Thermal processes possible for CRD’s long-term biosolid solution

The preliminary review of thermal processing pilots has found pyrolysis may be a long-term solution for the Capital Regional District’s treated sewage.

A report going to the Environmental Services Committee on March 29 said the CRD’s technical consultant, GHD, looked at more than 30 short and long-term options for the region’s Class A biosolids, which are provincially required to not get landfilled and must have a beneficial use.

Pyrolysis – a stage of oxygen-free combustion where organic matter decomposes at high temperatures – is one potential long-term option for Hartland Landfill and appears to be the “most promising” among them so far. A pilot project saw a London, Ont. facility pyrolyze 800 kilograms of CRD biosolids over two days last fall, reducing the mass of the sewage-derived dried pellets by about 70 per cent while creating syngas and biochar as byproducts.

Gasification posed another long-term possibility but a New Jersey-based pilot was delayed.

Despite valuable insights gained from the various projects, the consultant said they couldn’t definitively confirm their viability for dealing with CRD biosolids. Should the region keep chasing thermal solutions, GHD recommended moving forward with an advanced thermal processing site trial within the CRD.

Two options provided for the committee include: that the board starts to take proposals for an advanced thermal site trial or that it waits to receive bids until after public consultation is complete. While the former option is recommended, both call for a consultation plan to be implemented in the fall.

Once a thermal technology proposal is selected, the report says provincial approval for a trial at Hartland could take between 18 months and two years – while the CRD must submit its long-term biosolids plan before July 2024.

The trial is expected to cost between $5 million and $10 million. Greenhouse gas implications and contaminant monitoring would be included and compared to what the report called “the known low environmental risks of biosolids land application and other non-thermal reuse options.”

The report says a detailed plan for engaging with First Nations, local governments and the public will be presented at a July committee meeting.

The companies selected for the multiple pilots were also asked to look into processing the CRD’s solid waste along with the biosolids. The consultant said pyrolysis was not suitable for the dual-processing based on currently available technologies. The CRD report stated it could allow bidders to propose processing biosolids and other landfilled materials if an advanced thermal trial is pursued.

READ: CRD approves sending treated sewage to Nanaimo area as short-term measure