A 1.5-MW bubbling fluidized bed combustor for the ecologically safe co-combustion of wet sewage sludge with wood chips was constructed. The technology was designed for small wastewater treatment plants, serving a population of 20-60 thousand inhabitants. In the tests, sewage sludge from the commercial Niepolomice plant was used as the feed-stock. Addition of the wood chips to the sludge resulted in a decrease in the nitrogen oxide content in the flue gases from 600 to 400 mg/m(3) and an increase in the carbon monoxide concentration up to 400 mg/m(3). The heavy metal were concentrated not only in the ash but mainly in the dust from the chimney. The polyaromatic hydrocarbons were concentrated in the flue gases and water from scrubbers.