Sewage Treatment

Background

A pulp and paper mill was processing 500 gpm (720,000 gallons per day) of sludge, with 3% solids, through four presses. The dewatered solids are burned, and the filtrate is returned to the waste treatment system.

H2S, present in the sludge, is liberated at the presses. The levels typically run from 40-100 ppm. However, levels spike to 750 ppm, depending on throughput volumes and feed composition.

Solution

We tested ENVIRO-SCRUB® continuously injecting varying amounts of product directly into the diluted sludge. We added the product at the suction side of the surge tank pump. H2S levels were monitored both in the vapor phase off of the presses and the filtrate. ENVIRO-SCRUB® reduced H2S levels to 10 ppm or less during a twenty-four hour test.

Results

The mill is currently using the product during spike (H2S) periods. The injection pump is activated and H2S levels are reduced within fifteen minutes. The mill plans to automate the feed pump to be activated based on the monitored H2S levels.

A second forty-eight hour test was conducted by plant personnel with the same results. Treating rates were found to be acceptable from both an economic and efficiency standpoint. The mill is now using ENVIRO-SCRUB® to control this
point source