May 2018
May 2018 - last edited May 2018
If you only have the base game, there's not much to do with the garbage dump itself, other than the incinerators. However, if you add a recycling center, you will greatly reduce the amount of garbage produced and get some income from selling the metal, alloy and plastic. Make sure your Sims are educated, and either use the recycled goods as resources for factories (if you have any that need those resources), or put up a trade depot with warehouses for each of the recyclables, and export to the global market to make cash. Recycling is very dependent on education level and length of time they've been educated; ideally you want your education level to be 100% for a few Sim-months, but they will nominally recycle starting around the 3-book education level. If you have the Cities of Tomorrow expansion, you can research garbage atomizers at the Academy (level 3). Those will process the garbage a little bit faster, with zero pollution.
Sewage is kind of the same thing; other than adding more treatment tanks, there's nothing to upgrade. CoT expansion includes an Academy research unlock that lets you place a Sewage Sanitizer that will convert all sewage into potable water. Very space-agey designs for both Academy upgrades. Personally, for sewage, I prefer to do the "unlimited water" trick: build your sewage treatment center right next to your water plant. The sewage plant filters everything and dumps clean water into the ground, and the water plant sucks it up to supply the city. You don't need the more expensive water filtration tanks, just the cheaper pump tanks, and you have unlimited water for your city.
July 2018
You forgot to mention about game bugs. You cannot get recycling from another city, for example. I have two cities, one with a recycling plant with all trucks, another with population 300k and high education. I cannot get recycling plant working with neighbours.
And if you check internet, there's a game bug since launch.
July 2018