NOVELTY - Process (P1) for treating municipal solid waste (MSW) involves: (a) feeding waste material into a pressure vessel; (b) agitating the vessel while having steam pressure in the vessel; (c) depressurizing the vessel, and applying vacuum to the vessel; (d) discharging the vessel; (e) classifying the treated waste to obtain at least a fibrous fraction; and (f) treating the gas emitted during the application of the vacuum with a fluid to clean the exhaust gas from solid and volatile contaminants, by using a vacuum pump to achieve a vacuum of less than or equal to 0.8 bar (abs).    USE - For treating municipal solid waste (MSW) in an autoclave process, useful for making organic fiber based fuel, which is useful for providing the energy requirement of a power plant on site of the MSW treating plant for providing green electricity (claimed). The fibrous fraction is also useful in a gasification or pyrolysis process, as organic feedstock for aerobic digestion (biological conversion by microorganisms), as filler for medium density fiberboard (MDF) panels, and in a number of soil amelioration processes like decontamination, substitution, manufacture and composting applications.    ADVANTAGE - The method provides an improved method for treating municipal solid waste (MSW) by an autoclave process using air-waste stream treatment, that involves indirect heating with thermal fluid, forced steam transfer, autoclave design, waste treatment of contaminated air, and classifiers for better separation of fibers for glass or grit and processing. The improvements allow more efficient, safer, and environmentally friendly processing and better ed-products; as compared to the prior art processes. The fibrous end product formed meets part of energy requirements of a power plant, and provides green-electricity from renewable resources in an efficient and effective way, in view of the global warming. The step of creating vacuum in the vessel with a vacuum pump results in displacement of gas or vapor caused by moving part of the pump, compresses the gaseous fluid, and creates a lower inlet pressure applying vacuum to the connected system; as compared to the prior art use of eductor. The vacuum creation results in each batch having shorter cycle time compared to simply letting pressure off to atmospheric, no live steam is emitted, and vapors displaced during emptying the autoclave contain only extremely small concentrations of volatile organic compounds (VOCs). The method further involves treating the gas emitted during the application of the vacuum with a fluid (preferably process water that is recycled in the system) to clean the exhaust gas from solid and volatile contaminants, by using a vacuum pump, and in a scrubber to result a liquid stream that dissolves VOCs, condenses steam, and captures other contaminants; as compared to eductor that achieves only achieves single stage efficiency for gas-liquid contacting, uses much greater quantities of liquid (water) than the scrubber and requires that liquid to be provided at a much higher inlet pressure. The scrubber only requires a pump capacity of less than or equal to 200 m3 per hour, and a much lower pressure of 2 bar. Further optimization with respect to environmental burden is achieved when the washing water is recirculated. In the scrubber, steam is condensed, which increases the extraction rate of steam and/or air from the vessel. The use of process water allows keeping of as much of the dust and volatile components in the waste treating cycles, which is then broken down in a next cycle. The process water can also be used to wet the MSW material, and to produce steam within the vessel, and there is no need to use boiler quality feed water. The use of greater than or equal to 2 pressure vessels in an alternating fashion, by using steam from the discharge step for applying to another vessel, allows for efficient use of the vacuum pumps, as one pump or set of pumps can be used intermittently for the different vessels; and only one pump or set of pumps is needed for processing. The step of applying a vacuum after charging of the vessel, but before adding steam, more effectively increases pressure to obtain a fully saturated environment, and the air displaced by the vacuum pump which includes some VOCs is effectively cleaned in the scrubber; as compared to the prior art steam addition during loading to displace air, which requires emitting or handling of a large contaminated air steam stream to environment. The process further improves the energy consumption and/or the use of energy present in the process of treating MSW. This also increases the speed of steam transfer from one vessel to another, the time to discharge and to charge vessels is shortened, more efficient use of steam is made as energy losses are diminished, more steam can be extracted from the first vessel, less steam is necessary for fresh steam supply. The steam used for the direct steam injection is (more than 90%) and is derived from another pressure vessel used to treat waste; the amount of energy supplied during normal operation through (fresh) boiler steam is ( less than or equal to 25, preferably less than or equal to 10)%; and no fresh steam is supplied to at least one vessel during normal operation. The heating of the vessel is through indirect heating with thermal fluid, using conduits in vessel, and heated jacket; allows efficient use of available resources, and reduction or elimination of boiler steam and total thermal energy input. The average energy input is less than or equal to 125 kWh per tonne of waste. The process further involves classifying the treated waste through a screen to remove the 12 mm fraction comprising plastic (less than 2 w.%) (calculated on 60 wt.% moisture in the fibers), and treating it in an air classification device to yield a fibrous fraction comprising inorganic material (i.e. glass and grit) (less than 2 w.%) (calculated on 60 wt.% moisture in the fibers); and further separates different fractions including shattered glass and grit, and larger parts such as plastics and metals; air suction to catch dust and volatile material as an air stream, which is then supplied to washing or cleaning section; and subjecting majority of the fiber product, contaminated with glass and grit particle. Thus, method reliably separates small glass and grit particles, and plastics, which can reduce value of fiber as renewable fuel or compost. The fibrous fraction produced is suitable for use in operating power plant on site of a MSW treating plant, and is able to provide greater than or equal to 5% of the energy requirement of the plant.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) process (P2) to make organic fiber based fuel;    (2) method (M1) for providing green electricity;    (3) an apparatus (A) for treating municipal waste;    (4) a plant (P'1) for treating waste comprising: the at least one apparatus (A);    (5) a plant (P'2) to perform the process (P1) or (P2), or the method (M1); and    (6) an integrated power plant and waste treatment plant.