Biomas CHP for powering the pump & providing heat to domestic purpose
Low cost pump

Solution

The Plan is to pwer the pump using a gas powerd pump & the cogeneration heat produced by the gas is  used to maintain the temperature of the digester and also to power the domestic water heater.

We can use a 1 hp pump which can produce 10000 liters per hour. To run the system for 4 hours we require 2 meer cube of gas. This gas can be produced with 5 kg cow dung per day.       
The cost of the pump , biogas Digester , and the CHP plant will be within 1 lakh rupees.