THE SLURRYCARB™ PROCESS PRIOR TO DRYING: ECONOMICALLY CONVERTING BIOSOLIDS TO A RENEWABLE FUEL

Most biosolids in the USA are recycled via agricultural land application. In several states, including California, this practice is under attack as being unacceptable. Some agencies are seeking technologies, like thermal drying, to produce a more acceptable Class A product. While drying does produce a fine marketable product that can be used as fertilizer or fuel, it is expensive to evaporate water from biosolids containing 20%–25% total solids.EnerTech's patented SlurryCarb™ process chemically converts biosolids into a high-energy, renewable solid fuel, providing an environmentally and economically sound solution for biosolids management. The process heats biosolids under pressure to significantly improve dewaterability. Biosolids are mechanically dewatered to 50% total solids and fed to the dryer. Thus, the amount of thermal energy needed to dry the biosolids is reduced by almost two-thirds and the cost by about one-third.EnerTech has constructed a Process Development Unit (PDU) located in Atlanta. EnerTech's 54.5 liters (14.4 gallons) per hour PDU includes all the necessary pumping, heating, depressurizing and dewatering systems necessary to simulate a commercial scale SlurryCarb™ facility. The PDU has provided comprehensive engineering data from extended operations in the last twelve months. This paper includes final design criteria and an update on the status of the Rialto Regional Biosolids Processing Facility in Southern California.Construction of the 614 metric tons (675 wet tons) per day Rialto facility has started. The dried product from this facility will be used as a renewable fuel in lieu of coal in a cement kiln. This unique beneficial use lowers green house gas emissions, reduces ore consumption, leaves no residue for disposal, provides permanent recycling of the biosolids, and eliminates all the health and environmental concerns associated with agricultural use.