Methods for treating wastewater comprising adding to wastewater a defoaming and/or surfactant-effective quantity of at least one base-catalyzed branched reaction product comprising the following reactants:

• A) at least one compound of formula I

• wherein each X group is a halogen atom or one X group is a halogen atom and two X groups represent an epoxy oxygen atom, which is attached to two adjacent carbon atoms in the R¹ group to form an epoxy group, and R¹ is an alkanetriyl group containing from 3 to 10 carbon atoms; and
• B) at least one compound having the formula II

• wherein R² is a substituted or unsubstituted, saturated or unsaturated, organic group having from 1 to 36 carbon atoms; X is —O—, —S—, or —NR³— where R³ is hydrogen or a C₁-C₁₈ alkyl group; each AO group is independently an ethyleneoxy, 1,2-propyleneoxy, or 1,2-butyleneoxy group, n is a number of from 0 to 200; and Y is hydrogen, or Y can be a mercapto group or an amino group or a C₁-C₆ alkylamino group in place of a terminal —OH group, provided that when Y is mercapto or an amino group or a C₁-C₆ alkylamino group, n is at least 1;
• wherein the mole ratio of the linking compound a) to b) is from 0.1:1 to 5:1; and to wastewaters containing the above base-catalyzed reaction products.