Which of the following have been used to oxidize ammonia and to prevent algal growth?

• A. growth of hypomicrobium in presence of added methanol
• B. <i> Micrococcus denitrificans</i>
• C. cells encapsulated in liquid membranes
• D. Both (a) and (b)
• E. <i>Nitrosomonas europaen</i>