Challenge

An Eastern United States municipality was using potassium permanganate (KMnO₄) to control malodor in sewage sludge going to their belt press operation. Dry potassium permanganate was fed down pipes attached to the sludge belt press feed lines.  Although potassium permanganate adequately controlled the malodor in the sludge, the municipality was interested in evaluating new products which might reduce chemical treatment costs and be easier to handle than potassium permanganate.

Solution

A two month trial with VX-456, a proprietary mixed oxidant formulation for odor control was recommended.  Baseline data for potassium permanganate including the feed rate and the resulting concentration of hydrogen sulfide (H2S) in treated sludge would be recorded.  VX-456 would then be substituted for the potassium permanganate by injecting it directly from the product tote into the sludge line feeding the belt press.  Potassium permanganate feed would resume after the VX-456 trial period and a comparison of the data for the two odor control chemicals made.

Results

The potassium permanganate program cost the municipality approximately $19 per hour to maintain H₂S concentrations at below the target of 0.6 mg/L. Malodor was controlled with VX-456 at an average cost of $14.21 per hour, while maintaining H₂S concentrations below 0.6 mg/L during the hot summer months.  The results of the trial show that VX-456 is an effective control strategy for controlling malodors in sewage sludge.  It is easy to apply and may significantly lower the cost of chemical treatment when compared to potassium permanganate.