As the result of the biogas plant work , a lot of sludge (effluent) is formed, which can be used for various purposes. This article shows the possibility of appliance solids of effluent as an organic fertilizer, as well as fuel for generating thermal energy. The studied effluent was obtained after anaerobic fermentation of cow dung and biomass of the plant Amaranthus retroflexus L. In addition, mixtures of effluent with residues of plant biomass were examined . They are a mixture of seeds, stems and leaves in a ratio of 1:1,1:1,6. Five samples were examined: 100% effluent; 75% effluent and 25% biomass; 50% effluent and 50% biomass; 25% effluent and 75% biomass; 100% plant biomass. The content of nutrients (total nitrogen, phosphorus, potassium) in the samples significantly exceeds the indicators recommended by GOST 33380-2015. It was established that studied samples have high concentrations of copper and zinc. The studied effluent can not be used in its pure form as a fertilizer, but it is advisable to mix it with other components characterized by a “poor” mineral composition, such as peat. For the production of soil additives, the weight ratio of dry raw materials of effluent to lowland peat is 1:5. The lowest heat value of effluent in a mixture with plant biomass was from 12.4 MJ/kg to 14.1 MJ/kg. For heat value, it is most effective to use pure effluent and composite fuel consisting of 75% effluent and 25% biomass of the plant Amaranthus retroflexus L. The high ash content of the studied samples is due to the increased content of Cao and SiO2 oxides.