Section 6.1. Requirements for time and temperature treatment

There are a number of rules regarding the heating of AD materials including the temperatures which must be achieved, for how long, and how those temperatures are monitored. The rules vary depending on the types of materials. With regards to heating, the AD vessel is the vessel where the treatment of AD materials through time and temperature occurs but does not include any vessel used exclusively to heat materials before treatment. The "pre-treatment system" is a location used for temperature treatment of off-farm AD materials or on-farm AD materials that are fruit, vegetables or plant materials from the production and processing of fruit or vegetables prior to addition to an AD vessel.

(see s. 1. (1) "pre-treatment system", O. Reg. 267/03).

The average time AD materials must be treated in an AD vessel is at least 20 days, at a minimum of 35 °C at all times.

But the time can be reduced if:

  • A professional engineer designs the RMADF so that it is capable of reducing the content of total volatile solids of the materials in the RMADF by at least 50 per cent in less than 20 days
  • The RMADF is built to the professional engineer's design specifications; and
  • The average time the AD materials are treated is at least as long as the time specified by the professional engineer.

The temperature can be reduced if:

  • A professional engineer designs the RMADF so that it is capable of reducing the content of total volatile solids of the materials in the RMADF by at least 50 per cent at a temperature below 35 °C
  • The RMADF is built to the professional engineer's design specifications; and
  • The average temperature at which the AD materials are treated is no less than that specified by the professional engineer.

Off-farm AD material listed in Schedule 2 must be heated before treatment (in a pre-treatment system or off-site) or during treatment in the AD vessel for no less than one hour at no less than 70 °C, or no less than 20 hours at no less than 50 °C.

In order to meet the 1 hour or 20-hour time temperature requirement, material likely needs to be heated as a batch for that duration of time. Material that is fed and removed from a pre-treatment system or AD vessel on an on-going basis might not meet these regulatory requirements.

(see s. 98.9 (1) 5., 98.9 (1) 6., 98.9 (3), 98.9 (4), O. Reg. 267/03).

If the off-farm AD material listed in Schedule 2A is heat treated off-site, the heat treatment requirements listed above are the same. A statement from a professional engineer indicating that the off-site system is capable of performing this treatment is required.

(see s. 98.9 (1) 8, s. 98.9 (2.1), 98.13 (1.1) (b), O. Reg. 267/03).

Dissolved air flotation material from wastewater treatment (listed in paragraph 4 of Schedule 2A) must not have been removed from the facility where the wastewater is treated more than 10 days before it is received at the agricultural operation. Also, these materials must be transferred using a means that minimizes odour emissions if an offensive odour would otherwise be detectable beyond the farm unit where the materials are received.

(see s. 98.4 (1) 1.2, O. Reg. 267/03, and Paragraph 4, Schedule 2A – Off-farm Anaerobic Digestion Materials, Limited, Off-Farm Anaerobic Digestion Materials Protocol).

Unlike Schedule 2A materials, Schedule 2B materials must be heated at the RMADF.

When heating Schedule 2B materials, the material must have a dry matter content of less than 18 per cent and have a slump of more than 150 millimetres using slump test from Regulation 347.

(see s. 98.9 (2.1) and (2.2), O. Reg. 267/03).

Section 6.2. Temperature monitoring devices

The temperature inside the AD vessel is important for ensuring proper treatment. Each RMADF must have a device to monitor the actual temperature at which the materials are being treated.

In addition, at an RMADF that receives more than 10,000 cubic metres of off-farm AD materials in any 12-month period or any Schedule 2B material, there must be two devices for monitoring the actual temperature at which the materials are being heated. These two devices must be located separately to ensure temperature measurements are representative of the vessel contents. In addition, at these facilities a record of results showing time and temperature of heating must be kept, either as a graph, or kept in a form that is capable of being graphed, for instance in a spreadsheet.

As a best management practice, the temperature monitoring devices should be regularly monitored to ensure that they are measuring the temperature accurately.

(see s. 98.9 (2.3), 98.13 (1) 3.2, O. Reg. 267/03).