Pulp and paper technologies and improvements in environmental emissions to aquatic environments

Abstract

In recent years, there has been considerable study on the environmental impacts of kraft bleached pulp mills on the aquatic environment. These studies have focused on the discharge and toxicity of chlorinated organic compounds of AOX. Data from Scandinavian and North American mills show that the discharge of polychlorinated organic compounds can be significantly reduced with modern bleaching and effluent treatment technologies. An important step is to reduce the use of elemental chlorine (Cl 2 ) and to substitute other oxidizing agents, including, for example, chlorine dioxide, peroxide, and oxygen. These steps halt the formation of recently discovered by-products such as dioxins, as well as other highly chlorinated materials. In certain circumstances (e.g., fluff pulp mills), total AOX discharges have been reduced by over 90%, to as little as 0.1 kg/t. Analyses of effluents from these facilities also show that, contrary to lay expectations, remaining chlorinated materials have low chlorine substitution, are water soluble (will not bioaccumulate), and are easily degradable. Chronic toxicity testing in both laboratory tests, as well as environmental models (e.g., mesocosms) demonstrate that these modern processes virtually eliminate toxic effects in the receiving waters. These multiple technologies are being rapidly implemented by most Scandinavian and North American mills.

Wastewater Treatment and Reclamation: A Review of Pulp and Paper Industry Practices and Opportunities

“…During the last decades, there has been a drastic decrease in the use of molecular chlorine as a bleaching agent, and it has been replaced with chlorine dioxide (Elementary Chlorine Free, ECF), molecular oxygen, peroxide, or ozone (Totally Chlorine Free, TCF), which has led to a drastic decrease in AOX, PCDD, and PCDF (Shimp and Owens 1993;Rantio 1997). There are several modifications made to reduce the generation of chlorinated organic compounds from bleach plant effluents by employing modified strategies.…”

“…Polychlorinated dibenzothiophenes (PCDTs) are sulfur analogues of polychlorinated dibenzofurans (PCDFs) and have structural resemblance to PCDDs and PCDFs (Sinkkonen 1997;Koivisto 2001). In addition, other compounds may have dioxinlike toxicity, including the non-chlorinated ones, such as indocarbazoles, benzanthracenes, and benzoflavones (Paasivirta 1988).During the last decades, there has been a drastic decrease in the use of molecular chlorine as a bleaching agent, and it has been replaced with chlorine dioxide (Elementary Chlorine Free, ECF), molecular oxygen, peroxide, or ozone (Totally Chlorine Free, TCF), which has led to a drastic decrease in AOX, PCDD, and PCDF (Shimp and Owens 1993;Rantio 1997). There are several modifications made to reduce the generation of chlorinated organic compounds from bleach plant effluents by employing modified strategies.…”

Refractory organic pollutants and toxicity in pulp and paper mill wastewaters

“…Even with low concentrations (10-20 µg/l) reproduction and growth of fish are disrupted (Kostamo and Kukkonen 2003;. In addition, oxygen depletion is causing anoxia in fish and other aquatic species (Shimp et al 1993). However, the specific compounds causing these effects are hard to establish.…”

Caddis larvae (Trichoptera, Hydropsychidae) indicate delaying recovery of a watercourse polluted by pulp and paper industry

“…In comparison, a notable reduction in AOX values also resulted in Southern Lake Saimaa, where the transition from elemental chlorine to chlorine dioxide bleaching and finally to full ECF method occurred after 1992, together with introduction of activated sludge treatment, which led to a 62 % decrease in AOX emission (Oikari & Holmbom 1996). In some Canadian mills, the amount of total AOX have been only 0.1 kg per ton produced pulp, which indicates a reduction of over 90 % in AOX discharge due to modern bleaching and effluent treatment technologies (Shimp & Owens 1993). …”