NOVELTY - Obtaining (P1) drinking water from a liquid fraction of human or animal faeces (3) involves purification of liquid fraction (8) using biological filtration process. The process further involves reducing ammonia content of liquid fraction. The step of reducing ammonia content involves storing liquid fraction in storage tank (10) prior to biological filtration process (18), mixing liquid fraction with porous granules in storage tank, and aerating granules/liquid fraction mixture to stimulate growth of bacteria on granules for effecting decomposition of ammonia by unit of bacterial culture.    USE - For obtaining drinking water from liquid fraction of human or animal faeces (claimed) useful in sewage treatment plant.    ADVANTAGE - The process increases the reusability of cattle manure; provides a simple purification method that can be used all over the world to make drinking water available; does not take place in the vicinity of the storage tank; does not replace the existing storage capacity for the liquid fraction of animal manure at farms by a storage tank; and creates suitable conditions under which bacterial growth can take place such that the ammonia-decomposition process can proceed efficiently enough.    DETAILED DESCRIPTION - Obtaining (P1) drinking water from a liquid fraction of human or animal faeces (3) involves purification of the liquid fraction (8) using a biological filtration process. The process further involves reducing the ammonia content of the liquid fraction. The step of reducing the ammonia content involves storing the liquid fraction in a storage tank (10) prior to the biological filtration process (18), mixing the liquid fraction with porous granules in the storage tank to provide a mixture where a bacterial culture is present on the porous granules, and aerating the mixture of the granules and the liquid fraction to stimulate the growth of bacteria on the granules for effecting decomposition of ammonia by unit of the bacterial culture. INDEPENDENT CLAIMS are included for the following:    (1) a bioreactor unit (B1) used in process (P1) involving a housing to accommodate porous granules, unit for mixing a liquid fraction with the porous granules and unit for aerating a mixture of the porous granules with the liquid fraction to stimulate bacterial growth in a bacterial culture present on the granules, for biologically decomposing of ammonia in liquid fraction;    (2) a storage tank is fitted with the bioreactor unit (B1) for carrying out the process (P1);    (3) growing a bacterial culture on porous granules used in the process (P1) involving mixing the porous granules with a sample of a liquid fraction of human or animal faeces and aerating the porous granules and the liquid fraction for growing the bacterial culture on porous granules.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic diagram of process for obtaining drinking water from a liquid fraction of human or animal faeces.    Faeces (3)    Liquid fraction (8)    Storage tank (10)    Biological filtration process (18)    Beaker (20)