state-of-the-art ammonia recovery TECHNOLOGY

Vacuum Stripping and Absorption (VaSA) technology converts aqueous ammonium (NH4+) to free ammonia (NH3) by bringing a feed i.e digestate or other wastewaters such as landfill leachate to boiling under vacuum at a temperature below the normal boiling point, under which ammonia is efficiently stripped out of the feed due to formation and upward transport of water vapor bubbles, sucked by the vacuum through a demister to an absorption column, and absorbed to a sulfuric acid solution to form ammonium sulfate crystals, a sellable fertilizer. VaSA saves operational costs by eliminating the costly pretreatment for solid/liquid separation relative to other ammonia recovery processes and reduces operational costs by eliminating the external supply of a stripping agent as in the gas stripping processes. VaSA increases solids solubilization and biodegradability, thus accelerating hydrolysis and increasing biogas yield. Under the vacuum stripping conditions, vacuum-enhanced alkaline/thermal treatment disintegrates EPS aggregates, increases rupture of cell walls, and destroys lignocellulosic structures, thus improving dewaterability due to decrease in bound water and conversion of lignocellulosic materials having highly hydrophilic surface into more hydrophobic cellulose and lignin. VaSA elevates traditional Class B biosolids to meet U.S. Environmental Protection Agency's pathogen reduction requirement Alternative 1 for Class A biosolids. VaSA was invented at SUNY College of Environmental Science and Forestry, Syracuse, NY and has been granted a U.S. Patent number.