A bioreactor designed to produce N2O from organic nitrogen and/or reactive nitrogen in waste is coupled to a hardware reactor device in which the N2O is consumed in a gas phase chemical reaction, e.g., catalytic decomposition to form oxygen and nitrogen gas. Heat from the exothermic reaction may be used to generate power. The bioreactor may use communities of autotrophic microorganisms such as those capable of nitrifier denitrification, ammonia oxidizing bacteria, and/or ammonia oxidizing archaea. A portion of the N2O dissolved in aqueous effluent from the bioreactor may be separated to increase the amount of gas phase N2O product. The amount of the gas phase N2O in a gas stream may also be concentrated prior to undergoing the chemical reaction. The N2O may alternatively be used as an oxidant or co-oxidant in a combustion reaction, e.g., in the combustion of methane.