Design and testing of a cost-efficient bioremediation system for tannery effluents using native chromium-resistant filamentous fungi

In Arequipa (Peru), a small-scale tannery industry cannot afford costly or complicated methods for effluent treatment. In this work, we designed and tested a bubble column bioreactor for tannery effluent treatment based on the native filamentous fungi Penicillium citrinum and Trichoderma viride. The bioreactor construction used low-cost materials, with an easy-to-handle design. The parameters considered for testing were based on current Peruvian legislation. In the bioreactor, P. citrinum successfully reduced the effluent content of sulfides, chemical oxygen demand (COD) and total suspended solids (TSS) and removed nearly 80% of the chromium (VI) after 120 h of reaction. The resulting treated effluent had a composition within the maximum limits permitted by Peruvian legislation. Trichoderma viride also reduced the content of TSS, COD and sulfides, but decreased the chromium (VI) concentration by only ~ 20% after the same reaction time. Both filamentous fungi were able to grow in the experimental conditions used and the bioremediation process occurred with no significant alteration in pH. These findings indicate that a bubble column bioreactor using P. citrinum as a bioremediator agent provides low-cost, effective technology for treating effluent waste produced by artisanal and small-size tannery factories in the region of Arequipa.