Wow! Thats a rough one. I thought the incredibly exciting niche of paper shredding was hard Well, I would be interested to know about some of the crazy stories of some of the guys picking up and dumping the trash. Have they ever found anything cool? Anything illegal? That type of thing.
You could compare pricing for a geographic region that you service and make it very graphic heavy. For example where we are some municipalities make you use their dumpsters. Others there are multiple companies all vying for business. You could get the data on the different prices for the different dumpster sizes across all the companies and municipalities in your region and do a mini graphic to accompany a blog post about that. Then you could contact all your typical customers and let them know about this handy reference. This would be good especially if your client was the lower price or has some other unique selling propostion since it would be good for his business.
I know that isn't earth shattering, but there is always a fun way to put a spin on a boring niche. I am sure others will have good ideas too