Test Results

Laboratory Testing of DOWN JOHN™ at Iowa State University and Oklahoma State University

Both universities have a strong focus on agriculture.

Test 1:   Reduction in Toxic Hydrogen Sulfide Gas.

Formation and buildup of poisonous hydrogen sulfide gas is a problem in hog farm deep manure storage tanks. People have died when storage tanks are opened, from gas inhalation. Tests performed at Iowa State University found that the addition of the DOWN JOHN™ carbon alone, reduced the hydrogen sulfide gas by 97%.

Test 2:   Reduction in Toxic Ammonia Gas.

The production of ammonia gas from hog feces and urine that collects in a hog barn sub floor open pit, contaminated the air in the building, becoming a respiratory problem for the hogs, staff and also the cause of sheet metal and equipment corrosion.  The addition of the DOWN JOHN™ brown liquid bacteria solution alone, when tested at Iowa State University, was found to reduce the ammonia formation by 74%.

Test 3:   DOWN JOHN™ Performance in a Septic Tank System.

This test ran for a 12-month period to evaluate the digestion properties and efficiency of DOWN JOHN™ in a low volume septic tank system. Results show that with the presence of DOWN JOHN™:

  • pH remained constant
  • sludge buildup did not happen
  • solids digested and system stable for a 12-month period
  • digestion rate increased in strength over time
  • gas analysis showed the absence of methane
  • effluent was found to be rich in fertilizer nutrients
  • effluent contained no E.coli or other pathogenic bacteria


A low volume septic system was developed for use in poorer countries where there is not a lot of flush water available. The testing was based on the septic system accepting daily, the feces and urine input from 15 adult males, eating a diet of 85% carbohydrates and 15% protein and living in an environment of 80-85ºF. in temperature. These conditions approximate a central African village diet and weather conditions. Becase human waste was not available, hog waste was substitited at an amount equivalent to 15 adullt men.


  • 20 pigs were fed a high-grain based diet comprising 85% carbohydrate (corn meal) and 15% protein (soy bean meal) were used to produce manure and urine.
  • The primary septic tank was loaded daily with manure and urine on 1/22/14 equivalent to 15 adult humans.
  • A proprietary bacterial treatment package (DOWN JOHN™) was added on 1/31/14.
  • The tanks were maintained at a temperature of 81 – 85ºF.
  • Outflow of tanks began on 2/14/14.
  • Samples of manure entering and effluent exiting the tanks were collected and analyzed for nutrient concentration on a weekly basis.
  • Tanks were sampled continously through January 2015.


  • Results are shown in the graphs below.
  • The pH of the effluent exiting the tanks averaged 7.2 with very little variation.
  • 1030 kg (2,266 lbs) of swine manure had been added to the primary tank with a total solids content of 11.73%.
  • Dry matter (total solids), carbon, nitrogen, and phophorus exiting the tanks increased until approximetely 10 to 12 weeks of operation but then plateaued (Figure 1).
  • The N:P:K of the effluent exiting the tank was 0.79% N, 0.23% P, and 0.37% K or a 3.4:1:1.6 ratio (elemental basis).
  • The percentage removal of nutrients from the exiting slurry ranged from 30 to 50%.  This implied that for every 1 kg of nutrient added to the tank, 0.50 to 0.70 kg exits the tank with the difference captured by the tank (Figure 2).
  • Sludge samples and depth were recorded on 7/21/14, sludge depth in the primary tank was 6 inches with a total solids content of 14.9%, carbon = 8%, N = 0.85%, P = 0.50%.
  • Bacterial DNA sequencing of the microbial community in the effluent and sludge was conducted and all species found were non-pathogenic.


  • Sludge buildup in the tanks did not seem to be an issue, at 6” maximum.
  • Tanks performed better than originally expected in nutrient removal.
  • The concentration of nutrients in the tanks appeared to have plateaued at approximtely 10 to 12 weeks post start-up.
  • Continuing analysis will determine multi year long term performance of the tanks for treating fresh manure .

Figure 1.  Percentage concentration of nutrients in the effluent of Tank 3 by week.

Down John Lab Testing Data

Figure 2.  Percentage removal of nutrients in exiting slurry

Down John Lab Test Results  

Discussion of Results

  •   The system remained pH stable. 
  •   The DOWN JOHN™ was very effective at digesting solids and stable for a 12 months period. 
  •    The slope of the graphs in Figure 1. show the rate of increase of the biomass population with time and therefore digestion capability.
  •    The liquid effluent produced is a very effective N:P:K composted fertilizer for crop nutrition.
  •    Very little sludge had collected in the primary tank and analysis showed un-ground partial corn kernels and animal hair composition.
  •    Gas analysis showed the system did not generate methane.
  •    The DM and TC graphs show best that the tanks were not fed fresh manure in weeks 16,17,18 and weeks 22,23,24. The graphs at these points,  show a drop in digestion activity which is resumed when tanks are again fed, starting weeks 19 and 25. Activity quickly resumed when there was fresh manure input. The students entrusted with feeding the tanks had exams then vacations at those times, and the tank feeding responsibility was overlooked in error. This situation demonstrated that the tanks will be restored to activity, if the food supply is interrupted for up to a month. 

Test Coordinator