Bioprocesses to the rescue of the pork industry

The aerobic thermophile bioreacter is being developed at the Institut Armand Frappier.ZoomZoom
© Joanna Prime

Article published in the Courrier Laval on May 29, 2007.

Have you ever smelt that characteristic odor telling you that a pig farm is nearby? Well, rest assured, spreading manure is not allowed between October 1st and April 1st. However, each of the 3 million pigs in Quebec continues to produce from 4 to 5 liters of liquid manure per day. What can be done with these 13.5 million liters equivalent to 7.5 Olympic swimming pools daily of smelly excrements? Some researchers have shown interest in the problem and here is a solution.

"The manure is transformed into a recoverable solid stable product with no foul odor and no pathogens" says Dr. Pierre Juteau, researcher at the INRS-Institut Armand Frappier. This substance could replace synthetic inorganic fertilizers used by farmers and horticulturists who would prefer not to use manure at this time. The treatment consists of collecting the manure in a reactor containing microorganisms. "It's an aerobic thermophile treatment similar to a composting system but in liquid form" explains the researcher. Bacteria, in the presence of air, decompose the manure and generate a high temperature (up to 70°C). This heat, maintained by other microorganisms, kills the pathogens present in the excrement. Nitrogen, a chemical element present in manure in large quantities, is concentrated into ammonium salts in the bioreactor. A phase separator, placed at the exit of the bioreactor, isolates the solids from the liquids. Phosphorus, an element even more abundant in the manure than nitrogen, ends up mainly in the solids. The solid, odorless concentrated products formed become easily exportable inorganic fertilizer.

Pork producers must export their surplus excrement outside of their area. Regulations stipulate that the addition of phosphorus on farmland depends on the needs of the type of crop grown there. When nitrogen and phosphorus are spread on soil excessively, they leach out of the soil and pollute waterways, making the water unfit for consumption or swimming. For many producers, these agricultural regulations significantly decrease the doses of manure that can be applied to the field. The surplus excrement related to a very active pork industry thus becomes a major problem. "The main objective is to extract value judiciously from manure products", says François Boutin, assistant managing director and director of environmental services at the Fédération des Producteurs de Porcs du Québec.

The bioreactor developed by the scientists at the INRS-Institut Armand Frappier is currently under study, but others are already available on the market. They all have the same disadvantage: their cost. Treating manure in this manner costs the producer 5 times more than simply spreading it without treatment. Even if the Quebec Ministry of Agriculture offers some aid, the main deterrent to using this treatment is the price.