Impact of pulp and paper mill wastewater on crop and soil

Tabulated and graphical results are presented from laboratory and field studies on the use of pulp mill wastewater for irrigation, following treatment in anaerobic lagoons; the lagoon effluent still had a high lignin content and colour. The wastewater was suitable for application to coarse-textured soils with salt-tolerant crops such as maize, barley, and wheat. Irrigation with the wastewater increased the percentage of exchangeable sodium in the soil, but even after 3 years there was no appreciable reduction in crop yield or in the hydraulic properties of the soil. Further studies showed that the problem of increasing sodicity of the soil could be overcome by diluting the pulp mill wastewater with chlorination and hypochlorite wastewater.