Enhanced deflocculation of dehydrated sludge by rhamnolipid treatment coupled with thermal hydrolysis

The effect of a biosurfactant, rhamnolipid (RL), coupled with a thermal treatment was investigated to determine its impact on improving the deflocculation of dehydrated sludge from wastewater treatment processes. Results showed that the RL treatment positively impacted sludge conditioning to weak acidity and hydrolyzed the carbohydrates and proteins released from the matrix of the extracellular polymeric substance. When RL was coupled with high temperature thermal treatments (65 and 95 °C), soluble chemical oxygen demand and chemical oxygen demand solubilization increased by 9.6-19.7 times and 13.4-29.3%, respectively. The RL treatment reduced antibiotic resistant bacteria by 5.4-98.4%, and antibiotic activity was further accelerated by high temperature thermal treatment. The combination of biosurfactant and thermal treatment can effectively deflocculate dehydrated sludge and should be considered an alternative technology for the sludge management process.