It's always worth knowing as much as possible when it comes to anything to do with our house and how it effects the environment
. I've written the following article to help inform you about sewage disposal and anything which you may not know about. Don't forget that you may think nothing of sewage disposal but if it isn't taken care of properly it can really damage the environment.
If you haven't heard of screening before this is a great way to help the environment. The waste water is checked for large objects which shouldn't be in there such as rags, cans, sticks, twigs, plastic packets etc. Sometimes these things get in the waste water by mistake and this is the case often with mains drains. As mains drains can sometimes take in storm water there will be lots of drains on city streets where rubbish can slip down by mistake. Some rubbish, which has to be screened, is from people who have put it in which isn't very smart. If this rubbish wasn't screened it would end up in lagoons and rivers after the water has be sterilised. This rubbish would then only hinder the environment and possible harm wildlife. This screening is often done with a ranking mechanism.
The next thing which happens in sewage disposal, which you may not know about, is grit removal. Once the objects have been removed from it the flow or velocity of water is changed so that sand and grit in the water is allowed to settle along with pipes in which the water is traveling. Waste water will easily pick up grit and sand along the way especially if the system allows storm water in as the rain will easily bring along anything it comes across on the roves down into the sewage system.
Don't forget that this sort of stuff doesn't need to happen with cesspit emptying as the tank often does a lot of this work. Sewage works in a completely different way with cesspit emptying to mains drains.