[The] "temp"... is an inflatable structure at the stable orbital point between the Spider world and their star.
It is part of the hydroponic systems where CO2, organic waste and and raw materials are processed by genetically engineered plants and microorganisms in to the oxygen and ingredients used by the food synthesizers, among other things.
And the very next paragraph after the line you quoted partially answers the question:
The duty here was scut work, about as low as things could get, cleaning the bacterial filters below the hydro ponds. Down here, the plants didn't smell so nice. In fact, robust good health was signaled by a perfectly rotting stench. Most of the work could be done by machines, but there were judgment calls that eluded the best automation, and that no one had ever bothered to make remotes for. In a way, it was a responsible position. Make a dumb mistake and a bacterial strain might get across the membrane into the upper tanks. The food would taste like vomit, and the smell could pass into the ventilator system. But even the most terrible error probably wouldn't kill anyone — there were still the bactries on the ramscoops, all kept in isolation from one another.
- A Deepness in the Sky