What is the typical time for knee swelling to go away after meniscus arthoscopic and ACL reconstruction surgery?

1-4 weeks. It sometimes depends on the type of reconstruction as well as bleeding within the joint. Because of this, it is difficult to predict the amount and duration. Most of these resolve as the body seals and starts to heal. The body also starts to absorb everything over the first month.
Swelling. Swelling in the knee for acl surgery can last at least 3 weeks; for isolated meniscal surgery swelling can last 1 week.
Varies with surgery. Most of my arthroscopic surgery patients for menisectomy have most of their swelling gone within a few days and are walking normally within a week. For the acl patients, the time frame would probably be more like 4-6 weeks.