Ann: Hazer Group and Water Corporation Agree MOU, page-152

I would imagine that once they have an full analysis of the digester output they will be able to get some good indications of the scale of the treatment required. As @Megafauna noted, the rest of the world seems to have come to grips with filtering biogas so the processes are well studied. It's just Australia that seems to ignore it.

One would therefore think that the Watercorp agreement could be relatively quick once that is sorted out, it's just all the things that Hazer has to in the background that will take the time. I can foresee the filtering system being imported, and those sorts of things usually have long leads by the time you factor in delivery (like up to 9 months).

I think the time frames they have suggested are pretty well in line with what one would expect for this sort of process system procurement and construction.