Rapid sand filtration is a purely physical drinking water purification method. Rapid sand filters (RSF) provide rapid and efficient removal of relatively large suspended particles. Two types of RSF are typically used: rapid gravity and rapid pressure sand filters. For the provision of safe drinking water, RSFs require adequate pre-treatment (usually coagulation-flocculation) and post-treatment (usually disinfection with chlorine).
with great suddenness the car in front stopped abruptly, and we almost hit it Synonyms short, suddenlyRelated Words surprisingly, unexpectedly; directly, immediately, incontinently, instantaneously, instantly, promptly, pronto, right, right away, right off, straightaway; fast, full-tilt, posthaste, quick, quickly, rapidly, readily, snappily, ...
If the weather changes abruptly, from bright and sunny to pouring down rain, you're going to get wet. When something happens abruptly, it is sudden and unexpected. Almost anything can change abruptly, and it will always take you by surprise, whether it's the movement of a car, the mood of a movie, or the behavior of your dog. If you've ever had a conversation with someone who spoke to you abruptly, you may have found them a little rude.