▁fol d ▁in ▁number ▁compared ▁to ▁one ▁macro ▁b ubble ▁having ▁same ▁volume . ▁ ▁Micro fl ot ation ▁enables ▁b ub bles ▁in ▁size ▁ 4 0 - 7 0 ▁ μ m ▁with ▁rise ▁rates ▁from ▁ 3 – 1 0 ▁m / h . ▁The ▁rise ▁rate ▁is ▁slow ▁enough ▁not ▁to ▁destroy ▁the ▁frag ile ▁f lock s ▁forming ▁an ▁ag gl omer ation ▁of ▁particles ▁with ▁weak ▁mut ual ▁bond ing ▁and ▁high ▁enough ▁to ▁allow ▁time ▁for ▁separation ▁of ▁the ▁ag gl omer ation . ▁With ▁the ▁attachment ▁of ▁particles ▁to ▁b ub bles ▁the ▁size ▁range ▁of ▁" f lock - b ubble " ▁grows , ▁and ▁the ▁rise ▁veloc ities ▁grow ▁simultaneously . ▁The ▁separation ▁rate ▁is ▁acceler ated ▁leading ▁to ▁residence ▁times ▁of ▁combined ▁chemical ▁precip itation ▁and ▁fl ot ation ▁from ▁ 1 0 ▁to ▁ 6 0 ▁minutes ▁with ▁need ▁of ▁small ▁foot print ▁areas ▁of ▁treatment ▁plants ▁and ▁decre asing ▁the ▁cost ▁structures ▁of ▁treatment ▁processes . ▁ ▁A ▁distribution ▁of ▁b ubble ▁sizes ▁between ▁ 2 0 ▁and ▁ 5 0 ▁mic rons ▁is ▁the ▁necessary ▁requirement ▁for ▁an ▁optim um ▁fl ot ation ▁result . ▁Even ▁a ▁small ▁number ▁of ▁b ub bles ▁with ▁diam eters ▁of ▁above ▁ 1 0 0 ▁mic rons ▁can ▁disable ▁a ▁fl ot ation ▁separation ▁process , ▁because ▁larger ▁b ub bles ▁rise ▁more ▁quickly ▁and ▁cause ▁tur bul ence , ▁which ▁sever ely ▁dest ro ys ▁already ▁build ▁air - f lock