A review of methods for the thermal utilization of sewage sludge: The Polish perspective

On the basis of demographic projections, it is estimated that the quantity of sewage sludge which will be produced in Poland between 2010 and 2018 will increase from 612.8 thousand tons (dry basis, d.b.) to 706.6 thousand tons (d.b.). Currently, the predominant method for the disposal of this sludge is its storage and agricultural application. However, the legislation taking effect in the next few years will effectively block these avenues of sewage-sludge disposal. Therefore, effective methods of thermal sewage-sludge utilization must be developed. Here we review the state of knowledge and technology in thermal methods for the utilization of municipal sewage sludge to obtain useful forms of energy such as pyrolysis, gasification, combustion, and co-combustion.