What is this thing that the police knew nothing of that you keep going on about, and why would it have prevented them considering the possibility that Madeleine's body had ended up on a landfill site?
The oven is on, so let me split this into 2 parts.
I have no reason to believe that, at the time Madeleine went missing, the police understood that all of the rubbish in Barlavento (the western half of the Algarve) went through a single site. People discussing the case around 2007/2008 appear to think there were multiple landfill sites, and that even the councils were first fly-tipping before later transporting to one of several dumps.
The process of Luz to transfer station to Barlavento landfill took quite a while to emerge. It is not an obvious concept, nor do I think the police track European Directives or inspect landfill sites.
The most likely scenario is that they hadn't a clue.
I can remember in the UK vaguely around that time getting recycling rolled out. There was a small green wheelie bin for grass and tree cuttings. Then came plastic crates, for plastic, metal, cardboard/paper, glass etc. Batteries were not to be put in the rubbish, they were to be taken to a shop that sold batteries, which was now required by law to have a receptacle for used batteries. Electronic components were not supposed to go into the general waste. Shops selling electrical and electronic goods were required to handle these, whether one bought a new product or not. I hope I do not need to go near fridges, freezers or materials like used engine oil, paint cleaner etc.
I had no idea of why at the time, and I didn't care. Recycling seemed to me to be a good thing for the sake of our children and grandchildren, so I recycled.
As I have made clear, despite 30 years in one place, I have no idea where my landfill site is, nor do I know if it goes through an intermediate transfer station.
Bottom line is simple. I cannot think why the PJ should have known about Barlavento landfill, UNLESS THEY HAD ALREADY INVESTIGATED IT. Who knows, maybe they did in the Cipriano case, but it appears a different tack was taken on that one. I am not familiar with the Cipriano case therefore I shall keep my comment short. I believe the method of body disposal was dismemberment, into a fridge, into a car, and into a car crusher in Spain. I have great difficulty with the fridge and the car crusher, but like I said my experience of the Cipriano case is minute.
I need to check the oven, so I will move on to the second element of your post.
Assuming they were ignorant of the system, what was to stop them thinking - ahhh, landfill! Nothing. Not a single thing.
The only element of importance is how long it would have taken them to establish that there is a single landfill site in the whole of the Algarve, fed by multiple transfer stations.
I have made clear earlier in the thread that if they got on with it as a matter of priority, they should have been able to crack this within a couple of days of deciding that the 188 bin check was insufficient.
By that time, the whole of the western Algarve had layered in lorryload after lorryload of rubbish. It is NOT landfill unique to Luz, it is landfill for a large number of town and cities.