Just a guess, but could it mean that collectors go door-to-door to collect hazardous waste.

Does "patrol collections" fit with the context? i.e. where groups of people are organised into "patrols" to make the collections?

Not really sure, but I think we have something like this here. Twice a year householders can put out hazardous/bulky waste alongside the wheely bin for collection (all other times it has to be transported to the depot by the householder) and the municipality makes special collections. I assume housing associations, blocks of flats etc have one fixed depot point for occasions like this.

I guess the point is to make sure hazardous waste ends up in the right place, however often the collection is, rather then being put in the wheely bin 'cos it's easier.