ABSTRACT
This chapter provides an overview of the toxic chemicals and other objectionable components present in pulp and paper mill effluents, compares several aerobic and anaerobic treatment processes available for treating these effluents, and focuses on urgently required research needs in this area. Since the pulp produced corresponds to approximately 40%–45% of the original weight of the wood, the effluents are heavily loaded with organic matter. The treatment of wastewaters from pulp and paper mills tends to become mill-specific, and it is for this reason that the knowledge of possible contaminants present in the wastewater, their origins and degree of toxicity, and available treatment technologies becomes so essential. Resin acids are tricyclic diterpenes that occur naturally in the resin of tree wood and bark and are transferred to process waters during pulping operations. They are weak hydrophobic acids and are toxic to fish at concentrations of 200–800 µg/L in wood processing wastewaters.
