Christchurch's biosolid waste could become a future energy source, according to a new report.

The Christchurch City Council is debating how best to deal with an estimated 80 tonnes a day of biosolid waste produced by city residents. At present it is trucked to the former Burwood landfill as covering material. However, within 2 1/2 years that land will not be able to take more waste.

The council has set aside $22 million in its draft Long Term Council Community Plan for a facility to process biosolids, but has yet to decide how best to process the waste. If no solution is found, the waste will be trucked to the Kate Valley landfill -- shortening the lifespan of the dump at an estimated cost of $3.54m per annum, and failing to meet national waste strategy targets for the handling of biosolids.

The city council this week considered the final report from a University of Canterbury team into how best to reuse biosolid waste.

The university team held six workshops and a web-based workshop which canvassed the opinion of six interest groups on four different waste management options. Having considered those options, some of the more than 100 people who attended the workshops were brought together to develop strategies from the information gathered in the first series of meetings.

After considering incinerating the waste, producing energy from it, applying it to the land but excluding any food-related use, or applying it to the land with no restrictions, a preference for energy production emerged.

Nearly 75 per cent of participants supported using biosolids as an energy source, so long as emissions to the air were controlled and monitored, the report by Joanna Goven and Lisa Langer said.

"A common theme was that biosolids should be regarded and used as a resource," the report said.

"However, there was disagreement over what that would mean in practice."

While some said it was important to use biosolids to "close the nutrient loop" and return to the land the nutrients taken from it by people, others felt applying human biosolids to the land was unacceptable pollution of the spiritual and cultural dimensions of the land.

"Using biosolids to produce energy was seen by some as the best or most acceptable use of biosolids as a resource."

At last week's council meeting, councillors agreed to forward the report to a portfolio group for consideration.

Mayor Garry Moore said it was an excellent report, and came as the result of an interesting process.

"It's the sort of stuff staff usually get and we don't see," Moore said.

He said there were still many steps on the way -- including consultation with residents -- before a solution was put in place.

Cr Sue Wells said the report did not represent grassroots community consultation, and did not take into account the possible cost of options.

Wells said it was an "academic, philosophical, very high-level discussion" -- but she was comfortable with its issues and options being explored and agreed it should have further discussion.

City waste and water manager Mark Christensen said the use of biosolids was "a very sensitive issue". He said it was an unusual community consultation process as it was done "up-front".

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