Dense-phase pneumatic system conveys hydrated lime to treat sewer sludge
Conveying dry, hydrated lime with a dense-phase pneumatic system and adding the dry lime directly to sewer sludge eliminates the problems incurred by injecting the sludge with a hydrated lime slurry.
Valley Forge Sewer Authority, a municipal corporation in Phoenixville, Pa., collects and treats waste water from eleven communities in suburban Philadelphia. Once collected, the waste water first enters a primary clarifier -- a settling tank where gravity removes primary sludge. The waste water then enters an aeration basin that converts the water-soluble portion -- sugars, starches, ammonias, etc. -- into water, carbon dioxide, and energy. From there, the waste water goes to a secondary clarifier where the bacteria settles. The waste water then goes through a pressure filter that removes any remaining solids. After filtration, the waste water is disinfected and discharged into a river.