Odorous air is withdrawn from the Trickling Filters by an odorous air fan and into an odor control scrubber tower. Two towers (one standby) service Trickling Filters 1 & 2. One tower services Trickling Filter 3.
The foul air is brought into contact with a mixture of Sodium Hypochlorite, Sodium Hydroxide and softened water and is sprayed over a media made of plastic pieces. Softened water is required to ensure that scale does not buildup.
As the air is forced through the media, Hydrogen Sulfide is stripped from the air. The treated air is discharged to the atmosphere through the tower. The spent solution is returned for reuse.
The nitrifying trickling filters serve a dual function, oxidizing ammonia to meet effluent water quality standards and biologically treating odorous sulfur compounds in the exhaust air from the dissolved air flotation thickeners, the centrate return tank and the solids handling building. Forced air ventilation systems transfer foul air from three dissolved air flotation thickeners, and a centrate equalization tank to three NTFs. Geodesic dome covers enclose the NTF tanks, ensuring uniform distribution of foul air over the biofilm surface, preventing short-circuiting and enhancing odor treatment. The combined foul air from both sources discharges into the top of the NTF enclosures, moving downward through the media concurrent with the wastewater flow. Treated air drawn from underneath the NTF media is discharged to the atmosphere through a centrifugal fan. Foul air flow to each NTF unit is approximately 9,900 cfm. Use of the nitrifying biofilm for foul air treatment avoids the cost for another expensive chemical scrubbing system.