The Biosolids Debacle

Most land based treatment processes remove solids from sewage effluent prior to final treatment and disposal of the liquid. These “biosolids” must then be dealt with. For the current project, “biodigesters” were chosen as the representative biosolid technology. These devices “gasify” some of the solids. The gas created can then be used to create heat and/or electricity or can be upgraded to create fuels.

Used appropriately, biodigesters are an excellent technology. For the proposed sewage treatment project, however, there are problems. Firstly, a lot of space, about 2 hectares or 5 acres, is required. Since, it’s not easy to find 2 hectare sites in urban areas, the site chosen was the Hartland Landfill, some 17 kilometres from the proposed treatment plant in Esquimalt. Because a commitment has been made to avoid truck traffic through Esquimalt, a 17 kilometre pipe line will have to be built from the plant to Hartland.

Secondly, biodigesters only gasify about 40% to 50% of solids. The remainder emerges as a residue compost material. If the feedstock is clean organic material, this compost is an excellent soil amendment for agriculture. Sewage biosolids, however, are not clean organic material and there is growing resistance to residue compost being applied to land. For this reason, a decision was made to ship the residue to the lower mainland where it will be burned in cement kilns as fuel. Unfortunately, there is no guarantee the cement kilns will need the fuel. If they don’t, the backup plan is to bury the residue in the Hartland Landfill. This is completely inconsistent with current efforts to extend the life of the landfill.

In addition, the “biodigester approach” is expensive. Initial capital costs are expected to be about $265 million including the pipeline. Net operating costs, after subtracting the value of gas created, are expected to be an additional 3 to 4 million per year.

Given these problems, I approached a BC based company well known for their innovative gasification technology and asked them to give me a “ball park” figure as to site requirements, capital costs and net operating costs. Their answer - site requirements of less than one acre, capital costs of  $35 - $40 million and net operating costs of 3 to 4 hundred thousand per year. The much smaller size requirements would mean that sites much closer to the treatment plant could likely be found. Also, the difference in capital and operating costs represents a potential savings of over $200 million.  As an added benefit, their technology gasifies 60% to 85% of biosolids. So, there would be less residue to deal with.

I presented this information to the CRD committee handling the project with a recommendation to investigate alternative biosolids technologies further. The information was received with skepticism and it was pointed out that no “redundancy” was provided for (With biodigesters, 4 would be built with only 3 being used at any one time). To answer this concern, I went back to the company and asked for estimates including 100% redundancy with a complete second set of equipment available in case of breakdown. Their answer - site requirements of around an acre, capital costs in the range of $60 - $70 million and the same net operating cost as before.

I took this new information to the committee, but the committee and staff declined to investigate further. The reason given was that such proposals could come at the “procurement” stage when companies actually bid on the project. It is possible that this might occur. At the procurement stage, however, a provisional budget will have been set and control of the project will have passed out of the hands of locally elected officials. There is a very real possibility that different biosolids technologies such as the one described above will not even be considered.

I remain dumfounded in regard to how the whole process of biosolids treatment has been handled. I don’t know that the alternative I suggested would work out. Nevertheless, with all the potential advantages, including savings of over $200 million you’d think that there would be every incentive to investigate further. Unfortunately, that was not the case.





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