NOVELTY - Co-firing system comprises: first chamber of a coal combusting apparatus configured to pulverize a coal feedstock; and second chamber of the coal combusting apparatus configured to pulverize a processed biomass pellet feedstock. The processed biomass system configured to make processed biomass from unprocessed organic-carbon-containing feedstock that includes e.g. free water, intercellular water, and at least some plant cells. The processed biomass system comprises: beneficiation sub-system, coal cleaning sub-system, blending sub-system and pelletizing sub-system.    USE - The co-firing system is useful for combusting coal in a coal combusting apparatus with less adverse by-products (claimed).    ADVANTAGE - The system utilized for combusting coal at low-cost.    DETAILED DESCRIPTION - Co-firing system comprises: first chamber of a coal combusting apparatus configured to pulverize a coal feedstock comprising processed biomass/cleaned coal blended compact aggregate that comprises at least 10 wt.% coal having a sulfur content of at least 50 wt.% less than that of the content of sulfur in the coal before it passed through a coal cleaning sub -system and at least 10 wt.% processed biomass from a processed biomass system and to feed the pulverized cleaned coal feedstock into the coal combusting apparatus in a first concentration of feedstock; second chamber of the coal combusting apparatus configured to pulverize a processed biomass pellet feedstock from the processed biomass system and to feed the pulverized processed biomass pellet feedstock into the coal combusting apparatus in a second concentration of feedstock with the weight ratio of the first concentration to the second concentration is 1-9:9-1. The processed biomass system configured to make processed biomass from unprocessed organic-carbon-containing feedstock that includes free water, intercellular water, intracellular water, intracellular water-soluble salts, and at least some plant cells comprising cell walls that include lignin, hemicellulose, and microfibrils within fibrils. The processed biomass system comprises: beneficiation sub-system configured to convert the unprocessed organic-carbon-containing feedstock into a processed organic-carbon-containing feedstock with characteristics that include having an energy density of at least 17 MMBTU/ton (20 GJ/MT), water content of less than 20 wt.%, and a water-soluble intracellular salt content that is decreased more than 60 wt.% on a dry basis from that of the unprocessed organic- carbon-containing feedstock, coal cleaning sub-system configured to convert un-cleaned coal into cleaned coal having a sulfur content at least 50 wt.% less than that of the content of sulfur in the un-cleaned coal before it passed through the coal cleaning sub -system; blending sub-system configured to convert the cleaned coal and some of the processed biomass into processed biomass/cleaned coal blended compact aggregate with a weight ratio of cleaned coal to processed biomass of 19:9-1 and pelletizing sub-system configured to convert some of the processed organic-carbon-containing feedstock into processed biomass pellets. An INDEPENDENT CLAIM is also included for process of co-firing coal and processed biomass for combusting coal in a coal combusting apparatus with less adverse by-products, comprising passing un-cleaned coal through a coal cleaning sub -system to form cleaned coal having a sulfur content that is at least 50 wt.% less than that of the content of sulfur in an un-cleaned coal, making a processed biomass feedstock pellet in a processed biomass system via a processed biomass system process, comprising inputting into the processed biomass a system comprising a first and a second subsystem an unprocessed organic-carbon-containing feedstock that includes free water, intercellular water, intracellular water, intracellular water-soluble salts, and at least some plant cells comprising cell walls that include lignin, hemicellulose, and microfibrils within fibrils, passing unprocessed organic-carbon-containing feedstock through the first subsystem, a beneficiation sub-system via a beneficiation sub-system process, to result in processed organic-carbon-containing feedstock with characteristics that include having an energy density of at least 17 MMBTU/ton, passing the processed organic-carbon-containing feedstock through the second subsystem, pelletizing sub-system via a pelletizing sub-system process, to result in pelletized processed biomass pellet feedstock and passing the cleaned coal with part of the processed biomass through a blending sub-system via a blending sub-system process to form a processed biomass/cleaned coal blended compact aggregate that comprises the processed biomass/cleaned coal blended compact aggregate and the processed biomass in a wt ratio of 1-9: 9-1, providing the processed biomass/cleaned coal blended compact aggregate to a first chamber of the coal combusting apparatus, where the first chamber is configured to pulverize coal and feed the coal into the coal combusting apparatus in a first concentration weight of feedstock, and providing part of the processed biomass pellet feedstock to a second chamber of the coal combusting apparatus, the second chamber configured to pulverize the processed biomass and feed the processed biomass into the coal combusting apparatus in a second concentration weight of feedstock with the ratio of the first concentration weight to the second concentration weight is 1-9:9-1.    DESCRIPTION OF DRAWING(S) - The figure illustrates schematic view of microwave sub-system comprising reaction chamber.    Microwave sub-system (1800)    Reaction chamber (1810)    Cylindrical wall (1811)    Reaction cavity (1812)    Transport mechanism (1818)