The Pyrochar project, funded by the Seventh Framework Programme, has allowed to develop a thermo-chemical process for treatment of sludge coming from civil wastewater treatment systems.
Treatment of sludge
The sludge (15-20% DM) coming from mechanical dehydration (centrifuge or filter press) is sent to a dryer, whose thermal energy is supplied by the exploitation of the syngas produced. The drying process reduces the moisture content of mud from 80 to 10%. The dried sludge is then sent to the pyrolysis reactor which treats the sludge at a temperature of 750-850°C . The obtained syngas is used to power a boiler or a CHP unit that produces the thermal energy needed for the dryer. If exploited in a CHP, after being purified in a catalytic filter, the exploitation of syngas can also produce the electrical energy needed for the system.
Exhausted air can be treated in a biofilter or with an active carbon system. The Biochar is quickly cooled in a condenser.The sludge is reduced to about 5% of its initial weight, free from pathogens and odours. The Biochar produced can be exploited as a solid fuel and/or fertilizer.