Bioremediation of colour of methyl violet and phenol from a dye-industry waste effluent using Pseudomonas spp. isolated from factory soil

Methyl violet, a basic dye, is manufactured using phenol and dimethylaniline as the raw materials. It is, therefore likely that the waste effluent arising from such units may contain the dye and unused chemicals. Since such pollutants may be toxic, their removal becomes necessary. The studies were therefore aimed at their bioremediation using microbial species.
Four species of Pseudomonas , namely Ps. alcaligenes, Ps. mendocina, Ps. putida biovar B and Ps. stutzeri , were isolated from cattle dung enrichments and the soil samples in the premises of the factory manufacturing methyl violet, nearby Pune.
All the four species of Pseudomonas were able to remove phenol and methyl violet with simultaneous reduction in chemical oxygen demand (COD), total organic carbon (TOC) and ammoniacal nitrogen from the waste effluent and the removal was found to be optimum at the original alkaline pH (range 7.45–10.6) of the waste effluent, at ambient temperature (28 ± 2°C under aerated culture condition, at inoculum density of 1.5 × 10⁸ cells ml⁻¹ of the waste effluent and incubation period of 24–48 h. Thus, Pseudomonas spp. isolated from the environment of the dye industry itself and thus naturally adapted could be used for bioremediation of these pollutants.