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 were being burned, and the filtrate was being returned to the waste-water treatment system.
H2S in sludge was liberated at the presses. The H2S levels typically ran between 40-100 ppm. However, there were some spikes in H2S levels reaching about 750 ppm. These H2S surges were due to changes in throughput volume and feed composition.
- Q2 Technologies tested Enviro-Scrub® at the pulp and paper waste-water treatment system as shown in Diagram 1. Varying amounts of Enviro-Scrub® were injected continuously and directly into the diluted sludge. The scavenger was located at the suction side of the surge tank pump. The H2S levels were monitored both, at the vapor phase off the presses and in the filtrate. Enviro-Scrub® reduced H2S levels to 10 ppm and even less during the twenty-four hours that the test lasted.
- The pulp and paper mill is currently using Enviro-Scrub® when H2S spikes occur. The injection pump is activated when this happens and the H2S is reduced to compliance levels within 15 minutes. The pulp and paper mill plans to automate the feed pump linking it to H2S monitors so that it activates when needed.
- A second forty-eight hour test was conducted by plant personnel at the pulp and paper mill and they obtained the same positive results. H2S was reduced to acceptable levels at a reasonable cost. The facility is now using Enviro-Scrub® to control H2S directly at the source.