The state of Nitrogen, Phosphorous and Potassium during Anaerobic Digession
You're the man who grows coconuts and had a small problem with mimosa plants which you now intend to compost. Don't forget that coconut fronds blown down by the wind and any other waste products from the palms can all go into your compost. In England, earthworms are highly valued in the compost heap, as they help the vegetation break down more efficiently, but I'm not sure how available worms are in Mangalore. If you have a machine that can chop your mimosa cuttings into tiny pieces, that will also help them to compost. Some of the nitrate produced by their roots will find its way to your coconut palms if they are nearby.

Yes, there will be nitrate, phosphate and sulphate in your compost, especially nitrate manufactured by the roots of your mimosa plants. Anaerobic composting still leaves nitrates, phosphates etc in the final product, but also creates methane, which is a very potent greenhouse gas best not released into the atmosphere. The compost also requires an airtight container, so your worms would be suffocated. If your compost is of sufficient quantity to make it worth while, you could tap off the methane and use it as a fuel for cooking. 

I think the aerobic process would be best suited to your needs, therefore your compost heap will need to be well aerated. Make a bed of twigs to  build your compost heap on, and that will let air in underneath. You will also need to turn the compost over occasionally to let more air in. Aerobic composting does not produce methane. If you see a thriving population of worms in your compost, things are going well.