Treatment of tea industry wastewater using coagulation-spinning basket membrane ultrafiltration hybrid system

The present study delivers the significant effects of the coagulation-spinning basket membrane ultrafiltration on the treatment of tea industry generated effluent. Response surface methodology (RSM) was applied to optimize the process parameters, namely, alum dosage (50-300 mg L^-1), pH (4-10), stirring speed (10.47-62.83 rad s^-1), and stirring time (30-180 min) during the pretreatment of effluent. Prior to final treatment, the spinning basket membrane filtration was performed to explore the permeate flux decline behavior at different parametric conditions such as, applied transmembrane pressure drop (TMP drop: 207-414 kPa), rotational speed (10.47, 31.41, 52.36 and 73.30 rad s^-1) and membrane MWCOs (5-50 kDa). Artificial neural network (ANN) analysis helps to compare the theoretical flux decline behavior with the experimental data. Modified Hermia's models were used to identify the reversible and irreversible fouling as well as cake layer formation. The decrease of cake filtration model constant from 1.31 × 10⁷ to 0.56 × 10⁷ m^-2 s indicates the minimization of concentration polarization by virtue of membrane basket rotational speed. The effects of various parameters on the permeate quality have also been verified. The maximum improvement of permeate clarity of 94.46% was observed when the membrane basket rotation was 52.36 rad s^-1. With changing MWCO of 50 to 5 kDa, the removal of chemical oxygen demand has been increased from 87% to 96.70% at a rotation of 52.36 rad s^-1.