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, ...
4. to deal (a person or thing) a blow with a broad flexible object. 5. (sometimes foll by: down) to toss, fling, slam, etc, abruptly or noisily. 6. (Phonetics & Phonology) (tr) phonetics to pronounce (an (r) sound) by allowing the tongue to give a single light tap against the alveolar ridge or uvula.