NOVELTY - The method comprises providing a quantity of anaerobic digestion effluent (1), adding the effluent to a biomass at 50 degrees C in an insulated tank to form a mixture (3) having a solids concentration of 20%, fermenting (4) the mixture in the insulated tank for a time period of 5-10 days, and isolating the wet solids from the liquid. The method is carried out at a temperature of 30-60 degrees C. The biomass is added to the effluent till a concentration of 20-30% solids is reached. The solids are separated from the liquid by leaching or pressing. The isolated wet solids are used as a fertilizer (7).    USE - The method is useful for processing anaerobic digestion effluent (claimed) to produce a biogas and a semi-solid secondary digestate that is useful as a fertilizer, where the effluent is obtained from an anaerobic digestion of organic material such as sewage sludge, municipal waste, industrial waste forest waste, agricultural waste and animal waste, and the biogas is directly useful as gaseous fuel for heat and power generation or upgraded to natural gas-quality biomethane for transportation fuel.    ADVANTAGE - The method is capable of simply processing the anaerobic digestion effluent.    DETAILED DESCRIPTION - The method comprises providing a quantity of anaerobic digestion effluent (1), adding the effluent to a biomass at 50 degrees C in an insulated tank to form a mixture (3) having a solids concentration of 20%, fermenting (4) the mixture in the insulated tank for a time period of 5-10 days, and isolating the wet solids from the liquid. The method is carried out at a temperature of 30-60 degrees C. The biomass is added to the effluent till a concentration of 20-30% solids is reached. The solids are separated from the liquid by leaching or pressing. The isolated wet solids are used as a fertilizer (7). The biomass comprises cellulosic agricultural waste, animal waste and plant crop material. A biogas (8) is isolated from the fermentation mixture. The effluent is added to biomass in a single process system.    DESCRIPTION OF DRAWING(S) - The figure shows a flow diagram of a method for processing anaerobic digestion effluent.    Anaerobic digestion effluent (1)    Solid mixture (3)    Fermenting the solid mixture (4)    Fertilizer (7)    Biogas. (8)