Bioremediation and toxic removal efficiency of raw pharmaceutical wastewaters treated with a cyanobacteria-based system coupled with valuable biomass

The focus on wastewater treatment is a growing trend in the pharmaceutical industry, since pharmaceutical wastewater (PWW) contains a significant load of organic material, nutrients and toxic compounds. In this study, the biotreatment of raw PWW was studied (with different initial concentrations of Dissolved Chemical Oxygen Demand (d-COD), 600–6300 mg d-COD L−1), using a cyanobacteria-based cultivation system (under batch, semi batch and continuous mode operation) with Leptolyngbya sp. The aim was to develop an effective treatment process (evaluated in terms of Dissolved Chemical Oxygen Demand (d-COD) and nutrient removal efficiency) without adding external mechanical aeration, capable of generating simultaneously valuable biomass. In batch and semi-batch bioreactors high d-COD, NO3−-N and PO4−3 removal rates were achieved (up to about 71 %, 96 % and 86 %, respectively) with maximum biomass productivities between 55 and 234.8 mg L−1 d−1, while pH adjustment was not necessary. In continuous mode operation (using HRT of 5 and 2.5 d), d-COD, NO3−-N and PO4−3 removal was also significant (61 %, 90 %, and 62 %, respectively, for the feed concentration of 1550 mg d-COD L−1), while toxicity tests of the specific untreated and treated PWW revealed a significant attenuation of the toxic potential. The biomass produced also contained high carbohydrates, proteins, lipids chlorophyll-a and phycocyanin, up to 33.78 %, 41.40 %, 11.75 %, 10.33 ± 0.03 mg g DW−1 and 42.17 ± 3.56 mg g DW−1, respectively, with a methane yield of 479.19 ± 16.52 mLCH4 g TS−1.