Abstract: An injection and mixing device for the introduction of flocculant into aqueous material, such as sewage or sludge, prior to dewatering is disclosed. The device includes an angled housing and injection means for introducing the flocculant into the housing countercurrent to the incoming flow of aqueous material. The combination of the turbulence caused by the angled housing and the countercurrent injection evenly and rapidly disperses the flocculant within the aqueous material regardless of the material's solids content. A downstream sparger ring is also disclosed for use with high solids content material.

Abstract: An improved rigid filter plate for sludge dewatering is comprised of a filter element of two or more sizes within the range of 0.2 to 0.002 inch of irregular hard particles of aluminum oxide or similar materials, and of a supporting element of larger particles all bonded with an adhesive bonding agent. A process for manufacturing the improved rigid filter plate is also set forth.

Abstract: An improved process for recovering and recycling coagulant present in water treatment sludges. The improvement comprises several steps. First, enough acid is added to the sludge to solubilize most, but not all, of the coagulant in the sludge. Next, the acid-treated sludge is filtered on a non-mechanical horizontal filter to produce the recovered coagulant in solution as the filtrate. The recovered coagulant has a greater coagulative effect, when later recycled to treat raw water, than the mole equivalent of commercial coagulant. A portion of the recovered coagulant is discarded to control the increase in concentration of unwanted impurities in the recovered coagulant. Finally, this process permits neutralization and later removal of the filtered sludge on the surface of the non-mechanical horizontal filter.

Abstract: An improved rigid filter plate for sludge dewatering is comprised of a filter element of two or more sizes within the range of 8 to 100 grid of jagged, irregular hard particles of aluminum oxide or similar materials, and of a supporting element of larger particles all bonded with an adhesive bonding agent. The particles in the filtering element increase in average diameter progressing from the upper surface to the lower surface of the element. A process for manufacturing the improved rigid filter plate is also set forth.