Eichhornia crassipes-based tertiary treatment of Kraft pulp mill effluents in chilean central region

Abstract

This paper presents experimental results on the implementation of Eichhornia crassipes–based tertiary lagoon to treat effluents generated by a 300 ton d−1 Kraft pulp mill in Chile. Results show that E. crassipes rapidly adapted to the tertiary lagoon conditions. Active growth was maintained even during a cold winter, protected by the wastewater heat content. A 1000 m2 seeding area extended to 2300–6200 m2 after a month of growth, with a monthly harvested biomass and nitrogen uptake were 1.1–5.4 ton (dry wt.), and 18–127 kg N, respectively. E. crassipes growth was adequately described by a first order model, with an estimated rate constant ca. 0.03 d−1 and 0.06 d−1, for winter and summer seasons, respectively. A management strategy based on such model, to account for seasonal variations in growth rate while keeping a constant nitrogen uptake capacity, is proposed here.