Removal of zeolite type a during primary sedimentation and its effect on metal removal

Using two pilot plants operated in parallel, treating settled sewage the removal of the detergent builder zeolite type A during primary sedimentation has been studied. With one zeolite free pilot plant acting as a control to the other it was also possible to determine the effect of zeolite on suspended solids and heavy metal removal over a range of hydraulic loadings. At both influent concentrations of zeolite studied (30 and 60 mg l⁻¹) zeolite removal was substantial under all conditions. No evidence of enhanced removal of suspended solids in the presence of zeolite was observed. Removals of lead, zinc, copper and chromium were slightly enhanced in some experiments. The observed improvements in metal removal appeared to be strongly influenced by the sewage matrix.