NOVELTY - A feed pump (14) is provided to supply sample from the incoming fluid flow into a container. The sample is injected with bacteria selected to enhance the performance of the plant, and the sample is retained for a time period, so that bacteria is cultivated within the sample. An outlet pump is arranged to return the cultivated bacteria in the sample, to the incoming liquid flow.    USE - For improving performance of liquid treatment plant e.g. waste water treatment plant.    ADVANTAGE - Pre-digestion of fats, oils and greases by reducing channel, tank and pipe blockages is performed. Improves sludge settlement characteristics, reduced biological oxygen demand loading to sludge plant and reduces fog. Improves denitrifying characteristic, sludge compaction in sludge consolidation tanks, solid/liquid separation in the digester, gas production by volume and return liquors to plant. Reduces sludge volume for disposal, temperature fluctuations in digester and energy input to digester. Is possible to increase capacity of complex inflexible engineered system and improves sewage treatment plant without major refurbishment of plant and portable assembly.    DETAILED DESCRIPTION - The feed pump and outlet pump are connected to the container containing single tank (9). Sensors (12,13) are provided for monitoring liquid level within the tank. A dosing valve (15) is provided for controlling the outlet pump, to pump liquid from the tank at relatively low rate. The feed pump is energized and de-energized to pump liquid at relatively high rate, when the monitor liquid level falls and rises to a predetermined lower and higher levels, respectively. The breeder tank and dosing tank are respectively connected with feed pump and outlet pump for transferring liquid from the breeder tank to dosing tank. The liquid level sensor is arranged to turn OFF the outlet pump, if the liquid level in the tank to which the outlet pump is connected falls below a predetermined limit. The circulating tank is provided for circulating liquid within the tank. A recirculation line is provided for recirculating pumped liquid from upstream of the dosing valve to the tank to which the outlet pump is connected through the dosing valve. The dosing valve is fully opened to reduce the risk of blockage. The outlet pump is connected to recirculating line in which a throttle valve, balance valve and purge valve are connected in series. The purge valve is closed to reduce the risk of blockage. A dispenser is arranged to dispense a predetermined dose of bacteria by energizing the feed pump and a strainer is arranged to receive the bacteria from the dispenser and the sample from the feed pump, so that cultivated bacteria returns liquid to flow upstream of the settlement tank in sewage treatment. An INDEPENDENT CLAIM is included for method for improving performance of liquid treatment plant.    DESCRIPTION OF DRAWING(S) - The figure shows the schematic view of the tank.    Single tank (9)    Sensors (12,13)    Feed pump (14)    Dosing valve (15)