The issue in this project was handling the sludge generated at plants that are designed to remove Iron/Manganese/Arsenic/Barium from wells. The small footprint of the treatment plant without sludge lagoons historically presented challenges. All of the wells that feed to these plants are over the MCL for Iron/Manganese/Arsenic/Barium and could not go directly to the sewer system.
The residuals also had concentrated levels of co-occurring contaminants, such as lead, copper, barium, arsenic or radionuclides. The removal of co-occurring contaminants did pose disposal problems leading to a hazardous waste classification and interfering with local limits by publicly owned treatment works (POTWs).
Sampling was done to identify the characteristics of the residuals. Once sampling had been completed water was filtered to meet all sanitary sewer requirements and discharged according to the applicable permits. Then a mobile centrifuge was used to dewater the remaining residuals and a “cake” (a more concentrated solid waste consisting of 20% solids) was generated. Throughout the process samples were collected to determine contaminants impacting disposal alternatives.
The overall goal of this process was to reduce the waste from a large unmanageable quantity to a small amount of dry material that depending on being non-hazardous or hazardous to be disposed at the appropriate landfill meeting all federal, state and local requirements. This project resulted in cost savings of 1.6 million Dollars to the owner.