0.45 kg solids  which is

• 0.225 kg is in dissolved form,

• 0.112 kg in suspension form

• and 0.113 kg settle-able form.

The solids in sewage composition of both organic about 40% and inorganic matter about 55%.