SOURCE:

Faculty: Engineering
Department: Chemical Engineering

CONTRIBUTORS:

Okolo, B.I;
Onukwuli, O.D;

ABSTRACT:

KOLOThe continuous industrial development in Nigeria has resulted in the generation of industrial wastewaters. The wastewaters are usually discharged without proper treatment which affects the environment. There are several techniques applied in the treatment of wastewaters but coag-flocculation and adsorption processes was applied. Thus, the present work focused on the utilization of natural coagulants/adsorbents in the removal of turbidity in wastewaters. The aim of this study was to investigate the removal of turbidity from paint and brewery industrial wastewaters using sequential coag-flocculation and adsorption processes. Theobjectives were to: prepare and characterize biocoagulants from Detaruim microcarpum (DMC), Xanthosoma (CYC), Hibiscus esculentus (OSC) and Crassostrea virginica (ODC) and biosorbents from Mucuna pruriens (MSA), Canaruim schweirfurlhi (AESA) and Crassostrea virginica (OSA); study the various coag-flocculation/adsorption parameters such as pH, dosages and contact time; study the adsorption isotherms, kinetic and thermodynamic of the process; and optimize the process using response surface methodology (RSM).The biocoagulants and biosorbents were produced and characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF). Jar test and batch adsorption processes were carried out in order to determine the effects of process parameters on the turbidity removal. The experimental data were evaluated by four isotherm models (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich) and four kinetic models (pseudo-first-order, pseudo-second-order, Elovich and intraparticles diffusion). The process was optimized using RSM. The resultsof characterization of biocoagulants and biosorbents showed that the materials are good for the removal of turbidity from the wastewaters. The removal efficiency of turbidity is dependent on the initial wastewater pH, dosage and time. The optimum turbidity removal efficiency of 90.45% wasobtained at 100.53mg/L, pH 2 and settling time 24.45min for coagulationwhile the optimum removal efficiency of turbidity for of 99.8% was obtained with 26.66mg, pH 6.66 and contact time 69.6min for adsorption. The experimental data fitted well to Langmuir isotherm model and pseudo-second-order kinetic model.The thermodynamic study showed the adsorption process was spontaneous and endothermic in nature.This work has shown that coag-flocculation and adsorption are very effective in turbidity removal from paint and brewery wastewaters.This work has successfully transformed natural and abundant materials into coagulants/adsorbents that can be used for wastewater treatment. Hence, these coagulants and adsorbents are recommended for wastewater treatment.