Process:

The client's process is the primary treatment of wastewater from a poultry kill and cooking plant. Wastewater flows from the kill process to the screening process where all large material is screened out. The resultant wastewater is treated with ferric chloride to break the emulsion. Air is then induced into the stream followed by immediate flocculation with an anionic polymer. The flocced solids rise to the surface of the Dissolved Air Flotation tank (DAF) and the subnatant leaves the DAF to sewer or onsite further processing. (captive anaerobic lagoons or activated sludge plants)

Problem:

Excessive solids carryover to the subnatant and extreme variability in the treatment process.

Resolution:

Consideration was given to flow equalization but space limitations did not make this a practical solution. A P.I.D. pH controller was set up to control caustic and ferric sulfate feed rates. Progressing cavity pumps were selected to insure continuous feed rates of the chemicals. All chemicals were injected in line for rapid homogenous mixing.

Solids carryover were reduced 75% concurrently with BOD₅

Serendipity:

• Drier DAF float and subsequent drier product off the belt press.
• Reduction in iron, caustic and polymer usage.