In a 3- to 4-quart pan over medium heat, combine oil, celery, and onion. Stir often until onion is limp, 4 to 5 minutes. Add rice and mix well.
Add 4 cups broth and bring to a boil over high heat, stirring often. Reduce heat to simmering and stir often until rice is tender to bite, 12 to 15 minutes.
Add scallops, peas, and ginger. Stir until scallops are opaque but still moist-looking in center of thickest part (cut to test), 5 to 7 minutes. Add lemon juice, and a little more broth if a creamier texture is desired; mix well.
Spoon risotto into wide bowls. Sprinkle with basil and garnish with lemon wedges. Add salt and pepper to taste.