Industrial Control of Odor Using Specialty Enzymes

Effectiveness of ZymeOut

Additional studies to control Sulfate Reducing Bacteria (SRB) were conducted for industries that have the ability to chlorinate their process water or their waste water in addition to using Zymeout.

ZymeOutTM  is very effective without any other additional treatment. The use of ZymeOutTM breaks the sulfur cycle by preventing the formation of sulfide within the slime layers.  It is not a biocide and does not harm any bacteria – aerobic or anaerobic.  It allows the slime layers to break up on there own by disrupting the capability of sulfate reducing bacteria (SRBs) to form and fortify the slime layers.  This results in slime layers naturally sloughing off. Most hydrogen sulfide (H2S) gas is formed in theses slime layers. When slime layers are controlled, the SRB is controlled. Addition of chlorine along with ZymeOut proved very effective. 

ZymeOutTM Used with Biocide - Addition of Chlorine Study

A leachate contaminated with SRB was fed into two 5 gallon containers filled with a nutrient source, sulfate and water.  Nitrogen gas was continuously passed through the containers to eliminate any oxygen and to provide a gas flow in which to measure H2S produced from the containers. This sealed reactor provided optimum conditions for SRB to thrive.  At day 4 treatment began. About 5000 ppm of a 1.0% solution of sodium hypochlorite was added to one of the reactors.  An identical amount hypochlorite was added to the other reactor, along with about 1500 ppm of ZymeOutTM(labeled as EC in the figure).  The hydrogen sulfide levels measured in each reactor over time are presented in the figure below.  The reactor with ZymeOutTM went to zero H2S production over about 8 days, and stayed at zero for greater than 8 days thereafter (reactor was not monitored after 8 days - test was complete).  The reactor with bleach alone required another identical dose (5000 ppm ) of hypochlorite at day 10, which suppressed H2S production for less than 1 day.  From the data in the figure below, it is clear that the ZymeOutTM can work cooperatively with inexpensive biocidal compositions such as hypochlorite to effectively extend the useful lifetime of  biocides.

The graph above shows that chlorine alone stops all SRB activity only temporarily, even after a repeated dose on day 10. The SRB in the slime layers wait for the biocidal effects of the chlorine to pass, then the SRB come right back.

With the addition of ZymeOutTM and chlorine, the slime layers are penetrated over time and the chlorine wipes out the SRB for the long term.