NOVELTY - Separable fat contained in waste water is separated and reduced by biological break down with the aid of microbial liquid culture. The fat containing waste water is treated in a combined fat separator/bioreactor (1) with two different modes of operation, a separator function used during waste water addition and bio-reactor function used during remaining periods, alternately.    USE - For processing fat containing waste water released from dish washing machines and other cleaning in restaurants, bakeries and food processing industries (claimed).    ADVANTAGE - Fungus culture have higher tolerance for toxins and have higher reaction rates, thereby enables splitting of proteins, starch and fat. The system is very simple and reliable. The system does not demand pre-treatment of waste water. Instead needed decomposition and elimination of fat, for complete break down occur directly within the biological process under influence of the air injection. The air injection disintegrates the fat layer to make the fat easily available for the microorganisms, especially to increase the bio-availability of the fat, and to achieve efficient oxygenation, achieve an even microorganism distribution by good mixing, and even out pH variations. A combination of continuous separator function (during operative periods) and batch-wise bioreactor function (during the daily shut down) is enabled in the same container. This provides equipment for completing fats separator with the bioreactor function in a simple way. A simple tube pump is sufficient for dosing of bio-culture, as addition can be done via an open pipe which does not cause a pressure drop. Intense mixing causes elimination of toxicity. The process results more through break down of fat, and reduces the need for draining and simultaneously eliminates problems associated with fatty acids in the sewage works. By adding small amount of ammonia to the air used for oxygenation, growth conditions for the microbe species is improved. As the system demands no control of pressure drop in pipes and it is principally immune to disturbances due to choking in pipes and/or nozzles. Automatic operation control (time or flow control) is easily achieved by guiding system. The risk of poisoning is much lowered in the process, as reacting with organic material in the dirt eliminates chlorine compounds rather fast. This causes that addition of chlorine compounds does not poison the microorganism if the addition does not happen in close connection with the changeover from fat separator function to bioreactor function.    DETAILED DESCRIPTION - Separable fat contained in waste water is separated and reduced by biological break down with the aid of microbial liquid culture. The fat containing waste water is treated in a combined fat separator/bioreactor (1) with two different modes of operation, a separator function used during waste water addition and bio-reactor function used during remaining periods, alternately. The changeover from separator to bioreactor function is done by the addition of a liquid culture of microorganisms containing living bacteria and/or fungi and breaking down e.g. fat, proteins and starch, at which the liquid microbe is added and distributed by air injection in an intermediate layer between the sludge layer and the floating fat layer. The air injection continues after addition of microbe culture to sustain the bioreactor function. The changeover from bioreactor to separator function is done by shutting of the air injection.    INDEPENDENT CLAIMS are included for the following:    (1) process for removing and eliminating fat in waste water; and    (2) equipment for completing the fat separator    DESCRIPTION OF DRAWING(S) - The figure shows the fat separator which can be converted into a fat separator/bioreactor.    Container (1)    Fat zone (6)    Sludge zone (7)    Pipe system for the addition of liquid microbe culture to the separator (10)    Pipe system for air injection (11)    Perforated plates for air distribution (12)