Abstract: The invention disclosed here is a process or system for treating the effluent from a BCTMP pulp mill. The effluent is evaporated to produce a water condensate and a remaining waste product concentrate. The condensate is recycled for use in the BCTMP mill, or is dumped into the environment. The concentrate is incinerated in a recovery boiler. Incineration results in the recovery of certain reusable chemicals. At least some of such chemicals are fed back into the effluent while it is being evaporated, to buffer it, and thereby prevent the carryover of undesirable organic acids into the condensate. This ensures sufficient condensate purity for recycling it in the BCTMP process, or for otherwise dumping it into the environment.