Venturi Aeration, Inc.

Venturi Aerators Shut down Septage Odors at Pennsylvania Septage Treatment Facility

Kline Services, Inc. operates a septage collection, processing and treatment facility in Salunga, PA. Historically, the facility has experienced numerous foul odor complaints from neighbors. The source of odors was hydrogen sulfide and mercaptans emanating from their two (2) 100,000-gallon open top equalization and mixing (EQ) tanks. These two tanks had been equipped with Lightning Mixers for equalization and mixing and to induce dissolved oxygen from ambient air sources at the surface of the tank. Unfortunately, the Lightning mixers released more hydrogen sulfide into the air than they oxidized in the liquid, and they did little to achieve the required BOD reduction for permit compliance.

Solution:

Kline’s was referred to Venturi Aeration, Inc. by their consulting engineer, Glace Associates, in Harrisburg, PA. Venturi staff members visited the site with the engineer and determined that only one (1) venturi aerator was required for each 100,000-gallon tank to achieve the desired odor control, to accomplish mixing and oxidation, and for BOD reduction.

Hydrogen sulfide molecules in septage that are pumped through the venturi aerator unit are immediately oxidized by the oxygen derived from ambient air. This is a first order chemical reaction. The venturi aerator provides 2.2 volumes of ambient air to one volume of liquid being processed. It transfers 20% of the available oxygen in the 2.2 volumes of ambient air into the liquid (20° C @ sea level). Further, the residual oxygen not used to oxidize H2S into soluble SO₄ is used to effect biological reductions of BOD. The Kline facility had been experiencing problems achieving their targeted BOD discharge permit limit, <200. Since the addition of the venturi aerators the facility has consistently experienced discharge levels <90 for BOD.

The kinetic energy of the discharge from the venturi aerators is used for mixing and equalization. The liquids are drawn into the venturi aerator from the bottom of the tank. The discharge is tangential to the sidewall of the tank causing the liquids in the tank to spin. Because of spinning solids migrate to the center of the tank where they are drawn back into the pump for resuspension and digestion in the treatment tank.

The addition of the venturi aerators in the EQ tanks has solved several operational problems for Kline’s. First, and most notable, is the lack of odor complaints from the neighbors in a nearby apartment complex. Second, it allows Kline’s to “eliminate” their hefty surcharges associated with discharges not in compliance with their permit, and third, it helps reduce operational costs.