I said in Jim Mora's show on National Radio this afternoon that Wellington's  Moa Point sewage treatment plant uses the energy equivalent of 6000 barrels of oil per day. A producer raised his eyebrows and later asked if I meant litre, or gallons. 

I've now lost confidence in my memory. I recall the engineer telling the story, and his reference to barrels. But he may have given the 6000 figure as an equivalent.  I must follow up to get the right figure.

The current operators, United Water, should be able to clarify on Monday, if no one else does before that.  The process captures the solids for landfill disposal, and treats the remaining liquid with UV light before it is discharged to Cook Strait. It is energy intensive, but cannot possibly use 6000 barrels of oil equivalent.