Cases study

Pet food production: odour abatement with chemical-physical filter

We solved the problem of malodorous emissions and chemical contaminants in an animal feed company with a dry chemical-physical filtration system

Field of activity

Food processing industry

Activity

Pet food production

Location

Sud Italy

Emission criticality

Noxious smells coming out of the purification plant

Service supplied by Labiotest

Design and installation of a DKFil® dry chemical-physical filter

The critical emissions of the feed production plant

In the production chain linked to the livestock sector, odour problems do not only affect livestock farms.
In fact, even companies involved in the production of pet food are often faced with the difficulties of odour emissions from their plants.

Pet food, commonly called pet food, can be of animal and/or plant origin.
In the production of pet food of animal origin, by-products of the human food industry that come from animals slaughtered under veterinary supervision are used. Parts of the animal that are not used for human consumption (e.g. heart, lungs, kidneys, livers) and all that remains of the carcass (bones, blood, intestines, tendons, ligaments, etc.) are used.
Usually only raw materials from species accepted in the human food chain such as beef, lamb, poultry, pork, fish, rabbit and game are used.

Given our specialisation in the treatment of odour emissions, we were contacted by a historic company in southern Italy that produces around 450,000 tonnes per year of pet food, both dry and wet.
The critical odour issue they reported to us developed from a wastewater treatment plant serving their production facility. 

The stages of the production process

The actual production process of pet food consists of several steps by which all the ingredients are prepared, weighed and mixed: the result must be a homogenous product that can undergo treatments, physical or thermal, to improve its quality.

The main processes that pet food undergoes are:

  • Expansion
  • Drying
  • Extrusion
  • Flaking
  • Rolling
  • Pelleting
  • Heat treatment
  • Cooling
  • Crumbling and screening
  • Coating and greasing 

Odorous emissions from the waste water treatment plant

The odour emissions of pet food companies are mainly related to the processing of raw materials and the various stages of drying, extrusion and mixing of ingredients.

In the specific case of our client, the odour criticality was linked to the wastewater treatment plant serving the plant where raw materials are processed and into which the washing waters coming from the slaughtering and processing departments are conveyed.
In particular, the critical issue concerned the sludge storage tanks, so we were asked to convey and treat the air coming from a floater and centrifuge room.

Since the area was already confined and also presented a cirticity related to the emission of contaminants, the treatment of the outgoing air using dry chemical-physical filtration technology was considered for the reduction of odours and pollutants. 

The solution: the DKFil filtration system

After studying the situation and the analytical data provided by the customer on the effluent to be treated, our technicians drew up a customised design for the critical emission issue.

We then installed a new air treatment filtration equipment with a DKFil® system complete with internal demister, inverter, fan and connection piping.
The air purification unit was sized and designed according to the flow rate of the emission to be treated and the chemical and physical characteristics of the odorous molecules to be eliminated.

The chemical-physical treatment system includes:

  • a chemo adsorption activity with neutralisation and chemical oxidation by suitable reagents present on the solid substrates making up the filtering bed;
  • and a physical adsorption activity by means of special extruded activated carbon substrates with a high specific surface area.  

The use of a demister unit

To optimise the process of filtration and treatment of the effluent, we have included an internal demister unit.
Its function is the pre-treatment of the air flow through separation of the condensed phase on a coalescing filter, to safeguard the filter bed and partially remove water-soluble substances.
The condensed phase, separated from the flow, is collected at the bottom of the unit and discharged by means of a shut-off valve. 

Achieved results

Through the use of our DKFil® system, the customer has seen a significant improvement in critical odour levels, as evidenced by olfactometric investigations which revealed a reduction in odour concentration of 85%.

In view of the excellent results obtained, the customer is considering installing a further filtration system to serve another critical area of the purifier.