Possibilities for the recovery of sludge from municipal wastewater treatment plants through the design and production of concrete

The main objective of the present research was the design and realization of a concrete recipe of resistance class C16/20, based on the incorporation in the form of addition of sludge from the treatment plant of Baia-Mare City, Maramureș County, Romania. Until now, this type of sludge has been used on agricultural land as fertilizer. What makes it reshaping its use in construction materials is that this sludge contains in addition organic elements and hazardous heavy metals that can be retained in the matrix of the concrete mixture. Thus, based on the experience of making mixtures of cathode glass with Pb, from the recycling of old monitors, it was observed that that the migration in time of Pb from the matrix of the material was below the limit imposed by current legislation. Failure to recover this sludge leads to long-term storage on large surfaces of land that will be contaminated or it will have to be stored on concrete or packed platforms, situation which increases the cost of disposal. The paper will present methods and results obtained in the research, which support the use of sludge from sewage treatment plants in dry granular form for strength concrete class C16/20 obtaining but with limited applicability. The final objective of the research is to provide a new alternative solution for the disposal and recovery of this hazardous waste.