Bioremediation of Textile Industrial Effluents Using Nutraceutical Industrial Spent: Laboratory-Scale Demonstration of Circular Economy.

This research reports the first-ever study on abundantly available, environmentally friendly,
low-cost and ready-for-use Nutraceutical Industrial Cumin Seed Spent (NICUS) as an innovative
adsorbent for bioremediation of a bisazo Acid Red 119 (AR119) dye, a probable mutagen from
textile industrial effluents (TIEs). The experiment at the laboratory scale is designed to suit the
concepts of sustainability and valorisation under the domain of circular economy. The experimental
qe value obtained was 96.00 mg g−1
. The optimised conditions of parameters are as follows: pH
of 2; adsorption time, 210 min; adsorbent dosage, 0.300 g L−1
; particle size, 175 µM; initial dye
concentration, 950 mg L−1
; orbital shaking, 165 rpm and temperature, 50 ◦C, producing an impressive
value of 748 mg of dye adsorbing on 1 g of dry NICUS. The adsorption capacity of NICUS obtained
from the quadratic model developed for process optimisation gave values of 748 mg g−1
. As a
prelude to commercialisation, five variables that affect the adsorption process were experimentally
studied. For the feasibility and efficiency of the process, a two-level fractional factorial experimental
design (FFED) was applied to identify variables that influence the adsorption capacity of NICUS.
The identified variables were applied to scale experiments by three orders. Nine isotherm models
were used to analyse the adsorption equilibrium data. The Vieth–Sladek adsorption isotherm model
was found to be the best fit. The pseudo-second-order reaction was the appropriate mechanism for
the overall rate of the adsorption process. Mechanistic studies related to mass transfer phenomena
were more likely to be dominant over the diffusion process. Techniques such as SEM, FTIR and CHN
analysis were used to characterise NICUS. The dye-adsorbed NICUS obtained as “sludge” was used
as a reinforcing material for the fabrication of composites using plastic waste. The physicomechanical
and chemical properties of thermoplastic and thermoset composite using dye-adsorbed NICUS were
evaluated and compared with NICUS composites. Prospects of integrating Small and Medium
Enterprises (SMEs) into the circular economy of Nutraceutical Industrial Spent (NIS) are discussed