Sewage sludge recycling as part of the circular economy



The disposal and further processing of sewage sludge is being increasingly strictly regulated by the legislator, as the importance of recovering finite resources is steadily increasing. As population density increases, so does the amount of sewage sludge produced and, at the same time, the demand for food and the associated need for fertilizers.

Professional dewatering, thickening, drying of sludge as well as thermal sewage sludge utilization contribute significantly to closing the nutrient cycle. On the one hand, this enables the recovery of valuable phosphorus, and on the other hand, it continues to enable the use of sewage sludge as a CO2-neutral energy source.

The prerequisite for obtaining a phosphorus-rich, detoxified ash is mono-recycling of the sludge. Here, our sister company SÜLZLE KOPF SynGas sets new standards with its patented process. Through the thermal utilization of sewage sludge and the resulting synthesis gas, the energy bound in the sewage sludge can be used far more efficiently. Thus, high efficiencies in energy recovery from sewage sludge are possible even in small sewage treatment plants. Due to the reduced energy costs, the sewage sludge recycling plant pays for itself within a few years.

Small wastewater treatment plants in particular are unable to find a suitable, financially viable solution among the technologies established to date for thermal treatment. A compact, decentralized recycling plant on the site of the sewage treatment plant creates long-term cost and disposal security. The sewage sludge recycling process fits perfectly into the processes of the wastewater treatment plant and ensures flexible on-site energy utilization.

Customers such as cement and power plants, which have previously used dried sewage sludge as an additional fuel, will also face the challenge of phosphorus recovery in the future. The upstream connection of the SÜLZLE KOPF SynGas fuel gas module separates the material flows in the incineration process, thus ensuring that the phosphorus is removed. Finally, an ignitable syngas is provided for the auxiliary firing.