Assessment of anammox, microalgae and white-rot fungi-based processes for the treatment of textile wastewater

Abstract

The treatability of seven wastewater samples generated by a textile digital printing industry was evaluated by employing 1) anammox-based processes for nitrogen removal 2) microalgae (Chlorella vulgaris) for nutrient uptake and biomass production 3) white-rot fungi (Pleurotus ostreatus and Phanerochaete chrysosporium) for decolorization and laccase activity. The biodegradative potential of each type of organism was determined in batch tests and correlated with the main characteristics of the textile wastewaters through statistical analyses. The maximum specific anammox activity ranged between 0.1 and 0.2 g N g VSS-1 d-1 depending on the sample of wastewater; the photosynthetic efficiency of the microalgae decreased up to 50% during the first 24 hours of contact with the textile wastewaters, but it improved from then on; Pleurotus ostreatus synthetized laccases and removed between 20-62% of the colour after 14 days, while the enzymatic activity of Phanerochaete chrysosporium was inhibited. Overall, the findings suggest that all microbes have great potential for the treatment and valorisation of textile wastewater after tailored adaptation phases. Yet, the depurative efficiency can be probably enhanced by combining the different processes in sequence.

Fig 1. Principal component analysis plot of the physicochemical parameters (arrows) of the seven textile wastewater samples (black dots).

Fig 2. Average maximum specific anammox activities (SAA^max) achieved after the first (grey bars) and second (black bars) spike of nitrite in the control test (C) and in assays performed with the seven TWs.

Fig 3. Recovery time representation.

Panel C represents the trend of Fv/Fm for the control while the others show the trends of Fv/Fm for each TW, expressed as % of the control. The red lines indicate the recovery time.

Fig 4. Images of the microalgal cultures in TW4, TW6, and in the control tests (C) captured the day of inoculation (T₀) and at the end of the tests (T₁₅).

Fig 5. Temporal trend for the fungi (A: P. ostreatus, B: P. chrysosporium) and algae (C: C. vulgaris) cultivations.

The first panels on the left represent the average trend for each tested TW sample while the other panels represent the effects of the relevant physicochemical properties identified by the Multiple Linear Regression analyses.