NOVELTY - Water source heat pump and sludge digestion integrated system comprises a gravity sludge concentration tank (2), a water pump (13), a water source heat pump unit (3), a water heating device, sludge digestion tanks and a marsh gas generator (11). The water inlet of the water pump is connected with a sewage treatment device. The water pump is connected with the water source heat pump unit. The water source heat pump unit is connected with a mud-water heat exchanger. The sludge outlet of the sludge gravity concentration tank is connected with the sludge inlet of the mud-water heat exchanger.    USE - Used as a water source heat pump and sludge digestion integrated system.    ADVANTAGE - The system ensures comprehensive utilization of water, heat and energy of sewage treatment plant and hence greatly improves energy conservation, emission reduction and sludge treatment effect and is environment-friendly.    DETAILED DESCRIPTION - Water source heat pump and sludge digestion integrated system comprises a gravity sludge concentration tank (2), a water pump (13), a water source heat pump unit (3), a water heating device, sludge digestion tanks and a marsh gas generator (11). The water inlet of the water pump is connected with a sewage treatment device of the sewage treatment plant. The water pump is connected with the water source heat pump unit via a filter. The hot water outlet of the water source heat pump unit is connected with a hot water inlet of a mud-water heat exchanger. The sludge inlet of the gravity sludge concentration tank is connected to the discharging processed sludge port of the sewage treatment device. The sludge outlet of the sludge gravity concentration tank is connected with the sludge inlet of the mud-water heat exchanger, which is used for discharging heated sludge from the sludge inlet through the mud-water heat exchanger and for connecting with the sludge inlet of the sludge digestion tank. The sludge digestion tank is provided with a marsh gas outlet, which is connected to a gas supply pipe of the marsh gas generator by passing through a desulfurizing tower (8), a gas holder and a biogas pressure booster. The marsh gas generator is provided with a waste heat recycling device. The hot water outlet of the water heating device is connected with the hot water inlet of the mud-water heat exchanger. The cold water outlet of the mud-water heat exchanger by a circulating pump is connected with a cold water pipe of heat recovery device of the biogas generator and cold water pipe of water source heat pump unit. The electrical output of the marsh gas generator is connected with the power supply circuit of the sewage treatment device.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the water source heat pump and sludge digestion integrated system (Drawing includes non-English language text).    Gravity sludge concentration tank (2)    Water source heat pump unit (3)    Desulfurizing tower (8)    Marsh gas generator (11)    Water pump (13)