There are several things that must happen with this drain.
1. it must have a trap to prevent sewer gas from entering the space. This gas will present an explosion hazard. It may also present a poisoning hazard. Hydrogen sulfide gas is very toxic. While in low concentrations it smells like rotten eggs, at toxic levels it paralyzes the sense of smell and then kills.
2 the drain needs an air gap. This means that the end of the drain pipe from the equipment must be above the edge of the pipe. That is so that if sewage backs up the drain, it will not go into the equipment. (It also will present a way to get sewage into the crawl space. The current installation will also allow sewage into your crawl space. Further, it does not appear to have been installed by a professional. There is no visible glue on the joint.)
If the equipment drain is for filter backwash, it can be plumbed into a sanitary tub with the washing machine drain or into the same drain as the washer is.
Terry, Your answer is much better than mine, but I love talking about the reasons behind the rules. ( and possible optional solutions)