I've been here three and a half years now and have four hectares that have been neglected for years so I know something about weeds.  You'll have to accept that weeds are a major factor here.  Just look at the agricultural (and wild) land around you.  The local farmers accept weed control as routine.  I've tried most available methods and the best method depends on several factors.  One is the area you need to treat (bearing in mind it will have to be repeated on a regular basis).  Using bleach would not be practical on a large sacle.
Roundup and Glyfasato (spelling ?) have been mentioned.  They're the same thing but Roundup is rather expensive.  All the co-operatives (including Sol D'Ebre) sell Glyphosate products.  The price has varied a bit over the last couple of years but averages about €40 for 5 litres.  That having been said.  That's enough to treat a very large area at the correct dilution (about 5 hectares at a dilution of 1% i.e. 100ml in 10litres of water).  Apparently there is no advantage in using a stronger mix.  I've found it can take a week for there to be any visible sign of wilting and several weeks for the weed to look completely dead.  Also, some weeds succumb more readily than others.  If I'm going to treat an area that hasn't been done for a while where the everage weed height is say half a metre, I strim/brushcut first then wait a week or two for new growth to emerge before spray.  This is because if you just spray, you will still be left with upright dead weeds that look even worse than when they were green.  You'll find that at this time of year, with a bit of patience, the dead weeds will gradually crisp in the hot sun and gradually crumble away.  Be aware though that any decent rain fall will soon set off fresh growth so it's rather like painting the forth bridge.  A fact of life out here.  I'll continue this in a second post as the screen is playing up.