Reduced biomass production using acid effluent from a kraft bleach plant

In bench-scale trials, biomass production was reduced hip to 48% by conditi oning recycled activated sludge with acidic first-stage kraft bleaching eff luent in a heated contact chamber. However, this intensive sludge treatment reduced the BOD removal from 98% to 89%. In pilot plant trials, biomass pr oduction was reduced by 26% through an in-line conditioning of the recycled activated sludge with an acidic first-stage bleaching effluent without a h eated contact chamber. Over a period of 21 days, sludge conditioning did no t affect the removals of BOD and COD. Costs of neutralization of combined m ill effluent, and supplemental nutrient demand, were also reduced by these sludge conditioning methods.